[alpovs]

if i use a single-ended source, it´s completely useless to change the dual op-amps. i´m right? thank you

That was my thought too but the modders cannot answer this question. Nobody has seen a schematic of this amp, yet the opinion is that the two more expensive dual OpAmps are the summers. If that is correct than obviously they are not in use in singe-ended in single-ended out type of usage of this amp, so there is no reason to mod them.

 

[alota]

  That was my thought too but the modders cannot answer this question. Nobody has seen a schematic of this amp, yet the opinion is that the two more expensive dual OpAmps are the summers. If that is correct than obviously they are not in use in singe-ended in single-ended out type of usage of this amp, so there is no reason to mod them.

thank you. i´m completely ignorant about schematic and electronics, but if the use is only to convert the signal...

 

[sunneebear]

I have changed the two dual opamps in my H10 and yes there is a improvement in both XLR and RCA inputs. While it is not as great as the singles used in the amplification circuit, to me the benefit is enough that I think it is a feasible investment.

I do not know how the converter works in the H10 but I had a short stint in pro audio a long time ago that I know that the gain in the balanced line is higher than the unbalance line. So if this converter works in a similar fashion as pro audio equipment then the dual opamps are used in both XLR and RCA lines to bring the voltage up or down.

 

[alota]

I have changed the two dual opamps in my H10 and yes there is a improvement in both XLR and RCA inputs. While it is not as great as the singles used in the amplification circuit, to me the benefit is enough that I think it is a feasible investment.

I do not know how the converter works in the H10 but I had a short stint in pro audio a long time ago that I know that the gain in the balanced line is higher than the unbalance line. So if this converter works in a similar fashion as pro audio equipment then the dual opamps are used in both XLR and RCA lines to bring the voltage up or down.

Thank you. My only doubt is related using a single ended source. Two dual op-amps are a little expensive for an amplifier that costs around 350.

 

[alpovs]

That was my thought too but the modders cannot answer this question. Nobody has seen a schematic of this amp, yet the opinion is that the two more expensive dual OpAmps are the summers. If that is correct than obviously they are not in use in singe-ended in single-ended out type of usage of this amp, so there is no reason to mod them.

thank you. i´m completely ignorant about schematic and electronics, but if the use is only to convert the signal...

Actually I do not know that. That's what others are saying. And I don't know if they are correct - there's no schematic.

 

[Madman242]

Someone that knows Chinese could message Huang_cs on Taobao and ask him about the dual op-amps.

 

[Ggroch]

Does the H10 come with any kind of user guide?  I am boxing mine up and have no manual.  Did I lose it, or does it come documentless from the factory?
 
If there is one, is it available to download somewhere?    It would be nice to have at least a descriptive graphic for the dip switches (not to hard to figure out, but nice to have.

 

[Madman242]

  Does the H10 come with any kind of user guide?  I am boxing mine up and have no manual.  Did I lose it, or does it come documentless from the factory?
 
If there is one, is it available to download somewhere?    It would be nice to have at least a descriptive graphic for the dip switches (not to hard to figure out, but nice to have.

I ordered mine directly from Huang_cs and it did not include any documentation.

 

[lucianpescaru]

Posting just to confirm that AD797 sounds way better than the original (OPA134 sounds 'nice' but veiled) or even OPA627 in the voltage gain stage. Details, soundstage, it's all there with my HIFIMAN HE 560... but still on the warm side.
 
Still using LM49860s for input stage, waiting for AD823s to arrive
 
With the LM49860s for input it seems that is more detail but it sounds more aggressive than the original OPAs or maybe that's the source (Benchmark DAC 2).
 
Will report back with AD823 vs LM49860 impressions.
 
Edit
Swapped inputs with LM6172 I had around. The aggressive (mid-highs) sound of is gone compared with LM49860 but so is the detail and prat. Gave them the night to burn-in but... back to 49860 it is, until the AD823s arrive.
 
Edit2
AD823s are here, swapped, initial impression is very good, LM49860 aggressive & coarse presentation is gone, everything seems smooth and detailed. Maybe just the bass 'prat' is a little bit worse but will see how it sounds after a day of two.
 
Edit3
Quick swap to check the bass lines and the LM49860 sounded 'bloated' in LF and without treble extension. Back to AD823s for good.
 
Edit4
After one day of burn-in AD823 sounds like it's supposed to with the HE560, open, detailed, bass lines complement the overall presentation and are not too proeminent. Hope it gets better with time
Sennheiser HD600 also sound very nice, they scale very well with the amplifier used.
Audio-Technica ATH AD2000x and Beyerdynamic T1 1st gen sound better straight from the Benchmark amplifier, as they tend to sound too bright from the Gustard. Maybe OPA627s in voltage amplification stage would do the trick for Beyerdynamic T1 (darker presentation) but I ain't changing the AD797s for that.
Happy camper overall.

 

[gug42]

Cool, good news. Thx for sharing

 

[lucianpescaru]

  Anybody knows what voltage the main supply capacitors are? Is 25V enough or I have to replace with 35V as the originals are? Thanks.

 
I'll answer my own question, the main supply capacitors run at ~29Vdc so 35V 16mm diameter if one wants to replace those.
 
I ordered some Nichicon 3300uf 35V for audio UKA1V332MHD to replace the originals... not that it sounds bad now but just because it might sound better with those. Will let you people know how things go.

 

[sunneebear]

If you've read this thread from the beginning you will find that some say this amp takes a very long time to break in. I kind of agree with that and I think most of it is due to the bank of capacitors. If so, I don't know how you can remember what the old capacitors sound like. I do hope that you do change the capacitors and get back to us.

 

[lucianpescaru]

If you've read this thread from the beginning you will find that some say this amp takes a very long time to break in. I kind of agree with that and I think most of it is due to the bank of capacitors. If so, I don't know how you can remember what the old capacitors sound like. I do hope that you do change the capacitors and get back to us.

 
Simply put I have a good sense of what sounds good (female vocals and piano, general sense of air around each instrument or cymbal).
 
Anyway just changed for 16x Nichicon 3300uf 35V for audio UKA1V332MHD. They are taller than the originals but fit nice under the cover and also rated at 105C. After a couple of hours presentation is already better, cleaner overall. Anyway I can sleep better at night.
 
Also installed a mains filter while at it http://uk.farnell.com/epcos/b84773a0004a000/filter-inlet-iec-4a-250v-ac-dc/dp/2317968?ost=2317968 which I think helps clean the sound. Be wary you have to file the back banel little by little, it's not a direct fit, just file carefully until you get the filter in the right position in and lined with the screw holes.
 
Photo just before the caps arrived, cleaned the through-holes (thank god no lifting traces, used a toothpick, 100W soldering gun and a solder pump) and with the Nichicons installed.
 
Over 50000uf of capacitance baby
 

 

 
Just more natural and detail galore wraps it up. Fornication in me ears 

 with HE560. I'll edit this post two-three days later to wrap it up.

 

[wwmhf]

Looking forward to your updates!!

 

[wwmhf]

The first picture in your post makes me to like this amp more. It will be nice toy to play with ...