From powe–(at)–wdc.com Sat Jul 20 12:08:12 CDT 1996
From: O’Connor Newsgroups: alt.guitar.amps
Subject: Re: TS-808 opamps
Date: Sat, 20 Jul 1996 04:04:25 -0700
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There is nothing magic about one manufacturer’s 4558 op-amp over another.
This is a standard dual op-amp device and if it carries the 4558
designation, then the prefix doesn’t matter– all of the companies
licensed to make the part use the same topology and meet the same
performance level. The suffix can denote differences in temperature
limits or case material, but these are irrelevent in a pedal.

If you can hear a difference between ’4558′-designated components, then
you must have an active imagination.

By the way, later Tube Screamers used a low power version of this chip,
that otherwise performed as well tonally, with a slight increase in hiss.

Kevin