I just put together some RIAA simulations -- the original Dynaco PAS, Koren's modification, the Audio Research SP3a and SP8. Here's what the deviation from the standardized RIAA curve look like:
An externally hosted image should be here but it was not working when we last tested it.
Here's the actual "measured" results from my PAS preamplifier -- note the difference from that calculated by SPICE from the schematic. Note that the output is taken without intervention of the balance or tone controls.
An externally hosted image should be here but it was not working when we last tested it.
Yup... That sure looks like a curve that could have come off the PAS I had in college. It worked great with the little AR 4a and such, which tended to roll off starting at about 100 Hz. Dynaco may even have designed the PAS to boost the bass a little.
And at a max of 2dB it ain't much, might add a little robustness to the flavor 😉. I wouldn't be surprised if cartridge loading might not have just as much effect on deviations (though probably on the other end of the spectrum).
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