[Sganzerla]

 It is a company that makes audio gear.
 Here is - LINK
 
 Daisangen, let me know if your amp dies, as it looks like you are a much hardcore headphone user than me.

 

[TheMaestro335]

Hello All,
I just installed my

OPA627AU with Class A Biasing Mod

It does open up the soundstage! Much better than the stock op amp!No more congestion in the middle of the soundstage. More space around the instruments better detail. My question is about the gain setting. I use the Matrix with 701's and HD 600's, did anybody else change there gain setting to 18 from 10? 18 just seemed to be on the verge of distortion at low levels.

 

[daisangen]

I and from what I've read, most other guys as well, prefer 10 for K70x and HD6xx. Your ears should make the final decision, though.

 

[Kuze]

Quote:

Hello All,
I just installed my

OPA627AU with Class A Biasing Mod

It does open up the soundstage! Much better than the stock op amp!No more congestion in the middle of the soundstage. More space around the instruments better detail. My question is about the gain setting. I use the Matrix with 701's and HD 600's, did anybody else change there gain setting to 18 from 10? 18 just seemed to be on the verge of distortion at low levels.

 
It was discussed earlier, many including myself noticed, truthfully i found it quite odd, why should 18dB and higher sound like crap compaired to 10dB.
 

 

[TheMaestro335]

Thanks Guy's,
I only noticed this when I changed the op amp.

 

[ev01ut10ndt]

Have you guys compared the OPA Earth with the OPA627 with class A mod? It certainly makes sense to go with the OPA Earth since the parts price for the 2Xopa627+resistors+adapter is close enough if not going through tam's audio. 

 

[Elar]

I may have got the wrong impression from some pictured of OPA Earth I have seen, but will that fit in the M-Stage case? It seems too tall to me to fit.

 

[ninjikiran]

Quote:

I may have got the wrong impression from some pictured of OPA Earth I have seen, but will that fit in the M-Stage case? It seems to tall to me to fit.

It is too tall, you need the extension cable to rest it on the PCB.

 

[livewire]

Here you go, again. (this was posted earlier in this thread by jtam)
 

 

[jtam]

Good catch!

 
Quote:

Here you go, again. (this was posted earlier in this thread by jtam)
 

 

[ev01ut10ndt]

For the one whos did the OPA627+class A mod:
 
Did you guys find 0db gain to be the most detailed? Using my HD650s, I found that as I increased the gain, the blurrier everything sounded (less detail in treble probably). I'm not wanting any more in volume as its already at 12 oclock for the 0db gain, so I'm happy with it. Only with more dynamic classical recordings does it go up to 3oclock at max.
 
Did you guys choose 10db and 18db for the stock OPA because of the harsher highs? I found that 18db worked well for the stock OPA. 
 
 
I forgot to add: I got the 627+mod from Tam's Audio. It was a big difference in terms of dealing with the harsh highs as you guys have mentioned. Enough so that at 18db, it was almost too smooth for me and hence why I dropped it down to 10 or even 0db gain. I found it to be a necessary mod...my Senns are no longer grados but senns as before. 

 

[TheMaestro335]

Hello I purchased the upgrade from Tam's audio. I cannot figure out what gain setting is the best. I use 701's and HD600's. I have the setting at 10db, but I think it sounds like it is on the verge of distortion? 18 is nice but as you stated it is not as detailed. Maybe I should try 0db?

 

[ninjikiran]

 
Quote:

Hello I purchased the upgrade from Tam's audio. I cannot figure out what gain setting is the best. I use 701's and HD600's. I have the setting at 10db, but I think it sounds like it is on the verge of distortion? 18 is nice but as you stated it is not as detailed. Maybe I should try 0db?

 
Distortion? I don't get any of that with my 702's @ 10 gain.  0 gain is ok, but sounds a bit weaker and might not be pushing enough power as some songs(very small %) actually take it near the 100% mark.  It could be placebo or not tuning the knob properly but there seems to be less impact @ 0 gain.  As in more thud than boom~
 
That being said ignore my perceptions of 0 gain and try it yourself going in blank slate.  It might work perfectly for you~  I would still be worried about distortion though since there shouldn't be any unless your songs are mastered improperly or have levels of compression I haven't seen since the beginning of MP3's.  It could be your headphones(did you blow out both drivers by playing way too loud??) or the amp itself.  Hell it could even be something as simple as a faulty opamp.  Perhaps you should buy a new one and see what happens.  Would be best if you buy one thats not the same as the one inside the unit in that case if you still hear any distortion at least you have a spare opamp thats different

.

 

[sunneebear]

With the few mentions of distortion at higher gain, could it be the source.

 

[dlaloum]

Given the way the system works, my suspicion would be that at a certain level of gain we are starting to creep out of class A mode and back into class AB mode.
 
If you are already running in AB - as in when the unit is in stock configuration - there would not be an audible threshold of change.... but with Class A on OPA627, as we drop back to AB mode the difference is much more obvious...
 
Just a guess - some work with multimeter/CRO would be required to confirm it...