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Nuforce uDac 2 RMAA measurements.

post #1 of 19
Thread Starter 

Since I don't believe this has been done yet, let's get a look at the uDac-2 measurements with RMAA.

http://audio.rightmark.org/products/rmaa.shtml

First, a little background, I purchased a uDac 2 on 21/01/11 on Amazon and received it on 27/01/11 in Beijing, congrats on the fast delivery. And as I said on a previous post, the uDac-2 was a disappointment at first because of numerous audio glitches, dropouts... especially in WASAPI, but like most problems in Windows, they sometimes disappear after a restart (and sometimes reappear later). So, I did those tests in a bug free session. The test was run under Win & using the latest version of RMAA

 

The uDac was set at 100% volume via the windows audio device panel at 24 bit 96 kHz, studio quality, the loop in was the line in of a Macbook Pro, that is to say that the ADC is a Cirrus Logic CS4206A (AB 71), the line in was set at + 0 dB, recording at 24/96. the Headphone out of the uDac 2 was used, and the potentiometer was turned up to around 2 o'clock to get the appropriate volume.

 

As a reference point, the headphone out of the Macbook Pro was used, likewise volume at 100%, set at 24/96, enhancement disabled, it happens to be the appropriate volume for the line in.

The test were run at 16/44 and 24/96. I used the headphone out because it is the way I plan to use the uDac 2, it's line out may give better results (but they are still affected by the potentiometer).

 

A few more words before we begin, the uDac 2 is marketed as having a better potentiometer than the uDac 1 to allow better channel tracking and usability with sensitive IEMs, it turns out that the potentiometer has a huge channel imbalance at between 8 and 9 o'clock where at one point the right channel is 8 dB weaker than the left one (the point was found by using headphone and then measured with RMAA, so it may not be the max point), before 8, it's relatively balanced even if I didn't measure anything. The imbalance slowly rights itself before reaching a plateau around 10 o'clock to 2 o'clock where the left channel is 0.3 to 0.4 dB louder than the right one. Somewhere between 2 and 3 o'clock, the imbalance disappears completely, both channel are matched within 0.1 dB.

For your information, both channels of the headphone out of the Macbook Pro are matched within 0.1 dB. The issue if channel imbalance was also confirmed by ear.

 

Finally, please note that all the information here concerns only m uDac 2 unit, whether it is representative of all uDac 2 is a valid question. Likewise, don't consider my results as gospel since experimentation errors may have occurred.

 

Link to the RMAA files if you want to get a more detailed view than what is below http://www.mediafire.com/?e8pqsktlxabc8ln (PM me if the link breaks).

 

EDIT: Apparently, I'm not the only one to have channel imbalance issues http://www.head-fi.org/forum/thread/533779/nuforce-udac-2-hp-disappointing-using-with-hfi-780-imbalance-issue

 

EDIT: A replacement unit has been sent, I'll update the conclusions once I receive it.


Edited by khaos974 - 1/28/11 at 4:00pm
post #2 of 19
Thread Starter 

RightMark Audio Analyzer test report

 

Testing device SPDIF Interface (4- NuForce µDAC 2)
Sampling mode 16-bit, 44 kHz
Interface DirectSound
Testing chain External loopback (line-out - line-in)
RMAA Version 6.2.3
   
   
20 Hz - 20 kHz filter ON
Normalize amplitude ON
Level change -0.7 dB / -1.0 dB
Mono mode OFF
Calibration singal, Hz 1000
Polarity inverted/inverted



Summary

Frequency response (from 40 Hz to 15 kHz), dB
+0.09, -0.12
Very good
Noise level, dB (A)
-92.3
Very good
Dynamic range, dB (A)
92.9
Very good
THD, %
0.017
Good
THD + Noise, dB (A)
-67.8
Average
IMD + Noise, %
0.088
Good
Stereo crosstalk, dB
-90.2
Excellent
IMD at 10 kHz, %
0.034
Good
General performance
 
