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Rolling Op-amps in Gustard H20 Headphone Amplifier

amirm

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#1
I reviewed the Gustard H20 which is a high-end headphone amplifier yesterday. Its owner kindly sent me some high-end op-amps to "roll" in there to see what difference it makes.

The task was pretty easy. The top screws come out of the H20 and if you tilt the unit, the lid falls out exposing its pretty guts:

Gustard H20 Headphone Amplifier Teardown Review.jpg

Everything is surface-mounted so not replaceable other than the pair that are socketed. You can see that I swapped one of the channels to Sparko's Lab SS3602 from TI/National LME 49720:

Gustard H20 Headphone Amplifier Sparkos Lab SS3602 LME 49720 op amp rolling.jpg


There is massive price difference with the LME retailing for just $2.68 and the Sparko's for whopping $79.80. There better be good bit of improvement for it to be worth putting two of those in there for nearly USD $160.

Op-amp Rolling Audio Measurements
Since the Gustard H20 performance is poor in unbalanced mode, I decided to run the dashboard using my balanced load of 50 ohm:

Gustard H20 Headphone Amplifier Sparkos Lab SS3602 LME 49720 op amp rolling Audio Measurement.png


This is at max volume using 4 volt input which should stress the op-amps. But we see no difference to speak of. SINAD is the same for both (the difference goes either way in every snapshot so not material).

How about at other input/power levels? Let's see:

Gustard H20 Headphone Amplifier Sparkos Lab SS3602 LME 49720 op amp rolling Power vs THD Audio...png


Don't mind the spikes here and there. The level of distortion is so low that the power supply noise gets in the way and causes variations from time to time. There is no difference really across the full spectrum of input/output levels.

Let's run a high-resolution FFT to see what differences there might be at very small levels:
Gustard H20 Headphone Amplifier Sparkos Lab SS3602 LME 49720 op amp rolling 1 kHz FFT Audio Me...png


As noted, the distortion profile is different but not an audible thing since mains noise is higher than it. And we are talking about distortions that well below 120 dB each.

FYI, I ran this test to 1 Mhz and the Gustard H20 was very stable with no signs of oscillation in either channel with either op-amp.

That does not mean the Sparko's lab is a good choice here. I left my test run at full output level for a few minutes and the Sparko's channel started to produce a lot more distortion (down to 90 dB SINAD). I suspected thermal stress and I was right. Touching the Sparko's told me it was running quite hot. IR imaging shows that:
Gustard H20 Headphone Amplifier Sparkos Lab SS3602 LME 49720 op amp rolling Temperatures.jpg


As you see, the Sparko's op-amp is the hottest component despite a number of power transistors in the H20! Maybe this is within its spec and at any rate, you would not be using the H20 at full volume. Still, more power is being used here and there may be longer term consequences.

Conclusions
A while ago I rolled the op-amps in the Topping D10 DAC with no resulting difference. The story repeats here with the much more expensive op-amp from Sparko's Lab showing no improvement whatsoever in the performance of Gustard H20. The H20 has excellent performance in balanced output and so it makes sense that this is all she can produce even if the Sparko's lab is better. We are actually limited by the mains noise here (which the Sparko's may have less immunity to).

So the message remains the same: don't waste your money on such "upgrades" unless they come with tangible, measurable performance improvement. Don't "trust your ears" because you don't know what they are hearing. All you know is what you are perceiving and after spending $160, you may talk yourself into these upgrades sounding better. They do not and cannot.

------------
As always, questions, comments, recommendations, etc. are welcome.

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maty

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#2
"Don't "trust your ears" because you don't know what they are hearing..."

Well, I can hear differences between some op-amps. Many times very easily, and with loudspeakers (my modified KEF Q100 5.25" coaxial speakers). And more easy with JRiver than foobar2000 (I do not like as a player, only as a tool).

