X-Fi USB DAC

INTRO: I’ve been testing portable reasonably priced USB partly in the hope of finding one that’s a good match for pairing with my 02 headphone amp. The C-Media based inexpensive USB DACs from FiiO, Turtle Beach and Syba were all disappointing. What happens if you spend a bit more money ($35) for a similar DAC from one of the biggest names in PC audio? Creative offers the X-Fi Go Pro as their “thumb drive” portable DAC. How does it measure up to the C-Media DACs already reviewed?

CREATIVE SOUND BLASTER X-FI GO! PRO THX TRUESTUDIO SB1290: For all the money Creative spends on marketing, and after Apple elegantly slaughtered them in the portable player market, one might think Creative could at least adopt user-friendly product names. I think they only left out “Turbo”, “Audiophile” and “Ultra”. Fortunately the DAC is simpler than the convoluted marketing mess. There’s a whole range of X-Fi products, but I’m just going to call this one the “X-Fi” for simplicity. It’s a lot like the Syba USB DAC with an integrated USB plug, 3.5mm headphone/line out, microphone jack, LED, and nothing else. It does, however, come with a USB extension cable which is handy for accessing recessed USB ports or where the DAC might block other ports. And it has a cover for the USB plug making it look a lot like a Zippo cigarette lighter—more clever Creative marketing targeting old school smokers.

OOOOH THX! Once upon a time THX was a rigorous certification process reserved for some of the best home theater gear. THX amplifiers, for example, were required to deliver certain levels of power, over a wide bandwidth, at low distortion, with all channels driven. Now, sadly, it seems THX is just a logo and/or a software license that manufactures buy to slap on most anything. THX certified wine opener anyone? For the X-Fi it’s about the supplied software rather than the hardware. THX has put their name on a suite of me-too digital audio processing that’s not very different than similar products from SRS Labs, Dolby, and many others including the stuff Creative did on their own years ago. They’re just DSP routines that alter your music in assorted artificial ways. Some might find it useful—especially for gaming or movies with headphones. These sorts of DSP effects, to my ears, nearly always sound cheesy and artificial much like the “cathedral” mode on your home A/V receiver. The THX licensed DSP is is part of the bloatware Creative wants you to install on your PC and has nothing to do with the DAC hardware itself.

BLOATWARE SKIPPED: The last time I installed Creative software on my PC it wrecked all sorts of havoc. It’s even worse than iTunes. Creative’s massive install took over file associations, became the default media player, installed various video CODECs that broke other CODECs, tried to index my music collection and promptly locked up, etc. With Creative having already burned that bridge with me I simply used the X-Fi with native Windows drivers.

WINDOWS INSTALLATION & 24 Bit? The X-Fi installed smoothly in both XP and Windows 7 (minus THX DSP, 3D effects, etc.) without needing any third party drivers. Windows 7 reported it as a “Sound Blaster X-Fi Go! Pro”. Only one sample rate is available, 44100, but interestingly there’s a choice for 16 or 24 bits. Is the X-Fi really capable of 24 bit operation? If so that would be a significant plus as it allows using the PC (or player software) volume control and still, in theory, maintain close to 16 bit resolution to the DAC.

SUBJECTIVE SOUND QUALITY: Running the X-Fi into my 02 headphone amp the sound quality was good with no obvious problems. There was, however, some audible hiss. Connecting headphones directly the results depended on which headphones. My DT770 Pro 80s sounded fairly good, there was not enough power for my HD650s, and my UE SuperFi 5s sounded pretty bad and also revealed audible hiss.

MEASUREMENT SUMMARY: The overall results are substantially better than the C-Media offerings and generally respectable for a $35 DAC. The weak areas are noise, low level linearity, low frequency roll off into 32 ohms, and a somewhat high output impedance. I would not use the X-Fi with any headphones under 60 ohms if you want the best sound quality. It also lacks enough power for a lot of high impedance headphones. I ran several tests with both the 16 and 24 bit modes and could not detect any difference. The letter grades range from A to F where A is excellent and F is Fail (unacceptable):

