Matamp GT120 Tube Amp Clone


This is a build of a clone of the Matamp GT120 using a chassis and PCB purchased from Hillbish Design.

When you purchase a PCB from Hillbish Design several build docs are included such as a schematic, layout, (limited) BoM, some assembly photos, and a voltage chart. Given this is part of the product you're purchasing from them I won't include them here out of respect, though Nathan Hillbish has posted his schematic on a couple of forums so you can find that fairly easily if you want to take a look.

I used Mercury Magnetics transformers in this build - the part numbers are in my BoM below. Some of the power transformer secondaries (the 6.3V 10A heater suuply and CT for the EL34s) use very thick wire. I had to jerry rig a couple of things to get those wires hooked up - see the photos below. I also modified the layout slightly as there was a fairly awkward point-to-point section between the boost knob and V1 that I didn't really like. I moved that to a terminal strip.

I started off using a rainbow ribbon cable to connect the Bass and Treble pots to the board as suggested in the supplied docs. The ribbon cable I had on hand was pretty low quality and the leads kept breaking, so I switched to using regular hookup wire while keeping a similar colour scheme.

An interesting note about the FX loop in this amp; it's a parallel loop set to about 40% mix or so. I guess the idea was that you patch in a 100% wet reverb or delay. I'll probably never use it - in practice it's not very useful.

Current State: The amp is completed to the point of firing it up and running it through it's paces. I still want to tidy up some of the lead dress and remove some excess lead length in various parts of the amp. Overall it's sounding good but needs a bit of tweaking.



Here are some in-progress build photos. I'll try to label them at some point.


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