Another amplifier project, the Muzak tube amp.

Hello, steemians, and welcome to da workshop, eh!

This is another tube amplifier that I was given to rebuild into a guitar amp.

This was originally an amplifier that would have been used in a retail store for background music before the tube amps were replaced with solid state amps. This amp has an output power of probably 10 to 12 watts it uses a pair of 6V6GC power tubes. The original circuit configuration in this amp was setup for microphone inputs and auxiliary inputs from a radio or tape player. The original tubes used in the preamp aren't really suitable to guitar amp use, so I had to rebuild most of the amp to make it into a guitar amp. Unfortunately, I didn't take any pictures of the amp before I pulled it apart and rebuilt it. I worked on it the first time in the winter of 2016-17. This is what it looked like after the rebuild. The 3 tubes that are together in a row are the power tubes and the voltage rectifier tube. The other 2 tubes are the preamp tubes.

The inside of the amp. Because this is a single channel amp, the circuitry is pretty simple.

After I finished rebuilding this amp, I tested it to make sure it worked and then put it on the shelf for the summer. I pulled out last fall to demonstrate it the person who brought the amp to me, and it had a lot of buzz, more than it should, so I had to go back into the amp to solve that problem. Usually, the buzz comes from ac leaking into the signal path because of leaky filter capacitors not stopping the ac. The only way to solve that problem is to replace the filter capacitors, so that's what I ended up doing. I had to order the parts before I could finish the job.
I have one of the capacitors installed in this picture.

With both capacitors installed.

The circuitry looks like this after the rebuild. The main difference is the wiring to the bottom of the power supply capacitors. If you compare the 2 circuit pictures, you can see the differences.

The amplifier sounds a lot better now, much less buzz, and the amp is a bit stronger now. I did a bit of testing and I was pretty satisfied with it. It tends to start into distortion a bit early compared to the volume, but I think that's because of the circuit design, it's loosely a copy of an older Ampeg design. One of these days when I figure out how to do it, I'll attempt to make a demo video of the amp.

Well, that's all I have for this post, I hope you found it interesting!

Thanks for stopping by and checking out my post, eh!

Feel free to leave a comment or a question for me if you would like.

May the Steem Force be with you!