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csown

(A)

In Reply to: Another opamp shootout. posted by Ehien on May 24, 2003 at 09:18:24:

What supply voltage did you use on these? Was the cube modded to supply lower voltage for the 8620? I am curious, because I tried 8620 in the BC myself, and it plays, but the voltage is too high for its rating. I did find the 8620 to be slightly thin in the BC, but in other applications, the 8620 is far more balanced (825 too uncontrolled and thick-sounding). I had planned to lower the voltage but hadn't gotten around to it yet because of other projects. I've been using 825 in my phonostage - I use Michell GyroDec w/ SME IV so I have no problems with lack of warmth/thinness/bass - and I have to say that I've been 100% satisfied with my phono setup for at least 5 or 6 months.
-Chris

Follow Ups:

Ooops... +/-15V - Ehien 13:47:10 05/25/03 (2)
Actually they are more like +/-14V when they get to the output opamp.
AD8610 and 8620 were acquired for trying in my DAC where +/-12V are provided. If fact I was a bit hasty and sort of forgot the fact that 8610/8620 are spec'ed at +/-13V when I tried it in BC. +/-14V likely don't hurt anything. But you are right that it can very possibly cause the bright and lean sound I heard with them.
Yeah I know you like AD825 the most in your system. But have you tried AD826? I was surprised at how good it sounded and preferred it in my system over AD825. Give it a try if you haven't. It's dual so can be directly dropped in. Dirt cheap too.
Have fun!
Ehien
- About AD8620... - Ehien 00:47:59 05/26/03 (1)
  I lowered the voltages from the PS of Black Cube to +/-13V and left AD8620 in the socket for 6 hours before I heard it tonight. Well, guess what... csown was right. AD8620 sounded quite good and not as bright or lean as when +/-15V were applied.
  The most amazing part for me was that with CDs of the same albums playing synchronically, vinyl and CD sounded pretty much idential in terms of tonal balance, image locations, focus, transients, etc. Guess I was hearing the house sound of good ADI opamps. My DAC has AD845 as gain and output opamps.
  OPA637 didn't sound good with +/-13V. The bass was more pronounced and a bit loose. Adjusting the PS back to +/-15V brought back its magic. I still prefer OPA637 (warmer, more presence and immediate), although with +/-13V AD8620 was very good too.
  Thanks for the reminder. Otherwise I might misjudged a good opamp.
  Man these are almost as fun as tube rolling. OPA637 remain in its seat. But I keep other good ones for the days when my taste or system changes.
  Have fun!
  Ehien
  - :) - csown 08:03:11 05/26/03 (0)
    I've also found that OPA6x7 needs about 15V to sound good. I have been using AD chips in my DAC - interestingly, in I/V conversion, AD8610 and OPA627 sound absolutely identical. So obviously the cheaper one wins. I love the 637 - very romantic and warm. It just doesn't work in many applications. I've been planning on moving my cube to dual 637's SMD at some point... If only I had more time!
    I'll order some 826's next time I buy some AD chips. Thx for the tip.
    Again, thanks for the report!
    -Chris

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