[sdiy] John Hardy discrete op amp

[Antti Huovilainen]

On Sun, 7 Feb 2010, cheater cheater wrote:

> How do they perform? Are they good for very hot mixing stages such as in 
> mastering mixers?

See here: http://www.sg-acoustics.ch/analogue_audio/ic_opamps/index.html

Summary: Pretty good audio performance, but you can get the same or better 
much cheaper from a single IC opamp if you don't need more than +- 18V 
rails (990 has max +- 24V) and don't need to drive very low impedance 
loads.

> Other than them being real expensive, would it be feasible to, for 
> example, build a filter out of those?

The input offset current is listed as 2.2 uA, so you'd need a buffer 
before the opamp and that makes it rather pointless.

Antti

"No boom today. Boom tomorrow. There's always a boom tomorrow"
   -- Lt. Cmdr. Ivanova