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Objective Reviews & Commentary - An Engineer's Perspective

April 1, 2012

April Fools Update

nwavguy-dscope-benchmarkLATEST NEWS: Despite the relative dearth of articles lately I’m alive, well, and have been spending a lot of time on the ODAC project as well as the usual blog comments, emails, etc. I’ve made some good progress on the ODAC and several partial articles are coming together for the blog. Here’s a brief update and some more ODAC tidbits…

WARNING (update 4/25): This article was published April 1st which, in the USA at least, is a day when journalists enjoy publishing fictitious articles. Even The Economist joins in the fun. This article was my attempt but I think The Economist did a better job.

BLOG COMMENTS: With my infrequent recent articles, and ever increasing traffic (over 1 million unique visitors with 900K in the last 8 months), some articles have hit 200+ comments each. Unfortunately Blogger stops displaying new comments past 200. Hopefully Google will eventually correct the limitation, but until then, I can only make room for new comments by deleting old ones, or closing the articles to new comments. So if I deleted your comment, or you can’t post, don’t take it personally. Talk to Google.

FUTURE ARTICLES: I hope to publish articles more frequently to keep things flowing better and distribute the volume of comments across more articles. That should help prevent running into the 200+ limit. Here are some partially completed I hope to get online soon:

  • Timex vs Rolex – As the release of the ODAC grows near, I think it’s important to shine more light on how how sound quality and audio performance relate to price. This article attempts to further explain what demonstrably matters versus what’s usually marketing hype and snake oil. I’ve received several ODAC-related questions about balanced configurations, 24/192 support, S/PDIF vs USB, NOS DAC chips, UAC 2, pre vs post filter ringing, paralleling DAC chips, etc. I also have several new and interesting references to include. And I’ve learned more myself since I wrote my Subjective vs Objective Debate last May. The goal is to roll all that up into a general interest article. Or, if it gets too long, perhaps two articles.
  • ODAC Measurements – Just when I think the ODAC is ready for production, I find something else or discover a new measurement technique that reveals a new aspect to refine. Some tweaks have worked out for the better, some made no difference, and some were a big step backwards. For example, power supply noise can be a source of jitter. So I added additional filtering to the digital power supply. The filtering, to my surprise, seriously increased the jitter. Theories are nice but measurements are reality. I’ve reverted back to the previous design at least as often as I’ve moved forward. Once the design is finalized, Real Soon Now, I’ll be publishing a full set of measurements. I’ll include some comparative results from other devices like the Benchmark DAC1, FiiO E10, a Chinese headphone DAC that’s had some good reviews on Head-Fi, and perhaps even a pro sound USB interface.
  • ODAC Details – The details article will cover the design choices, components used, unveil my partner in crime, document who will be offering the ODAC for sale, enclosure details, how the ODAC will integrate into the ODA headphone amp, etc.
  • ODAC Blind Testing – Once the cat is fully out of the bag more blind listening is on the agenda. I plan to expand my preliminary efforts comparing the ODAC to the Benchmark DAC1. Then I hope to arrange for others to participate in blind tests perhaps against other well regarded DACs. Once there’s a reasonable amount of data, I’ll publish an article outlining the results. If audible differences are found, I hope to put some of my new measurements to good use in search of an objective explanation.
  • ODAC Future Offerings – Depending partly on the outcome of the Cheap and Cheerful ODAC in blind testing, and user feedback, there may be future DACs that will plug into the ODA headphone amp just like the ODAC. One possibility is an open source DIY version. And, if there’s a need for added performance to stand up to best DACs in blind listening tests, we already have some ideas for a less cheap but even even more cheerful (higher performing) version that will hopefully be plug-n-play compatible with the ODA.
  • ODA Initial Details – The ODAC continues to take priority but that’s about to change as soon as it’s released to production and work on the open source ODA desktop amp resumes.

benchmark dac1 xBENCHMARK DAC1 IN THE REAR VIEW MIRROR: The $1600 Benchmark DAC1 Pre’s impressive performance has been something of a Holy Grail for objective DAC designers. I previously mentioned my desire to at least come close to the DAC1’s performance in a few areas. But, with the latest round of ODAC improvements, I’m pleased to report the ODAC has left the DAC1 in the dust!

SOME ODAC NUMBERS: We’re still finalizing the design, but here are some recent preliminary measurements for the current ODAC prototype versus the FiiO E10 and the Benchmark DAC1 Pre. Some ODAC results are even at the measurement limit of the dScope (marked “dS limit”). The geeks in the audience may also want to check out the Tech Section at the end of this article.

Measurement ODAC FiiO E10 DAC1 Pre
Freq. Response 10 hz – 20 khz +/- 0.01 dB +/- 0.1 dB +/- 0.1 dB
THD+N 100 hz 0 dBFS 0.0003% 0.005% 0.0009%
THD+N 20 hz –1 dBFS 0.0002% (dS limit) 0.004% 0.0009%
THD+N 10 Khz –1 dBFS 0.0002% (dS limit) 0.004% 0.0007%
IMD CCIF 19/20 Khz –3 dBFS 0.0002% (dS limit) 0.013% 0.0005%
IMD SMPTE –1 dBFS 0.0002% (dS limit) 0.004% 0.0004%
Noise A-Weighted dBu 24/44 -117.2 dB (dS limit) -98.3 dB -105.4 dB
Dynamic Range –60 dBFS Ref 2V -127.5 dB (dS limit) -97.6 dB -110.9 dB
Linearity Error -90 dBFS 24/44 0.0 dB 0.0 dB 0.2 dB
Crosstalk 0 dBFS Line Out 100K -128 dB (dS limit) N/A -106 dB
USB Jitter 11025 hz J-test 24/44 Undetectable (dS limit) Very Good Excellent
Maximum Output Line Out 100K 8.4 Vrms 1.65 Vrms 2.5 Vrms (1)

NOTE 1: Maximum output of DAC1 is configured with internal jumpers
NOTE 2: DAC1 measured from unbalanced RCA line outputs with the volume set for 0 dBFS = 2 Vrms
NOTE 3: Measurements marked “dS limit” are beyond the dScope’s limits see:
dScope Specs
NOTE 3a: Above ODAC measurements made using techniques originally developed by AMB Labs
NOTE 3b: All ODAC prototype measurements are preliminary as of April 1st 2012 and subject to change

TIME FOR A DAC2? Benchmark seems to be resting on their impressive laurels. The ODAC’s performance documented above is evidence they might want to sweep the dust off their workbench, blow the cobwebs out of their audio analyzer, and raise the bar with the rumored DAC2. For now, however, it seems the ODAC may be a more credible USB DAC “benchmark” than the legendary DAC1 series.

FiiO SHOULD RECONSIDER: Even if they ever manage to supply the E17 to Amazon, FiiO should look at the table above and consider a different line of business. Perhaps they could supply those digital audio players that go inside greeting cards?

TIME FOR A SERIES IV? The ODAC has demonstrated Prism Sound might want to update their formerly impressive dScope Series III. In eight of the twelve measurements above the ODAC exceeded the limits of the current dScope. It’s my understanding, however, I can send my Series III back to the UK and have it rewired with Kimber Kable, Black Gate capacitors, a higher current power supply, and a special Qables silver power cord. These mods, I’ve read at Head-Fi, will vastly improve its measurement performance. So I might try that before upgrading to a fully optioned $50,000 Audio Precision SYS-2722 Platinum Edition.

BOTTOM LINE: I’m pleased the ODAC has not only come close to the Benchmark DAC1 but crushed it in many tests. It’s also encouraging, although frustrating, the ODAC is so good it’s largely beyond the measurement capabilities of even a very capable audio analyzer like the dScope Series III. If I can’t get my hands on an audio analyzer up to challenging the ODAC, we can send a board to Lirpa Labs for full analysis by the famous Dr. Loof Lirpa. Check back for more soon!

 


TECH SECTION


TECH INFO: As mentioned in the first section above, I’ll be publishing full measurements for the ODAC soon enough. For now, however, here’s a preview. One of the greatest challenges in a 24 bit DAC are residual and spurious sources of noise. This is especially true for a USB powered DAC. So here’s a preliminary comparison between the Benchmark DAC1 and the ODAC.

BENCHMARK DAC1 ABSOLUTE NOISE: First let’s look at the reference-grade DAC1’s performance reproducing a –90 dBFS 1 Khz signal. You can see the overall noise floor is impressively off the bottom of the graph hidden below –140 dB. There are, however, several visible spurious noise components reaching a maximum of –117 dB. When these spikes, and the unseen noise floor, are added together, you get 62 uV of absolute unweighted noise in the audio band. Using A-Weighting it’s –105.4 dBu. This is about -113 dB referenced to 2 volts. This is impressive performance for a USB DAC. The linearity is almost, but not quite, perfect at –90.1 and –90.2 dBFS in each channel for an error of 0.1 and 0.2 dB respectively. This level of noise and the linearity error should be inaudible:

DAC1 -90 dBFS Linearity & Absolute Noise Line Out 100K Ref 2 Vrms 24-44

 

ODAC ABSOLUTE NOISE: Here’s the ODAC’s even more impressive result. Note the absolute noise drops from the DAC1’s respectable 62 microvolts to only 0.04 microvolts or a staggeringly low 40 nanovolts. Put another way the Benchmark DAC1 has 1500 times more absolute noise! The weighted result of –117.2 dBu is the dScope’s native noise floor and measurement limit—not the ODAC. The actual noise of the ODAC is much lower—the math indicates it should be around –168 dBu! Note the total absence of any visible noise or spurious components down to –140 dB. The linearity is perfect at exactly -90.0 dB in both channels. Here the ODAC transcends merely transparent performance and elevates the ODAC into being a genuine oracle of audio revelation:

ODAC -90 dBFS Linearity & Absolute Noise Line Out 100K Ref 2 Vrms 24-44

NOTE: These are preliminary results as of April 1st and are subject to change.

