• 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.

Ampex 351 - Mic pre


I have come by an Ampex 351 machine, (for the unenlightened, this is a One-Track, All-Valve, 1/4" studio Tape machine) and the signal in understandably in a bad way (after many years of storage). So after weeks of deliberation as to wether to just re-cap, and recondition the thing to use it as an amazing sounding but fairly useless tape machine, or weather to rip out the input stage, convert it into a killer mic-pre, and waste the rest of this graet machine, I have decided to do the mod, and haul out the preamp.

Now, although I have a passionate interest for digging around in old tube-gear with my soldering iron, and even a tiny understanding of basic tube circuitry, I have very little experience with projects like this one.

If any of you have done this procedure before (I've heard that it's fairly common), please let us all know how it went, and what to look out for.

For the moment, I'll be gathering schematics, and components, and generally procrastinating.

And then I'll keep you all posted.

Here we go...