Very good

fr.png

Frequency response

Spectrum graph

From 20 Hz to 20 kHz, dB
-5.91, +0.09
From 40 Hz to 15 kHz, dB
-0.12, +0.09

noise.png

Noise level

Spectrum graph

 
Left
Right
RMS power, dB
-91.4
-91.4
RMS power (A-weighted), dB
-92.3
-92.3
Peak level, dB FS
-77.5
-80.0
DC offset, %
-0.0
-0.0

dynamics.png

Dynamic range

Spectrum graph

 
Left
Right
Dynamic range, dB
+92.0
+92.0
Dynamic range (A-weighted), dB
+92.9
+92.9
DC offset, %
-0.00
-0.00

thd.png

THD + Noise (at -3 dB FS)

Spectrum graph

 
Left
Right
THD, %
+0.0180
+0.0160
THD + Noise, %
+0.0384
+0.0375
THD + Noise (A-weighted), %
+0.0413
+0.0398

imd.png

Intermodulation distortion

Spectrum graph

 
Left
Right
IMD + Noise, %
+0.0892
+0.0862
IMD + Noise (A-weighted), %
+0.0483
+0.0470

cross.png

Stereo crosstalk

Spectrum graph

 
Left
Right
Crosstalk at 100 Hz, dB
-91
-89
Crosstalk at 1000 Hz, dB
-90
-88
Crosstalk at 10000 Hz, dB
-84
-83

imdswept.png

IMD (swept tones)

Spectrum graph

 
Left
Right
IMD + Noise at 5000 Hz,
0.0365
0.0357
IMD + Noise at 10000 Hz,
0.0316
0.0312
IMD + Noise at 15000 Hz,
0.0347
0.0337


 
post #3 of 19
Thread Starter 

RightMark Audio Analyzer test report

Testing device Headphones (Cirrus Logic CS4206A (AB 71))
Sampling mode 16-bit, 44 kHz
Interface DirectSound
Testing chain External loopback (line-out - line-in)
RMAA Version 6.2.3
   
   
20 Hz - 20 kHz filter ON
Normalize amplitude ON
Level change -0.9 dB / -0.9 dB
Mono mode OFF
Calibration singal, Hz 1000
Polarity inverted/inverted



Summary

Frequency response (from 40 Hz to 15 kHz), dB
+0.09, -0.09
Very good
Noise level, dB (A)
-93.6
Very good
Dynamic range, dB (A)
93.6
Very good
THD, %
0.0041
Very good
THD + Noise, dB (A)
-69.5
Average
IMD + Noise, %
0.036
Good
Stereo crosstalk, dB
-94.5
Excellent
IMD at 10 kHz, %
0.031
Good
General performance
 
Very good

fr.png

Frequency response

Spectrum graph

From 20 Hz to 20 kHz, dB
-5.91, +0.09
From 40 Hz to 15 kHz, dB
-0.09, +0.09

noise.png

Noise level

Spectrum graph

 
Left
Right
RMS power, dB
-92.7
-92.6
RMS power (A-weighted), dB
-93.6
-93.5
Peak level, dB FS
-79.8
-79.8
DC offset, %
-0.0
-0.0

dynamics.png

Dynamic range

Spectrum graph

 
Left
Right
Dynamic range, dB
+92.7
+92.7
Dynamic range (A-weighted), dB
+93.6
+93.5
DC offset, %
-0.00
+0.00

thd.png

THD + Noise (at -3 dB FS)

Spectrum graph

 
Left
Right
THD, %
+0.0039
+0.0044
THD + Noise, %
+0.0334
+0.0334
THD + Noise (A-weighted), %
+0.0333
+0.0334

imd.png

Intermodulation distortion

Spectrum graph

 
Left
Right
IMD + Noise, %
+0.0365
+0.0364
IMD + Noise (A-weighted), %
+0.0339
+0.0339

cross.png

Stereo crosstalk

Spectrum graph

 
Left
Right
Crosstalk at 100 Hz, dB
-96
-95
Crosstalk at 1000 Hz, dB
-93
-94
Crosstalk at 10000 Hz, dB
-82
-90

imdswept.png

IMD (swept tones)

Spectrum graph

 
Left
Right
IMD + Noise at 5000 Hz,
0.0324
0.0322
IMD + Noise at 10000 Hz,
0.0294
0.0293
IMD + Noise at 15000 Hz,
0.0322
0.0323


 
post #4 of 19
Thread Starter 

RightMark Audio Analyzer test report

Testing device SPDIF Interface (4- NuForce µDAC 2)
Sampling mode 24-bit, 96 kHz
Interface DirectSound
Testing chain External loopback (line-out - line-in)
RMAA Version 6.2.3
   
