MXR Phase 100

Joachim Verghese jocke at
Mon Mar 9 17:10:48 CET 1998

R.G. Keen wrote:

> I think it was always six stage, only four of which moved; two 
> were fixed, no variable resistance.

Now this is interesting! I automatically assumed the unit I opened
was a 6-stage device, since there were only three opto-couplers.

> Silonex parts. They're on the web, probably with descriptions of that 
> part.

Right. They're at

Scott wrote:
> Just opened my Phase 100.  I see 3 opto-isolators labeled 21L 312.
> There are 6 8-pin ICs (TI) SN72L022.  Is this 6 staged or only 3?

Six variable stages, since the optos are dual devices. Interesting
part numbers -- I'll have to do some investigation.

> There's a sticker inside with what might be a seial number?  705092.
> How can one tell if it is a "Dunlop re-issue"?

The Dunlop re-issue has a LED "on/off" indicator above the "MXR" logo,
and a 9V DC input beside the signal input jack socket.
Also, the intensity selector positions are reversed, i.e. the highest
settings are to the left. 

The op-amps are TL062s, and the output is reasonably noise-less
(especially for a stomp box). A picture of the unit can be found at:

Thanks, people, you've been very helpful!


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