Since it seemed more appropriate, I posted the following on rec.audio.pro, but
I did not get any replies:

Hi:

In my vintage hi-fi travels, I managed to pick up a mike (or studio?) preamp
made by General Precision Laboratory of Pleasantville, New York. It's a model
AP 6MW with a model number of 5086-5 (PA101 series). It appears to be a well
made unit with top quality parts: Daven level pot, Daven type T691 network
(T-pad, 500/500), UTC A-24 transformer, Sprague caps and Thordason power
transformer and choke. The tube compliment is 5Y3, 6J7 and 6SN7 x 2.

I also got what looks to be the original factory parts list, schematic and
blueprint (I acquired it from the son of a former employee of GPL). Dates on
the documentation indicate that it was made in the early 1950s. Here are some
photos of it:

http://members.aol.com/gerrye123/pre1.jpg

http://members.aol.com/gerrye123/pre2.jpg

Can anyone tell me anything about General Precision Laboratory in general (pun
intended) or this model AP 6MW in particular (like, what was it used for)?
Thanks!

Gerry