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Audio-GD NFB-11.38 Performance Edition Measurements (DAC, Preamp & Headamp)

VintageFlanker

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Audio-GD NFB-11.38 Performance Edition Measurements

PXL_20220417_191530293.NIGHT.jpg

Hi folks,

Here is my review, measurements-based, of the Audio-GD NFB-11.38 Performance Edition. This unit has been kindly loaned to me by @Audiophonics and costs 469€ tax incl. It is the last iteration to date of the NFB-11 DAC & headphones amp combo, which is the entry-level from the Chinese manufacturer, that has known a lot of hype on forums for the last 7 or 8 years.

Now that measurements are getting more and more popular, the brand is considered as kind of controversial. Some objective reviews of Audio-GD products effectively revealed notoriously bad performance... Main issues were not only their terrible results on the bench, but the fact that the manufacturer claimed measurements and specs impossible to replicate. Nowadays, the name Audio-GD itself is becoming somehow polarizing, leading to irrational feedbacks from either haters or fanboys. I personally do not pay attention to these, as I should focus on objective analysis only, and I will, no matter the brand.

"Performance Edition", right? I'll put its name to the test...

PXL_20220418_160952070.NIGHT.jpg


The front panel is the same as any others NFB-11. There are old school switches for inputs, Gain and outputs. The latter is useless (it does not work for variable/fixed) out of the box. No. You have to first open the unit and move a jumper inside to get it working... which, I'm sorry, is stupid. Volume control is analog, which differ quite significantly from the vast majority of modern DACs that are using digital attenuation.

PXL_20220418_161524696.NIGHT (2).jpg


The unit has its own integrated PSU. You got the regular USB/Toslink/Coax trio, with one unbalanced output. I have to admit that I liked the excellent quality of all connectors, each socket having a great grip/fit with cables.

Audio-GD claims 2.5V fixed output, which is not what you get using Low Gain (barely 1Vrms or so). Switching to High Gain gives you something much closer to specs, and this is the main setting tested for this review (with Cosmos set @2.7Vrms input). I also chose Toslink as the main input for measurements to come, and this, for a good reason. More on that later...

I would have liked to test different filters, but just like the fixed/variable setting, you have to put/pull jumpers inside... Even better, pins are inaccessible to me, being below the USB board. Am I supposed to remove the latter first? Since this is not my unit, that isn't going to happen.

PXL_20220419_211242341.NIGHT.jpg


Measurements

Disclaimer: Measurements you are about to see are not intended to be as precise or extensive than what you get from a 30k€ AP. There is obviously both hardware and software limitations here, so not quite apples to apples comparison with Amir's testing. For example, I estimated SINAD (AKA THD+N) to be usually 5 to 6dB worse with my measurements rig, when compared to ASR reviews of the exact same products. Still, this data is enough to have a pretty good idea if the gear is bad or not, stellar, broken, or sub-par...

- ADC : E1DA Cosmos (Grade B), set to 2.7Vrms input. Minimum phase filter.
- Software : RMAA 6.4.5 PRO and Multitone Loopback Analyzer 1.0.15.
- Method : 8 runs for each test, then I choose the closest to the average. All regular tests are running 24bits / 44.1Khz. For this review, I introduced a new Jitter test (48Khz, 1-24Khz bandwidth, 16 averages, 262k FFT, thanks @pkane;)) and improved the Multitone one (Now 64 tones, 192Khz, 20Hz-22Khz bandwidth, 10 averages, 262K FFT).
- Audio-GD NFB-11.38 : Optical input, 2.5Vrms fixed output (High Gain) for main results, unless specified otherwise.​

RMAA Summary

Test
Results
Rating
Frequency response (from 40 Hz to 15 kHz), dB​
-0.05, -0.08​
Excellent
Noise level, dB (A)​
-105.5​
Very Good
Dynamic range, dB (A)​
105.5​
Very Good
THD, %​
0.00449​
Good
THD + Noise, dB (A)​
-84.4​
Average
IMD + Noise, %​
0.00485​
Good
Stereo crosstalk, dB​
-74.1​
Average
IMD at 10 kHz, %​
0.00455​
Good


