Duncan Amplification

This beautiful 1961 Harmony H304 came in for a recap/tune up.

Definitely have a soft spot for other old Harmony amps.

This super old YBA-1 came in for some much needed restoration. Aside from the usual cap job, it needed the filament wiring redone and the three-prong power cable redone (note to anyone reading this: marettes and electrical tape is not the right way to do this).

This old girl was also kind of a weird one, as it’s sort of a transition model between the tube rectified models and the later solid state rectified ones. It had the hole drilled for the rectifier tube covered up and everything.

These are Carbon Composition resistors (or Carbon Comp for short), and they’re found in older electronics, including guitar amps.

While carbon comps sound very nice, they’re hilariously prone to failing, being noisy, or reading wildly out of spec.

If your old guitar amp is exceptionally noisy, there’s a decent chance one or more of these is partly to blame.

Back from the dead!

This 1965 Fender Bassman AB165 was gifted to me by a dear friend, and when it arrived, it was in very rough shape.

The previous owner had sent it off to be “modified,” and while my friend owned it, it worked briefly and then died.

Upon opening it up, I was flabbergasted at what I saw: the chassis had been “cut” (more like pried with a hammer) to tenuously fit a new power transformer (one way too big for this circuit), an old 7w output transformer (from an old radio speaker) siliconed to the PT, unused wires from the PT just floating around inside, resistors hooked together and fastened in place with more silicone, and so so much more.

Long story short, I replaced the power transformer, every capacitor in the amp, every resistor in the amp (easier to replace them all than play whack-a-mole finding faulty ones), both power tube sockets, and a preamp tube socket.

Anyway, she sings now.

New build coming together!

Building an amp that hasn’t ever existed before (which is to say the preamp circuit hasn’t been married to a power amp in one unit) is a challenging thing, even when you have schematics of both the preamp and power section.

It has certainly been a learning experience, swaying from exciting and fun to “wtf - why am I even trying this.”

After months of schematic revision (thanks to a few wonderful people out there on the internet for feedback), parts sourcing, designing the front and rear panels, building and wrapping the headshell, and more, this project is nearly ready to move some air.