What model Masco is this?

[bluzmn]

Does anybody know what model Masco amp this is (and where I can get the schematic)? The tube lineup is 6SJ7, 6SC7, 2x6V6 and 5Y3; the chassis has a vibrator on it, so it's an AC/DC model. Also, the back doesn't have the customary terminal strip with the impedances printed on it; how do I determine the correct impedance for the speaker(s) that I connect to it?

[JHow]

I can't help you with the model or schemo, but with regard to the OT and impedance question, the link below discusses this dilemma, how to figure out an unkown transformer. Basically, figure out turns ratio, calculate relfected impedance, make deductions about what your output tubes want to see and what imp. load your speaker(s) will create.

Output Transformer Impedance

also, geofex.com has info on transformer "reverse engineering" and testing.

[MWJB]

Bear in mind that Masco often ran lower primary Z on 6V6 tubes than is typical, 4.5K is listed for some of their 6V6 amps.

[Bruce / Mission Amps]

Looks like an ME-18P.... check this:
http://bluesharpamps.blogspot.com/20...ve-jr-cab.html
http://bluesharpamps.blogspot.com/20...unds-good.html
http://bluesharpamps.blogspot.com/20...co-update.html
It had the record player on it at one time too.

[bluzmn]

Thanks JHow and MWJB for your information on transformers; after all, that was the most important question. And Bruce - at first I thought it was an ME-18p, too; that's the reason I bought it. I asked the seller what tubes were in it, and only the preamp tubes had markings on them (and they were the same as in an ME-18p). Once I got it, though, I could see a faint 6V6 on the chassis in front of one of the power tubes, and as you know, an ME-18p has 6L6s. I liked the pretty pictures, though; that ME-18p looks to be in almost mint condition!