tag:blogger.com,1999:blog-6890046273025265768.post5529889450304460265..comments2024-03-18T03:10:30.572-07:00Comments on NwAvGuy: Cmoy eBay Headphone AmpNwAvGuyhttp://www.blogger.com/profile/00309644608738074125noreply@blogger.comBlogger64125tag:blogger.com,1999:blog-6890046273025265768.post-81044086902278217822012-03-05T23:27:53.555-08:002012-03-05T23:27:53.555-08:00The schematic and parts values seemed vaguely fami...The schematic and parts values seemed vaguely familiar. I think the amp you bought on ebay is not a cmoy, but rather an RA-1 clone.<br /><br />http://diyaudioprojects.blogspot.com/2007/08/grado-ra1-headphone-amplifier.html<br /><br />Except .... the feedback resistance is wrong, it should be 470k but ended up 470 ohms, so the gain drops from 6x to unity. Ebay. Shouda' known, right?Anonymoushttps://www.blogger.com/profile/05193319172747977071noreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-80471284924078093532012-01-19T03:44:37.369-08:002012-01-19T03:44:37.369-08:00Ok this is my last comment on this. I compared 2 D...Ok this is my last comment on this. I compared 2 Denon DCD825s last night. Mine has the 4556 with locally regulated power supply and direct coupled output. My friend's player has the 2134 with standard power supply (the PSR has to reject a load of digital hash) and 470uF output caps. After a lot of listening to a range of CDs using my Sonys and his HD600s I think that the direct coupled 4556 Steve Daviesnoreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-81822019663849466152012-01-18T06:27:53.902-08:002012-01-18T06:27:53.902-08:00@Steve, the friend/wife/girlfriend commenting some...@Steve, the friend/wife/girlfriend commenting something different has also been thoroughly debunked as invalid. Our senses are just not that reliable however much we want to believe they are. It would be like walking into a restaurant and saying the chef has switched brands of olive oil because of the smell in the air. And you can't walk into a room and "hear" a headphone amp NwAvGuyhttps://www.blogger.com/profile/00309644608738074125noreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-29494070989851465502012-01-18T02:41:11.711-08:002012-01-18T02:41:11.711-08:00When a friend walks in, listens, looks puzzled, th...When a friend walks in, listens, looks puzzled, then says "What have you done to the bass? The boom has gone. The sound seems better balanced.", I take it to mean that the change is audible. I was careful not to give any clue as to what was changed, yet he described pretty much what I was hearing.<br />And why not? The op amps are driving abnormal loads; 5m cable runs and feedback loopsSteve Daviesnoreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-25579086297891328302012-01-16T17:36:52.319-08:002012-01-16T17:36:52.319-08:00@Steve, believe what you want, but until you do a ...@Steve, believe what you want, but until you do a blind test you really don't know what you're hearing. Look up the BBC McGurk Effect video on YouTube. Our ears can blatantly deceive us. Sibilance is more subtle than hearing "Fa" when the someone is really saying "Ba". Check it out.<br /><br />To answer your question, the dScope analyzer is capable of detecting even NwAvGuyhttps://www.blogger.com/profile/00309644608738074125noreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-67974204323411328512012-01-16T10:14:45.666-08:002012-01-16T10:14:45.666-08:00I don't really think it is as simple as level ...I don't really think it is as simple as level difference. <br />Is it possible that the frequency response of the amplifier driving a reactive load actually peaks then falls? I have some CDs that have an annoying sibilance on vocals and perceived lack of higher frequencies (muted cymbals) with the OPA2134, and with the NMJ4556 there is little sibilance but a lot more of the higher frequency Steve Daviesnoreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-3422360678460236632012-01-16T08:18:04.226-08:002012-01-16T08:18:04.226-08:00@Steve, without doing a level matched blind test (...