Tube amp

[Fred75]

I have three of these tube amps, and know very little about them. If anybody has any info, please let me know.

I do realize these are not designed for audio, but don't know whether they are convertable or whether the parts are of some use to someone.

Also feel free to send me an offer if they are of use to you. Could also be interested in trades, +/- cash or whatever. I am looking for a large transformer (>1.5KVA, 50-0-50 to 55-0-55) and some caps for a power supply, among other things.

Cheers

[mikeford]

Maybe use the tubes, other parts in some other project. Main catch, and this is a guess, is that it might be some old aviation part and not designed for any type of normal power source.

[tubelab.com]

Main catch, and this is a guess, is that it might be some old aviation part and not designed for any type of normal power source.

Says 120 volts 60 cycles right on the side. That sounds normal for N.A.

My guess is some type of instrumentation amp. The metal can in the octal socket could be a mechanical chopper, but I can't quite read the writing. Two 12AX7's and a 12BH7 are preamp material.

[mikeford]

12bh7 is low power output like a bigger 12au7 I think? (not much of a tube guy)

[stereodude27]

The coupler labeled 101040 is for an amp controller.

LEEDS & NORTHRUP 101040

Leeds & Northrup was founded in Philadelphia by Morris E. Leeds as Morris E. Leeds & Company. Dr. Edwin F. Northrup, an educator, scientist and engineer, joined the partnership in 1903. The company produced high quality electrical measuring laboratory instruments. Until then, the best precision instruments came from Germany, but Leeds & Northrop provided an American-made alternative. The company produced a number of innovative measuring devices for education, science and industry, including the world’s first electronic recorder in 1929. Since 1978, the company has been resold and renamed. Since 1995, it has been part of the multi-national Heraeus Electro-Nite Co. and is now known as L&N Metallurgical Products Co., producing industrial molten metal sensors and instrumentation for the international market.

[tubelab.com]

12bh7 is low power output like a bigger 12au7 I think? (not much of a tube guy)

Yes the 12BH7 is a 12AU7 on roids. It can be plugged into a 12AU7 socket in some applications.

Leeds and Northrup made specialized test and measurement equipment for industrial applications back in the tube days. What does the label on thr round metal can with the brown plug on top say. I think the whole thing is some type of chopper stabilized amplifier, like an op amp. If the can is the chopper that will confirm it.

[Fred75]

Hi, thanks for all your input. These were part of some old equipment that came out of a research lab.

The label on the metal can with the brown wire is "S.P.D.T. Synchronous Converter" and "Converter Drive Coil"

[Fred75]

So I checked out the 12ax7 tubes and a video I found from audiotubes.com, and I think they may be the Telefunken smooth plate 12ax7's, not the red or blue tips, but the standard. I guess they were often used by Leeds and Northrup.

Does someone know a good project to use these in? Or a good commercial preamp using 12ax7's to try them out?

Arrrggghhh, I was trying to reduce my numbr of "projects"