Thomas organ guts for amp build?

[harpo57]

Hi! just joined! ok.. I salvaged the audio out of a thompson californian organ for guitar amp build., 2 12's ,the amp, a wire wound reverb unit and misc . If I can hack the amp for the input.(no luck on getting a schematic..) lots of wires going in it, power, headphone, aux.input.who knows what else.. Im hoping just tapping the volume control will do it. Also thinking it may have had a pre amp somwhere. Dont know.. any advice on that be nice. Curious about the reverb unit. Thinking of incorperating it in the build to find out what interesting sound effect one could get. Question is where to place it in the circut. Ahead the amp or after? I think the amp is stereo input, has R-L aux input, dual stacked pots on volume .., output for two speakers.(it had two speakers, diff.color wire for each one.) Im guessing the reverb is after amp? Placed between amp and speaker with a switch to direct output straight to speaker or go thru reverb? Thank you, harpo.

 

[Malcolm Irving]

Reverb goes between the pre-amp and the power amp. It can't handle the current that goes to a speaker.

EDIT: To expand on that a bit: There will be probably be a special 'reverb driver' stage (which might include a small transformer) somewhere after the first pre-amp stage, and another stage to recover the reverb signal and mix it back in with the straight through (or 'dry') signal before it goes to the power amp.

 

[harpo57]

I knew i was being a dummy... didnt get all the parts.. scrappin the build.. thank you.

 

[harpo57]

I must be confusing reverb with an "echo box". It had a spring wire in it too.

 

[Malcolm Irving]

Don't let me put you off!

A spring reverb has a small actuator which puts the sound vibrations onto the spring. That is a bit similar to a speaker but it works at much lower power levels.

 

[harpo57]

Thank you. I googled it. Reverb tank. Yea, lots to it. but with no wire diagram for the amp, idk.. im not as smart as i think i am.. ill look at it some more.. maybe its not as complicated as it looks. .

 

[Enzo]

Thompson organ? or Thomas? There may be some, but I don't know Thompson organs. Thomas organs was a major brand in its day, and they are common. Searching for the wrong name might be why schematics are not coming up.

Californian was a Thomas model name.

 

[harpo57]

Yes, Thomas.. brain fart... be nice to track down schematics.. i tried.. no luck yet.

 

[Malcolm Irving]

.. maybe its not as complicated as it looks. .

The main issue if you want to try this kind of thing is safety. Tube amplifiers have lethal high voltages in them and these lethal voltages can still be present even after the amplifier is switched off.