Another big opamp listening test

https://www.diyaudio.com/forums/everything-else/308514-opamp-listening-test.html

aa - Tesla MA1458, equivalent of LM1458 (dual LM741)

bb - National Semiconductor LM4562

cc - SGS Thomson TL072

dd - Burr Brown OPA2134
And others op-amps in others tests made by PMA in diyaudio.com


PS: now my second -and cheap- system sounds much better than 2017 or 2018. Much clean power!
 
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SIY

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#3
Well, I can hear differences between some op-amps.
Well, if ignorant "rolling" is done, yeah, sometimes there's real differences. Op amps aren't interchangeable just because they have the same pinout.

NB: I am NOT calling Pavel ignorant- he is an extremely sharp and capable engineer.
 
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#4
Hi Amir,

The differences between the measurement numbers in the unbalanced mode and the balanced mode seem fairly large. Nearly 20 times lower distortion and the corresponding 25dB better SINAD. Should we expect such drastic differences in a well-designed device (if it is)?

By the way, when you ran the test in the unbalanced mode, was the H20 equipped with the Sparko opamps or the 49720 opamps? You mentioned that the overheating of the Sparko caused the SINAD to drop to 90dB, and that is the same as you measured for the unbalanced mode. Is it possible that it was the overheating Sparkos that produced the poor results of the unbalanced mode? Just wondering.

Also, would the better numbers in the balanced mode change your conclusion regarding whether to recommend this device?
 
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amirm

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#5
The differences between the measurement numbers in the unbalanced mode and the balanced mode seem fairly large. Nearly 20 times lower distortion and the corresponding 25dB better SINAD. Should we expect such drastic differences in a well-designed device (if it is)?
No, it should have been good both ways. I know they emphasize "balance this and balance that" but they have the 1/4 inch jacks and this is an expensive unit so should work well either way. Its competitors do.
 

amirm

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#6
By the way, when you ran the test in the unbalanced mode, was the H20 equipped with the Sparko opamps or the 49720 opamps? You mentioned that the overheating of the Sparko caused the SINAD to drop to 90dB, and that is the same as you measured for the unbalanced mode. Is it possible that it was the overheating Sparkos that produced the poor results of the unbalanced mode? Just wondering.
No, the review was with stock op-amp. I only changed it for this test. So yeh kind of odd that it went down to the same level but that was a coincident.
 

amirm

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#7
Also, would the better numbers in the balanced mode change your conclusion regarding whether to recommend this device?
I took that into account in my original review. The issue with this amp is that it has very low gain and its gain settings are very close to each other. And then it costs so much more.

These aside, if you have it and use it for balanced output, it should be an excellent performer if the gain works out.
 

restorer-john

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#8
>75 degrees C on a discrete SMD 'opamp' is not conducive to long term reliability. Also, what current (class A?) is it pulling to get that hot? Two of them will clearly heat themselves up and the regulators supplying them in that very partially perforated case.

Edit: Looked up the data sheet. Apparently 28mA for the dual SS3602. Rails are +/-15V in Gustard?
 
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March Audio

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#9
"Don't "trust your ears" because you don't know what they are hearing..."

Well, I can hear differences between some op-amps. Many times very easily, and with loudspeakers (my modified KEF Q100 5.25" coaxial speakers). And more easy with JRiver than foobar2000 (I do not like as a player, only as a tool).

Another big opamp listening test

https://www.diyaudio.com/forums/everything-else/308514-opamp-listening-test.html



And others op-amps in others tests made by PMA in diyaudio.com


PS: now my second -and cheap- system sounds much better than 2017 or 2018. Much clean power!
I had a quick look at that link and the follow up test. My reaction would be that just looking for preference without a reference doesn't tell us much, especially with the small sample number.

The original recorded directly from the dac and not going through his test box should have been included in the files..... and I would wager that the original would not rate the highest.

Or a fundamentally different test where you are looking for difference from the reference.
 
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maty

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#10
That was a very easy test to overcome if you do not have big bottlenecks in the audio system, a very widespread problem that few are aware of, and those that are, many spend a lot of money and energy in changing the components of their team in a somewhat random way instead of solving these problems.

Other more complex tests I also always got over with JRiver. With foobar2000 I had problems sometimes (with and without ABX plugin) so I decided to discard it.