146 comments:

  1. Beating the teacher, congratulations sir you have become the master. Much respect.

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  2. Man, I am really impressed. I hope you will enjoy work as we enjoy your articles for a very long time. To mention the ODAC, were the initial measurements made the ODAC enclosed or the bare board on the desk. I am just curious.

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    1. My measurements so far have been bare board. It's entirely possible the performance will improve with a properly grounded metal enclosure. The special measurement techniques used for the ODAC in this article, however, yield the same results regardless of shielding.

      Delete
    2. This just keeps getting better. Special measurements techniques developed by AMB (ha) and your measurements are bare board (ha ha). This is too good.

      I just looked up Loof Lirpa. Very insightful.

      Delete
  3. If you include the comparative results from "pro" sound USB interface, my vote goes for E-MU 0404 USB. It has highly praised AK4396, and is really cheap used. Also here could be great example to prove again that the parts doesn't matter, if design is bad. I own it myself, and I'm just extremely curious how it measures.

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    Replies
    1. Or RME Babyface could be the target ;)

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  4. I discovered your blog a short while ago, and it's been very educative. I've bookmarked several of your articles and I often refer to them. Thanks for your healthy no-bullshit stance on the world of digital audio! However…

    "Even if they ever manage to supply the E17 to Amazon, FiiO should look at the table above and consider a different line of business. Perhaps they could supply those digital audio players that go inside greeting cards?"

    I think that's uncalled for. Can the ODA/ODAC compete on the price (€65), size (very small), convenience (just one cable) and portability of my FiiO E7 (which I happened to buy after reading your own review)? Incidentally, will it be available from Amazon with next day delivery?

    Don't get me wrong, I intend to get an ODA/ODAC combo myself, but I don't think you need to be smug about it.

    That said, thanks again for giving us a sane alternative to audiophoolery.

    ReplyDelete
    Replies
    1. Haha, I've been fooled. It did sound very odd. I didn't expect an April's Fool from you!

      Delete
  5. "NOTE 3b: All ODAC prototype measurements are preliminary as of April 1st 2012 and subject to change"
    Try harder ;)

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  6. You almost had me, right up to the 8.4VRMS output from USB power!

    Don't approve this post quite yet though please, I want to see if we get any "OMG NWAVGUY IS A WIZARD"-style responses.

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  7. You could create dummy-pages just for comments. Named just like the original article ("Early April Update comments page2" or so)...this way we won't lose useful information or questions. :)

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    Replies
    1. This is a swell idea.

      Delete
  8. I like your design for O2 amp.. i have some questions:

    is ODAC DIY? Would you publish a schematic for ODAC?

    & will there any bass boost in ODA?

    I hope in the future you can create some portable player like sansa, ipod, etc..

    thanks..

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    Replies
    1. It has been mentioned in the previous article that ODAC is not available for DIY because the DAC chip is not available to the general public. The schematic might be published in the future but definitely not now, reasons stated in the previous article or comments.

      Quite sure there won't be a bass boost, cos it defeats the purpose of the ODAC. you can look at the Digizoid ZO though. I've tried it and it works surprisingly well as a bass boost option.

      For great well designed portable players, look for more info on the tera player ;)

      Delete
  9. Did I say I love you? If I havent well I love you :-D

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  10. I was convinced until I saw Dr. Loof Lirpa :(

    Happy April Fools to you!

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  11. Thanks for the update on the current ODAC status. I've been following your articles with great interest and very much like both the O2 itself as well as the open way you presented its development. Keep up the good work!

    What's striking me in this article is the "FiiO SHOULD RECONSIDER" paragraph. It just does not fit with your style in the other articles and even sound a bit arrogant.
    Considering the data from your measurements it seems obvious that 99.9% of all users will not be able to hear a difference between either of the tested DACs. So why suggesting FiiO's performance is only good enough for greeting cards?

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  12. Well... maybe... an April foo joke? :) //oh

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    Replies
    1. God I hope not. What is with all these quazzi normal yet good announcements on 4-1!

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  13. NwAvGuy,

    Thanks for the great laugh.

    Ian

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  14. I was genuinely about to write a comment about how NwAvGuy has totally lost his way - that the tone of this post reeked of arrogance and was littered with subjective claims.

    Then I remembered the date.

    Goddamnit man, you almost had me.

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  15. I'm not even surprised that the ODAC can out-perform the DAC1. It's just too bad that I don't listen to music on my computer.

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  16. >NOTE 3a: Above ODAC measurements made using techniques originally developed by AMB Labs

    Comedy Gold!

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    1. These includes the Triple-Konnig Double Degaussed Loopback Variation and the Triger-Sellum Mathematical Derivation Procedure.

      Neither requires the product involved to be tested to produce excellent results!

      Delete
  17. I'm a highschooler with little to no knowledge of audio, electronics, audio benchmarking, or engineering. Unfortunately, this makes some of your articles a bit of a dry read for me. It still interests me, though, so I read all of your posts and try to follow along best I can.

    This one, though, had me howling on the floor.

    Thank you, and a Happy Loof Lirpa's Day to you! ;D

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  18. hehe :P

    Hope there is a real article soon, but this one was fun to read through.

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  19. Actually this article mught be a real info since there are already DACs with similar measurements. Look at http://www.anedio.com/index.php/product/d2_measure and here http://www.anedio.com/index.php/product/d2_specs and you will understand why. But seriously its april fools day so we all know what this article is about. Anyway looking forward to the real ODAC. Keep it coming man!

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    1. Thanks. There are indeed a few DACs that can challenge the dScope. The small, USB powered, cheap and cheerful ODAC isn't one of them. But the main goal is to have the ODAC be 100% audibly transparent--i.e. not alter the sound quality in any noticeable way. If it fails to live up to that goal, look for an ODAC+.

      If the ODAC proves to be transparent, those wanting better specs such as from Anedio (although last I looked they didn't have a USB DAC available), have plenty of more costly options. It's not unlike the O2 vs a Violectric V200. My design philosophy doesn't include expensive overkill unless it demonstrably improves the sound quality.

      Delete
    2. At some point, it has to start hurting the sound, I would think. Simple is ALWAYS better. Complete transparency using the least parts should be every manufacturers goal. Not some useless spec competition.

      I think you're doing it just right nwavguy.

      Delete
  20. GAH! I thought you were for serious.

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  21. In the grand scheme of things, I think some people would be surprised how close some of the options like FiiO E10, or maybe even the Asus Xonar U3 / Creative X-Fi Go come to the really expensive stuff like the Benchmark DAC1. We're looking at distortion levels say an order of magnitude worse, but still very low, probably difficult if not impossible to hear when music is playing. It mostly just looks like the noise level where the expensive gear starts pulling away.

    If the March update was any indication, you've already got the ODAC noise levels around the DAC1 in a previous iteration, so even April 1st measurement techniques aside, I think this is turning out to be a pretty great accomplishment. It's just not so great you can start destroying the specs on the spec sheets for the DAC itself. ;)

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  22. The only thing holding me back at this point is whether or not you'll include a Turbo button.. I can't listen to music anymore without one!


    Thanks for the great read today ;)

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  23. Hi NWAVGUY,

    I'm looking for a highly portable amp that can drive my DT990 PRO 250 ohms. The O2 seems fantastic but it is not as portable as I would like... I was considering the FiiO E5 or even the E7, E11, E10, or E17, but not larger or expensive. I was going to get the E5 but based on your review, it seems is a very compromised design... Do you have any suggestions outside of the FiiOs or even among the ones I mentioned, which one would you pick?

    Thanks.

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    Replies
    1. Of that lot, the E17 is mostly an unknown, so if you just need an amp, the E11 is the best choice. The E7 uses the same amp as the E5. The E10 can't be used as an amp.

      Delete
  24. Whoever made up this "holiday" was a genius.

    For more comedy gold check out what Schiit has placed into their new Circlotron using uber priced amp FAQ.

    "Oh crap, you’re meter-readers now!
    There’s nothing wrong with using measurements to improve designs, but that doesn’t mean we’re going to start using op-amps and bragging about parts-per-million THD. We still have ears."

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    1. I still want to measure an Asgard. I'm fairly sure it will be genuinely poor in many regards--as in audible flaws that make it less than transparent. Subjective ears are notoriously unreliable. Just like taste buds.

      Delete
    2. C'mon someone send him an Asgard!

      Delete
    3. Is there supposed to be any real advantage to this Circlotron topology?

      Given that someone's HD650s just got destroyed by what was supposed to be a relay protected Lyr I'm a little frightened by the idea of them making an even stronger amp...

      Delete
    4. An amp with an esoteric topology aimed at audiophiles having real advantages? Since when did Schiit sell things with real advantages? They're doing rather well on the OPAMPS ARE EVIL TEH SINGLE ENDS FTW OMG bandwagon. All they're missing is a product to capitalise on fears that picoseconds of jitter will make you a PRAT (think that's right)...no, wait, revolutionary new anti-jitter tech cometh!

      I think they've covered every major base, with the possible exception of boutique capacitors. Perhaps someone could drop them an email?

      Delete
    5. Hopefully it's clear to at least some readers of this blog Schiit Audio is very clever in their marketing and they artfully avoid publishing meaningful measurements or detailed specs they could be held accountable for. They would rather nobody shine a bright light on their rather "dirty" amplifiers.

      What's surprising to me is Jason Stoddard was very publicly opposed to my suggestion of using a relay in the Asgard to help with the massive headphone damaging transient problem. His public replies indicated he strongly disliked using relays. Now they have a product with roughly a few dozen relays in it. What's up with that? They could at least be consistent in their company marketing pitch. Jason seems more like a politician with his views changing with the moment...