   
20 Hz - 20 kHz filter ON
Normalize amplitude ON
Level change -0.7 dB / -1.0 dB
Mono mode OFF
Calibration singal, Hz 1000
Polarity inverted/inverted



Summary

Frequency response (from 40 Hz to 15 kHz), dB
+0.02, -0.04
Excellent
Noise level, dB (A)
-96.0
Excellent
Dynamic range, dB (A)
97.5
Excellent
THD, %
0.017
Good
THD + Noise, dB (A)
-72.5
Average
IMD + Noise, %
0.080
Good
Stereo crosstalk, dB
-90.0
Excellent
IMD at 10 kHz, %
0.014
Very good
General performance
 
Very good

fr.png

Frequency response

Spectrum graph

From 20 Hz to 20 kHz, dB
-0.16, +0.02
From 40 Hz to 15 kHz, dB
-0.04, +0.02

noise.png

Noise level

Spectrum graph

 
Left
Right
RMS power, dB
-95.2
-94.7
RMS power (A-weighted), dB
-96.3
-95.7
Peak level, dB FS
-69.1
-68.1
DC offset, %
-0.0
-0.0

dynamics.png

Dynamic range

Spectrum graph

 
Left
Right
Dynamic range, dB
+96.5
+96.2
Dynamic range (A-weighted), dB
+97.6
+97.4
DC offset, %
-0.00
-0.00

thd.png

THD + Noise (at -3 dB FS)

Spectrum graph

 
Left
Right
THD, %
+0.0179
+0.0160
THD + Noise, %
+0.0195
+0.0178
THD + Noise (A-weighted), %
+0.0249
+0.0226

imd.png

Intermodulation distortion

Spectrum graph

 
Left
Right
IMD + Noise, %
+0.0822
+0.0787
IMD + Noise (A-weighted), %
+0.0349
+0.0330

cross.png

Stereo crosstalk

Spectrum graph

 
Left
Right
Crosstalk at 100 Hz, dB
-91
-87
Crosstalk at 1000 Hz, dB
-90
-88
Crosstalk at 10000 Hz, dB
-84
-83

imdswept.png

IMD (swept tones)

Spectrum graph

 
Left
Right
IMD + Noise at 5000 Hz,
0.0187
0.0165
IMD + Noise at 10000 Hz,
0.0131
0.0120
IMD + Noise at 15000 Hz,
0.0130
0.0118


 
post #5 of 19
Thread Starter 

RightMark Audio Analyzer test report

Testing device Headphones (Cirrus Logic CS4206A (AB 71))
Sampling mode 24-bit, 96 kHz
Interface DirectSound
Testing chain External loopback (line-out - line-in)
RMAA Version 6.2.3
   
   
20 Hz - 20 kHz filter ON
Normalize amplitude ON
Level change -0.9 dB / -0.8 dB
Mono mode OFF
Calibration singal, Hz 1000
Polarity inverted/inverted



Summary

Frequency response (from 40 Hz to 15 kHz), dB
+0.00, -0.04
Excellent
Noise level, dB (A)
-101.3
Excellent
Dynamic range, dB (A)
101.4
Excellent
THD, %
0.0035
Very good
THD + Noise, dB (A)
-86.2
Good
IMD + Noise, %
0.0046
Excellent
Stereo crosstalk, dB
-98.3
Excellent
IMD at 10 kHz, %
0.0050
Excellent
General performance
 
Very good

fr.png

Frequency response

Spectrum graph

From 20 Hz to 20 kHz, dB
-0.17, +0.00
From 40 Hz to 15 kHz, dB
-0.04, +0.00

noise.png

Noise level

Spectrum graph

 
Left
Right
RMS power, dB
-100.1
-100.0
RMS power (A-weighted), dB
-101.2
-101.3
Peak level, dB FS
-73.9
-74.2
DC offset, %
-0.0
-0.0

dynamics.png

Dynamic range

Spectrum graph

 
Left
Right
Dynamic range, dB
+99.9
+99.9
Dynamic range (A-weighted), dB
+101.3
+101.4
DC offset, %
-0.00
-0.00

thd.png

THD + Noise (at -3 dB FS)

