My Project - And I need help...

[Hobobob74]

So, probably 5 years ago, I got this little gem of a PA Tube Amp. Its just been sitting in my basement ever since, but I finally might have found something to do with it.

It only has an old school mic. jack, but i have a converter to switch that to a 1/4" female jack to plug a bass or guitar or whatever into.

So, I'm thinking I'm gonna build a little wood cab to put it in and make a little head out of it.

Here is my questions:

1. The speaker connections are just for the wires. But there is a 8 ohm and 4 ohm screw. So how would I wire up a jack for say, 8 ohm? Ill attach a picture for a better idea, lol.

2. Can I just disconnect the volume and bass/treble pots, add wire, and put the knobs on the outside of my new 'head cab'.

Hopefully this turns out cool, lol

[Hobobob74]

some more

[Hobobob74]

underbelly

[Nate74]

1. The speaker connections are just for the wires. But there is a 8 ohm and 4 ohm screw. So how would I wire up a jack for say, 8 ohm? Ill attach a picture for a better idea, lol.

Drill a hole, put the female 1/4" jack into it, wire the appropriate wires to it, preferably with solder not masking tape.

2. Can I just disconnect the volume and bass/treble pots, add wire, and put the knobs on the outside of my new 'head cab'.

Yes.

[dhsierra1]

Originally Posted by Nate74

Drill a hole, put the female 1/4" jack into it, wire the appropriate wires to it, preferably with solder not masking tape.

yup. You'll want your ground wire connected to the "C" screw terminal and the hot (positive) to the 8 ohm screw.

Looking at that schematic seems like you'll have around maybe 8 or so watts. Go with a high efficiency speaker if you're going to put bass through it.

Looks like a fun project, good luck and keep us posted

[BassmanPaul]

Honestly I think you'll find that that amp will not give you a lot of low end. It'll make a better guitar amp.

[Steve Dallman]

It's not far from the design of a Champ. It could be wired to be a little more bass friendly, but you've got low plate voltage, limited B+ filtering, and about 5 watts. It could be made into a better guitar amp, but it would still be just a few watts. It has a pretty small output transformer to boot. You could put in a SS rectifier to get the voltage up some, and that would allow you to increase the B+ cap, which would aid a little in headroom.

[Hobobob74]

Yeah, I would probably just use it for a practice guitar amp.

But I've heard that it would make a good harp amp too

[B-string]

Nice little cathode bias Class A amp. Use shielded wire to extend the wire on the pots, old balanced mike cable will do.