      Their single-ended amps are, without a doubt, relatively poor performers on a test bench. Schiit, of course, will argue that doesn't matter because they're "designed by ear". But many of us know how unreliable that is (see my NuForce uDAC-2 review). Wine tasting preferences, when the prices are known, tends to closely follow the price of the wine. Overall people overwhelmingly prefer the more expensive wines. If you simply put the bottles in brown paper bags, and reverse the prices (i.e. the cheapest wine is labeled as the most expensive) you get the same result only now they're actually voting the cheapest wine as the best. The exact same thing happens with sighted listening of audio gear. See my Subjective vs Objective article and check out the McGurk Effect video. Our brains ALWAYS involuntarily filter what we hear. So designing by ear, as Schiit claims to do, is fundamentally flawed. It's been well demonstrated in dozens of well conducted studies.

      Delete
    6. Is there data that has been published somewhere that shows that "Their single-ended amps are, without a doubt relatively poor performers on a test bench." This is an honest question, not me being a smartass. It's possible that I just missed it because I haven't read all of your posts, but I thought you hadn't tested their products. I am genuinely interested in this data so if you could direct me to it I would appreciate it.

      Delete
    7. It's sort of like arguing the Ford Model T is better than a horse drawn buggy. Single-ended amps date back to the days of the Model T.

      Way back when some push-pull amplifiers suffered from audible crossover distortion. Push-pull is more efficient, has a much lower output impedance, usually much less distortion when delivering any sort of significant power, generally allows for higher levels of negative feedback, and can produce much more power. But many early examples suffered audible crossover distortion--especially in solid state amps using transistors. That gave the technology a bad name. Single-ended amps, by design, don't have crossover distortion. In the early days of transistors there were some problems with high levels of negative feedback (slew related distortion). And some argue single-ended amps are more simple and hence somehow superior.

      Finally, single ended amps are praised for their mainly even order harmonic distortion. It's true even order harmonics tend to be less objectionable, but the problem is the LEVEL of the harmonics. Any decent push-pull amp will typically have much lower levels of ALL kinds of distortion than a single-ended amp. So yeah, it may have roughly equal amounts of even and odd order distortion, but both are vastly lower than nearly any single-ended amp.

      It's like saying a digital camera that tints everything pink is somehow better than one that delivers accurate colors because pink is less objectionable than green. I'll take the accurate colors. Single-ended amps are like wearing rose colored glasses. They can alter your perception of reality.

      The four reasons above are the "grains of truth" behind the single-ended following among audiophiles. But they're all in the distant past and no longer valid arguments. Still, some try to argue a 1908 Ford Model T can somehow magically outperform a 2012 car. They're flat wrong. For anyone who begs to differ, I'll see them at the track. Modern cars are far faster, use less fuel, are quieter, ride better, require less maintenance, etc. There's no contest. Honestly, it's a fair analogy. Single-ended amps are like the Model T.

      It's fine to like really old cars, and even own them, but nobody should try to claim they can outperform modern cars. Anyone who believes so is living in a fantasy world. The same is true for single-ended amps that have to drive headphones or speakers.

      Crossover distortion has been reduced to being entirely inaudible with various design practices. That's especially true for op amps designed for audio use like those used the O2 headphone amp. Slew related feedback issues are also long gone. Today's transistors are vastly faster than those from the 70's and earlier. That eliminates the problems with negative feedback. And even the odd order distortion of modern push-pull amps are typically less than the odd order distortion from single-ended amps.

      Minimalism is nice for someone living out of their Volkswagen Van but the slight added complexity of a push pull amp is only a good thing in the way fuel injection is vastly better than a carburetor. The Model T is also an exercise in minimalism but that doesn't make it competitive with modern vehicles.

      Delete
  25. How does the ODAC hard numbers compare to Anedio D2 DAC? They have 'objective' measurements too.

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    1. They're in totally different leagues in terms of price, topology, marketing, etc. The DAC1 is a much closer competitor to the Anedio. But, ultimately, if the ODAC SOUNDS just as good, you have to decide why you want to spend ten times as much or even more. At some point more money only buys additional status, aesthetics, build quality, etc. Once you reach the point of audible transparency, spending more doesn't get you better sound. My upcoming Timex vs Rolex article will discuss this in much more detail.

      Delete
    2. isnt it saying "sounds just as good" design by ear? ;-)

      Delete
    3. "Sounds just as good," is easy to promise in this context, as if all the numbers are good the DAC shouldn't have any detectable "sound" of its own.

      Delete
  26. NOTE 3a ....pfff....LOL....good one...

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  27. Wow, you got me. I was honestly taken aback after that comment about FiiO and I didn't even think of April Fools until I started reading the responses.

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  28. Jokes aside, the blind listening tests should be performed on speakers, as DAC performance is believed to affect soundstage, most noticeable on systems that have a lot of potential in that aspect

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    1. I'm OK with that, but it's also good to keep in mind the primary intended application for the ODAC is the ODA headphone amp. And, especially among those reading this blog, far more have access to revealing headphones than similarly revealing speakers properly amplified, set up correctly in the room, etc.

      It may depend on what you're listening for (soundstage, etc.) but, in my experience, it's easier to detect small differences with blind ABX and my HD650 headphones than with speakers and amplification costing 10+ times more.

      The headphones largely remove some significant variables--notably the room, seating position, ambient noise, etc. The fewer variables you have changing the sound the easier it generally is to find small differences in the gear itself. The HD650s also have far lower distortion than most speakers and are free from crossover artifacts. But, ideally, it would be good to do both--headphones and high-end speakers.

      Delete
  29. Here is the upgraded DAC1 trade in program included. However not sure wheter they accept greeting card DACs :D
    http://www.benchmarkmedia.com/dac/dac1-hdr

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  30. No comment about Schitt? Looks like they killed another pair of expensive cans.

    http://www.head-fi.org/t/603648/my-hd650s-are-dead-upgrade-advice

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    Replies
    1. http://tinyurl.com/7uahvzb

      After catching the crap with the Asgard with Nw I can't say I'm surprised in the least. Their designs are bad, and they should feel bad - there's just no covering it up.

      Delete
    2. I have actually read responses to similar issues to the effect of "Darn kids these days, expecting that amps will not blow up their headphones if they don't turn the volume down to zero and wait before plugging their headphones in...I'm always careful."

      Regrettably, such responses are not sarcastic. I suppose it feeds into the audiophile idea that good audio should involve large amounts of hassle and money: accomplishing it with circuits stuffed with cheap opamps kills the mystique...

      As it happens, this particular example appears to have been caused by a faulty amp and a stupid consumer, who kept using it despite the fact that it clearly doing something strange at turn-on.

      That said, the stupidity of Schiit's initial and completely ridiculous shipping of an extremely high-power (for headphones) amp without ever measuring the turn-on thump on a production model still stands.

      Delete
  31. I was reading this thinking wow, sounds too good to be true.

    Though I do suggest you send your scope to get recabled and get the caps replaced ,;throw more audiophile grade mumbo jumbo at it and it'll just be better in every possibly way.

    Happy April Fools to you too :)

    Looking forward to the real article hah

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  32. I was reading this thinking wow, sounds too good to be true.

    Though I do suggest you send your scope to get recabled and get the caps replaced ,;throw more audiophile grade mumbo jumbo at it and it'll just be better in every possibly way.

    Happy April Fools to you too :)

    Looking forward to the real article hah

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  33. This is getting out of hand... we have all learned (from you mostly) that these kinds of THD and noise values are completely inaudible. So just release it already! THE ENTIRE AUDIOPHILE MARKET IS WAITING!
    (just my opinion)

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  34. My HD650s are waiting! Can't wait to end the upgrade bug once and for all.

    Also, I don't find your articles dry at all. The first half always serves to get me giddy.

    ReplyDelete
  35. 'Oh, new NWAVGuy article yay!'

    *Reads*
    *Thinks WOAH on measurements*
    *Reads 'Note 3A'*

    DAMMIT!!!!
    Looking forward to the real thing soon!

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  36. You might want to upgrade your Benchmark DAC1 USB to Benchmark DAC1 Thunderbolt. Now with more Gigahertz.

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  37. This is an awesome April Fools article! You had me for a bit.

    I'm getting an ODAC even though this article looks a little beyond reason. I liked the funny part about upgrading your dScope with the FOTM components.

    ReplyDelete
  38. This is off topic, and I can't vouch for it since I don't use blogger, but have you tried what's suggested at http://stramaxon.blogspot.com/2012/03/show-more-than-200-comments-on-blogger.html ? It seems like there is a way around the 200 comment limit. Just trying to help out, since less time moderating comments means more time on the ODAC, etc.

    ReplyDelete
    Replies
    1. I don't consider that off topic as I'd love to find a solution. That fix involves changing the comments from embedded with the article to being in their own window. Unless they've changed how that works, last time I tried it I wasn't at all happy with the interface. Having the comments be inline is what most people expect.

      The sad thing is there's a "MORE" link that shows up with embedded comments once you have more than 200. The link is supposed to display comments 201 and up. But it's does nothing. It's clearly a bug as it doesn't even work in Google's own Chrome browser.

      If I'm missing something here, I'm very open to other suggestions.

      Delete
    2. My bad, as I said, haven't used Blogger before. I googled "blogger 200 comments". There are some other options (e.g. http://www.mybloggertricks.com/2012/02/newest-200-comments-not-showing-in.html) but I'm not sure if that's what you're looking for. I'll stop from commenting now. Hopefully someone more familiar with blogger could offer a solution. Anyways, keep up the good work.

      Delete
  39. I thought I saw the last article reach 201 comments at one point but maybe I was seeing things?

    Story if I haven't shared already: I recommended someone on Head-Fi buy the Music Streamer II and M-Stage instead of the uDAC-2 and asgard - on account of the later two performing horribly and possibly blowing up one's headphones, and at least knowing that the M-Stage has a very quiet turn off "thump," and the former combination sounds good to my ears at the very least. Another member posted saying "don't listen to him" and I think the OP ended up getting the latter combination. It was one of the more enlightening experiences I had on Head-Fi. People don't seem to care the products they buy are schiiiiit. :P

    I wonder if they called themselves shit on purpose. . .