Measurement	X-Fi Go	FiiO D5	CM119	UCA202	TB Micro II
Freq. Resp. 10K	+/- 0.4 dB A	+/-1.5 dB C	+/-1.0 dB B	+/- 0.1 dB A	+/- 1.0 dB B
Freq. Resp. 33 ohms	+/-5.0 dB D	+/-1.5 dB C	+/-6.0 dB F	N/A	+/- 1.8 dB C
Output Imp Ohms	7.8 C	0.72 A	5.9 C	47 F	0.95 A
Max Output 10K	1.0V	1.5V B	0.95V C	1.12V B	1.34V B
Max Out 33 Ohms	0.75V C	1.4V B	0.68V C	N/A	1.26V B
Max Power 32 Ohms	18 mW C	61 mW B	14 mW C	N/A	50 mW B
THD+N 0 dBFS 10K	0.007% A	0.24% C	0.035% B	0.008% A	0.14% C
THD+N 100hz 10K	0.007% A	0.08% C	0.035% B	0.007% A	0.025% B
THD+N 1Khz 10K	0.007% A	0.08% C	0.035% B	0.007% A	0.02% B
THD+N 1K 33ohms	0.009% A	0.08% C	0.095% C	N/A	0.12% D
THD+N 10Khz 10K	0.009% A	0.04% B	0.090% C	0.009% A	0.11% C
IMD CCIF 10K/33	0.004% A	011% D	0.028% D	0.005% A	0.028% D
IMD SMPTE 10K	0.0005% A	0.80% D	0.012% B	0.002% A	0.02% B
Noise A-Wtd dBu	88.9 C	-90.0 C	-89.0 C	-88.8 C	-93.8 B
-90 dBFS Linearity	1.5 dB B	0.7 dB A	0.9 dB A	3.8 dB C	0.8 dB A
USB Jitter Jtest	VG B	Poor D	Poor D	VG B	Poor D

 

FIRST CLASS:

• Low distortion even at high frequencies.
• Flat frequency response into 10K
• Well behaved DAC filtering
• Relatively low jitter
• Highly portable
• Reasonably priced ($30 – $40)

ECONOMY:

• 24 bit option appears to be useless
• Marginal 7+ ohm headphone output impedance
• Rolls off deep bass into headphones below 60 ohms
• Marginal noise performance and dynamic range
• Marginal low level linearity
• Only 1 Vrms maximum output into 10K

O2 COMPANION: Used with an amp like the O2 with its own volume control, the X-Fi is a reasonable DAC with very flat frequency response, relatively low distortion and very low jitter. If you leave the PC/software volume control at maximum it has enough dynamic range to be quiet enough in most applications. If you want to use software volume controls, however, you might hear some noise in some circumstances.

BOTTOM LINE: The X-Fi Go performs vastly better than any of the three C-Media DACs I’ve tested. It gives the UCA202 a good challenge with similar distortion and even lower jitter while being significantly more portable. The downsides are higher noise, some low level linearity error, and not being suitable for many headphones under 60 ohms or any balanced armature IEMs. Used to drive a headphone amp, or powered speakers, the X-Fi makes a decent DAC—especially if a bit of noise under some conditions doesn’t bother you. Just don’t be fooled into thinking it supports 24 bit operation.

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TECH SECTION

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TECH INFO: I haven’t researched it, but I’m guessing Creative uses their own proprietary DAC chip in the X-Fi Go. Windows 7 thinking it’s capable of 24 bit operation is one clue it’s probably not a typical off-the-shelf part. If someone knows more, please leave a comment?

FREQUENCY RESPONSE: The frequency response with a 10K load (such as a headphone amp) was excellent being down only about 0.4 dB at 20 Khz with none of the filter-related ripple seen in the C-Media DACs. With a 33 ohm load, typical of portable headphones, it’s not so good. The X-Fi is –3 dB at 30 hz which is likely audible. With 16 ohm headphones it would be even worse. This indicates a capacitor coupled output with a cap that’s too small and is unfortunate. But used with a decent headphone amp (or to feed a powered audio system or speakers) the X-Fi is looking great so far:

THD+N vs OUTPUT 1 Khz 16 & 24 BIT MODES: This test starts at 10 mV (around – 40 dBFS) where noise dominates the measurement. The yellow line is with a 10K load and the X-Fi hits almost 1 volt with distortion at only 0.007%. This is a bit lower output than many USB DACs and well below the Redbook standard of 2 Vrms. In theory, 24 bit operation should lower noise and distortion at low levels. Repeating the test with the X-Fi supposedly running at 24 bits as shown by the red trace you can see it’s identical. So, at least for 1 khz THD+N vs Output level, there’s no benefit to 24 bits with the X-Fi. Into 33 ohms distortion is slightly higher but still impressively low. But maximum output is only about 750 mV due to the output impedance (more on that later). The second graph shows the UCA202 and Micro II for comparison (note the horizontal scales are different):

 

