Amp out/Speaker jack for 1950s Valco/Supro amp?

[David Dvorin]

I have a wonderful 1950s Valco made Supro (Comet?) Chicago 51 amp (5w?) with an original 10” Rola speaker that has had the associated transformer moved to the bottom of the cabinet. I really love to sound when you crank it up!
The speaker is hardwired into the amp. Does anyone here know if it possible to modify this to create a direct amp out and wire in a jack for the speaker?

I’d love to be able to use my Ox Box to record it’s output with speaker/room modeling as well as attenuate the speaker output a bit (it’s a tad to loud when I crank it at home) like I would with my other combos. Just not sure if this functions the same with this old type of speaker…

If anyone’s done this, let me know and maybe if it’s something I can manage without taking it to an amp tech (I’m pretty good at soldering, but ignorant about amp schematics, wiring, etc.). Thanks in advance!


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[sgosnell]

It's possible, but complicated. Running a tube amp without a speaker load will result in damage to the amp, and running a speaker output into an input designed for line level will result in damage to that equipment. It's not something you should be doing without a thorough understanding of the amp circuit and electronics theory.

[David Dvorin]

It's possible, but complicated. Running a tube amp without a speaker load will result in damage to the amp, and running a speaker output into an input designed for line level will result in damage to that equipment.

I totally get this, and have been utilizing my Ox Box to provide the proper speaker load in line with all of my other amps (Princeton, Victoria, SuperBee)…I’d never record straight into a line input! Ox Box takes care of that too, along with speaker/mic/room modeling that makes everything simple!:-)

No one has had this done to a combo of this era (field coil speaker)?