JFET RIAA preamp project started

20131006-180745.jpgNow is the time to upgrade my current RIAA stage. A bit unorthodox approach for a valve enthusiastic but you will see me now with my hands on sand. A very simple JFET input stage with a shunt cascode pair to drive the passive RIAA network. The final gain stage is an OPA604 with remaining part of the RIAA network. The Op Amp is forced into class A by a nice pair of BC847C forming a CCS.

Given the shunt cascode bipolar is an PNP Darlington formed by 2 BC860C low noise and the CCS has also SMD devices, I started by soldering these into 4 PCB adapters for SOT-23 devices

More to follow…(just a start)

 

Author: Ale Moglia

"A mistake is always forgivable, rarely excusable and always unacceptable. " (Robert Fripp)

3 thoughts on “JFET RIAA preamp project started”

  1. Not unorthodox at all. I prefer solid state for small signal level (i.e. phono preamp) and valve for power level (i.e. power amp). I would only mix or use one of the two technologies at line level. Cheers

  2. Ale,

    Tony from the Circle told me to come here, as I’m looking for an MM preamp design. But apparently you’re working on an MC one. Not for me then.

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