    ReplyDelete
    Replies
    1. O2 is totally on par or better than the m stage. I had little problems selling mine after getting the O2

      Delete
    2. I'm counting on it. I'm waiting for the ODA though. :)

      Delete
  40. Hi,

    This is only a suggestion that might serve him for a future project, and is not related with the ODAC but with the measures, specifically measures about the frequency spectrum as those published in this post.

    Measures as the power output or distortion are suspect, a 30W amplifier may sound more than a 100W (as shown by Matti Otala and Derek Scotland), and a no feedback amplifier with a 2% distortion may sound better that a feedback amp with a 0.003% distortion. Are not directly comparable.

    But the Spectral analysis may be more reliable, and an excellent aid for DIY to improve the audio equipment. The problem, as you said in one of his post, is that the free programs that can get the amateur is not reliable, would be necessary to have a measurement system like the one you have, which is available to very few.

    Perhaps you could recommend a software and a measuring amplifier, or design you one, that might be of some help for the amateurs. These may be a couple of examples within the post are some links to software and some measuring amplifiers:

    http://www.auriculares.org/foro/index.php/topic,1929.msg86685.html#msg86685

    http://www.auriculares.org/foro/index.php/topic,7589.msg87100.html#msg87100

    If you consider this suggestion interesting and decided to pass it to reality, may be able to include a small tutorial on how to use it to improve the work of amateurs.

    Happy days

    ReplyDelete
    Replies
    1. The work of Matti Otala was valuable in the 1970's but it's been progressively less valuable since then. His concept of TIM (slew related distortion) has become much more theory than reality since power transistors have become faster.

      Negative feedback could have some bad consequences back in the 70's but that was entirely related to the slow transistors available then. Today, feedback used properly is entirely a good thing. Modern experts, like Bruno Putzeys, have documented how negative feedback got its bad reputation and why it's no longer a concern. It's like comparing carburetors and fuel injection in cars. No sane person today would argue carburetors have the overall advantage.

      In terms of DIY amplifier measurements it's about more than just software. My RMAA article explains the limitations of RMAA but it remains as the best free option if you have the right compatible hardware, use it properly, and understand its limitations. To go much further requires specialized hardware. And the least expensive options I know of, even available used, are around $5000 and up.

      There's a massive difference between PC sound hardware measurements and those you can do with a dedicated modern audio analyzer such as those from Prism Sound (the dScope Series III) and Audio Precision (the SYS-2700 and APX series). PC sound hardware generally can only handle a few volts of input, is ground referenced to the PC, can't measure absolute voltages and levels, doesn't have calibrated gain, can't perform real-time measurements, and has many more limitations. Those who think they can work around most of that are fooling themselves. There's more in the RMAA article

      Delete
  41. It has been said that, "[f]igues don't lie, but liars can figure."

    Do you feel this is a key element to most marketing in audio?

    ReplyDelete
    Replies
    1. Most high-end audio marketing is more about emotion than blatant lies. Fortunately the FTC, at least in the USA, has some authority to go after those making seriously fraudulent claims. That doesn't stop a lot of companies from making claims that are difficult to verify or dispute however misleading they might be.

      I can legally claim Gallo makes the best wine in the world however much oenophiles might disagree. Similarly, Qables is free to claim their expensive snake oil cables somehow sound better to their ears even if they don't sound any different than a $3 cable in a blind listening test.

      When Schiit Audio claims their Asgard headphone amp has "Less than 0.1%, 20Hz-20KHz, at 1V" they conveniently leave out the load impedance which has an enormous impact on such measurements. Measuring with no load is nearly meaningless as to use a headphone amp you have to plug in headphones. Those headphones load the amplifier. The single-ended Asgard might meet that claim with no load or a very high impedance load. But I'll bet good money it won't meet it with say a pair of AKG Q/K 701s plugged in.

      And while on the topic, a recent Schiit post implied people are worrying about "parts per million" levels of distortion. Their own (likely optimistic) spec of 0.1% represents distortion that's about 60 dB below the signal. That's about the level of hiss on a cassette tape. Anyone who's heard cassette tape knows the hiss is often audible. A level of 0.1% is really 1 part per thousand, not million. And, because of how human hearing is non-linear, such a level can be audible. But Schiit is trying to spin things differently.

      So I guess to some degree, "liars can figure". The more frustrating aspect to me, is few companies publish sufficiently complete specs to even allow their claims to be verified.

      Delete
    2. Many high-end audio companies employ "customer testimonials" and quotes from reviews -- because the FTC can't touch them for that. It's not the company making the claim. They are just reporting what someone else said.

      So you have the high-end audio magazines making all kinds of quotable statements in reviews. The advertisers give the magazines money to run ads with the quotes in them. The readers subscribe to the magazines and buy the products. Those customers write letters of praise to the manufacturers (in order to establish that they are of the most noble breeding and taste). And those quotes end up in other ads. It's all one big circle ****.

      Delete
  42. Hmm....that Loof Lirpa joke got me too;)
    I'd like to know though, what highly appraised dac's like April Eximus DP-1 adds except colouring, design, build quality and versatile connections?
    Why benchmark with Benchmark, that is already an 'old' product?

    ReplyDelete
    Replies
    1. I already have a DAC1 Pre so it's a handy "benchmark" and it still stands up well to a lot of newer DACs in terms of sound and measurements. The main "new" features on more recent DACs are 24/96 USB support with native drivers and various methods of jitter reduction including asynchronous USB mode. The DAC1 already has those covered.

      The DAC1 is lacking the now trendy switchable filter modes but I think those are more a gimmick than genuinely useful. And it's not UAC2 but I consider that a good thing as it doesn't need proprietary drivers in Windows. The April Eximus is UAC2 so it needs a special driver to work with Windows.

      Hopefully the ODAC blind testing will include other well respected DACs in addition to my DAC1 Pre. As for the Eximus it's relatively similar to a DAC1 Pre. They both use ASRC, have several inputs including analog, etc. The Eximus adds an I2S input which is only useful if you have something with an I2S output and you can choose the ASRC sample rate. But I would expect them to sound very similar if not essentially the same.

      Delete
  43. This article posted by Monty on Xiph.org, is somewhat alarming, yet interesting: "24/192 Music Downloads ...and why they make no sense"
    http://people.xiph.org/~xiphmont/demo/neil-young.html
    I hope you could shed some light on some of the more technical details, I still need more coffe to continue with the second half, phew.

    ReplyDelete
    Replies
    1. I commented on the 24/192 article already in last month's post. I'll also be linking to it in the upcoming Timex vs Rolex article and commenting on it further. I mostly agree with what he has to say but it's important to realize he's mainly talking about file formats and not hardware--there are some significant differences. There are benefits to 24 bit DACs when the volume control is "upstream" of the DAC (i.e. in the digital domain). This is true even when playing 16 bit regular CD audio (16/44) music.

      Delete
    2. Hey thanks for that. Suddenly the recent slew of "high-def reference DAPs" just no longer make sense.

      Delete
  44. LOL Very funny! Keep up the great work. Glad to see you're keeping your humor about you in spite of the nay-sayers. Looking forward, actually drooling in anticipation, to the actual release info. It wouldn't surprise me if you did best the DAC1, as we've already been informed you beat it's dynamic range.

    ReplyDelete
  45. I can't wait for the ODAC to be released. I admired your work on the O2 amp and my build of it sounds very good, cleaner than my Bijou in a more transparent kind of way (but not as sweet due to lack of tubes which I sometimes prefer).

    The ODAC will be going in the audio chain for a new amp project I'm working on, and the amp is almost done. Once the ODAC is released, it will be purchased immediately, cased up, and put to good use!

    ReplyDelete
  46. Hi NwAvGuy,

    The O2 seems like a wonderful amp. However, given it size, it does not seem as portable as a lower quality (and cheaper) FiiO E5 or E6. Though these small gadgets are probably not up to the performance of an O2, they are certainly very practical to carry around. Do you have any plans to develop an amp of similar SWaP as the E5/E6? It could be powered by an internal small battery and optionally by something like this through USB:

    http://www.amazon.com/Duracell-Instant-Charger-Includes-Universal/dp/B002FU6KF2/ref=sr_1_1?s=electronics&ie=UTF8&qid=1333525525&sr=1-1

    ReplyDelete
    Replies
    1. There's a substantial difference in the not only quality but also output power between the E5/E6/E7 and the O2. Into 64 ohm headphones the E5 can only manage about 25 mW while the O2 can output about 400 mW cleanly on battery power--16 times more power than the FiiOs. Even the larger FiiO E11 doesn't have anywhere close to as much power as the O2. More power requires a more substantial power supply/batteries which takes up a lot more space. There's not much wasted space inside the O2.

      Unfortunately to do small right requires things like full custom enclosures, custom buttons/controls, Li-Ion batteries, all surface mount construction, etc. These let the designer utilize every cubic millimeter of space. To make those sorts of things practical and cost effective you need to make many thousands of them and have them commercially made (usually in a country with cheap labor). So it's not practical for a DIY or low volume amplifier.

      I could try to design something smaller with smaller batteries but it would not be as DIY friendly, Li-Ion batteries present safety issues, and it would still either be fairly large or unable to drive many headphones the O2 drives easily. For really small and elegant solutions commercial mass produced designs nearly always beat DIY.

      Personally, when portability is a high priority, I think a Clip+/Zip player (which has an amp that performs similarly in many ways to the E5/E6/E7) paired with compatible headphones is best. You can't beat one tiny little player you can clip to your clothes that has a much lower output impedance than any iPod I know of, doesn't require an outboard amp, another cable, another device to keep charged, etc. And you're also not reducing the battery life of your phone or needing to dig your phone out every time you want to skip a track, etc.

