how to make a guitar amp from an old transistor radio

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Comment by Timothy Wayne Groves on March 27, 2013 at 7:20am

I tried each wire from the volume control pot, from left to right they are brown,green,and red wires. Radio is on and is loud and clear. First was the green, when clipped the radio went silent, connect to guitar and nothing, connect guitar to circuit board and heard both. When I tried the brown wire it worked but the volume control was not working and radio and guitar could be heard. When I clipped the red it went silent and guitar could be heard through pot when connected. Grounded onto metal plate holding control knobs, and central wire to red leading to volume control pot. When the cbg is connected to my big guitar amp I have to really crank up the volume to hear it. I think the piezo in there is the problem....Thanks smojo, great video, very clear instructions compared to others I looked at.

Comment by smojo on March 27, 2013 at 5:30am

Timothy - sounds like you either got something not quite right with your wiring or the radio was faulty to start with. Did you try it as a radio first and did it sound loud and clear? If it was OK then double check how you've got it wired. They can sound crap with piezo's and OK with mag pups which is down to impedance mismatch but it should sound better than you described.

Comment by Timothy Wayne Groves on March 26, 2013 at 11:23pm

Here is what the insides look like.

Comment by Timothy Wayne Groves on March 26, 2013 at 11:21pm

I just tried this with a radio I got from e-bay for .99 cents. This one is an old sears am-fm-afc. It is powered by 3 C-cell flashlight batteries.  Using smojo's video and info from these comments here I got it done. It sounds like s#!t. There's no overdrive at all. It sounds ok with my Yamaha electric plugged in, but I can barely hear my Cigar Box in it. I have to put my ear right up to the speaker, it's very weak.

Comment by smojo on February 27, 2013 at 3:55am

Once you've identified the correct lug, cut the wire that is already connected. Make a not of it then if you get it wrong you can solder it back.

Comment by gregory on February 26, 2013 at 1:40pm

How do I know what to chop?

Comment by smojo on February 25, 2013 at 3:29am

Volume pot is the place. There's three lugs on it. One will go to ground so the ground on your jack socket needs to be wired to that. The "hot" or tip of your jack socket goes to one of the others, usually the centre. Connect to it then try a guitar plugged in and see if the volume pot still works properly. If the sound level doesn't change then move the wire to the other end lug and try again. You usually need to chop the feed that goes to that to stop the radio signal coming through.

Comment by gregory on February 24, 2013 at 12:03pm

I have an old airline that I can figure out where to hack into. The volume pot? The tone pot? Please help

Comment by KB on January 27, 2012 at 10:09am

I was trying to do this just a couple of days ago and couldn't figure out where to put the input. I guess I'll try again.

Comment by smojo on January 27, 2012 at 3:44am

Thanks guys, The guitar is an old Kay, I traded it with a converted cassette player amp and some cash. Yeah I like it too. BJ you only need a very simple signal/tone generator, just a simple flip flop oscialltor should do it. They can be made quite cheaply. I'll see if I can track down a diagram and post it.

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