Tube console for DSD location recording

If DSD is the ultimate current technology for capture (as I believe it is), then for me, discrete tube circuitry is the ultimate for amplifying the signal between the microphone and the DAC. To that end I am building a small portable recording console that is all discrete tube and transformer based.

It will be eight channels, designed both to do 8x2 stereo recording direct to 2 track DSD, as well as allowing for eight direct outs and returns to and from something like the Merging HAPI, for multi channel recording and mixing.

My background is as a recording and not an electronics engineer, so the circuit design is not mine but that of Ian Thompson-Bell, a mainstay at GroupDIY, and the proprieter of His efforts to enlighten about audio electronics engineering and his generosity of spirit are inspiring and only exceeded by his talent. This project would be impossible but for his designs and support.

The circuit design is fairly straightforward and uses half a 12AX7WB triode that goes into an SRPP which includes two halfs of a 6922 triode and uses NFB. A discussion of his design principles may be found at Custom Tube Consoles - Design Philosophy. I can say it is a very nice sounding circuit, having built a prototype.

It will be (just about) portable, being abot 110mm deep and 315Hx483W. as to the final, I am not yet sure but it should be able to achor a boat fine!

I have bult the power supply, and am now working on the chassis while I simultaneously teach myself how to design the channel circuit PCBs.

Here are a few pictures:

Power Supply:

Rear Panel:


  • Richard July

Hi, interesting project. Wish you success. Tubes generate a clean dynamic sound. Personally I restored and modified early tube based mic-preamplifers from AMPEX early tape recorders. Model 350. Very good as mic-preamp. Also a RCA mixer almost like showed on the custom tube consoles website. To be honest, the pain lies in the details. It is hum, tube noise (regular and sporadic) Hard to get very good tubes for the first stage. One drawback to my opinion is the usage of audio transformers which may modify the sound. Anyway, good project if the result will work well for your purpose.