10 watt guitar amplifier with tubes

My first fully self-built guitar amp worked with only one EL34 in the power amp. With a simple design, I wanted at least a little more power, as was achievable with an EL84 in SE operation (SE = single ended). Otherwise, I had can continue to take my old Telefunken Opus tube radio, which until then had to serve as a guitar amplifier.

I built the device as a portable combo amp. The case was made from an old cabinet drawer in which I inserted a baffle with the two speakers. On a small front-mounted aluminum plate, the input jack and the potentiometers for volume, bass and treble were mounted.

Since I could not organize a suitable for the EL34 SE output transformer, I used a slightly larger intended for the EL84 output transformer. Due to the secondary-side load with two five-ohm loudspeakers connected in parallel, the primary impedance was suitable for the EL34. The resulting loss of bass was acceptable for guitar sound. Finally, the transformer was designed for high-quality music playback and was able to transfer markedly lower frequencies at five-ohm termination, as delivered by an electric guitar. The amplifier made with its good 10 watts for rehearsals with the school band enough "noise".

Total renew of a Vox AC15 guitar amplifier

Many years ago, I was asked to restaurate an old Vox AC-15 combo amp. The device had been completely emptied, only the transformers were still on the chassis! Visually, the device looked excellent, so the effort seemed worth it and I got down to work.

Internet was not there yet and unfortunately I only came to a probably several times bathed in coffee and therefore barely legible circuit diagram. It is therefore possible that the circuit no longer matched the original device. Nevertheless, the sound of the device successfully reconstructed with unused NOS components and according to the circuit diagram shown was convincing.