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Friday, September 25, 2020

Making of 2A3 Mono Amplifiers


I have a set of 2A3 Monos in the making. Here some photos of the assembly.

This time the customer requested german engravings. Each mono block will have an external power supply. So the set will consist of 4 portrait style chassis, here the metal plates of the chassis, top plates, fronts and back plates:

The power supply top plates with sockets and resistors installed and part of the wiring done:

Main Power transformer mounted:

These amps will be used with very sensitive speakers so the 2A3 will be DC heated for hum free operation. The filament transformer is mounted under chassis:

The chokes for high voltage and filament supplies are mounted on a separate metal plate:

The finished power supply before it is inserted into the wooden frame:

One of the power supplies already finished. The wooden frame is teak:

Amplifier top plate with interstage and output transformers as well as capacitors mounted on the top side:

The driver tube will be a 6N7. Here the signal and ground wiring in place:

Chokes and two more capacitors are mounted on a separate metal plate:

Separate chokes for output and driver high voltage and for the 2A3 filament.

The amplifier almost finished only needs to be inserted into the wooden frame and the back plate needs to get connected:

In the next post I will show the finished amps. Stay tuned!

Best regards



  1. How about to make constant voltage tube power supply using 5992, 6080, 6SN7 and 0D3 then sound will be very beautiful,like a flower blossom sound and no noise from power supply, then naturally speaker will be very quiet when no input signals.

    1. These amplifiers are absolutely quiet even on the most sensitive speakers

  2. Hi Thomas,

    What made you decide to use the 6N7 here over the 6SN7 as used in your 300B amps? Thanks!

    1. Hi! I have used the 6N7 extensively for similar amplifiers. Read especially the early posts and the tube of the month post about 6N7