help valuing parts from 1971 Fender Twin Reverb.

[Justin Thomas]

Oh, well, if you want lower volume, inefficient speakers is one way to accomplish that...

Justin

[bob p]

Personally I hate triode-pentode switches because they knock perceived power very little and they kill bite and punch very much but being an experimental amp there´s many other options, from the variable +V thingie which can tame large amps down to whisper levels to some tasty PPIMV (which shine in "clean" amps such as Fender) to .... gulp!!! ..... some kind of attenuator.

^^ This.

I hate triode mode switching. I think it ruins the sound of a pentode and only serves to make an amp sound like ass. I have several commercial amps that used it for marketing, and it sounds great on paper. But in the real world I don't like it. I never use it on the commercial amps that have it, and I don't bother adding it to a build. I see no use in it.

With that said, there's no reason not to take a Twin Reverb project chassis and build something fun and low powered out of it. Redesign the amp to use two 6L6 instead of 4. Keep the OT and switch the speaker load to match the new plate resistance. You'll find that with that huge iron the amp will sound great. If weight is an issue, eliminate one speaker and plug the other side of the baffle.

One of the great things about Twin Reverbs is that they are one of the few Fender platforms that provide mid controls on both channels. I can't begin to tell you how important a mid control is if you're playing Jazz. Personally, I'd rather have a master volume Twin Reverb than any other Fender amp, regardless of it's weight. Yeah, I said it. I prefer the Master Volume amps because the two volume knobs can be used to provide very fine control over volume. It's hard to play standards in a piano bar if your non-MV amp has a jumpy response at the low end of the volume pot.

Another reason that I love twins as modding platforms is because they can be had dirt cheap, just because they're too big for the average guy who wants a small amp for his bedroom or basement. When fender was making these amps back in the 60s-70s, the little amps were inexpensive and the big amps were the ones that cost more. Now we've got the pricing structure for Fenders turned upside down, such that a Princeton Reverb costs as much as a Twin Reverb. Why? Because basement warriors are driving the amp market. Few people need a Twin any more, so they're cheap.

BTW, $600 is a lot for a project chassis. $350 would be a better price for an amp that needs work. You have to bear in mind that these amps don't fix themselves, and when an old Fender needs work, it needs work because somebody was too cheap to pay to have the work done. When you're looking at an amp that needs repair, be sure to subtract the commercial cost of the repair from what you're willing to bid, otherwise you'll be paying too much.

As an example of pricing, in the past year or so I picked up a Twin Reverb with original JBL for $700, a master volume mid-70s TR with EV-SRO for about $650, and a Super Twin Reverb that needed tubes and the reverb tank replaced for $350. Your time as a repair tech has value. don't give it away by overpaying for a broken amp.