Now that I am a little bit more experienced in amps after my first amp build, I decided to go with one of the most famous sounds of all time: The Dumble sound. This amp is modeled extremely closely after a Two Rock Custom Reverb Signature, which, gets extremely close to the clean Dumble Steel String Singer sound.
Unlike the Deluxe Reverb I previously built, this amp has a 3 tube reverb circuit. This means that 1.5 tubes act as the reverb driver and 1.5 tubes act as the reverb recovery. This, in combination with the 3-spring reverb tank provides an extremely lush, full reverb sound.
On my last amp, I fully hand wired the whole thing. While this was a good experience to have, all of the under-board voltage traces were kind of a pain in the butt to do. That's why for this build, I decided to buy a PCB from Ryan Colgan at thetonegeek.com. You may be thinking to yourself "PCBS just make it harder to service down the line because it is impossible to know where all of the traces are", However, this PCB has a hybrid design between a typical PCB amp and a hand-wired amp. All of the tubes are still hand-wired, as well as all of the connections between most of the components. The only things that aren't hand-wired are the under board voltage and signal traces, the part of point to point wiring that makes amp building suck. You can see a picture of the signal PCB below: As far as part sourcing goes, Ryan the tone geek has a whole spreadsheet of part selection recommendations. For the most part, I went with his part recommendations. These included Koa Speer resistors, Sprague Atom Power Capacitors, and 715 Series Orange Drop caps, similar to what is speculated was used in the original Two Rock. Thanks so much to Ryan for putting this whole amp parts list together and doing all of the research on the internals of the amp. Made my job as a builder so much easier.
This build is similar to a Dumble SSS build with a couple of major differences, one of which being the disappearance of one of the tubes.
Notice how there are two different colored wires: Blue and white. The white wire is actually Coax, a signal wire surrounded by ground. This is done to reduce the amount of noise in the amp. Also, some of the orange drop caps have lines on them. These are to mark the foil of the caps. This is also done to reduce the amount of theoretical noise within the amp.
When building the amp, I had one major difficulty with the amount of noise in the amp. Whenever there is noise in my amps that sounds like a ground hum, I try to connect a ground to areas that need ground. This allows me to check for continuity between grounds. I could just use my multimeter to do this, but I have found that this method is easier for me. Please note that I do this EXTREMELY CAREFULLY, as I have to do this while the amp is on. I eventually narrowed the area of noise down to the filament windings, which I then grounded one side. Now I have read online that this may be bad for the amp, however, I have had no problems since then with this. If you have an explanation as to why this is bad, as well as a solution to fix this, please shoot me an email. Any help I can get is much appreciated.
Overall, this build wasn't too hard, but was extremely informative on good amp build practices, including Coax and marking Cap foils. You are probably thinking the inside of the amp is a mess, to which I say "Yes it is, however, for my second amp build ever, I am still very proud." I would highly recommend this PCB over trying to build this point to point, and the ease of this hybrid PCB style amp build will probably mark the end of me building point to point amps because these are just as easy to service as a point to point amp (because everything is still wired by hand) and I don't have to worry about underboard traces. I am extremely happy with how this amp turned out and I love how it sounds. That being said, the fact that it isn't a combo makes it extremely difficult to transport from place to place, and it is extremely loud, so keep that in mind when thinking about building one of these amps. Below are some more pictures of the completed amp.