For this review, I chose to throw the grading scale from RMAA away, since it is clearly outdated and way too gentle to properly qualify this kind of performance. So I decided to adjust the rating to my own appreciation, based on many DACs I already measured. On this matter, I have to admit that I expected much worse numbers. Anyway, let's have a look at graphs in details:


THD + Noise (at -3 dB FS)
thd.png
Left​
Right​
THD, %
0.00611​
0.00287​
THD + Noise, %
0.00628​
0.00322​
THD + Noise (A-weighted), %
0.00806​
0.00395​

Frequency response

fr.png
Left​
Right​
From 20 Hz to 20 kHz, dB
-0.11, +0.02​
-0.18, -0.04​
From 40 Hz to 15 kHz, dB
-0.02, +0.02​
-0.08, -0.05​

Noise level

noise.png
Left​
Right​
RMS power, dB
-104.4​
-104.4​
RMS power (A-weighted), dB
-105.5​
-105.5​
Peak level, dB FS
-81.5​
-80.0​
DC offset, %
-0.0​
+0.0​

Dynamic range

dynamics.png
Left​
Right​
Dynamic range, dB
+104.3​
+104.4​
Dynamic range (A-weighted), dB
+105.4​
+105.6​
DC offset, %
-0.00​
+0.00​

Intermodulation distortion (swept tones)

imdswept.png
Left​
Right​
IMD + Noise at 5000 Hz,
0.00717​
0.00403​
IMD + Noise at 10000 Hz,
0.00495​
0.00314​
IMD + Noise at 15000 Hz,
0.00490​
0.00314​

Intermodulation distortion

imd.png
Left​
Right​
IMD + Noise, %
0.00619​
0.00350​
IMD + Noise (A-weighted), %
0.00381​
0.00228​

Stereo crosstalk

cross.png
Left​
Right​
Crosstalk at 100 Hz, dB
-73​
-73​
Crosstalk at 1000 Hz, dB
-73​
-73​
Crosstalk at 10000 Hz, dB
-73​
-73​

Surprisingly, overall performance navigates between "good", acceptable and below average, depending on what it is measured. There is nothing here that should be considered as a serious audible concern, worst being THD+N that is dominated by second harmonic. On the other hand, it is miles behind what we should expect from a decent ES9038 PRO implementation.

By the way, I noticed that the unit got quite warm after dozens of minutes. I wondered if this could affect the performance somehow. I launched these two runs, one few seconds after switching it on, the second after running for 4 hours:
Test
Just turned on
4 hours warm-up
Frequency response (from 40 Hz to 15 kHz), dB​
-0.05, -0.08​
-0.05, -0.08​
Noise level, dB (A)​
-105.4​
-105.5​
Dynamic range, dB (A)​
105.5​
105.4​
THD, %​
0.00449​
0.00457​
IMD + Noise, %​
0.00485​
0.00495​
Stereo crosstalk, dB​
-74.0​
-71.9​

Almost no change, except for crosstalk.

Now that we have seen the best case scenario, here comes trouble:

USB VS Coaxial VS Optical

Test
USB
Coaxial
Optical
Frequency response (from 40 Hz to 15 kHz), dB​
+0.02, -0.02​
-0.05, -0.08​
-0.05, -0.08​
Noise level, dB (A)​
-93.6​
-94.1​
-105.5​
Dynamic range, dB (A)​
93.6​
94.1​
105.5​
THD, %​
0.00451​
0.00444​
0.00449​
IMD + Noise, %​
0.00870​
0.00911​
0.00485​
Stereo crosstalk, dB​
-80.5​
-78.6​
-74.1​

Noise
ns.png

As said earlier, I chose Optical as the main input to test, mainly because others showed significantly worse results. The main issue appears to be noise for both USB and Coaxial, which is very unusual for the latter. It is literally the first time I observe so many disparities between the two S/PDIF inputs. In fact, I often do not even feel the need to measure both, as they supposed to perform 99% the same in every run... Not in that case. Far from it, to be honest. USB performance is a real shame, when you know Amanero boards alone are very expensive already (like ≈50$ if I'm not mistaken). There is really something broken here. Is it related to either poor implementation and design or lack of quality control? I honestly do not care. This is a brand-new unit that anybody could have bought, and it shows serious flaws out of the box. Period.