Spectrum graph

 
Left
Right
THD, %
+0.0032
+0.0038
THD + Noise, %
+0.0038
+0.0043
THD + Noise (A-weighted), %
+0.0046
+0.0052

imd.png

Intermodulation distortion

Spectrum graph

 
Left
Right
IMD + Noise, %
+0.0045
+0.0048
IMD + Noise (A-weighted), %
+0.0033
+0.0033

cross.png

Stereo crosstalk

Spectrum graph

 
Left
Right
Crosstalk at 100 Hz, dB
-92
-95
Crosstalk at 1000 Hz, dB
-97
-97
Crosstalk at 10000 Hz, dB
-82
-91

imdswept.png

IMD (swept tones)

Spectrum graph

 
Left
Right
IMD + Noise at 5000 Hz,
0.0059
0.0060
IMD + Noise at 10000 Hz,
0.0048
0.0044
IMD + Noise at 15000 Hz,
0.0046
0.0043


 
post #6 of 19
Thread Starter 

[DirectSound] SPDIF Interface (4- NuForce µDAC 2)  16 bit / 44.1 kHz
[DirectSound] SPDIF Interface (4- NuForce µDAC 2)   24 bit / 96 kHz
[DirectSound] Headphones (Cirrus Logic CS4206A (AB 71))  16 bit / 44.1 kHz
[DirectSound] Headphones (Cirrus Logic CS4206A (AB 71))   24 bit / 96 kHz

RightMark Audio Analyzer test


Testing chain: External loopback (line-out - line-in)
 

Summary

Test [DirectSound] SPDIF Interface (4- NuForce µDAC 2) [DirectSound] SPDIF Interface (4- NuForce µDAC 2) [DirectSound] Headphones (Cirrus Logic CS4206A (AB 71)) [DirectSound] Headphones (Cirrus Logic CS4206A (AB 71))
Frequency response (from 40 Hz to 15 kHz), dB: +0.09, -0.12 +0.02, -0.04 +0.09, -0.09 +0.00, -0.04
Noise level, dB (A): -92.3 -96.0 -93.6 -101.3
Dynamic range, dB (A): 92.9 97.5 93.6 101.3
THD, %: 0.017 0.017 0.0041 0.0035
IMD + Noise, %: 0.088 0.080 0.036 0.0046
Stereo crosstalk, dB: -90.2 -90.0 -94.5 -97.5


fr.png
 

Frequency response

Spectrum graph

 

ns.png

 

Noise level

Spectrum graph

 

dr.png

 

Dynamic range

Spectrum graph

 

thd.png

 

THD + Noise (at -3 dB FS)

Spectrum graph

 

imd.png

 

Intermodulation distortion

Spectrum graph

 

ct.png

 

Stereo crosstalk

Spectrum graph

 

 


 

This report was generated by RightMark Audio Analyzer 6.0

post #7 of 19
Thread Starter 

Am I surprised of the uDac 2's measurements? Not really, they are coherent* with those Nuforce puts on their website, thus I can't say I am disappointed of my unit because of those figures... Except for the channel tracking. The Udac 2 essentially becomes usable after 10 o'clock with a slight channel correction in Windows.

 

Am I surprised of the Macbook Pro measurements? Not really, my headphones sounded pretty good out of the MBP, and most onboard chips have reached a very good level those days.

 

Does the uDac 2 sound better than the MBP alone? Yes, probably because the headphone amp provides enough power for the headphones, they mostly feel tighter and better controlled, and I could wax more poetic but plenty of people have done so before me, after all this is only a listening impression. And MBP's headphone out tended to pick up stray currents here and there, thus there were often parasites with the sensitive headphones, the uDac gets rid of those problems. The uDac has some background moise from time to time, but you simply need to turn the potentiometer to the min and back to resume normal operations. Note that the measurements were performed with unloaded, they could change if a pair of headphones is attached.

 

Satisfied with the uDac? If it weren't for the channel imbalance, yes, as it stands, I'm forced to attenuate the volume in Windows to make the use the uDac in its potentiometer's useful zone (10 o'clock and beyond). The non flatness of the frequency response at 16/44.1 may encourage some to use the resampling feature in their player of choice, others may consider -1 dB @ 17 kHz and -2 dB @ 18 kHz beyond their hearing ability.