      Delete
    2. Thanks man. I have the Clip Zip, which I bought in no small part thanks to your advice, CNET advice, forums advice, Amazon reviews... You name it. And it.is.an.incredible.device. Currently it drives Audeo IEMs, and Koss KSC75 (60 ohm) really well.

      However, I also recently bought a 250 ohm headphone that responds really well to laptop and AV amps, but I have to crank up the Clip Zip to -10dB to listen to it. It sounds great to my ears, but I fear I'm pushing my Zip to its limits, and may not be experiencing all the bass impact and detail I should if I was to use something with just a little bit more juice.

      I read in Amazon that some guys drive these ~250 headphones with E5/E6/E7 amps added to their Sansa players... Those amps don't seem to impressive though. I don't know man, do you think any of these portable amps will help drive a 250 ohm headphone better than the Sansa amp by itself?

      Delete
    3. If your headphones get loud enough with your Clip, you're good to go. Running the stock firmware the Clip will not, pardon the pun, clip into high impedance headphones even at full volume. Running Rockbox it's possible to adjust the volume even higher and push the Clip into distortion. But -10 dB is fine. You really are getting the full bass impact as long as you're not pushing the player to clipping off the peaks. Getting all the detail is perhaps a bit more open to debate. Something like an iPod Touch and an O2 amp would have more dynamic range, less noise, and potentially a bit more detail, etc. But it's not a night and day difference.

      Unlike a lot of portable players, if it gets loud enough, the Clip doesn't have to make many excuses. It will play about 8 dB louder with the E5/6/7 amps. In round numbers the FiiO amps deliver about 1.3 volts while the player itself only delivers 0.5 volts. That's a significant boost in maximum volume.

      I still suggest using portable headphones that play loud enough with 0.5 volts so you don't have to drag around an amp. Buying new headphones is often cheaper or about the same price as buying a good portable amp like the O2. For home use, however, I would suggest an O2 or the upcoming ODA/ODAC.

      Delete
    4. Thanks man :)

      Delete
  47. Dear nwavguy I had a question that I haven't seen answered in your blog. Have you ever tried to debunk the LODs for DAPs as a waste of money? Also, i'm a proud owner of a 1st gen zune and have been loving it but am I in the stoneage of DAPs? What DAP is your favorite? Thanks, Jj.

    ReplyDelete
    Replies
    1. It would be interesting to compare the headphone output vs line out (LOD) of several different players using the dScope. From the limited comparisons I've done the line outputs usually have a small but consistent advantage. I can't say if the relatively small differences are audible in normal. In general, I wouldn't lose too much sleep over not using a line output with a portable player.

      Delete
  48. Given the cost of the dScope and Audio Precision analysers, have you considered turning your skills towards creating a similar unit for hobbyist use?

    ReplyDelete
    Replies
    1. That would be nice, but I'm not exaggerating when I say there's probably at least a few thousand man-hours of development time into a product like the dScope or the current AP analyzers. Between hardware that has to push the limits of what's possible, elaborate firmware running on the device, and the incredibly complex PC software, it's an enormous development effort. When you amortize the costs across only a few thousand units sold, and consider the advanced low-volume hardware, it also explains the five figure pricing.

      So, to put it another way, I'm not willing to invest many years of development work only to lose money. It's a huge effort and one best left, at least for now, to Prism and AP.

      Delete
  49. First HeadFi moved the O2 thread to the Sound Science section and now it's locked.

    http://www.head-fi.org/t/568705/review-nwavguys-o2-diy-amplifier/1545

    ReplyDelete
    Replies
    1. Certainly no conspiracy at work there. When people start derailing a thread with petty squabbling and it gets to the point that a satirical response is mentioned as possibly being construed as defamation you can't honestly expect things to go on much longer regardles of what product is being discussed. It's a shame that people had to ruin it by being so combative because there was a lot of good information in that thread (even if it did go off on some tangents).

      Delete
    2. I haven't been following the thread (the "signal-to-noise ratio" at Head-Fi is terrible as most of it is biased and/or misguided hype) but I'm not surprised. The O2 is a significant threat to Head-Fi advertisers/sponsors, a lot of more expensive products, and the egos and sensibilities of those who own those expensive products.

      In my experience any Head-Fi thread with significant interest that threatens the status quo ends up combative. Even the moderators and admins will sometimes add posts that just make things worse. Look at Kwkarth's comments in the Schiit Asgard thread. Jude claims he just wants to keep things clean and nice, but his own staff create conflicts, stir things up, and make lots of people angry.

      To put it another way, the Head-Fi admins and moderators have been known to create "petty squabbling" when they don't agree with the direction a thread is headed.

      Delete
    3. Actually, in this case (I was posting in the thread when it got moved to sound science) it was because a member speculated if there would be any changes in sound with different opamps in the O2. (There's a certain irony at work here.) The thread devolved into arguments about opamps, with more than a few members citing your statements on the matter - though linking to your website is no longer possible. The thread was then moved to sound science. I do not know why it was locked shortly after that, because I stopped posting there at that point.

      Delete
    4. Wow I hope they realize they are losing people by doing things like this.

      Delete
    5. Well, the main recent things that were going on before it was locked were:

      1. There were discussions about how sufficiently-good amps with all the correct properties (low enough noise not to be heard, low enough distortion, flat FR, etc.) driving headphones within their capabilities, should sound the same. I and some others referenced such things as the Carver challenge results, blind testing results, audio differencing to compare amp outputs, the fact that two amps very close to perfectly linear driving headphone loads should behave in very similar ways as an ideal LTI system (and thus behave predictably and close to each other for any audio frequency input), etc. Needless to say, on many audio forums there is some resistance to this idea.

      The last bit was labeled by one poster as "Some [engineers in this thread] offer assumptions based on theory and confuse people." I'm not at all offended by that statement, just confused myself.

      2. I suggested that sighted listening comparisons have little value in general, for the obvious reasons, and I linked Sean Olive's "Dishonesty of Listening Tests" as an example.

      3. Somebody preferring another amp over an O2 after doing a blind evaluation with the amps...level matched a couple dB apart, with the O2 set louder. Things got needlessly combatative over that, but there's nothing close to extreme or offensive there, so a lock is very arguably not warranted. It should be pretty clear that without level matching, the comparison loses some value as the amps can be distinguished by the volume. Anyhow, the poster says that such a comparison is good enough for him to convince himself, so that's that. That works for me; I'm not going to call people out for doing whatever it is they want to do.

      There was no involvement from moderators this time, except for one to lock the thread.

      Delete
    6. A few things about that thread as I see them:

      --There was no effort on the part of moderators to stir up any kind of arguments. At least at the end I didn't see any posts by moderators.

      --Like someone else mentioned above, some of the discussions that appeared, like opamp rolling in the O2 seemed very odd considering the nature of the amplifier being discussed. Other discussions like the merit of different cables essentially sealed the threads fate as a sound science forum resident.

      --I personally think that mikeaj's contributions were balanced and informative, though others didn't seem to like them.

      --I don't think that there should be any disagreement that the member discussing his personal comparison performed testing that was conducted in a manner that wouldn't hold up to scientific scrutiny. That member got out of it what he wanted to. I don't think it would be unfair to point out the flaws in his testing for the sake of the less informed that may be reading the thread. The thread collapsed, though after the "YOU'RE WRONG!!!!!" nature of some posts in response to that member. I think it was very clear that his response about a different member not being able to prove that they had performed comparisons was quite clearly a "NO YOU'RE WRONG!!!!" response that was partially a parody of his/her opposition's style but also clearly somewhat argumentative.

      If you read through that thread and maintain an objective perspective, it is quite clear that it was not either "side" that got the thread moved to sound science or got it locked. There were multiple occasions where posters seemed to think that condescension would win the argument for them. Multiple people representing different viewpoints contributed in this manner.

      I singled mikeaj out above because, in my opinion, he (presumably a he based on the name) did not resort to condescension in the misguided belief that it somehow made his arguments stronger. He instead let evidence speak louder than attitude which is more than can be said for most that emphatically participated in the debate.

      I understand the goal of the camp that supports using objective measurements to compare equipment. I agree. I do also notice that some of the loudest voices in that camp come across in the same manner as the religious zealots that knock on people's doors and tell me to repent or they will go to hell. People don't like to be called stupid even if (or perhaps especially if) it's true. I'm all for sharing valuable information with everyone that could use it, but people here and at head-fi need to understand that the abrasive way that it is often shared is going to keep many from seeing the truth in it.

      I think that is why you tend to see threads like this one full of posts by people arguing from completely different viewpoints with far less involvement by people in the middle.

      Short version: telling someone that they are an idiot because the equipment that they chose makes them happy shouldn't happen regardless of whether you think that they spent too much or not enough. Teaching or sharing information and lecturing or talking down to someone are not the same thing.

      --I am very much interested in the work that is discussed here. I plan on buying a JDSLabs built O2 on Friday. I am interested in the desktop version, but I don't think I have the patience to wait for it.

      --I also already have Schiit Asgard (purchased well before the K701 driver "crumpling" controversy). NWAvGuy, you have indicated that you are interested in testing this amp. I am interested in seeing the results. Is there a way that I could contact you about potentially arranging this testing?

      --I sincerely hope that I didn't cross the line into the preachy condescending style that I criticized above.

      Delete
    7. It would be very nice to see the Asgard tested, if only to act as a warning against "audiophile" approaches to equipment design.

      Delete
    8. Thanks for your comments. I don't want to turn these comments into an extension of the now locked debate at Head-Fi. It's the nature of forums to encourage debate and some topics are more "passionately" debated than others.

      Please excuse my cynicism but there's been evidence in the past the mods/admins at Head-Fi are often rather "indirect" in how they accomplish their goals. They've been known to fill threads with useless "noise" to dilute interest and make threads difficult to follow. They've also baited certain people into making comments that get them banned. So it wouldn't surprise me if they might have arranged for some of the "YOUR WRONG!" shouting to give them an excuse to lock the thread while making it seem like someone else's fault.

