Guitar Gear Forum

I have an older Vox amp, which has broken and doesn't seem repairable. I was going to cannibalize the speaker with the case and build my own amp. I'm not after ear shattering volume, just decent sound quality.

The speaker is 22W. if i grab one of the DIY plans from the net somewhere which is rated at 3W or 5W, are these going to produce enough output for this type of speaker to produce a clean sound?

Yes.. complete noob on this type of theory and Google just seems to point to max dB and volume ratings when talking about wattage. Any links or advice would be greatly appreciated.

Welcome to the fold brother! This is the best guitar/amp forum on the net!!!

Just wondering why you think the amp can't be repaired?
What model is it and can you post some pics of the chassis interior?

The ability of an amp to produce clean tones does not have anything to do with the wattage of the amp or the speaker.
However, you will not get as much "speaker distortion" running a 5 watt amp into a 22 watt speaker.

Also, importantly, how loud do you want/need it to be? Are you playing with others? a drummer? a full band?

5 watts into a 22 watt speaker should be fine for home alone playing, but not much more.

I'm usually only playing with mates at home, one other electric and an acoustic, no drums, so it doesn't need to be too much.

The current amp is a Vox Pathfinder. Similar to:

The issues were my 2yr old got onto the gain and volume knobs and just twisted them, so they now do complete 360's. I was able to jiggle them to get a connection, but this was dodgy and has now stopped working. I've removed and replaced both potentiometers, but still get no sound. It'll cost me a large stack of coin to get it diagnosed, more than it's worth to buy a second hand amp.

So... the plan is to have a crack at building my own via some plans from the net and insert it into the old chassis. Quite capable of building circuitry, just not up with the theory of speakers and output.

eek.. apologies if that image is a bit large.

you should just buy another amp honestly. But yes, your 5 watt build will work fine with the 22 watt speaker.

Buy a decent second hand tube combo amp.

Yes, you could buy two new Vox Pathfinders for the cost of a repair!

An amp build sounds like fun.
There are a few forumites with a lot of build experience. If you start a separate build thread and post photos of your progress, you will get more feed back to help you over any bumps in the road.

Currently, one of the GAB members is building a low wattage Firefly Amp. Do a forum search for "another firefly" and you'll find the thread. I'm goofing off at work, on my cell phone, otherwise I would be happy to add the link to the thread.

Hi Noewon and welcome,
First if you were close to where I live, I wouldn't charge you anything to diagnose the problem with your amp,
and second, I would fix it for the cost of the pots and to jam out a bit, providing that it is actually the pots.
As far as your concern about the speaker its a 6.5" speaker and you say it is rated for 22 watts.
Yes you can build any one of the low wattage amps from 1 watt to 10 watts and the little combo should sound
decent enough for what your are doing with your mates.
I would venture into the Firefly by Doug Hammond it is a sweet little amp and gives very good tone, its perfect for setting in the house and jamming out with friends. There are a lot of wonderful and helpful people here on GAB that can provide help and tips with your build,
and also not to forget AX84 is where you can find the schematic for the Firefly and other amp build questions.
Learn and respect the safety of working on tube amps, first, and then build and experiment.

oh by the way did I mention SAFETY,
that's the very first thing that you should learn first.
Tube amps and circuits are extremely dangerous they can KILL,KILL,KILL.
Don't let that discourage you, we all here cant stress enough about the safety precautions of working on tube circuits
Always keep one hand in your pocket when the inside of an amp is exposed.
they are fun,fun,fun

Back to your amp.
If the pots are mounted to the PCB (printed circuit board) check each circuit trace leading away from the pots for small noticeable
hair line cracks or breaks, if you find one or two, just scrape off the green coating and solder a bridge across the break.
If the doesn't work solder small wire jumpers from the pot legs to the next solder joint of each trace, make sure you don't short the traces together