Howdy! This is my first post here on The Nation, and I have an amp question.
I scored a VOX VT15, 15 watt amp in partial exchange for some work I'm doing for an aquaintence, and there's a problem with the potentiometer marked MASTER on the top panel. If I adjust the knob, I get loud static out of the speaker, and sometimes the volume cuts out all together. I have to kind of play with it to keep the volume up on it to the point that you can hear anything out of it.Other than that one annoyance, it sounds great. I think a CGB will sound great through it - and you can't beat free for a price.
My question is, do you think a bit of contact cleaner sprayed down into the potentiometer will do the trick, or do I need to replace that potentiometer?
Thanks in advance for your help.
Replies
For the cabinet carcass itself I'll probably go with biscuits rather than finger joints. The current cabinet is covered in black vinyl, and I like that look. I may change the color to brown (I have some handy) but nothing is written in stone. Black vinyl is easy to find cheap. I've decided that this will be for using, not setting on a shelf and looking at, so I'm not looking for a showpiece.
I'll grab some 1/4" when I get the 3/4" cabinet material and cut a new baffle for the speaker. Then again, if they have maple at a decent price, I might go that route and skip the vinyl covering all together.
Thanks guys.
I have a good woodworking background in cabinetry, so making a new amp cabinet isn't a problem. I can't tell you how many sheets of birch plywood I've cut into cabinet parts. It looks like the speaker itself is screwed to a piece of 1/4" luan plywood, but I'll most likely switch over to birch for that too. Still up in the air about whether to build a new cabinet or keep my eyes open for something that can be made into one.
Film at 11...
Ahhhh, cabinetry skills. So, no prob finger jointing it, then.
If you do go birch, then you definitely want the speaker baffle (technical term for the piece of wood the speaker is screwed to) made out of the same material. You want the speaker baffle to be relatively thin ( 1/4" or even less) compared to the cab frame. I think if you just built a new cab, without changing anything else, you'd find the amp sounds completely different, and waaaay better than it currently does. And that's without doing a speaker upgrade.
Just to update and finish out the story here, the contact cleaner worked like a charm. I pulled the back off the amp, pulled the amp out of the cabinet, and found the board the pots were soldered to. I then removed the screws that held that board onto the main amp board. I gave all of the pots a good sluicing out with the contact cleaner while turning them back and forth to knock any gunk loose while the cleaner was being sprayed. I put it all back together, plugged it in, plugged in the guitar, and whammo - it sounds great.
I did discover that the cabinet is about shot. It's made of particle board and it's coming apart in a few areas - especially around the speaker opening and along the back where the back panel screws onto it. I think I'll be making a new cabinet for it down the road. Who knows - if I find a neat old soap box or antique radio that doesn't work, I might swap the internals out into that.
Thanks for the help!
I've often been able to extend the life of crumbling particle board by "painting" the weak crumbling areas with a good coat of carpenters glue (Titebond).
When dry it completely seals and strengthens the effected area. Paint it into worn out screw holes as well and it will give enough new surface so the screws will have something to grip.
Like your contact cleaner ... it might be worth a try.
Thanks for coming back with, as Paul Harvey used to say, " the rest of the story." if you do decide to re-box the guts of the amp, try birch plywood. Many of the top amps use it, and it isn't all that expensive. The expense comes from finger jointing it. You could butt join it, with some decent wood or carpenter's glue like Titebond, and you might be amazed at how different the speaker and the entire amp sound. Particle board and MDF soak up sound.
Thanks very much for the reply. I know my limitations when it comes to anything electronic, so the replacement will be done by a tech if I need to go that route. Just wondered if anyone had had any success with the contact cleaner before I shell out the money to have it replaced.
Try the contact cleaner first, then check for a simple loose connection. Be very very careful if you decide to open it up; there are literally killing voltages inside. If you don't trust yourself, take it to an amp tech.