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Review and Measurements of Gustard H10 Headphone Amp

amirm

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#1
This is a review and detailed measurements of the Gustard H10 Headphone Amplifier with balanced input. It is on kind loan from a member. Seems like the H10 was released back in 2015 and is no longer available. It is listed for US $399 on some sites with no stock.

The H10 is quite large and heavy for a headphone amplifier:

Gustard H10 Headphone Amplifier Audio Review.jpg

The volume control is large which is nice. What is not so nice is its stiff feel despite the size of that knob. As shipped, the knob would slide past the max and min so I had to readjust and tighten the screw. Alas, the volume control shaft is round instead of notched so this problem will remain.

There is only a power switch and a 1/4 inch headphone jack.

Here is the back panel:

Gustard H10 Headphone Amplifier Back Panel Audio Review.jpg

As you see, there is a set of XLR inputs in addition to RCA. There is a dip switch to seemingly select between them but it doesn't do that. Instead, it just sets the gain appropriately -- both inputs are live at once. The rest of the dip switches adjust the gain and require mastery in morse code to figure out what they do. :) I could not find a manual. I left the switches all down for "low" gain and right one indicated by +12 as "high" gain. The switches interact with each other to provide half a dozen or more combination of gain. While this flexibility is nice, I much rather have a control in front than reaching in the back to mess with the switches.

Headphone Audio Measurements
For my measurements, I used the XLR input exclusively. Here is our dashboard view for 4 volt in, 4 volt out with the lowest gain:

Gustard H10 Headphone Amplifier Audio Measurements.png


We are missing the rated THD+N a bit but given the so many gain and volume knob setting, one can probably get to the number they have. SINAD (signal over noise and distortion) shows good design but not class leading in this day and age:

Best Headphone Amplifiers Measured and Reviewed 2019.png


Signal to noise ratio likewise lands in "competent" but not the best class:

Gustard H10 Headphone Amplifier SNR Audio Measurements.png


With respect to very sensitive IEMs, the SNR lands in the middle as well:
Gustard H10 Headphone Amplifier 50 mv SNR Audio Measurements.png


Frequency response is flat until you get to low frequencies:
Gustard H10 Headphone Amplifier Frequency Response Audio Measurements.png


The roll off indicates that there is a capacitor to isolate the output stage and headphone connection. Capacitors act like shorts at high frequencies but at lower one, present an increasingly higher impedance and hence that roll off.

Intermodulation versus output power shows higher baseline noise level but plenty of power at very low distortion:

Gustard H10 Headphone Amplifier IMD Distortion Audio Measurements.png


Most important test of a headphone amplifier is its power output at different load impedances. Let's start with 300 ohm which tests its ability to pump out voltage to drive high impedance headphones:

Gustard H10 Headphone Amplifier Power at 300 Ohm Audio Measurements.png


As we already could tell from IMD charge, there is tons and tons of power here. We also have more noise though especially in one channel that shows the "T" symbol.

Switching to 33 ohm, the performance drops some but still more than good enough:
Gustard H10 Headphone Amplifier Power at 33 Ohm Audio Measurements.png


Now higher gain doesn't give you more output because the limitation is current delivery, not gain/output voltage.

Output impedance is a very good 1.9 ohm:

Best Headphone Amplifier Output Impedance Measurement.png


Edit: original value was incorrect.

Listening Tests
I started testing with Sennheiser HD-650. Man, there is so much power available here to not only shake out the cobwebs from the transducers but your eardrum as well! :eek: As a result there is plenty of bass, detail and impact even in lowest gain setting.

Switching to Hifiman HE-400i showed another excellent performance with abundant amount of power and fidelity. It was so nice that I kept listening after the testing was over!

Mind you, there is no "class A" magic here. Just good old high-fidelity and transparent sound.

Conclusions
From measurement point of view, the Gustard H10 shows competence with no gross errors. Times have changed though since it came out and other products have claimed the top of the kingdom (Benchmark HPA4, Massdrop/drop THX 789 AAA and JDS Labs Atom). So the match is no longer even and the H10 falls behind.

The Gustard H10 though takes its revenge due to copious amount of power it delivers at exceedingly low distortion with no need to mess around with balanced headphone jacks and such. Its balanced input terminals help eliminate nasty ground loops and that is all you need.

Overally, based on good measurements and very impressive subjective listening, I am happy to recommend the Gustard H10. See if you can pick one up in the used market before folks read this review.

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Veri

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#2
Isn't the output impedance a bit of a concern?
 
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#7
I have one I got used off eBay three years ago, for really cheapo. Its only problems were a scratch on the top and a loose fitting volume knob.
The volume knob was easily tightened up and has never gotten loose again.

For me the XLR switch on the back needed to be up, for the XLR inputs to operate.

Good to see that while the H10 is older and discontinued, it is still quite a capable headphone amplifier.
I found the H10 is especially capable of driving my Massdrop X Sennheiser HD 6XX, and my ever increasing collection of planar magnetic headphones. I also have a vintage AKG K241 (600 ohms), that sound much better with the H10 driving them.