Switching back to the toslink input, I tested the preamp at several volumes, relative to different input settings (about -1dBFS for each voltage) of my Cosmos :​

Preamp
Test
3.6Vrms input (Max vol LG)
4.5Vrms input (HG)
6.7Vrms input (HG)
7.6Vrms input (HG)
8.5Vrms input (Max vol HG)
Frequency response (from 40 Hz to 15 kHz), dB​
+0.07, -0.23​
+0.32, +0.21​
+0.19, -0.01​
+0.14, -0.12​
+0.09, -0.22​
Noise level, dB (A)​
-95.5​
-104.2​
-104.3​
-104.1​
-104.0​
Dynamic range, dB (A)​
95.5​
104.2​
104.4​
104.2​
104.1​
THD, %​
0.00262​
0.00216​
0.00528​
0.00862​
0.012​
IMD + Noise, %​
0.00586​
0.00282​
0.00527​
0.00827​
0.011​
Stereo crosstalk, dB​
-75.0​
-75.6​
-77.9​
-78.4​
-78.7​

Results are surprisingly consistent between the very different levels when looking at dynamic range and noise ! Only THD goes higher along with output. You can get up to almost 9Vrms, which is crazy high for single ended. There is still a bit of channel mismatch at some levels, between 0-0.1dB and 0.3dB in worst cases (at 4.5Vrms). To me, the NFB-11.38 could act as a fairly capable preamp:​

ct.png
fr.png


I cannot test headphones output extensively without a proper load board. Still, I measured a few captures at fixed voltages :
Headphones amp
Test
Headphone out Low Gain at 1.7Vrms
Headphone out High Gain at 6.7Vrms
Frequency response (from 40 Hz to 15 kHz), dB​
+0.09, -0.19​
+0.13, -0.15​
Noise level, dB (A)​
-96.6​
-104.6​
Dynamic range, dB (A)​
96.7​
104.7​
THD, %​
0.00248​
0.010​
IMD + Noise, %​
0.00586​
0.00963​
Stereo crosstalk, dB​
-85.9​
-87.0​

thd.png

After checking back my data, the 3rd harmonic peak is also there at 6.7Vrms with the RCA line out, so finally not introduced by the headphones amp itself. I am pleased to see that the headlamp is performing almost on par with line outs, which is very uncommon, in a good way !​


Jitter tests

Optical
Jitter AGD NFB11.38 Toslink.png


USB
Jitter AGD NFB11.38 USB.png


Coaxial
Jitter AGD NFB11.38 Coaxial.png

Optical did not show any problem when it comes to jitter. USB on the other hand acted really crazy, with one run out of three showing really weird shapes. You see one of them on the graph. Coaxial at last was more consistent, but pretty bad in just every way.​


Multitone 64

Optical
Multitone 64 AGD NFB11.38 Toslink.png


Coaxial
Multitone 64 AGD NFB11.38 Coaxial.png


USB
Multitone 64 AGD NFB11.38 USB.png

When looking at multitone, toslink, again, performed the best, yet with some unremarkable score of 86dB TD+N. Needless to say, USB and Coaxial repeated their quite bad performance like in any others tests...


Bonus

PXL_20220418_162533392.NIGHT (1).jpg

Since I had no choice but to open the unit to get it working, you get a free teardown.​

PXL_20220418_163816617.NIGHT (2).jpg
PXL_20220411_195434586 (2).jpg



Conclusions
It is clear that the Audio-GD NFB-11.38 "Performance Edition" (I insist on quotation marks) does not deserve its so-called appellation. I could not imagine how mediocre would have been the non-performance NFB-11.38 at this point. I have been told that this series has been designed by Audio-GD to measure well, as opposite to their R2R DACs... Well, it is quite a failure in that regard.

Maybe all of this would only be related to the discrete Non-FeedBack architecture, but that is not an excuse when you get two digital inputs out of three that are flawed that way. Yes, I have no doubt that these second and third harmonics are here on purpose, but do not tell me these messed-up noise and jitter are any kind of intentional. On the other hand, assuming you would need optical input only, what do you get, really ? In fairness : near-good-enough DAC, at least suitable for 16 bits content, with both powerful headphones amp and strong preamp, that all perform cohesively with each others. Last chance for the manufacturer's redemption could be the AS-1, supposedly properly engineered with common op amps and balanced output...