@Steve, without doing a level matched blind test (something that requires two identical pieces of gear for comparing op amps--i.e. two identical headphone amps with a different op amp in each) you really can't draw any conclusions. It's been proven over and over we humans can't rely on our ears when we know what we're listening to. It's called sighted listening bias and it'NwAvGuyhttps://www.blogger.com/profile/00309644608738074125noreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-42141537905817115392012-01-16T08:07:07.692-08:002012-01-16T08:07:07.692-08:00Having been an OPA2134 fan (I changed all the op a...Having been an OPA2134 fan (I changed all the op amps in my CD player to this chip) I was quite skeptical that the 4556 would sound as good as the OPA2134s. I bought some 4556s in horrible smd packages that would not even fit properly on my carriers and replaced the headphone drivers. The phones are 32R Sonys. The sound is definitely different - there is a lot more detail in the high frequencies Steve Daviesnoreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-7953303220017146942012-01-15T06:13:25.926-08:002012-01-15T06:13:25.926-08:00@Anon, comments like yours help promote myths that...@Anon, comments like yours help promote myths that have no basis in objective fact. Perhaps you should read:<br /><br /><a href="http://nwavguy.blogspot.com/2011/08/op-amps-myths-facts.html" rel="nofollow">Op Amp Myths & Facts</a><br /><br />And then:<br /><br /><a href="http://nwavguy.blogspot.com/2011/08/op-amp-measurements.html" rel="nofollow">Op Amp Measurements</a><br /><br />And then NwAvGuyhttps://www.blogger.com/profile/00309644608738074125noreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-37793265304257960382012-01-14T17:01:51.537-08:002012-01-14T17:01:51.537-08:00This is a ridiculous article. All these supposed ...This is a ridiculous article. All these supposed CMOY amps using an opamp are terrible driving a dynamic load. You can't just place a dummy resistive load on the output then hook a scope up, you have to use mics to get a signal from the cans themselves.<br /><br />Within it's current capability, the two opamps sound quite different directly driving a load, but if at all interested in Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-13216016226742387082011-12-01T21:40:36.460-08:002011-12-01T21:40:36.460-08:00JDS does offer a dual battery option now. It's...JDS does offer a dual battery option now. It's their 2.03 version.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-5583346412577228112011-10-18T21:26:05.542-07:002011-10-18T21:26:05.542-07:00Does JDS offer a dual battery Cmoy? The ones I'...Does JDS offer a dual battery Cmoy? The ones I'm aware of use a single battery and rail splitter which is very different. See: <a href="http://nwavguy.blogspot.com/2011/05/virtual-grounds-3-channel-amps.html" rel="nofollow">Virtual Ground Amplifiers</a>.NwAvGuyhttps://www.blogger.com/profile/00309644608738074125noreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-48853137321871421472011-10-18T20:00:14.701-07:002011-10-18T20:00:14.701-07:00So JDS cmoy and this are virtually the same?? Or t...So JDS cmoy and this are virtually the same?? Or there is a difference?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-89713628202722073622011-10-01T15:40:24.236-07:002011-10-01T15:40:24.236-07:00The JDS Cmoy uses a 20 mA TI rail splitter which i...The JDS Cmoy uses a 20 mA TI rail splitter which isn't up to the challenge with many headphones.NwAvGuyhttps://www.blogger.com/profile/00309644608738074125noreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-71860991253230805262011-09-29T20:55:59.295-07:002011-09-29T20:55:59.295-07:00And the JDS cmoy?
