Nick,

Thanks, I could also try an small active 'buffer' stage to prevent loading
on the cartridge and accidental phantom damage. This stage would have to be
very quiet so SS I expect. I agree with having the network after the
preamp, loss of gain would probably not be too much of a concern. The HV-3B
Input Z = 6,200 ohms, o/p Z = 24.3 ohms. With a frequency response to -3 dB
points Sub 2 Hz to over 300 kHz -its also good for seismic or bat
measurements ;-) This is looking like another winter project to get me back
into building circuits once again :-)
I don't have spice as I've been away from circuit building for many years.
I'll do a google search to see what comes up.

Mike


"Nick Gorham" wrote in message
.. .
Mike Gilmour wrote:
To audio techies. Is the anything against my occasionally using a
Millennia
Media HV-3B microphone preamp as a phonostage just by heading it with an
RIAA network. I hate to see it sitting lonely at quiet times ;-)
Thanks.

Mike



I guess not, but you would have to take into account the impedance of
the cartridge when calculating the RIAA, and also the effect the loading
of the network would have on the cartridge. Also take into account the
input impedance of the preamp on the network.

It may be better to have the network after the preamp, then you would
have better noise performance, and the network calculation could be
simplified. You would need to know the output impedance of the preamp,
but I guess this could be low enough to be ignored, you will also need
to know the input impedance of the amp its feeding, and also any
capacitance in the connection. This does assume the input impedance of
the amp is constant with volume, or its going to be a bit hard to
calculate the network.

May be best to do a SPICE simulation, using a inverse RIAA network
feeding the amp, and then fiddle the network after the amp (with
required loading) to obtain a flat response.

--
Nick