By the way, I think the ABX plugin + foobar2000 has some problem, at least in my superoptimized W10 Pro for multimedia playback. Before with 1703 and 1709 compilation and now with 1809.
 

daftcombo

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#11
Well, I can hear differences between some op-amps. Many times very easily, and with loudspeakers (my modified KEF Q100 5.25" coaxial speakers). And more easy with JRiver than foobar2000 (I do not like as a player, only as a tool).
If JRiver is better (seems you think it's more "transparent"), why don't you use it instead of Foobar2000?
It would surely be of more effect than rolling op-amps.
Or is all just a dream?
 

maty

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#12
I use JRMC from v21 or v22. Now, v24 64 bits. With Kernel Streaming, like foobar2000. Both with 50 ms and other conf.

http://jplay.eu/forum/index.php?/topic/1143-why-kernel-streaming/#entry18613

The key is to optimize the OS to play multimedia. It is amazing what can change the sound depending on the different tweaks. For many months I have a detailed but pleasant sound that does not tire. The music well / very well recorded, which is what I hear, has life. Acoustic instruments.

Now I get excited much more often than a year ago. But this is not the thread.
 

daftcombo

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#13
I use JRMC from v21 or v22. Now, v24 64 bits. With Kernel Streaming, like foobar2000. Both with 50 ms and other conf.

http://jplay.eu/forum/index.php?/topic/1143-why-kernel-streaming/#entry18613

The key is to optimize the OS to play multimedia. It is amazing what can change the sound depending on the different tweaks. For many months I have a detailed but pleasant sound that does not tire. The music well / very well recorded, which is what I hear, has life. Acoustic instruments.

Now I get excited much more often than a year ago. But this is not the thread.
Any thread on this forum about Kernel Streaming?
I highly doubt what you wrote but would be happy to test.
My soundcards have ASIO drivers only though.
 

maty

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#14
I also doubted so I decided to verify it by myself.

By the way, with Linux I have not achieved the same sound (or image), which links me to Windows for multimedia.

As far as I know there is no specific thread about KS, ASIO, Wasapi ...

PS: If you are interested, on Android my choice is Neutron Music Player. But so I just use the phone for music.
 

March Audio

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#16
I use JRMC from v21 or v22. Now, v24 64 bits. With Kernel Streaming, like foobar2000. Both with 50 ms and other conf.

http://jplay.eu/forum/index.php?/topic/1143-why-kernel-streaming/#entry18613

The key is to optimize the OS to play multimedia. It is amazing what can change the sound depending on the different tweaks. For many months I have a detailed but pleasant sound that does not tire. The music well / very well recorded, which is what I hear, has life. Acoustic instruments.

Now I get excited much more often than a year ago. But this is not the thread.
........ Shall I.............. No I'm going to decline this one....
 

daftcombo

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#17
PS: If you are interested, on Android my choice is Neutron Music Player. But so I just use the phone for music.
Using a smartphone is a great way to have a completely silent source.
But I'm still after an Android app which allows convolution. Can the Neutron Music Player do it?
 

gvl

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#19
If op-amp rolling doesn't make things worse it should be recommended, after all money waste is what this hobby is all about.
 

maty

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#20
Neutron only has parametriq EQ. DSP, 64 bits processing, resampler... but not convolver.

http://neutronmp.com/technology.html

It works with VST3 plugins

https://www.google.com/search?q=vst3+plugin+convolver

and

  • Effects (software): Chorus, Distortion, Echo, Flanger, Phaser, Pitch shifter, Ring modulator, Equaliser, Compressor, AGC, ReverbI3DL2
  • Filters (software): Low Pass, Low Pass Occlusion, High Pass, High Pass Occlusion, Band Pass, Band Stop 'notch', Peaking EQ, Low Shelf, High Shelf, High Pass Butterworth, Low Pass Butterworth, Band Pass Butterworth, Band Stop Butterworth (2-nd order)
  • 3D sound
  • Directional sound with audio cones...
- End of topic -
 
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