Intact Audio

I'm planning to build Gary Pimm's phono circuit. Its actually a variation on Kurt Strain's circuit from what I've read. Anyway, for getting things up and going, I have parts to do the standard EQ in Rs and Cs, but I'd really like to explore using a RIAA inductor.

What would be any appropriate RIAA inductor for such a circuit? I know that the CCSs I'm using (updated CCS, not the ones shown in circuit) have a Zout of about 500 ohms.

Would using a RIAA L require an input cap as well as an output cap? If so, how would you size it?

Schematic:


page:
http://www.pimmlabs.com/web/phono.htm

Hey Josh,

IF the output Z is indeed 500 ohms you can go with a 600R LCR network and simply place a 100 ohm resistor in place of the 22.1K resistor. You will probably have to tune that resistor in circuit to get the best measured response. (say the output Z of the CCS is really 480 ohms then you will in theory need 120 ohms)

The question you need to ask yourself is: how will the Low Zout of the CCS sound driving a 700 ohm load? (100 ohms series + 600R LCR) If you want to increase the load value seen by the CCS you could try Revintages idea of increasing the LCR value and increase the size of the series resistor. If you went with a 1500R LCR and a 1K series resistor your load now becomes 2.5K.

dave

Thanks Dave,

I wasn't sure if the impedance of the LCR should match the Zout of the CCS or not.

There is also the option that I take the output from the anode of the tube instead of the mu-out from the CCS, then I could use the more traditional LCR value I'd suspect. Decisions-decisions.