MOTM

> Certainly the TL072 is "better" but the 4558 has a distinct sound to them
> which
> is why they are used.

Has anyone managed to quantify this distinct sound? I don't doubt that it
exists; I'm just curious whether it's some sort of frequency-response
characteristic or non-linearity or something else that can be described
quantitatively.
 
> In fact, if you look at all the world's "audio stuff" built from 1985 to
> 1995,
> the 4558 was king!

Looks like it goes back further than that. The Mu-Tron Bi-Phase I bought
recently is full of 4558s.

--Adam
(keeping fingers crossed for the Schreiber clan)