      Obviously, it's hard for most of us to know how things go down behind the scenes at Head-Fi. But, in my opinion, their track record is relatively poor. My personal experiences with what some of the staff say in public versus what they say and do privately indicates you cannot accurately judge their actions by their public response (or lack of public response).

      Those who haven't read it might want to check out the Banned at Head-Fi article and also the comments. Many others came forward after I wrote that article with their similar experiences with Head-Fi and some of what happened behind the scenes. Some only messaged me privately. But it all points to Jude and crowd being extremely inconsistent, at times very heavy handed, and mainly interested in protecting their stream of income and free gear from sponsors however they can.

      Delete
  50. http://www.headfonia.com/nwavguys-objective-2-by-jdslabs-and-epiphany-acoustics/

    The review is subjective and to not be taken seriously, I know, but this bit is puzzling me.

    "With the Sennheiser HD650, I even experimented with EQ’ing to get to make it to sound as it usually does with a whole bunch of other amps, but I quickly abandoned that attempt. I really don’t find the Senns to pair well with the O2."

    I'm really curious, has anyone else had any experience of the HD650 sounding different, and I mean as noticeable as this guy makes it out to be, on the O2 compared to other comparable amps? I'd ask on a forum, but I only know about Head-Fi and they don't seem to be fans of the O2.

    ReplyDelete
    Replies
    1. I own HD650s and listen to them often with my O2. I also used the HD650 in my blind comparison of the O2 against the Benchmark DAC1. The HD650, being relatively high impedance, is less likely to have frequency response interaction with amps with a high output impedance. And it's also less likely to tax the current limits of amps. So, in short, I think it's most likely normal sighted listening bias. I'm very confident the HD650 sounds the same on the O2 as the DAC1 and that would extend to lots of other accurate well respected headphone sources like the Violectric amps.

      As I said below, I'll gladly arrange for a public blind test of the O2 against a much more expensive amp. Listerns can use the HD650 and their favorite source and music.

      Delete
  51. Very nice. Well done. Bought it all the way, hahah! :-)

    ReplyDelete
  52. Good April's fool joke at Headphonia:

    http://www.headfonia.com/nwavguys-objective-2-by-jdslabs-and-epiphany-acoustics/

    Wow what a bunch of nonsense! I don't pay attention to those sites, but if they claim a "review by ear", they should do a "blind review by ear". I hate unscientific reviewing.

    BTW, what's up with the Nelson Pass quote?

    ReplyDelete
    Replies
    1. Apparently the O2 simply can't manage the big-amp-esque sound of such paragons of engineering as the Schiit Asgard. In fact, it can't even manage the bass quality of a CMOY and is less detailed than...the Mini3. Perhaps the ODA could include a "Add IMD" button? That said, I suspect the overwhelming majority of the differences can be accounted for with failures to volume-match and the usual review presumption of bias immunity.

      As the above poster said, there's a nice bit of condescending "Real audio designers understand that we need to listen to our products" to close the review.

      Oh well, standard audiophile FUD. Sighted, not even volume matched, and hence completely and utterly meaningless.

      Delete
    2. Thanks Willakan. It's a bit difficult for me to say things like that without being criticized, as understandably, I'm perceived as not exactly unbiased myself on this issue.

      As for Nelson Pass I have a lot of respect for the man. He's shared a lot of his time and knowledge with the DIY community and he's put a lot of time into getting the most out of single-ended power amplifier designs--not an easy task. But, that said, he's also selling expensive amps with his name on them. And, as a rule, a $300 Emotiva likely measures better overall than most, if not all, of his amplifiers. So it stands to reason Mr Pass would choose to emphasize sound quality over specifications.

      I'm going to publishing more soon on this very topic as it's far from black and white. There are several ways to view high-end amps like those sold by Pass.

      Delete
  53. Hey NwAvGuy.
    Would a 5.1 DAC be an option you and your financial investee would consider (assuming this is somewhat profitable for said investee) after the ODAC has been completed?

    I understand that it'd probably be a lot harder then simply running three ODACs in parallel. Along with the input needing to be HDMI/thunderbolt/firewire for lossless 5.1/bandwidth's sake. Nevertheless, would it be ruled out at this stage?

    ReplyDelete
  54. There are no plans for a 5.1 DAC. Sorry.

    The Headfonia review is an interesting read. As I see it, there are five main issues:

    1 - Sighted listening bias is huge. I've provided several examples of well run studies that demonstrate how our brains seriously alter what we hear when we know what we're listening to. See my Subjective vs Objective article. Just like with the Benchmark DAC1 that also measures very well, many people hear what they expect to hear--a "clinical" or "lifeless" sound. But it's much easier to give the DAC1 a good review as it's ten times the price and is not as big of threat to other products. And the much higher price people also helps its cause in terms of listening bias. But, in reality, I'll happily challenge Lieven to a public blind listening test between the O2, DAC1 and any of the Violectric amps. I'm confident he will not detect any difference.

    2 - Some amps do alter the sound (some would say they're "colored"). That especially includes amps with a higher output impedance, those overloading their op amps, using tubes, single-ended designs, or using a virtual ground--including most Cmoys. Even in a blind test these amps might stand out because they're not sufficiently accurate to begin with.

    3 - The concept of "headphone and amp synergy" is flawed in many ways. First of all, most headphone amps are not designed for a specific headphone. They're marketed as being suitable for a wide variety if not most all headphones. Second, even if you follow a reviewer's specific recommendation to pair Amp A with Headphone B that combination only sounded good to THAT REVIEWER USING HIS MUSIC. It's like a wine reviewer saying the Smith 2007 Cabernet goes well with a certain cheese. But with a different cheese he prefers the Wilson 2008 Merlot. The next person might have the opposite opinion. Once you start using headphone amps as non-adjustable equalizers that alter the sound you open up an impossibly subjective can of worms that's more about personal tastes than the product in question. Finally, buying an intentionally "colored" amp to correct for some headphone flaw is very limiting in terms of your ability to listen to other headphones--current or future--with that amplifier. If you buy Lieven's pitch, you might need a different amp for each headphone

    4 - Headphone manufacturers don't design their headphones to require "correction" by a colored amplifier. The entire audio signal chain is designed to be as accurate as possible. The recording engineers mixing and mastering the music we listen to strive to use accurate amplifiers like the O2. If you want to hear the music as the artist and headphone manufacturer intended, you want to keep the signal as accurate as possible. Accurate gear is a transparent window to your music, colored gear forces you to listen to your gear.

    5 - Follow the money. While reading the Headfonia review you're being bombarded with ads for other headphone amplifiers in the right hand column. Headfonia obviously receives revenue from the very industry they're reviewing. While that's not uncommon it is a conflict of interest. Having worked in the industry I can testify there are some unspoken rules that you either follow or risk negative consequences. Just ask Peter Aczel.

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    1. Headfonia is so predictable in their review outcome and will rarely or never rate a lower priced product above a higher priced one. I bet if you sold the O2 amp to them with a very nice enclosure for $2000, suddenly it sounds amazing.

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    2. That's been done several times and that's always the outcome. There's an AES paper where, among other things, they did a "bait and switch" with an amplifier for a group of listeners of an audiophile club. They thought they were listening to an amp costing thousands but it was really a $200 cheap amp hidden away. There will be more on this in my next article. We indeed often hear what we expect to hear. It's unavoidable with sighted listening.

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    3. HI NwAvGuy,

      I agree with the bias vs price correlation. I remember there was a race between a Lamborghini Murcielago vs a plane looking Mitsubishi Lancer FQ400. I personally was expecting the Lamborghini to beat the living crap out of the Lancer... apparently it didn't :)

      On headphones... recently I learned that human perception of frequency response may be a function of sound pressure level. A headphone that may sound right at moderate volumes, may sound way too bright at high volumes. A headphone that sounds veiled at moderate volumes, may sound great at high volumes. Therefore certain colored amps may go well with certain headphone designs (depending on what HRTF they are shooting for). Things get more complicated when headphones are purely designed by ear. However, I also feel that an HP amp should be flat, well extended in frequency, low impedance, and low in distortion/noise characteristics. An inexpensive passive notch filter should be able to correct perceived frequency response to personal taste...

      If HP manufacturers designed a single well behaved HP, and supplied consumers with a few generic passive filters to best suit the HP to their personal tests things would be nice. Instead, they sell you a bunch of different HP with different characteristics due to the housing and many times with the same driver... And many times the housing and physical damping do a sort of mediocre change in frequency compared to what a good passive circuit can do... On the other hand one can probably make more money giving the customer 5 HP, instead of just one with different HP eq jack adapters...

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    4. The frequency response vs volume issue is well documented--originally by Fletcher and Munson. It's very real. If Leiven at Headfonia didn't use an appropriate meter to level match the O2 to the amps he compared it to, and the O2 was a few dB lower in volume, it would inherently sound more "thin" due to the way human hearing works.

      In my opinion headphones to some degree have to be "designed by ear" because they closely interact in acoustic ways with human ears. And, unlike a test dummy and microphone, human ears vary widely in shape, perceptions, abilities, etc. But electronics, like a headphone amp, are not subject to variations in acoustics or the shape of your ears. They will always perform the same for every person that listens to them regardless if they have small ears or large or if they're in a stadium or the bathroom.

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    5. I think I read somewhere (maybe here) that sighted listening can trick your brain into thinking you're listening to something better, so you can tell people a $5 DAC/AMP is actually $5000 and parts of the brain will light up, believing the sound is amazing.

      And I think that's what the audiophile community at large is about, tricking themselves into thinking their gear sounds better, and they're fine spending their money on that.

