[sdiy] OP275 [was: Re: Audio mixers]

Paul Perry pfperry at melbpc.org.au
Thu Jun 23 04:16:41 CEST 2011

On the presented evidence, I think I'd back Douglas Self against the writer 
of the OP275 app notes.

1. Whatever the merits of otherwise of the front end, I doubt it is the 
source of the extra distortion when feeding a 600 ohm load. This "sound of 
jfet" business is just marketing BS.

2. In the app notes, a negative impedance filter is presented with the claim 
that the OP275 in the frequency-dependent negative resistor is not in the 
signal path... well, somebody who could say that, has a great career waiting 
in Washington.

All in all, this shows just what we have lost with the demise of Jim 
Williams and Bob Pease.

paul perry Melbourne Australia

----- Original Message ----- 
From: "Paul Schreiber" > From "article" (cough):
> "THD below 1 kHz is definitely non-zero with the 600R load."
> This person has outed themself as a TOTAL IDIOT and hence, everything he
> says is best avoided.
> Paul S.

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