http://www.jdslabs.com/products....And the JDS cmoy?<br />http://www.jdslabs.com/products.php?page=cmoyRafaelnoreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-41639871463910132592011-09-28T22:07:01.199-07:002011-09-28T22:07:01.199-07:00The Cmoy I tested is fairly true to the RA1. There...The Cmoy I tested is fairly true to the RA1. There are other eBay "RA1" amps, however, that use ground splitters. The O2 is a significant step up from any of them including the actual Grado.NwAvGuyhttps://www.blogger.com/profile/00309644608738074125noreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-28660132657074015142011-09-28T20:38:22.488-07:002011-09-28T20:38:22.488-07:00O.k. So that means this RA1 clone on ebay isn'...O.k. So that means this RA1 clone on ebay isn't quite one. Thanks. Still waiting for my O2 to get built. The E7's good, but I'd like to input the Emu 0204's 2V signal into it, hence my interest in those ebay cmoys and the E6. The latter would probably be more useful in portable use once the O2 is done, I guess.Reticulinoreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-25844840657118536662011-09-28T08:10:23.753-07:002011-09-28T08:10:23.753-07:00@Reticuli, the O2 performs even better at 1X gain ...@Reticuli, the O2 performs even better at 1X gain than the measurements I've shown at higher gains. It's main advantages over the dual battery Cmoy are:<br /><br />- Double the output current to better drive lower impedances.<br /><br />- Double the output power dissipation (half the heat per op amp chip) with one IC per channel.<br /><br />- Rechargeable batteries and AC power.<br /><br NwAvGuyhttps://www.blogger.com/profile/00309644608738074125noreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-35572466788490379212011-09-28T03:51:38.525-07:002011-09-28T03:51:38.525-07:00So the real RA1 (and its true clones) uses a rail ...So the real RA1 (and its true clones) uses a rail splitter? I assume it has no added output resistance? The layout on ampedup77's and fred_fred_2004 is obviously indicating they are this same RA1 clone that is distinctly different than the cmoy nwavguy found on ebay. I'm wondering how its performance compares. If anyone spots a DIY vendor on ebay that's selling the ones with the Reticulinoreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-80608615999579198432011-08-20T09:34:35.556-07:002011-08-20T09:34:35.556-07:00Most 4556 amps I've seen (which have been most...Most 4556 amps I've seen (which have been mostly minimalist Cmoys) don't add any output resistance to the 4556. The 4556 by itself is well under my 2 ohm rule of thumb. Only if the designer decides to add resistance would it be higher. Behringer, for example, adds 47 ohms to the output of the headphone op amp in the UCA202. But it uses a much less capable op amp than a 4556.NwAvGuyhttps://www.blogger.com/profile/00309644608738074125noreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-34541539608901684062011-08-20T09:28:07.255-07:002011-08-20T09:28:07.255-07:00Thank you for help.
I know that Behringer's M...Thank you for help.<br /><br />I know that Behringer's Micromon MA400 have NJM4556 for headphone output. Sorry for maybe silly question, but... did this guarantee low output impedance and good perfomance of this headphone amp? <br /><br />Behringer's tech support said me:<br /><br />"The MA400 uses one stereo NJM4556 op amp to drive the output and the manufacturer does not specify Alexanderhttps://www.blogger.com/profile/15159424909912522964noreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-76304692338288177622011-08-20T07:54:14.426-07:002011-08-20T07:54:14.426-07:00I would not design a Cmoy with any other op amp be...I would not design a Cmoy with <i>any</i> other op amp besides the NJM4556. Nothing else even comes close except perhaps the OPA551. The OPA2604 is only rated for 600 ohm loads or higher. The THD is only rated into 1000 ohms. That rules out nearly all headphones. And it has half the current capability of the 4556. It's a very poor choice to drive headphones directly. See my <a href="http://NwAvGuyhttps://www.blogger.com/profile/00309644608738074125noreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-44634085373975908532011-08-20T05:59:10.411-07:002011-08-20T05:59:10.411-07:00This is CMOY with OPA2604 x 2:
http://www.ebay.co...This is CMOY with OPA2604 x 2:<br /><br />http://www.ebay.com/itm/OPA2604-x-2-Headphone-Amp-kits-CMOY-/250842462148?pt=LH_DefaultDomain_0&hash=item3a676037c4<br /><br />Do you think its sound not worse than 4556 Cmoy?<br /><br />OPA2604 is a good amp for this schematic?Alexanderhttps://www.blogger.com/profile/15159424909912522964noreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-53089341197083737142011-08-10T03:28:59.181-07:002011-08-10T03:28:59.181-07:00It is nice to see someone targeting audiophiles wi...It is nice to see someone targeting audiophiles with sensible devices that don't cost a kings ransom to buy. The typical high end hi-fi equipment have prices so ludicrously high, its hard to take it seriously. High end headphone amps that would be overpriced even if they were made of solid gold. You could fill a bath with electronic components for the prices these companies charge. Your amp Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6890046273025265768.post-13447532691447133052011-07-29T09:48:05.919-07:002011-07-29T09:48:05.919-07:00Good info on the 4556...is this the one that you&#...Good info on the 4556...is this the one that you'll be using in the O2? Thanks for taking the time to write all of this up...it's greatly appreciated.J.A. Clarknoreply@blogger.com