[sdiy] John Hardy discrete op amp

[cheater cheater]

Antti,
thanks for your email, it was very informative.

> The input offset current is listed as 2.2 uA, so you'd need a buffer before
> the opamp

but for example the stages in the 303 filter aren't completely
buffered, right? So, maybe that's not such a bad thing?

Cheers
D.

On Sun, Feb 7, 2010 at 10:40, Antti Huovilainen <ajhuovil at cc.hut.fi> wrote:
> 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
>