About the Blog

About once per week since 2021, I’ve been asked if I’m looking to hire an intern or apprentice. I never was and I’m still not but I sometimes bring them on anyway. The intern has always been a young guitarist looking to learn and possibly start a career as an amp tech. When a repair comes in the first question is, “What do you think is wrong with it?” And I respond, “I have no idea!” And I don’t. I could guess but that would put me in the same camp as those hundreds of internet forum users blindly throwing out ideas of what’s wrong with a DSL40C or a Blues Junior. Marshall Forum user jonathanmayorHSS from Toledo says, “no doubt the output transformer failed if the tubes are still lighting up.” kidADrock_mapletop chimes in, “My buddies Hot Rod Deluxe just needed a different tapered volume pot. Problem solved.” Anyone on the internet can say anything they want. And they do! They do it with great vigor and passion.

The unfortunate truth is jonathanmayorHSS, kidADrock_mapletop, and I don’t know what’s wrong with your amp unless we look at it and troubleshoot. How do you troubleshoot?

Bob pretends to examine a transformer in his first workshop in 2021. Please note the ill-fitting shirt, disheveled appearance, and farmer's tan. 3 signs of a quality troubleshooter!

Most of the time, you have to know how the amp circuit was intended to function. Sometimes it is as easy as, “damn that looks like a mouse was electrocuted in there.” That actually happened once. Our poor intern found it and together we gave it a Judge Amps funeral (into the shop vac.) You also may get lucky and see a component that exploded, caught fire, or simply vanished like DB Cooper. But one must keep in mind there is reason why that component failed and you’ll need to see what else is wrong that caused it to jump off an airplane with all that cash.

My intention with this blog is to share my practical knowledge, a very basic idea of how a guitar tube amp circuit works, and therefore give you a starting point to troubleshoot and repair an amp. The bonus here is that this is the same knowledge needed to build or modify an amp! So, if you want to make a Marshall 2203 preamp with a Deluxe Reverb output section and mod it like Mike Soldano did in the 80’s and then put it all in a Princeton sized chassis, you can do that! (That’s actually my Judge GD20 amp. Feel free to borrow that idea.)

I will walk you through some popular circuits stage by stage, throw some jargon at you, and sometimes give you my two or three cents. I’ll never tell you what the best thing is or what parts sound bad because neither of those things exist. I’ll never criticize your taste or tell you that you aren’t a good enough guitarist (the Gerald Weber approach.) The exception is if you have a YouTube channel filled with only blues licks. That does sound bad.