High end OP's - LM6171 vs. OPA604 vs. OPA627 vs. ...

Archived from groups: rec.audio.high-end (More info?)

Friedrich Stockhammer wrote:
> Hi,
> an old question - what is your experience for this OP's in Audio High End
> amplifiers? Which have the most "true, unsophisticated sound"? :-)
> LM6171, OPA134, OPA627, OPA227, OPA604, AD812, AD823, AD8610 or other new
> OP's - but DIP case preferred.
>
> I listen all this OP's on my side
> http://www.stockhammer.at/hifi/audioproject1.php
>

The 5532 is a superb audio opamp, so I am not sure why you would want to
replace it. Having said that, if you have fairly high source resistances
in your application, you can get a lower overall output noise by using
opamps with lower input current noise. The OPA134/2134/4134 from
TI/Burr-Brown are excellent. But I doubt very much if you can hear the
difference between those and the 5532. All these have very low
distortion even at 20KHz.

Check out the specs of the OPA2134 here:

http://focus.ti.com/lit/ds/symlink/opa2134.pdf

Since the differences are so subtle, if any, you are totally at the
mercy of sighted bias when you compare the sound. Make sure you have
some test equipment, especially an oscilloscope, to check that you have
not made any mistakes, and that there are no oscillations.

Archived from groups: rec.audio.high-end (More info?)

Friedrich Stockhammer wrote:
> Am 26 Feb 2005 19:24:44 GMT schrieb Chung:
>> The 5532 is a superb audio opamp, so I am not sure why you would want to
>> replace it. Having said that, if you have fairly high source resistances
>> in your application, you can get a lower overall output noise by using
>> opamps with lower input current noise. The OPA134/2134/4134 from
>> TI/Burr-Brown are excellent. But I doubt very much if you can hear the
>> difference between those and the 5532. All these have very low
>> distortion even at 20KHz.
> These question are not for replacement - I want this but I have not done
> till today - in my old CD 650, but these OP's are for an new pre- and
> headphone amp.
>

For preamps, my recommendations still hold. For headphone amps, you need
different parts and not simply opamps. Designing a low power headphone
amp for portable use, and designing for a home AC-powered application
have different trade-offs. You should check out the National LM4908.