Tube amp project

fly135 · #1 December 17th, 2006

I bought a tube amplifier off eBay about 6 months for $60. I thought I try making an amp from old stuff. Pretty much on a whim and as usual I didn't get around to messing with it. It's been sitting on my shelf in a box all this time. Well, since it near Xmas and I'm taking some vacation, I thought I'd take it out and see what's up with my eBay deal. The link is to a 9 minute video of me bringing it up and then noodling on my new Squire Aff1inity Telecaster, that I got yesterday from eBay. Don't beat me up on the playing. It's pretty ragged. Most of the video is me bringing it up. The download is just under 9 Meg.

http://amp.panelmagic.com/tubeamp.wmv

OldG · #2 December 17th, 2006

Great video,Fly.

I really liked the sound of the Tele driving those tubes - very tasty!

I was wondering if you planned to mount the amp into that Marshall cab, or build its own case maybe?

coldethyl · #3 December 17th, 2006

I enjoyed watching that video Fly.
You'll have to do a second installment of the tube amp video when you go to your next phase of the project.

allthumbs · #4 December 17th, 2006

Enjoyed that.

krissovo · #5 December 17th, 2006

You got guts thats for certain! what a cool project

fly135 · #6 December 17th, 2006

Next phase is to make a schematic. Then I'll buy all new tubes and caps. I'm curious to figure out what the "signal input" and "driver" connections are. They seem to be isolated into a circuit all by themselves, except for a pair of light bulbs (inside where they can't be seen).

The amp cuts in and out until it warms up a bit. Then it works great for a while. Then it starts to lose power. It actually puts out some decent tones for a while. Can't really tell from the crappy playing and the camcorder mic. It has a dark tone. definitely needs EQ.

I anticipate building a box and making a head amp out of it. If I really take a hankering to it, I may move on to making a combo amp.

chuckswood2001 · #7 December 17th, 2006

http://www.netads.com/~meo/Guitar/Am...a2g-notes.html

Hey Fly, check this out, maybe there is some info that will help u, dont know but maybe if u follow some of the links u can get some helpful info

Chuck

lorispencer · #8 December 17th, 2006

cool. i will keep you in mind when my old tube twin reverb finally gives up the ghost.

fly135 · #9 December 18th, 2006

chuckswood, I followed the links and there was some good info I bookmarked. Thanks for the help.

lori, still on the beginning of the learning curve. But I hope this project ramps me up quick. I'm a sucker for gadgets, and taking things apart.

allthumbs · #10 December 18th, 2006

I'm guessing already know about death caps on some of those old amps fly. Watch out for it or you will have to change your nic to fry. Probably doesn't have one, but better to be sure.

fly135 · #11 December 18th, 2006

allthumbs, thanks for the heads up. The rectifier tube 5Y3 does in fact have a large electrolytic cap that filters the rectified voltage of the power transformer. I think 300V qualifies as deadly and the size of the cap is probably plenty big enough to stop your ticker.

Did some more research and found out that it's a reverb amp out of an organ. I found some very similar schematics an even figured out the "light bulb" circuit with the signal input and driver connections. The reverb amp takes the output of the main power amp into the signal input. It runs through the light bulbs for volume compression, as the hotter a bulb gets the higher the resistance. Then the driver output goes to the reverb tank. The output of the reverb tank goes into the RCA jack, which takes mic level inputs.

Once I get my schematic drawn, I'll be able to tell if it's set up for 15 watts (or even 18W as the eBay seller claimed). That's my hope. The PT seems to be beefy enough.

chuckswood2001 · #12 December 18th, 2006

If u can find one of the reverb tanks out of an organ, they are usually an acutronics 4 spring tank and are the best made, u can prob hook it up and it will give u reverb with ur amp, im making a reverb unit using this tank, using transistor circuit for it

Chuck

fly135 · #13 December 18th, 2006

Chuck, the whole amp is designed to amplify the reverb. So it would be either one or the other. There really isn't a separate circuit that allows a dry/wet reverb mix.

fly135 · #14 January 15th, 2007

The lastest on this amp is that the circuit isn't really suitable for a guitar amp. Fortunately I've managed to find a design online that matches the basic components tubewise. So it's time to gut the circuit board and rewire. Lucky for me my job involve electronics and my boss has tons of older circuit components sorted in bins that he's onvited me to take what I need. Here's the amp design I'm looking at turning it into....

http://www.ampmaker.com/ak03x.asp

schematic....

http://www.ampmaker.com/pp18guide/pp18sc2.jpg

This one uses a solid state rectifier, but I'll be keeping the tube rectifier.

Unfortuantely, I've started a huge home project of ripping out carpet, painting, and putting in laminate flooring. So my electronic hobby is going on hold till that's done. But... I just found a Fender Pro Jr on Craigslist and picked it up for $150. So my yearning for a 15W tube amp is under control.

Rockerbob · #15 January 15th, 2007

I kinda like the overdrive it has. Turn it up to Eleven!