*I suppose the were for the line out.


Edited by khaos974 - 1/27/11 at 4:00pm
post #8 of 19
Thread Starter 

Nearly 2000 views and not a single comment? This almost has to be a record.

post #9 of 19

Have you contacted NuForce about the channel imbalance?  It could be an issue with a run of units -- it's worth checking to say the least.

post #10 of 19
Thread Starter 

I'm not optimistc about them doing something for the .4 dB imbalance, there's a note on their website that indicates that a .5 dB imbalance is acceptable to them, but I have contacted them about the other imbalance issue.

post #11 of 19

Thanks for the measurements, very informative and helpful. I was a bit disappointed with the THD + noise though. But in the end you cannot expect too much from a 100$ unit. The udac is already a bargain. :)

post #12 of 19
Thread Starter 

On the plus side, the THD+N figure is still below the level what transducers can achieve.

post #13 of 19

Thanks very much for the RMAA!

 

I'm somewhat surprised by the severe rolloff at 16khz+.  I realize that this is probably not an audible issue for most people, but what is going on there?  That should not be happening, even at 16/44.  It's there for both the udac-2 and Macbook test...

 

??? 

 

Also, can you do a loaded test with a low impedance headphone?  If you have an IEM with a crossover, even better.

post #14 of 19


 

Quote:
Originally Posted by odigg View Post

Thanks very much for the RMAA!

 

I'm somewhat surprised by the severe rolloff at 16khz+.  I realize that this is probably not an audible issue for most people, but what is going on there?  That should not be happening, even at 16/44.  It's there for both the udac-2 and Macbook test...

 

??? 

 

Also, can you do a loaded test with a low impedance headphone?  If you have an IEM with a crossover, even better.


First, it's *essential* to do a loaded test. I would assume most here (this being head-fi after all) are more concerned with headphone use. And headphone outputs have to be loaded for any sort of meaningful test results. The problem is what to load them with?

 

Loading can make an enormous difference in the results. In my blog you can see a device, when measured with no load, delivers nearly perfect frequency response and impressively low 0.006% THD. But when properly loaded it rolls off quite badly at low frequencies, rises at high frequencies, and has 8 times more THD. We're not talking about small differences here. For more details, please see my blog post on RMAA and scroll down about a third of the way to "TEST LOADS ARE CRITICAL".

 

As for the other numbers and results, like the high frequency roll off, that might be the result of all sort of things and not necessarily the fault of the uDAC 2. RMAA has LOTS of serious problems and limitations. And it's hard to trust the numbers and graphs it blindly spits out unless all sorts of other conditions are controlled and known. Sadly, you usually can't really compare one person's RMAA results to someone else's.

 

Or, to put it another way, I can make a $10 Chinese no-name USB audio device look better in RMAA than a megabuck audiophile outboard DAC. That said, it's also entirely possible the uDAC 2 has a high frequency roll off as displayed. There's no way to know without more testing.

 

And a 0.4 dB channel imbalance is no big deal. A lot of headphones are worse than that--even expensive ones. Generally a 1 dB difference is on the edge of human perception. So anything less is generally considered inaudible. That said, at really low uDAC volume settings, I'm not surprised if there's some audible imbalance--especially when using efficient headphones. I discuss that in my Gain and Headphone Amps/Dacs blog post.

 

I'm going to be doing a more in-depth test of the NuForce uDAC-2 (not the HP version) on my blog. It will be measured with a true professional audio analyzer as well as RMAA.

post #15 of 19


The rolloff is probably the cut-off filter of the RMAA at 20kHz, it is a very sharp slope.  See the uDAC measurement as part of the 25 USB DAC plots.

 

http://www.nuforce.com/hp/docs/review/DAC-Headphone-Amp-Tests-PlotOnly.pdf

Quote:
Originally Posted by odigg View Post

 

I'm somewhat surprised by the severe rolloff at 16khz+.  I realize that this is probably not an audible issue for most people, but what is going on there?  That should not be happening, even at 16/44.  It's there for both the udac-2 and Macbook test...

 

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