Anyway, my sincere thanks again to @Audiophonics for sending me this product, even when knowing the risk of not so great results !

Flanker rating: Meh
 
Last edited:

Matias

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Great review, thanks! Cool pictures too.

And again, if you checked the DAC's measurements with a Cosmos ADC, so could have AudioGD... Shame on them!
 

YSC

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Disappointed by that this don’t measure as broken as other audiogd dacs, tbh this thing does improve from the old audio gd things
 

Grotti

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What an effort this must have been! Thank you very much for this revealing review and, of course, kudos to audiophonics for loaning the unit to you: I wish more retailers would act like this.... I will surely consider them for my next purchase: this kind of behavior should be rewarded!
 

trl

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Great review, thank you

I would love to see few ARTA or REW graphs in the future, if possible.

BTW, I'm OK with the two GND wires tied together on the RCA plugs, but those white wires touching the top metallic part of the caps shouldn't be there.

P.S.: Some measurements could be found here: http://www.audio-gd.com/Pro/Headphoneamp/N11P/NFB1138PEN.htm. Find the diffs, if any. :)
 

Lupin

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Thanks for the review

Might not measure the best, although not nearly as bad as I expected, but I'm willing to deal with that as the front hardware switches are so super damn convenient. Real shame that brands like Topping don't release a top notch measuring DAC with hardware switches.
 

rebbiputzmaker

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Just wondering did you bother listening to it at all? I mean it is a piece of audio equipment after all, might’ve been worthwhile to see if the lack of measurements had any audible effects?
 

Koeitje

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Just wondering did you bother listening to it at all? I mean it is a piece of audio equipment after all, might’ve been worthwhile to see if the lack of measurements had any audible effects?
Why spend money on gear with clear issues if you can just get something that doesn't have them?
 

rebbiputzmaker

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Why spend money on gear with clear issues if you can just get something that doesn't have them?
I said nothing about buying it or spending money I was just curious about listening to it I’m not defending the item at all just wondering if there was any sound coming out of it.
 

fordiebianco

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Thank you for doing an excellent (and surely time consuming) review. Very helpful.
 

Vict0r

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Fantastic review! Lovely pictures too. Very moody. :D

Oh, bumped into a sentence that could use an extra word. :)
"In fairness : near-good-enough DAC, at least suitable for 16 bits content, with both powerful headphones amp and strong preamp, that all perform cohesively [with] each other."
 
OP
VintageFlanker

VintageFlanker

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Edit: warm-up test added.

Very nicely done. Promoted to home page.
Very much appreciated! :)

Just wondering did you bother listening to it at all?
There is no way I pair this with my main speakers (Buchardt A500s), my RCA to XLR cables being way too short. Still, I gave it a short listen with headphones and it sounded alright. I could have Coax and Optical running in the same time and may play to do an A/B blind test switching between both. If ever I have the time before sending it back...

(and surely time consuming)
You can't imagine.;)

BTW, I'm OK with the two GND wires tied together on the RCA plugs,
That's what I thought as well. After all, just every stereo TRS output does have shared GRD for both channel. But it is still unusual to see this in a DAC of that size.
I would love to see few ARTA or REW graphs in the future, if possible.
I agree that both are undoubtedly more accurate, but I still have to find a repeatable protocol for each (would probably be REW at the end, at least for aesthetic purposes;)).
 

YSC

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Actually quite a pitty that with such detailed and complicated/sexy looking internals they managed to make it that bad... even compared to those huge case with a tiny board and a few OPAMP units
 

nyxnyxnyx

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I tried one of this and another named R2R.11 from AudioGD. I think my experience is similar to what you described. Nothing was really concerning about audible issues, I didn't hear hum or noises or anything buzzy. The sound was quite alright too, but it's a bit blurry and smoothed out when I A/B it with more resolving amplifiers like topping a90 and atom.
Still, that might be someone's favorite kind of sound, and that might go well with certain headphones. I'm more worried about the poor soldering jobs and other safety issues that we are not aware yet...
 

amirm

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I said nothing about buying it or spending money I was just curious about listening to it I’m not defending the item at all just wondering if there was any sound coming out of it.
How would it generate all these measurements if there was no sound coming out of it?
 
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