Altec 342B Tube Amplifier - What is it good for?

[tigerzilly]

I'm a tube amp junkie but I don't see the value in old tube amps unless they're good for guitar. Tube amp technology is well suited to the guitar, otherwise its just old junk IMO. I had an Altec 342B tube amplifier dropped in my lap recently. Its a four channel tube PA head. It has a nice vintage look. I'm not sure if I should be excited about it. I'm inclined to fix it up, but what is is good for? Is there a potential guitar amp conversion here?

Here are some pics.

[The Dude]

Don't let the tube hi-fi nuts hear you say that!
And, sure,...... why not build a guitar amp out of it? I do agree, there's not much use for it as a P.A head these days.
The schematic is in the instruction manual here:

http://greatplainsaudio.com/wp-conte..._oper_inst.pdf

Edit: Step 1- Get rid of the selenium rectifier!

[Enzo]

ANY tube amp has guitar amp potential. It is a metal box with power tube, preamp tubes transformers. and it is all wired up and works. Hell, it might sound cool as it is. But if not, you can do like THOUSANDS of people have done with old Bogen amps, and convert it.

You could modify each channel and have four different preamps. A MArshally one, a Fendery one, who knows...

I'll bet my lunch money the power stage wouldn't change a whit in a conversion, so there it sits, ready to use. The preamps? Well regardless, the heaters are wired up at least. A lot of stuff probably can be left. I bet a lot of plate resistors can remain. I suspect a lot of change involves what is between stages, like tone stacks and stuff.

Oh, I just looked closer. Those lovely mic impedance transformers - the green things. You don't want those, send them to me. I'll, uh, recycle them properly. No really, sell those. What number/type are they?

If the thing is just too ratty to recover, well you got good iron in all likelihood, a basis for a project.

example transformers for sale:
https://www.ebay.com/itm/Pair-ALTEC-...0AAOSwI~teQNz3

They are asking $600 for just a pair of them, you have four.

[g1]

For sure try it with guitar as is. One of my best sounding guitar amps is a supposed 'PA' mixer/amp, all stock.

[The Dude]

Looking at the schematic, this thing has a lot going for it already. DC filaments on V1-V3, adjustable bias, etc. You could also cascade the first 2 triodes of each pair of inputs and make a 2 input amp for some overdrive capabilities.

[Justin Thomas]

To be fair, one of the best comments I ever got about one of my builds was when one friend said to another that he didn't realize he was even singing through a PA until he asked me to turn up the treble a bit. The "PA"? My Spitfire clone through a garage-sale 4x10" homemade column.

Don't discount tubes for PA. I tend to think most PAs sound like crap anymore.

Justin

[tigerzilly]

You guys got me motivated! Time for the ceremony to begin!

I notice three toggle switches on this that aren't shown in the manual. Curious what thats about.

[Enzo]

They are not stock. What are they wired to? If I had to guess, they might be on/off for each channel. I suspect this PA amp was used in an installed system rather than a travelling show. And those switches might have been added for something like room switches in a PA in something like a church or school.

[tigerzilly]

Pics with the chassis out.

[tigerzilly]

They are not stock. What are they wired to?

There is a wire harness that goes from the toggle switches to the output terminal strip.

[tigerzilly]

I always get that ooh ahh feeling when open up an old amp. Especially when it all looks original.

[The Dude]

What does the terminal strip go to? Maybe the OT? I'm guessing the switches turned speakers on and off in certain rooms like Enzo said.

[tigerzilly]

What does the terminal strip go to? Maybe the OT? I'm guessing the switches turned speakers on and off in certain rooms like Enzo said.

Yep. It looks like it goes from OT to switches, then to output strip.

[The Dude]

Not a great idea, but not the first time I've seen it done.

[Leo_Gnardo]

Those lovely mic impedance transformers - the green things. You don't want those, send them to me. I'll, uh, recycle them properly. No really, sell those. What number/type are they?

If the thing is just too ratty to recover, well you got good iron in all likelihood, a basis for a project.

example transformers for sale:
https://www.ebay.com/itm/Pair-ALTEC-...0AAOSwI~teQNz3

They are asking $600 for just a pair of them, you have four.

I wuz gonna say... Just finished working on an Altec 1567 mixer that had a full brace of these mic/lin transformers, plus its output transformer. Of course its owner is holding on to ALL of them, he's a studio owner, got them golden ears y'know.

But since you don't need 'em, they're of no value in a guitar amp, yeh send 'em to Enzo. Or me.