THD+N 100 hz 0 dBFS & OUTPUT IMPEDANCE: With the PC volume at maximum, and a 0 dBFS input, the X-Fi produces about 1 Vrms at very low distortion (shown in yellow). The harmonics are below the magic –80 dB threshold. Even the ultrasonic components are below –80 dB. With a 15 ohm load, the output drops to 0.65 Vrms indicating an output impedance of 7.8 ohms at 100hz. Part of that is the output capacitor. At 1 khz it’s slightly better at 7.1 ohms. This is a marginally high output impedance and is similar to the iPod Touch 3G. Following the “1/8th Rule” the X-Fi should ideally only be used with headphones that are 60 ohms or higher. It’s an especially poor match for Balanced Armature IEMs such as Etymotic, Shure, Ultimate Ears, Westones, etc. The output impedance, and capacitor coupled output, explains why my Ultimate Ears didn’t sound quite right. But, just like the frequency response above, used with a headphone amp the X-Fi will work reasonably well:

THD+N vs FREQUENCY: Here’s the THD+Noise plotted from 20 hz to 20 Khz into 10K (yellow) at 775 mV (0 dBu) and 33 ohms (blue). The 10K plot is impressively flat and entirely below 0.01% which is very good performance for such a small inexpensive DAC. It’s similar to the UCA202 up to 5Khz, and notably better above 5 Khz. Into 33 ohms you can see the effect of the electrolytic output capacitor increasing distortion at low frequencies and the amp apparently doesn’t like to drive low impedances above 13 Khz (it was likely clipping). So, once again, the X-Fi does fairly well if it’s driving an amp, but not so well driving headphones. The second graph shows the UCA202 and Micro II for comparison:

SMPTE IMD 10K: The X-Fi does very well here with everything around –90 dB or lower (please ignore the errors in the caption):

 

SMPTE IMD 33 OHMS: Even into 33 ohms, the X-Fi still does fairly well. The output capacitor is causing some trouble as can be seen by the 2nd harmonic at 120 hz just above –70 dB but that’s relatively benign THD. The IMD is still extremely low:

CCIF IMD 44 Khz 10K: The X-Fi also does well here for an inexpensive DAC into 10K. It’s particularly amazing the side bands to the high frequency signals are below –100 dB! The overall result, due to the higher difference component at 1 Khz, is not as good as the UCA202 but they’re very close. They’re both massively better than any of the C-Media DACs such as the FiiO D5 shown in the third graph for comparison:

 

CCIF IMD 44 Khz 33 Ohms: The X-Fi also does well here driving 33 ohms and very similar to the result above into 10K:

NOISE & LINEARITY: The X-Fi is a bit disappointing for noise at about –89 dBu A-Weighted and 50 uV of raw noise into most any load. This is no better than the $12 Syba DAC. It’s also slightly worse than average for linearity with a 1.5 dB error but that’s not likely to be audible and is still better than the UCA202’s error. I repeated this test operating (supposedly) at 24 bits and got the same result. Consistent with the distortion sweep, it’s apparent the supposed “24 bit” mode is just just creative marketing—pardon the pun. The X-Fi, in either mode, falls well short of of the theoretical 96 dB total dynamic range for 16 bits. The raw dynamic range is 1V/50uV or only 86 dB which yields an Effective Number Of Bits (ENOB) of only 14 bits. This is a bit noisier than even the UCA202 which already isn’t especially quiet (shown in the second graph for comparison). If you plan to use the X-Fi by itself, or use a software volume control with an external amp, you will hear some hiss under some circumstances:

 

JITTER: Here’s the spectrum from the dScope’s J-Test for jitter. The two things to look for are the number and level of symmetrical sidebands and the “spread” at the base of the 11025 hz signal. The second graph is UCA202’s jitter for comparison. The X-Fi does a significantly better job all the way around. The sidebands are lower in level and the spread is significantly less. This is excellent jitter performance for a cheap USB DAC:

 

24 BIT OPERATION: The X-Fi reports to Windows supporting 24 bit operation but no matter what I tried I couldn’t get anything but around 14-15 bit performance from it. Perhaps the driver is sending 24 bits over USB but the X-Fi Go might be simply discarding the 8 least significant bits or otherwise is unable to do anything with them. That’s a disappointing result and some might argue deceptive. If the X-Fi really is receiving 24 bits all the way to the DAC it might be the DAC and analog performance are poor enough they’re masking any benefit. But even if that’s the case, I would still expect to see lower THD at low input levels from reduced quantization distortion and I did not.

RESAMPLING: Creative has a reputation for re-sampling 44 Khz to something else—either on the PC side or in their hardware. I didn’t see any signs of that with the X-Fi Go. It only supports 44 Khz and if that wasn’t its native sampling frequency you would expect whatever that is (i.e. 48 Khz) would be reported to Windows. In addition you can see a 44 khz component in the spectrum graphs indicating that’s what the DAC is really running at.

