Tube Amp Archive

I really like these pens when I need a little extra flux. https://www.elexp.com/products/060720rma-flux-pen-formula-186?variant=42038609740004¤cy=USD&utm_source=google&utm_medium=organic&utm_campaign=Google%20Shopping&utm_content=Kester%20186%20RMA%20Soldering%20Flux%20Pen%2C%20Rosin%20Mildly%...

Some pairs of tubes will naturally bias up lower than others. You may pop in a different pair and find that the dissipation is too high. If you want to keep using that pair of tubes, keep following Sluckeys advice. FWIW, a colder bias setting will give you a much richer tremolo effect if that's impo...

I was going to ask if the PI cathode resistor connected to pins 3 and 8 is the correct 470 ohm value. Many builders have accidentally installed a 470k resistor in this spot and the result is very low volume. From your pic, it appears that you used the correct resistor though. Did you bundle the grid...

I was looking for a way to switch between my four amp heads and four cabs a few years ago. My situation was much simpler because I didn't need to switch the heads while they were powered up. I simply needed a way to connect different heads to different cabs without pulling them out of the shelving u...

@xxmicrocutsxx...I also had a lot of hum with my MT15. I found this post on another forum and after replacing the v6 effects loop tube with a 12au7 and the v3 tube with a 5751, the amp is now much quieter and actually sounds better. https://sevenstring.org/threads/prs-mt15-how-i-eliminated-the-fx-lo...

Many of the solder joints do appear to be "cold" joints and the turrets could definitely use a bit more solder. A larger tip on your iron is also helpful when soldering to the turrets. The input and output jack wiring is a common area for mistakes in new builds so make sure that you check those area...

I routinely place my OT at the opposite end of the chassis, directly over the preamp end of the board. I was concerned about creating noise in the preamp with the OT being right over it but so far, all of the builds have turned out very quiet.

I built one earlier this year and it really is a great sounding amp. I used Jason's revised board and went with the tube buffered effects loop with global master volume. Mine has a nice, gradual volume ramp up and the global MV is very useful when playing late at night. As for the crosstalk in your ...

These pots cost a bit more and they do not offer a push/pull but for all other use, they have performed very well for me. They work especially well for volume controls because they have a very smooth and even audio taper. They are the only pots that I use now for volume/gain controls. https://www.tu...

I have had that same static type noise pop up in a couple of my builds. In every case, it was a cold solder joint on the power rail or tube cathode circuit. They can look good but still not make a solid connection. I take a can of compressed air, turn it upside down and apply a tiny blast of freezin...

@Privatpig...if you are still experiencing a volume drop, check to see if the 470 ohm PI cathode resistor isn't a 470k by mistake. It sits between two 1 meg resistors and connects to pins 3 and 8 on the PI tube. This mistake pops up quite often in new builds and it will cause a very low volume from ...

Are you plugged into the main speaker jack and not the extension jack by accident? You must plug into the main jack for the amp to produce sound. Also make sure that you are not plugged into the limiter when biasing and trying to play through the amp. Edit: Looking at the schematic, it appears that ...

I have often needed to drop the value of the resistor that is inline with the bias pot. If it is a 47k or 56k, lower it down to the next value and try again.

I got caught up in the same situation as you when planning my first Marshall style builds ten years ago. I went down the rabbit hole buying Piher resistors, mustard caps, Lemco silver mica and many other NOS parts that were used by Marshall. The two amps turned out fine but after building many other...

The original SLO ran all AC heaters but the newer models produced by BAD are using DC on the first couple of tubes.