Special thanks to the member who lent you his unit for testing!
 
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GGroch

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#8
A couple of notes on the Gustard H10.

I understand the design was copied from the Violectric V200. If you look inside both you will see similarities and differences. The Violectric has a single toroidal transformer, the Gustard has two.

You really should look inside the Gustard because it could solve the loose volume knob problem. In the attached photo you can see the volume pot is at the back of the chassis connected by a metal rod. It is likely the screws at the back are loose.

You should also really look at the insides to see if the four socketed Op Amps are original. I believe the H10 was the first amp Burson Audio made upgrade kits for. While the amp is no longer made you can still get the op amps. Because they are socketed op amp swapping is very popular among H10 owners. It would be interesting to see how Burson or other op amps impact the measurements. I wonder if they would send ASR a free set for testing? In the photo those really tall red things are Burson op amps.

I owned a Gustard H10 for several years and liked it a lot. The build quality and the ability to micro-manage gain juiced my expectation bias and I thought it sounded great. Gustard.jpg
 

JohnYang1997

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#9
A couple of notes on the Gustard H10.

I understand the design was copied from the Violectric V200. If you look inside both you will see similarities and differences. The Violectric has a single toroidal transformer, the Gustard has two.

You really should look inside the Gustard because it could solve the loose volume knob problem. In the attached photo you can see the volume pot is at the back of the chassis connected by a metal rod. It is likely the screws at the back are loose.

You should also really look at the insides to see if the four socketed Op Amps are original. I believe the H10 was the first amp Burson Audio made upgrade kits for. While the amp is no longer made you can still get the op amps. Because they are socketed op amp swapping is very popular among H10 owners. It would be interesting to see how Burson or other op amps impact the measurements. I wonder if they would send ASR a free set for testing? In the photo those really tall red things are Burson op amps.

I owned a Gustard H10 for several years and liked it a lot. The build quality and the ability to micro-manage gain juiced my expectation bias and I thought it sounded great. View attachment 31405
I believe it's not a complete copy but a reference. Because original v200 or actual copies should have very low output impedance 0.1ohm.
EDIT: this one has very low impedance as well.
you may check out the measurements on reference audio analyzer
https://reference-audio-analyzer.pro/en/report/amp/violectric-hpa-v200.php#rw3
In terms of opamp rolling. I have done measurements a year and a half ago. And best noise performance is with opa827 in the front and opa2227 near the discrete section. But this is without the modification of resistors. The noise is mainly caused by the high value resistors in the signal path. And I later on experienced better distortion performance with lower impedance load with everything opa827. Opa1611 and lme49710 should be good candidate for best distortion but the current noise overwhelms the over performance. That being said with deeper modification on the circuit can give better performance. But i gave up on modifying it further.
 
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nemesisrobot

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#10
Very nice! As others have said, this is very close to the Violectric V200 in terms of design so I’m interested if the V281 puts up similar numbers given that it’s essentially two V200s put together to achieve the balanced output.
 

JohnYang1997

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#11
The design is actually push-pull design. So not traditional single ended class A. The heat is pretty decent, not hot just warm.
If the discrete stage is the same as v200, there will be +8db gain at the output stage with 0db at input. Not sure how H10 is implemented. It seems to have better power supply noise than v200 also.
The best thing of this design is they run on +-30V. Superb power with high impedance load, especially 600ohm ones.
 

JohnYang1997

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#12
Very nice! As others have said, this is very close to the Violectric V200 in terms of design so I’m interested if the V281 puts up similar numbers given that it’s essentially two V200s put together to achieve the balanced output.
V281 when run on balanced, can have over 3W power into 300ohm and 2.7W into 600ohm. Absolutely madness. Voltage swing from balanced output actually rivals most unbridged power amps.
 
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#13
Thanks for measuring this Amir! And thanks to the person sending their one in. Looks like I will be keeping the H10.
I was told this was not a copy of the violectric, only that some believed it was.
 

trl

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#14
Opamp rolling did H10 to oscillate the audio chain and the internal MOSFET regulators to blow away. PCB is black and opaque, so really hard to investigate where the traces go and to get the schematic on the paper.

This was happening on at least two HeadFiers, if I remember with SS V5 opamps. Worth mentioning that V5 has a max. supported voltage of +/-15V while H10 has +/-16.5 V, although the blowing away thing happened within few seconds on some headfier.

Worth mentioning the overheating from inside H10 (feel free to read on HeadFi about it).

P.S.: I personally tested SS V5 duals on +/-18V and nothing was blowing away. The test was for no more than 30' with case closed. Regulators were NJM7818/7918, headamp Matrix HPA-3B.
 

amirm

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#18
Sorry guys. When I measured the Benchmark HPA4 I had to use a different fixture and overrode the formula in Excel. Not knowing that it then started to auto-fill that formula rather than the standard one. Impacted half a dozen ones which I just finished correcting.
 
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