TECH COMMENTS: Used to drive an amp like the O2, powered speakers, or other gear with a line input, the X-Fi Go! is a decent DAC with the exception of mediocre signal-to-noise numbers. If you leave the software volume at maximum and control the volume from the amp/speakers/etc. it should have enough dynamic range for most applications. I put it slightly ahead of the Behringer UCA202 in most regards. The maximum output is a bit limited but most amps should still have enough gain. I would not recommend it to drive headphones under 60 ohms and especially not balanced armature IEMs. It also does not have enough output for a lot of higher impedance headphones including the popular Sennheiser HD600/650.

FiiO D5 DAC

INTRO: This is another article in a series of inexpensive USB DAC reviews including the Turtle Beach Micro II and Syba C-Media CM119. Like both of those DACs, it uses yet a different version of an all-in-one C-Media chip (the CM108). So how does FiiO’s least expensive USB DAC measure up against it’s peers?

FiiO D5 USB DECODER: The D5 is a bit different than the other two C-Media DACs. It doesn’t plug directly into the USP port but instead has a short detachable USB cable using a mini USB plug allowing use of other cables. And, true to their tradition, FiiO manages to include several extra features not found elsewhere at this low price. The build quality is impressive using a full metal enclosure instead of plastic. FiiO also includes volume up/down buttons and mute buttons for the output and microphone. There’s an LED that shows it’s been acknowledged by the operating system and another for the Mic Mute. Plus you get two microphone jacks instead of one, a headphone out, a separate line out, and a coaxial digital output. When you consider the D5 has the same $25 street price as the Turtle Beach Micro II, FiiO gives you a lot more features.

FiiO D5 VOLUME CONTROL: The volume control isn’t a “local” volume control in the analog domain after the DAC (as in say the NuForce uDAC-2). Instead it’s really just a remote control for your PC’s volume control. Pressing the up and down buttons on the D5 changes the volume settings for the D5 in Windows (I didn’t test OS X or Linux). So it does not help preserve full 16 bit resolution at lower volume settings. Using the controls on the D5 is no different than using your PC’s volume control which causes a reduction of bit resolution at anything but full volume. Still the volume buttons could be useful, especially if you use a long USB cable and the D5 is located away from the PC or allowing volume adjustment without turning the screen on or logging onto a “locked” PC.

WINDOWS INSTALLATION: The D5 installed smoothly in both XP and Windows 7 without needing any drivers. Windows reported it, interestingly, as a “C-Media USB Headphone Set”. The only sample rates and bit depths available are 16/44 and 16/48 as shown to the right in Windows 7 (click for larger).

SUBJECTIVE SOUND QUALITY: There was moderate hiss and noise with my Ultimate Ears IEMs and it was noticeably worse than the Turtle Beach Micro II and about the same as the Syba CM119. The sound quality seemed similar to the Micro II with its odd dynamic range control turned off but the D5 has more output and seemed to sound a bit better driving 16 ohm headphones than the Syba CM119. A blind test would be required to know for sure, but I’m fairly sure the D5, like the CM119 and Micro II, has some audible flaws.

MEASUREMENT SUMMARY: The overall results were not very impressive and generally similar to the Turtle beach Micro II and Syba CM119 which use two other chips from C-Media. This doesn’t speak well for C-Media based products when three different DACs, using three different C-Media chips, all have significant problems. There are some differences between the three. The D5 has the highest line and headphone output voltage and the lowest output impedance but the Micro II and CM119 have better frequency response into a line level load. The CM119 does especially poorly with lower impedance headphones. Here are the results compared to the $12 CM119, $25 Turtle Beach Micro II, and the $30 Behringer UCA202. The scores are “A” (excellent) through “F” (unacceptable):

Measurement	FiiO D5	CM119	UCA202	TB Micro II
Freq. Resp. 10K	+/- 1.5 dB C	+/- 1.0 dB B	+/- 0.1 dB A	+/- 1.0 dB B
Freq. Resp. 33 ohms	+/- 1.5 dB C	+/- 6 dB F	N/A	+/- 1.8 dB C
HP Output Imp	0.72 Ohms A	5.9 Ohms C	47 Ohms F	0.95 ohms A
Max Output 10K	1.5 Vrms B	0.95 Vrms C	1.12 Vrms B	1.34 Vrms B
Max Output 33 Ohms	1.4 Vrms B	0.68 Vrms C	N/A	1.26 V B
Max Power 32 Ohms	61 mW B	14 mW C	N/A	50 mW B
THD+N 0 dBFS 10K	0.24% C	0.035% B	0.008% A	0.14% C
THD+N 100hz 10K	0.08% C	0.035% B	0.007% A	0.025% B
THD+N 1Khz 10K	0.08% C	0.035% B	0.007% A	0.02% B
THD+N 1Khz 33ohms	0.08% C	0.095% C	N/A	0.12% D
THD+N 10Khz 10K	0.04% B	0.090% C	0.009% A	0.11% C
IMD CCIF 10K/33	011% D	0.028% D	0.005% A	0.028% D
IMD SMPTE 10K	0.80% D	0.012% B	0.002% A	0.02% B
Noise A-Wtd dBu	-90.0 C	-89.0 C	-88.8 C	-93.8 B
-90 dBFS Linearity	0.7 dB A	0.9 dB A	3.8 dB C	0.8 dB A
USB Jitter Jtest	Poor D	Poor D	Very Good B	Poor D

