Gustard H20 headphone amp
Jun 27, 2021 at 11:40 PM Post #496 of 646
Just take it into a different home, perhaps in a different neighbourhood too and see if it does the same. What are the odds to have the same DC voltage on a different home few km/miles away from your place? If it will do the same, then maybe the transformer has an issue or the internal power regulators are drawing too much power out of the transformer; if so, then something inside your H20 might be the culprit. You may also use a cheap 3-pole-plug power reading device to check the current/power drawn by the H20 with volume to the min. and with the volume to normal listening levels too.
 
Jun 28, 2021 at 4:39 AM Post #497 of 646
This is powerconditioner I use, it is just a large toroidal isolation transformer.

https://www.powervar.com/products/power-conditioners/gpi-series-1-power-conditioners.
If it is problem is from the powerline then this will start buzzing instead of your H20.

It stops DC and reduces the harmonics going to the H20.
Buzzing is the transformer's way of dealing with the powerline harmonics.

If you have other connected audio equipment with toroidal transformers in them and they do not buzz, the transformer in your H20 may be defective.
Thank you for your suggestions. I understand use case for isolation transformers, they care for galvanic isolation with consequence of advantages. Yes, I have connected more devices to the same power outlet/phase and this is only one with issues. Original owner says it has slight hum but for may taste it is loud when I can clearly hear it from 2m away. :/ Device is new and unused, original owner had two, one silver one black, so one must go. He also says that Gustars starts poking with transformers used and is using now second grade technical transformers not intended for audio use...
 
Jun 28, 2021 at 4:41 AM Post #498 of 646
Just take it into a different home, perhaps in a different neighbourhood too and see if it does the same. What are the odds to have the same DC voltage on a different home few km/miles away from your place? If it will do the same, then maybe the transformer has an issue or the internal power regulators are drawing too much power out of the transformer; if so, then something inside your H20 might be the culprit. You may also use a cheap 3-pole-plug power reading device to check the current/power drawn by the H20 with volume to the min. and with the volume to normal listening levels too.
Hi, thank you for suggestion. I'll try it connected to UPS APC Smart 700 to see if it makes any difference.
 
Jun 28, 2021 at 4:44 AM Post #499 of 646
One more question, is anybody here using H20 with Douk SA200 OP amps? I'm considering to change stock OP AMPs for Sonic Imagery Labs 994Enh-Ticha or Douk SA200 amps. Thank you for your opinions.
 
Jun 28, 2021 at 10:21 AM Post #500 of 646
hi @b00b! I like your mods on H20 presented here. If you can sort those mod by importance/SQ impact what will be your chart please? thank you!
 
Jun 28, 2021 at 1:21 PM Post #501 of 646
One more question, is anybody here using H20 with Douk SA200 OP amps? I'm considering to change stock OP AMPs for Sonic Imagery Labs 994Enh-Ticha or Douk SA200 amps. Thank you for your opinions.
I used the Sparkos ss3602 with good results. They took a while to settle, they were bright with transients at first. Now they sound nice when they warm up while playing music. I'm looking on trying the Sonic Imageries eventually. Let us know about the sa200's when you install them.
 
Jun 29, 2021 at 11:50 PM Post #502 of 646
hi @b00b! I like your mods on H20 presented here. If you can sort those mod by importance/SQ impact what will be your chart please? thank you!
Start with the following
1) IXYS schottky diode mod
2) Epcos filter capacitor mod.

Once you will have done this you will get a much better feel on the complexity of the job.

If you are confident proceed with replacing the voltage regulators with the Sparkos units.
 
Aug 24, 2021 at 10:07 AM Post #503 of 646
Hi, new Talema replacement transformers arrived today, installed them and now is my amp dead quiet, no humm! :) Original transformers installed in H20 was Talema labeled too, but those are fakes and not audio dedicated one, but cheap generic transformers. New original Talema is down on the picture and Gustard fake one is up.
Maybe it can make sound of the amp even better too, but I doubt I can hear the change. Maybe mains noise measured by ASR went down who knows...

EDIT: After communicating with Talema representative and clarifying: those transformers installed by Gustard are not fake, but only generic transformers not suitable for audio devices. It seems this is fault of bad comunication between Talema and Gustard or cost saving purpose on Gustard side.
 

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Aug 24, 2021 at 2:37 PM Post #505 of 646
Was the hum mechanical noise or audible through headphones?
Only mechanical, some loose windings I suppose... But it was audible in 2m away in silent parts of music while listening at night. That bothered me a lot. :frowning2:
 
Aug 24, 2021 at 9:45 PM Post #506 of 646
New OPA1656 opamp from TI.
Was not expecting much from a 3USD device.
Mouser and Digikey stock this part.

Performance was an unexpected surprise, it challenged the Ticha 994 for top performance spot on the H20.
Main advantage is much cooler running compared to the 994.

Quite easily surpassed the performance of the Sparkos.

B0ED3B4E-5385-4060-AB50-94B5030FB504_1_105_c.jpeg



Mounted on the H20
1629855822177.jpeg
 
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Aug 24, 2021 at 10:17 PM Post #507 of 646
Only mechanical, some loose windings I suppose... But it was audible in 2m away in silent parts of music while listening at night. That bothered me a lot. :frowning2:
Wow, glad you got that sorted out. Did it cost a lot for the XFMRs? Was installation difficult?
 
Aug 24, 2021 at 10:44 PM Post #508 of 646
New OPA1656 opamp from TI.
Was not expecting much from a 3USD device.
Mouser and Digikey stock this part.

Performance was an unexpected surprise, it challenged the Ticha 994 for top performance spot on the H20.
Main advantage is much cooler running compared to the 994.

Quite easily surpassed the performance of the Sparkos.

B0ED3B4E-5385-4060-AB50-94B5030FB504_1_105_c.jpeg


Mounted on the H20
1629855822177.jpeg
Yeah, I'm thinking of getting the '994s sometime. The Sparkos ss3602 sometimes sounds slightly tilted up in the treble. Sharp and pronounced transients (Sss, Ttt) on some songs until they get good and toasty warm from playing constantly for about 20-30 mins. After that time they seem to mellow and get really transparent.
 
Aug 25, 2021 at 3:09 AM Post #509 of 646
Wow, glad you got that sorted out. Did it cost a lot for the XFMRs? Was installation difficult?
Thank you, Installation is very easy = unplugging old transformers, lose two screws, replace transformers, tighten screws and plug new transformers. Price was nearly 300EUR for two transformers with shipping.
 
Aug 25, 2021 at 3:09 AM Post #510 of 646
Yeah, I'm thinking of getting the '994s sometime. The Sparkos ss3602 sometimes sounds slightly tilted up in the treble. Sharp and pronounced transients (Sss, Ttt) on some songs until they get good and toasty warm from playing constantly for about 20-30 mins. After that time they seem to mellow and get really transparent.
I find my ss3602s mellow out after being left on overnight or longer, not too great when running up from a cold state.
 

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