Spicy phono preamp

[pto892]

Here's a picture of my new RIAA phono stage which I built using a Vintage Electron PC-5A board and the modifications detailed by Norman Koren in his Spiced Pas webpage. The PC board and assorted parts were assembled into a small black Hammond enclosure, while the power supply was built using a leftover aluminum project case. I wanted to use an external power supply to reduce and/or eliminate any hum, and this seems to have worked out. The supply itself uses a Hammond 263CX trannie and a Sovtek 5Y3GT rectifier, which feed a LCLC circuit that uses a 4H/32 ohm and 1.5H/32 ohm combination of chokes and filter caps. The chokes and can cap came from Triode, and I also used a Triode supplied Mitchell 12.6v regulated power supply to provide heater voltage. Anyway, the power supply produces 290v B+ and a rock steady 12.6v heater feed-you can't see it from the picture but inside it is very busy with the 2 chokes, Mitchell power supply, and wiring. The umbilical is nothing more than a XLR connector from Radio Shack. The tubes are just some el cheapo Russian 12Ax7 (Procomm brand), but they seem to work quite well. This was a difficult project overall for me, but the preamp has worked great from the first powerup last night.

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[TomMcNally]

Nice project - congrats ! Are you running the phono stage directly into a power amp, or into another preamp/linestage ?

... tom

[pto892]

It has a fixed gain, so it's being run into my Aikido preamp.