FIRST CLASS:

• It’s cheap
• Nice build quality
• Volume & Mute controls
• Coaxial digital output

ECONOMY:

• Likely worse than many built-in (motherboard) sound outputs
• Significant low frequency roll off from headphone and line outputs
• High overall distortion, especially at low and high frequencies
• Relatively noisy
• Relatively high jitter

BOTTOM LINE: The extra features, especially the Mic Mute button, make the D5 especially well suited for things like Skype and web chat. But, otherwise, it’s external features and impressive build quality are only “skin deep”. What’s inside is yet another poorly performing C-Media chip. Of the three C-Media based USB DACs I’ve tested this one has the most features and highest output but is slightly less laptop friendly for portable use. Each of the C-Media DACs I’ve tested has a few unique relatively strengths and weaknesses. See the Measurement Summary above and Tech Section below for more details. As a secondary audio source for non-critical applications, or perhaps as a primary source for voice chat, Skype, etc, the D5 is a reasonable choice. For high quality audio, however, the Behringer UCA202’s line outputs perform far better for about the same price. And, as documented in my next two reviews, there are some better choices for portable USB “thumb DACs” for only slightly more money.

 

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TECH SECTION

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TECH STUFF: Based on information from the web, the D5 appears to use the C-Media CM108. Like the CM119 and CM102, used in the Syba and Micro-II respectively, it’s a fully integrated single chip that does everything necessary for a USB headphone DAC with a few extras thrown in. The volume control is simply another USB endpoint to allow remote control of the PC operating system volume and mute control. This is natively supported in Windows XP, Vista and Win 7 with no special drivers.

HEADPHONE TESTS: As with the other recent DAC tests, I used a 33 ohm load to represent typical portable headphones in the 16 – 80 ohm range. I also spot checked a few results into other impedances from 15 to 600 ohms. These tests were made from the headphone jack.

LINE OUT TESTS: I used 10K which is the typical input impedance of many headphone amps, such as the O2, and powered speakers. Performance into 22k or 50K loads will be very similar. I ran a few tests at 100K. I used the line out jack for these tests.

FREQUENCY RESPONSE: The other two C-Media based DAC’s had relatively flat low frequency response into 10K but not the D5. From either output it rolls off the bass so it’s down about 3 dB at 20 hz. This implies an undersized coupling capacitor that’s “upstream” of the line out buffer and headphone amp. Some might argue this amount of roll off is inaudible as the ear is less sensitive at very low frequencies, but it’s still disappointing. It means significant phase shift much higher in the audio spectrum and with headphones and recordings that go down to 20hz, you just might hear the loss of deep bass. The high frequency performance suffered the same poor filtering, ripple, and early roll off as the other two C-media DACs. Again, this will create significant phase shift in the audio range. Besides the line output roll off, the other big difference is the 33 ohm headphone load didn’t change the low frequency roll off. So apparently it’s a direct coupled headphone output. The second graph shows the Micro II for comparison. Note the Micro II is flat to below 10 hz into 10K and even does a bit better into 33 ohms:

 

THD+N vs OUTPUT: The D5 has slightly higher maximum levels than the Micro II but somewhat more distortion into 10K. The headphone jack into 33 ohms managed a relatively impressive (for this class of product) 1.4 Vrms. Into 15 ohms that dropped to 1 Vrms before hitting 1 % THD and into higher impedances it would hit 1.5Vrms. Power levels into 16, 32, 80, 150, 300 and 600 ohms are 63 mW, 61 mW, 28 mW, 7.0 mW and 3.7 mW respectively. While the headphone jack has more output than average, the distortion from both jacks is disappointingly high—generally around or well above the 0.05% goal. The second graph shows the Micro II for comparison (the trace colors are swapped and horizontal scales different):

 

100 hz 0 dBFS THD+N & OUTPUT IMPEDANCE: The first graph shows the line output can mange the same 1.5 Vrms as the headphone output into high impedance loads. At 0 dBFS the distortion was 0.24% which isn’t great but I’ve seen worse. At least the worst of it is the 2nd harmonic. In the second graph the D5 headphone output is over 1% THD at 1.04 Vrms. Removing the load increases the output to 1.09 Vrms for an output impedance of 0.72 ohms. This is fairly impressive and is another sign there are no output capacitors. The third graph shows the Micro II for comparison:

