• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Amp ID

Mjw9mm

Member
2019-12-01 9:40 pm
Would appreciate help identifying this older tube amp. Thanks.
 

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PRR

Member
Paid Member
2003-06-12 7:04 pm
Maine USA
www.diyaudio.com
It's a Williamson or derivative, I bet. In the day, you could buy kits; some guys punched chassis and wound iron. You'd have to be very obsessive to narrow it closer than that.

It looks like a bigger/better class of Williamson.

Trace the small-tube circuits. Williamson is not unique but if you find something odd, then I picked a wrong path. Trace the big tube OT leads. Williamson is pure Triode but a lot of copies got built as UltraLinear. Show the speaker connections. A very original Williamson OT has a scad of terminals you jumper different ways for different impedances; copy-cats often simplified this. (However some totally different amps also have a dozen secondary tags..)