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    6. Agree. But it is not the end goal of a revenue making company, being HP manufacturer, AMP manufacturer, or any other for that matter, to give the consumer the best product for the best price... The goal is to get revenue. One would think that having the best product for the best price, with the consumer well being in mind, SHOULD yield revenue... Not the case.

      There is a lot of social psychology research money into product development. And that includes naming, packaging, pricing, brand identity, adds, type of community exposure, ... You think there is some weirdness going on with amp companies selling sub-par products at high prices based on weak claims? You should see what really large corporations like Procter&Gamble, Johnson&Johnson do and put their money on.

      I'm an EE myself, and I'm 100% with you on headphone amp design. Buying 100 uneven amps for each of your 100 uneven headphones is not really a philosophy with consumer best interests in mind. Having 1 good amp, for your 1 headphone (sound signature you like), is probably better. If you want different signatures for different content, then make a cheap ol circuit to modify it for you... But don't spend another > $1k on an uneven, questionable amp to get the experience. And don't get me started on cables...

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  55. Did we ever come up with a name for the ODAC / ODA combo?

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    1. There were several suggestions in the comments to the March article but I don't believe any decision. It's a topic best left for the next ODA article and perhaps can be finalized when the panel graphics are determined. We engineers are often not the best at things like product names. But it would be nice to have a consistent way to refer the the pair.

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  56. OUDAC (Objective USB Decktop Amp/DAC) is the one I like personally , seems to make sense. What doesn't make sense to me is the concept of more expensive = better. Why aren't the subjective crowd more interested in blind testing? Maybe they enjoy setting fire to money but I don't. I'm purely interested in enjoying the music.

    As a mediocre mastering engineer as well as a rabid consumer of music, I'm aware of the work that goes in to mixing down then mastering, and I can't see why you'd want to buy an amp to eq (/add distortion) all your albums in the same way. Why not just buy one neutral solid-state amp and a nice EQ adjustable to suit your phones or mood? Or just enjoy what you were supposed to without any further processing. It really baffles me. The pics on Headfonia are always very nice though.

    Can't wait for the OUDAC design to be completed. Am saving to invest in the JDS or Epiphany build.

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    Replies
    1. Because it is part of the audiophile hobby to boast with expensive equipment* that is better than everyone else's.
      *) It seems that for many equipment is more important than music.

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  57. Is there any chance you'll consider support for 88.2 khz?
    Many are now converting SACD images to wav, and 88.2 is preferable to 96 for these.
    If not, which transports with support for 88.2 would you recommend for use with your ODAC/O2Amp?

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    1. The ODAC is basically done at this point, and the USB interface chip unfortunately doesn't support 88.2. It's not something we can fix. Hopefully there will be some newer USB interface chips released.

      One option is using offline (non-real time) high quality sample rate conversion to convert to either 96 Khz or 44.1 Khz. I know 44.1 might seem like blasphemy to an SACD fan, but there really is not an audible difference. You can prove that to yourself with the Foobar ABX comparator that lets you do your own blind comparisons. And plenty of others have explained why it doesn't matter and have done the listening studies to back up their claims. See: http://people.xiph.org/~xiphmont/demo/neil-young.html

      There is some evidence 24 bit formats can be audibly superior. So you might strongly consider 24/44 instead of 24/88 and it also has the advantage of taking up half as much space. Also, if you already software that rips to 88, it's trivial to convert to 44 without any audible artifacts, etc. It's more difficult to convert from 88 to 96.

      I'm not sure which 24 bit DACs support 88.2. I know several use the same chip the ODAC uses and hence don't support it. The HRT DACs might. And I'm fairly sure Centrance does with the DACport and DACmini but you should check to make sure it's supported via USB and not just S/PDIF.

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    2. The Music Streamer II supports 88.2k.

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  58. Just reading through the comments at Headfonia: it struck me (aside from the sudden revelation that nobody liked the O2 with the HD650s all along...which none of the users at Head-Fi seemed to have noticed before...) that out of many of the people who accept the O2 is actually reproducing the input signal, but louder, there's often a feeling of "Ah, but TRUE neutrality sounds horrible! It's more musical when you do X to it."

    Now, there are various ways to disagree with that (such as your rose-tinted spectacles analogy), but it actually strikes me as a valuable opportunity to prove another point. I've been looking for an excuse to learn to program...

    The basic idea is a VST, which can be used with Foobar and the like via free VST wrappers, which allows the addition of precisely controllable intermodular/harmonic distortion spectra to the input signal, as well as providing simulated FR rolloff, with accompanying phase distortion.

    It would go something like this (excluding things like upsampling/parsing file/ect):

    1. Perform FFT on input signal to split into component sinusoidals.
    2. Scale their amplitude according to an equation approximating FR of amplifier.
    3. Create harmonic and intermodular distortion products and scale according to desired levels of distortion. This seems pretty straightforward for harmonic distortion, but looks more complex as far as IMD is concerned.
    4. Recombine everything and output.

    It would certainly be interesting: the next time someone declares spending $3000 on high 2nd-order THD is perfectly rational, one could suggest that they simply simulate it for free in software.

    Anyway, does anything like this already exist? Are there any mathematical/theoretical pitfalls that would make looking at something like this a waste of time?

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    1. Well, in some ways, what you're suggesting has long since been done. You can buy $100 DSP audio processors, like the DSP2024P Effects Processor, that include tube amp profiles and much more. The good ones not only take into account frequency response and distortion but also phase characteristics to recreate spatial effects. The more realistic you want the software model to be, the more complex the DSP work.

      Not surprisingly the more subjective audiophiles consider such DSP to be "synthetic" and hence somehow inferior. But added crud is added crud and added roll off is added roll off. There's litte difference in where it comes from. The true test, of course, is a proper blind test. And, as Bob Carver showed the world many years ago, he could make his cheap solid state amp sound just like a pair of $8000 tube monoblocks by dialing in the right amount of performance degradation. And he did a good enough job even the golden ears at Stereophile had a very difficult time telling the amps apart.

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    2. Its a little more complicated than that. Have a bandlimited signal go through an FFT (make it sufficiently long... say 16k bins). Then try having half the band have one scale, and the rest on another... sort of like a brickwall filter... I can almost guarantee you that you are not going to like what you get. This is because a sharp cut off in the frequency domain corresponds to a lot of ringing in the time domain (including sampled digital time domain). Its kind of related to the fact that a sharp pulse corresponds to a sync function in the other domain.

      One has to be careful with the roll of so that the reconstructed signal looks decent... Lots of papers and studies on this believe me.

      But if careful, you can end up with something really nice... and could replicate quite a few of "audiophile" effects very well... If one has a good understanding of digital filtering, one can do things that analog filters cannot practically do.

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    3. I've seen lots of "tubeifiers" and indeed fantastically complex DSP processors, but I have yet to find one which focuses on simply adding different types of distortion mathematically. Lots of things promise to simulate tube amps and the like, but they're not transparent (in the operational sense rather than the sound quality sense): you can't say "I want a virtual amp with 3% THD, mainly X harmonic at lower frequencies but with increasing Y harmonic as you approach 20khz."

      Those which do exist are often expensive and external or aren't aimed at exactly what I'd want to do.

      The Carver Challenge is very much the thing that got me thinking about it. Going down your full list of things that affect SQ and getting rid of ones that are unlikely to be a problem/very hard to simulate...if I were to tell this hypothetical VST what the distortion spectrum of, say, the Asgard, looked like at 20hz and 20khz, with it interpolating the composition of the distortion as it went between the two, how close would it sound? Would the effects of output impedance need to be simulated too for a close match?

      Most likely a nice idea rather than reality anyhow, unless I can persuade programmer friend that digital signal processing is much more interesting than 3D graphics.

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    4. With how fast processors are now days I don't think it would be too hard to makes a product with basically a UCA202 sort of playback/recording interface with a bit if software that measured amplifier X into load Y and just created a brute force transfer function between the output and the input.

      I'd like to do something like that but since I have very little experience with any halfway modern languages I think that figuring out the programming, compiling, and hardware to software interface would be harder for me to do than the actual math. All the math I think I'd need would be a brute force equation solver like in my trusty graphing calculator but hooked up to my 3.9GHz i7 920 instead.

      I could probably write that kind of thing in TI BASIC or something if it was fast enough and had the inputs and outputs but I have no idea where to start doing that kind of thing on a PC. I must be too old school despite being pretty young. Object oriented languages inspire me to nearly homicidal rage...

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  59. Is it possible for headphones to be designed to compensate for high output impedances. For instance, Beyerdynamic's amp (A1) has an insanely high output impedance of 100 ohms, and is designed for their headphones. I suspect that they must have compensated for that on the headphone end.

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    1. I own Beyer DT770 Pro 80's and can say, without question, they sound fairly awful from a very high impedance source. And I've seen email correspondence with Beyer support that's very inconsistent in their recommendations about impedance. You might try asking them and seeing what sort of response you get (if any). I honestly don't know what's going on with their own headphone amp unless someone felt compelled to conform (almost) to the little followed and largely obsolete IEC 120 ohm standard. It could also be their (very poor) way of trying to offer an amp that would work with their high impedance cans but not literally damage their sensitive low impedance IEMs.

      If you haven't seen it, there's a link in my Output Impedance article to Stereophile's comments on the IEC standard--they basically laughed at it. And likewise the Benchmark paper Sonic Advantages of Low Impedance Headphone Amps is also well worth a read. Perhaps the appropriate product manager at Beyer should also read both articles. I don't know.

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  60. Wow. Can I just say those measurements are INSANELY awesome for a ~$100 DAC? I would stock up on these so that when you stop producing them I can make a huge profit.

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  61. Some comments on the Headfonia article now that I've read it.

    "At $249, the Asgard is not technically as clean as the O2, but it behaves and overall sounds like a bigger amp than the O2." Gotta love that line. I bet is sounds like a bigger amp when your staring at it in a sighted listening comparison with the O2. I also love all of the BS on the last page.