 

THD+N vs FREQUENCY: The D5 did especially poorly on this test at 0 dBu (775 mV). There’s little difference between the line out jack into 10K and the headphone output into 33 ohms. Both are around 0.06% to 0.10% over most of the audio spectrum and much worse below 100 hz and above 14 khz. This is not what I would call a “clean” DAC. As can be seen by the second graph of the Micro II, it’s significantly worse than even similar C-Media peers. The third graph shows the $30 Behringer UCA202 which has about twenty times less distortion (0.007%) from its line output jacks. An extra $5 buys much better performance despite the UCA202 being a much older design:

 

SMPTE IMD 33 OHMS: Even at only around 400 mV the dScope’s calculated SMPTE value of nearly 0.8% was pretty awful. Some of the IMD products clustered next to the 7 Khz signal are well above the desired –80 dB, as is the THD from the 60hz signal. The rest of the spectrum isn’t so bad. While the calculated value is higher, the spectrum is very similar to the Micro-II:

 

CCIF IMD MICRO II 44 Khz 33 Ohms: The D5 wasn’t quite as awful as the Micro II on this test but it was still fairly similar with lots of distortion products above –80 dB. This is rather poor performance:

 

CCIF IMD MICRO II 44 Khz 10K: Into 10K the CCIF IMD is only slightly better than into 33 ohms above. This is similarly bad to the CM119 and Micro II. The 48 Khz sampling rate was also similar to the Micro II. The second graph shows the Behringer UCA202 for comparison and more how it should look:

 

NOISE & LINEARITY: The weighted noise of the D5 was about 5 dB worse than the Micro II and very similar to the Syba CM119. This is marginal noise performance but is still acceptable for some applications and similar to the UCA202. The linearity was very similar to the Micro II and CM119 with less than 1 dB of error. The second graph shows the Micro II for comparison:

 

JITTER: Here’s the spectrum from the dScope’s J-Test for jitter. The result shows a lot of low frequency jitter (“spread” in the 11025 hz signal) almost identical to the Syba CM119. It’s much worse than average even compared to the $30 UCA202. At least the frequency accuracy (clock accuracy) is very good as shown by the frequency reading on the left. The second graph shows the UCA202 for comparison. Note how the “spread” is confined to below –118 dB on the UCA202 but reaches up beyond –70 dB with the D5:

 

TECH SUMMARY: Having reviewed the Turtle Beach Micro II, Syba CM119, and now the FiiO D5, it’s fairly obvious three different C-Media USB DAC chips all suffer some of the same major weaknesses. They include:

• Poor High Frequency and IMD Distortion
• Poor Jitter Performance
• Poor High Frequency Response
• Poor High Frequency Filtering (frequency response ripple in the audio band)
• Excessive Phase Shift In The Audio Band
• Excessive Low Frequency Roll Off Via Headphone Outputs (and line output for the D5)

To be honest, I would not choose any of these DACs for myself except for voice chat or a similar non-critical application. And for that use, the FiiO D5 is probably the winner because of its extra controls and features. Otherwise all three C-Media based DACs offer relatively poor audio performance. It’s likely most computers have better sound hardware built in—especially if it’s by Realtek, Intel, or Creative. The relatively poor performance of these three C-Media DACs also makes me wonder about C-Media in general. Some high end DACs, like the Schiit Audio Bifrost, use C-Media chips and I have to wonder if they too have excessive jitter, etc? Check back soon for two more DAC reviews that offer better performance.

C-Media CM119 DAC

INTRO: This is another in a series of inexpensive USB DACs such as the Turtle Beach Micro II I reviewed a few weeks ago and the Behringer UCA202. It’s the least expensive DAC I’ve tested with a street price around $13. This example is from Syba but there are similar products based on the same C-Media CM119 chip. So how does it measure up against the more expensive Micro II?

SYBA C-Media CM119: The CM119 is not only the cheapest USB DAC I know of but also the smallest. It's smaller than many flash thumb drives and has only microphone and headphone/line out jacks. The USB plug is part of the DAC. The housing is translucent and there’s a green LED inside that lights up when the CM119 is recognized by Windows. There’s no volume control or other controls. It doesn’t come with any accessories and should work fine on most PC’s without deeply recessed USB jacks. It may block access to nearby jacks as it’s considerably more bulky than a typical USB cable. If you have a jack problem, you can always get a USB extension cable or simply get a DAC that comes with such a “pigtail” like the Turtle Beach Micro II and others.

WINDOWS INSTALLATION: The CM119 installed smoothly in both XP and Windows 7 without needing any drivers. Windows reported it as a “Generic USB Audio Device”. The only sample rates and bit depths available are 16/44 and 16/48 as shown to the right in Windows 7 (click for larger).

