The Amp Garage

It seems to have gone away with taking the tank out of the cab. Not sure about if the amp needs caps or not.

That is something I feel I'm prepared to do and would like to do if it is good for the amp. How can I test for the need of a cap job?

Just any type of foam?

Took the tank out, put it on a pillow and everything seems fine! Popped the original RCA 12AT7 back in and it sounds perfect.

Question is, how do I put the tank back in such that it will not do this anymore?

Alright, finally got my old Sovtek Mig up and running now I have a new project. My '72 Twin started humming with the reverb turned all the way up. It slowly builds up to a consistent tone that goes away when the reverb is turned down or off. Bought a NOS GE 12AT7 today and swapped it for V3, same pr...

Thanks everyone. Put in a new set of SED 6L6GC's and got the bias squared away. I am very confident at biasing now! Also, I never remember the amp sounding so good! Now onto getting the parts for my 5E3. Thinking of picking up a boothill amp kit and classictone transformers. JJ and EH tubes at first...

Alright I got the amp opened up, immediately saw a fried screen resistor and replaced it. Measured resistance from P1:CT and P2:CT - Both 37 Ohms. Plate voltage is at 545v, for which I calculated 38.5ma for each tube as per Weber Bias calculator (6L6GC) running at 70%, which for 2 tubes is 77ma. Cal...

martin manning wrote:There's a good project for you- everyone needs a dummy load.

Any links you recommend?

Another question I have:

Do I need to have a load on the output when biasing or doing work on the amp that is not producing sound?

Yes its really a great amp. I'm really excited to get some new tubes in it and be able to work on it myself. I bought it for $400 in 9th grade, I will never sell it, it was my first tube amp and from what I hear it is a great amp to learn about amp design with.

Thanks for all your help.

Is this the bias pot?

Thanks for all your help, I am very excited to get working on this when I get back home to Philly. Preparing to work on amps, I am thinking about some new tools that may come in handy. I already have a nice hakko soldering station, DMM and some pretty decent hand tools that I have picked up here and...

Would a bias probe help in any of this? As I said before I am hoping to embark on a lifetime of amp building and I rarely mind spending money on tools to improve the process.

Thanks for the help. I will do some of the suggested reading and report back when I am actually with the amp. It does not seem that difficult. I assume that both sets of tubes will not be operating at exactly the same current since there is only one adjuster, am I looking for the best compromise bet...

Hello All, This is my first of hopefully many posts in the amp building community. I have spent the last few weeks reading up as much as I can on tube amp theory and studying and analyzing designs. I am not 100% confident with some details (particularly math) but I can surely look at a schematic and...