    IIRC he complained about the bass on the Beta 22 as well. I wonder if it's just due to the lack of a treble roll off or something (if not the usual reasons of being a sighted comparison). Obviously accurate amps are not something audiophiles can appreciate. Too bright and not musical enough!!!!!111. Ever heard the term "solid state glare?" :P

    I had to type that twice grr.

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  62. Perhaps it's just the cynic in me, but this is starting to seem more sales-driven than it was when the idea was first introduced.

    ReplyDelete
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    1. What idea are you referring to, the ODAC, Headfonia or something else? Hopefully you picked up this particular article was partially a sarcastic April Fools joke.

      Delete
  63. I've been getting comments twice lately for approval and they're often slightly different. What's happening that's causing people to have to enter their comments twice?

    ReplyDelete
    Replies
    1. If you write the comment before logging in, the site seems to require that you re-input the comment after you log in. That's what happened in my case anyway. And I used the opportunity to slightly clean up my first post.

      Delete
    2. Thanks. The weird thing is even the rejected comments seem to be making it through. I have very little control over the comment input beyond turning them on/off, requiring approval, adding a message, and choosing between embedded or non-embedded comments.

      Delete
  64. I think you need to do an electrostatic amp when time permits,

    this is in all seriousness. Nudge-nudge. I don't know if you've heard electrostatic headphones, but it would be nice to hear your opinion on them. I'll leave it at they're the best, and not because they cost a lot either, dynamic phones definitely do seem to .. Pale in comparison. Would you share your thoughts with me on what you think about the supposedly greatest experience, speaker or headphone, with us?

    Own an O2 with my HD 800 and LCD-2's. Very nice. I've heard many, many amps up to the highly venerable Balancing Act, which was very nice. But I want to give thanks NwAvGuy and express that unless you're a "tube guy", there seems to be an utter obsolescence of dynamic amps up to at least the multi-thousand dollar range.. Coming from somebody who has a lot of experience with (at least hearing 15+ $500 different amps) There is nothing that compares to the O2 in the dynamic world that has a sane price.

    Sorry if that was messy, ^^

    Lastly, what do you think of the Gilmore designs?
    (the T2, KGSSHV (this one most notably as it's all solid state), BH)?

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    1. Thanks for the kind words on the O2. I can't say I agree with all of Gilmore's ideas--especially for dynamic headphone amps. But I do think he probably has among the best DIY electrostatic amps but that's just a guess. That said, I would probably buy one of the lower priced (relatively speaking) Stax amps (the 252 or 323 if I remember my models correctly)--at least for Stax cans. My Stax experience has been limited but I've liked what I've heard. I've had my eye on the SR-207 with either of the above amps.

      It's hard for me to pick a "greatest experience" headphone as many I own, and some I've heard, each have their own particular strengths. One nice thing about headphones, compared to speakers, is it's much easier to have and store several different cans and pull out the ones best suited to the immediate requirements--open or closed back, type of music, comfort, etc. That was one incentive for the O2--one amp to use with any of them.

      Of what I own, if I have to pick just one, it's the HD650. I've heard the HD800 enough to decide they have some advantages (more exciting highs, even more spacious and open, and much higher build quality) and disadvantages (less comfortable, higher listening fatigue, and a bit harsh with poor source material).

      Delete
    2. It would be *seriously* awesome if you could get into the engineering and physics behind 'stat amps sometime after the ODAC, ODA, and you other planned articles are finished.

      I don't really know too much about it and since they're uncommon it's hard to find information that's not either a gushing audiophool impression overly technical and assuming tons of background knowledge.

      It's hard for me to know who to take seriously. I'll find a person who seems to know what they're talking about who will criticize some type of amplifier for a reason I can see is a valid engineering error and then later see them saying that "interconnects will make or break a Stax system" or decry delta-sigma DACs and praise R2R NOS models.

      When I see people saying that the 007 and 009 need an amp with more current capacity than the Lambdas do despite the Lambdas being less efficient and having more capacitance my audiophool BS detector pegs at maximum but since I've never tried those combinations of 'phones and amps and don't understand the physics as well as I do with normal amps I can't really say anything definitive.

      Assuming that it's all audiophool BS the SRM-323s is probably the way to go. According to Stax's specs it has 400Vrms output compared to the SRM-252S' 280Vrms and the only stronger one Stax sells is the SRM-727II at 450Vrms. Its $1200 more and for some strange reason has no feedback on its output stage. Even the audiophools say you should mod it to add the feedback back in. Its supposed to be pretty easy since it's identical to an older model (the 717 IIRC) except for some different jumpers and resistors that remove the feedback.

      Outside of Stax, the Woo Audio ones are deliberately voiced to be tube-y, the HeadAmp BHSE has a huge wait, and the Ray Samuels and Rudistor amps are allegedly terribly designed amp circuits.

      Delete
  65. Been following your blog a long time, so first I wanna say big thanks for posting so much of your knowledge and also for going out and creating these amazing hi-fi products in such a way as no one ever has before.

    Not sure if this is the right place to ask, but since it's the most current article and it also relates to the O2/ODAC/ODA, I'll give it a shot; What is your opinion on after-market/'upgrade' PSU? If an amp/DAC can be powered by plugging it directly into a wall socket, is there a meaningful difference in instead plugging it into some sorta extra PSU unit? Years ago I bought the 'upgrade' PSU along with my first <$100 amp/DAC, because A) the company said it would make the sound way nicer, B) the customer reviews agreed, and C) because 'upgrade' PSU are extremely common units being sold in hi-fi'dom, and since I was new, I thought that those three reasons were more than enough. Since then I've come feel that basically these optional add-on PSUs are basically no different than the whole cable thing, so thus just one more hi-fi snake-oil.

    Reading the tech sections of your blog has been incredibly enlightening and has also sparked my interest since you spend so much time discussing the power side of the components. I understand that how a device handles how its powered makes a difference, but what if any noticeable difference comes from having that power's source come from a special unit plugged into the wall versus just plugged directly into the wall, assuming the item is meant to work both ways?

    Thanks! Again, big ups on the blog!

    Cheers

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    Replies
    1. Thanks for all the praise. I'm about to publish (hopefully in the next few hours) a large article that, indirectly, addresses your question about power supplies.

      Unless the "standard" power supply was so poorly engineered or specified that it's not up to the task upgrading won't help. And, frankly, it would be stupid to sell a product with a grossly inadequate power supply.

      This is especially true for players, pre-amps, and DACs which always require about the same amount of power regardless of volume setting, what they're connected to, etc. With a headphone amp the power requirements can change with the volume and type of headphones. But, again, the power supply should be designed to handle full output into the worst case load.

      The above devices nearly always use regulated power supplies. The regulation filters out any variations in the AC supply. So power conditioners, upgraded supplies, etc. rarely make any difference.

      Where power supplies can make a substantial difference is in high power amplifiers (and receivers) that drive speakers. Their power supplies are typically unregulated. The power supply can also be a large portion of the raw cost and weight of the amplifier so there's a strong incentive in many products to minimize the cost and size.

      The above is why a "110 watt X 7 channel" $500 receiver can't really output 770 watts of power but a 110 watt x 7 channel $3000 power amp probably can. The receiver manufactures usually get creative with their specs. But with all channels driven, the real power per channel is typically only one quarter to one third the rated power (i.e. 25 to 40 watts) unless it's a huge flagship receiver. That's because the power supply is falling on its face when asked to drive all channels at once to full output.

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  66. I've switched from embedded comments to using a pop up window to see if it solves some of the problems with comments lately. The downside is comments are no longer "threaded" and it's a bit less elegant all the way around. Please let me know what you think and check out my latest What We Hear article.

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  67. There are those who will start to build KGSSHV's soon. Which should be an all around better option, on all fronts accept for nostalgia of tubes... than the bhse. No 1-2 year wait, $6,800 + your paying shipping, and 180 watts of displaced heat. Did we also mention it's not a tube circuit designed to sound solid state. I won't say more.

    Needless to say, there is A LOT of hype surrounding the bhse. ALWAYS has a lot of hype. It is a phenmominal amp for the 7's, but on good authority from more than two people who have heard 9's specifically from the BHSE, WES, and KGSSHV, those who have heard from all three found the HV as the one that "brings me closest to the music". There's much more than this, but it's best..

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  68. I just take a peek and I discovered your post. I had a great time reading it. Big thanks for sharing.


    Charles A

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  69. I always become suspicious when headphone-user complain about the bass .
    Bass-heads usually want to FEEL the bass and that just aint gonna happen with cans, unless you turn up the volume enough to start your ears reducing their mid-range sensitivity . That way you DO feel the bass, the insane levels make your skull resonate !

    Anyway, listening-tests are worthless unless the listener publishes his audiogram and documents the levels .

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  70. I'm baffled. Which parts of the article are true and which are false.
    I looked at the ESS document sabrewp.pdf and they seem to have similar unbelievable graphs.

    My heart missed a beat at the mention of Kimber cable but I am beginning to think there was some truth in the measurements after all.

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    1. A good April Fools article starts out appearing true and factual and gradually becomes more unbelievable the further you read. The idea is at some point, hopefully near the end, the reader realizes they've been fooled.

      The measurements for the FiiO and DAC1 are correct. The measurements for the ODAC are fiction. I'll be posting the real ones soon enough.

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  71. Hi NwAvGuy, I've been reading up on your blog's articles for quite some time now. I do wish I had found you before purchasing my iBasso D7, but it's a bit too late for that now...

    Anyway, I'm really excited for your ODAC/ODA combo. Are you planning on testing against the relatively less expensive offerings from Emotiva, Cambridge Audio, and Headroom? I think those would be some interesting comparisons, even if those products are a bit more expensive. These are companies (maybe not HeadRoom) that provide the detailed specifications that you call for.

    Also, having Comment as: Disqus can't hurt, can it? ;P

    ReplyDelete

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