SUBJECTIVE SOUND QUALITY: There was moderate hiss and noise with my Ultimate Ears IEMs and it was noticeably worse than the Turtle Beach Micro II. The sound quality with balanced armature Ultimate Ears and Mee M11+ 16 ohm dynamic IEMs was not very good. The bass performance was poor and the highs seemed noticeably harsh and “edgy”. Using the CM119 to drive my O2 amp was notably better but it still didn’t sound quite right.

MEASUREMENT SUMMARY: The overall results were not very impressive and in some ways worse than the already marginal Micro II. The CM119 struggles with headphones below 80 ohms resulting bass roll off and more distortion. The output impedance at 100 hz is marginally high while the high frequency distortion and jitter are relatively poor. Here are the results compared to the$25 Turtle Beach Micro II and the $30 Behringer UCA202. The scores are “A” (excellent) through “F” (unacceptable):

Measurement	CM119	UCA202	TB Micro II
Freq. Resp. 10K	+/- 1.0 dB B	+/- 0.1 dB A	+/- 1.0 dB B
Freq. Resp. 33 ohms	+/- 6 dB F	N/A	+/- 1.8 dB C
HP Output Imp	5.9 Ohms C	47 Ohms D	0.95 ohms A
Max Output 10K	0.95 Vrms C	1.12 Vrms B	1.34 Vrms B
Max Output 33 Ohms	0.68 Vrms C	N/A	1.26 V B
Max Power 32 Ohms	14 mW C	N/A	50 mW B
THD+N 0 dBFS 10K	0.035% B	0.008% A	0.14% C
THD+N 100hz 10K	0.035% B	0.007% A	0.025% B
THD+N 1Khz 10K	0.035% B	0.007% A	0.02% B
THD+N 1Khz 33ohms	0.095% C	N/A	0.12% D
THD+N 10Khz 10K	0.090% C	0.009% A	0.11% C
IMD CCIF 10K/33	0.028% D	0.005% A	0.028% D
IMD SMPTE 10K	0.012% B	0.002% A	0.02% B
Noise A-Wtd	-89.0 dBu C	-88.8 dBu C	-93.8 dBu C
-90 dBFS Linearity	0.9 dB A	3.8 dB C	0.8 dB A
USB Jitter Jtest	Poor D	Very Good B	Poor D

FIRST CLASS:

• It’s cheap & simple
• It’s small and highly portable

ECONOMY:

• Likely worse than many built-in (motherboard) sound outputs
• Significant low frequency roll off with headphones under 80 ohms
• High overall distortion, especially at low and high frequencies
• May not fit recessed USB jacks or may block other jacks
• Relatively noisy
• Relatively high jitter

BOTTOM LINE: It was interesting to see how much USB DAC $13 will buy. It’s half the price of the Turtle Beach Micro II and has relatively similar performance. The CM119 at least doesn’t suffer from the Micro II’s dynamic range problem. But unless you have an especially lousy headphone output on your PC, the CM119 might be a step backwards. It could be useful as a second sound source allowing routing say your PC’s system sounds to inexpensive desktop speakers. It’s also OK for casual listening with inexpensive headphones or for skype/chat use. But for high quality listening, especially with headphones below 80 ohms, there are much better options for not much more money. Check back for more DAC reviews soon.

 

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TECH SECTION

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C-MEDIA CM119: The CM119 chip in this Syba DAC is similar to the CM102 in the Turtle Beach Micro II. Both integrate the USB interface, DAC, filtering, and headphone “amp” all on a single chip. While this keeps the size and price down, the performance isn’t that great. At least the CM119 doesn’t default to having dynamic range compression enabled like the CM102 in the Micro II. Many motherboard chipsets, like the better ones from Realtek, offer better overall performance.

LOADS USED: I used a 33 ohm load to represent typical portable headphones in the 16 – 80 ohm range and at 10K which is the typical input impedance of many headphone amps, such as the O2, and powered speakers. Performance into 22k or 50K loads will be very similar. I ran a few spot checks at 15 ohms, 80, 150, 600 and 100K ohms even if the results are not always shown in the graphs.

