• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Custom preamp with 417A / 5842 phono stage

Erno Borbely designed a FET phono stage that was later adapted for tubes by Joe Tritschler (aufioXpress Jan 2010). I had two PCBs made with his circuit, but with a couple of mods including the ability to add Lundahl step-up transformers and switch between MM & MC cartridges.

I put the phono stage into one of my chassis, along with a modified Erhard PAS Akido line stage, a HV regulator, and an input relay PCB that I had made. The input PCB automatically shorts out unused inputs.

Also included is an IR remote-controlled volume control with mute function. An external power supply provides 12V and 358V that will be regulated to 300V for the two gain PCBs.

Rear Panel 8.jpeg
Pre open top view.jpeg
Front view no top.jpeg