Author Options:

Could this be used as a guitar amp or converted into one? Answered


Could I convert that into a guitar amp? Im thinking that because its mono and not stereo it should work fine? Any thoughts or suggestions?



9 years ago

I suppose it could work...with some caveats:

-- It might have a weaker preamp stage than most guitar amps. iPods and audio lineouts have stronger signals than passive guitar pickups. Two preamp stages are the norm (for triodes), and this has only one.

At best, since it's not designed for guitar, it's probably "cleaner" than you might want, signal-wise. Doesn't mean it's not modable, though. But it would be a difficult "first-timer" tube project...

One option would be to add an additional solid-state preamp stage (as a stompbox, for instance.)

-- I'm not sure how those metal-case tetrodes would work in a guitar context. Most amp power tubes are pentodes (tried and true.) They might be fine; I just don't have a clue. Certainly has some oddball tubes, none of which (other than the rectifier) are normally found in guitar amps.

-- Any old tube gear should be retrofitted with a three-prong cord, and grounded appropriately for safety. And it's a "mystery amp," so no schematic. You'd need to trace and document the circuit before modding. It seems to be fully isolated (power transformer) so that's a plus...

If it can be had on the cheap, it might be worth the gamble. On the other hand, you can usually find guitar tube amps in the 3-4 watt range for under $100. They at least would be a known quantity (designed for guitar.)

That one has some positives--

-- Two small-signal pentodes in the preamp stages should mean plenty of gain. In modern amps, pentodes are rarely used for the preamp, but they were very common before dual triodes became commonplace. Those tubes would have been used in guitar amps at one time.

(Here's a schematic for a guitar amp with 6J7 preamp tubes.)

-- A single-ended 6L6 power stage is probably 6-10 watts. Ten watts of tube power through a decent speaker cab will be LOUD.

-- It's got high quality transformers. (NEVER, under any circumstances, operate a tube amp without a load (the speaker.) It will fry the output transformer. )

And some negatives:

-- It's pretty old. It's very likely some of the caps are bad. The longer it sat without use, the more likely they're shot. It may no work at all currently, or it may kinda work. That means rebuilding. Likewise for the tubes, which are untested.

-- The transformers are quite nice... Thordarson is a good name, and it's condition is very "restorable." There's value here for audio wonks-- given the likely need for recapping, the price may climb out of the cheap "project" range...

Is it possible or easy at all to make a shcematic for the first amplifier I asked about?

From the photos alone, or from the amp itself?

In your opinion which one should I get?

If I owned the amp itself? And if I had the right tools like a multimeter and capacitor checker ETC.

Look like it should, but watch the price. L