FREQUENCY RESPONSE: The frequency response with a 10K load (such as a headphone amp) at 16/44 is acceptable but not great. It’s down –1 dB at about 15 Khz. The steep roll off above 12 Khz is typical of a cheap DAC running at 44 Khz and is due to cost savings in the digital and analog filters and similar to the Micro II. This will likely create significant phase shift in upper audio range. The slight peak around 8 Khz is also disturbing and likely indicates poor DAC filtering. The biggest problem is what happens to the bass when you plug in headphones. The low frequency roll off is even worse than the Micro II. This is likely because the small size and/or tight budget didn’t leave much room for properly sized output capacitors. Into 16 ohms it’s 3 dB down at a very audible 100 hz. Into 33 ohms it’s –3 dB at 50 hz and – 6 dB at 20 hz which could still be audible with good headphones. Into 80 ohms it’s –3 dB at 20hz which is marginal but acceptable. With higher impedance headphones the bass response would be OK. The second graph shows the Micro II for comparison:

 

THD+N vs OUTPUT: The CM119, into 10K, is even worse than the Micro II. The distortion is fairly high at low levels and doesn’t fall below the desired 0.05% line until about 400 mV and hits a maximum output of 950 mV at 0 dBFS and full volume. Into 33 ohms the distortion is always above 0.05% and the max output is about 880 mV. This works out to 48 mW into 16 ohms, 24 mW into 32 ohms, 9 mW into 80 ohms, 5 mW into 300 ohms and 2.5 mW into 600 ohms. The second graph shows the Micro II for comparison (the trace colors are swapped):

 

100 hz 0 dBFS THD+N & OUTPUT IMPEDANCE: The undersized output capacitors hurt the CM119 at 100 hz in this test. Into 15 ohms it only managed 680 mV at full volume and 0 dBFS. But into 100K it managed 950 mV. That works out to a relatively poor output impedance of 5.9 ohms at 100 hz. At 1 Khz, where the output capacitors were much less of a problem, the output impedance is 1.1 ohms. The distortion was also relatively high—again partly due to the output capacitors. The second graph shows the Micro II for comparison which has significantly more output and a lower output impedance:

 

THD+N vs FREQUENCY: The CM119’s THD+Noise plotted from 20 hz to 20 Khz into 10K (yellow) was very similar to the Micro II and showed the same strange behavior above about 5 Khz. Into 33 ohms (blue) it was even worse than the Micro II hovering around or above 0.1%. This is relatively poor performance but might be acceptable for non-critical applications. The Micro II and Behringer UCA202 are shown at 10K in the second graph for comparison:

 

SMPTE IMD 33 OHMS: The result here is marginal. The third harmonic of nearly –70 dB at 180 hz is the biggest cause for alarm. The even bigger spike at 120 hz is more benign 2nd harmonic distortion which is less likely to be audible. The spikes above and near –80 dB around the 7 Khz signal are true IMD and also not a good sign. Overall, the CM119 scores a better reading on this test than the Micro II but that might be partly due to the slightly lower output level. This test was run at full volume at the highest digital output possible (just under 0 dBFS combined) but because of the undersize output capacitors, and lower overall output, the CM119 could only manage 613 mV. The second graph shows the Micro II for comparison at 0 dBu (775 mV) with a considerably bigger “IMD mountain” around the 7 Khz signal:

 

CCIF IMD MICRO II 44 Khz 33 Ohms: The CM119 wasn’t quite as awful as the Micro II on this test but it was still really bad with lots of distortion products above –80 dB. As with the SMPTE test above, I suspect the lower level helped out the CM119. The second graph shows the Micro II:

 

CCIF IMD MICRO II 44 Khz 10K: Into 10K the CM119 was nearly identical to the Micro II but neither is very respectable. The 48 Khz sampling rate was also similar to the Micro II. The second graph shows the Micro II for comparison while the third graph shows the vastly better performance of the $30 Behringer UCA202:

 

NOISE & LINEARITY: The weighted noise of the CM119 was about 5 dB worse than the Micro II and the un-weighted noise was about 3.5 dB higher. This is marginal noise performance but is still acceptable and similar to the UCA202. The linearity was very similar to the Micro II with less than 1 dB of error. The second graph shows the Micro II for comparison:

 

JITTER: Here’s the spectrum from the dScope’s J-Test for jitter. The result shows a lot of low frequency jitter (“spread” in the 11025 hz signal) but it’s slightly better than the Micro II. Still, it’s much worse than average even compared to the $30 UCA202. At least the frequency accuracy (clock accuracy) is very good as shown by the frequency reading on the left. The second graph shows the Micro II while the third graph shows the UCA202 for comparison. Note how the “spread” is confined to below –118 dB on the UCA202 but reaches up beyond –70 dB with the C-Media DACs:

 

TECH COMMENTS: The CM119 performs similarly to the marginal Turtle Beach Micro II but with even more severe low frequency roll off into headphones and even higher overall distortion. Used to drive an amp, powered speakers, or perhaps fairly sensitive dynamic headphone of 80 ohms or more it’s marginally acceptable for a low cost DAC. But it’s best used for non-critical applications like voice chat, Skype, etc. For high quality applications driving an amplifier or powered speakers the UCA202 offers much better overall performance. Check back for more DAC reviews soon.