Will a MC phono preamp overload and distort with a higher output MC cartridge?


I have a Benz Micro high output moving coil cartridge which specs listing an output of 1.6 mv into 500 to 47K load. This is a little weak to drive a MM phono preamp. I have been looking at the HiFi Tube Phono MC Turntable Mini Class A single-ended preamp which lists an input sensitivity of 0.3 to 0.5 mv. Would my Benz Micro overdrive this preamp into distortion or does the sensitivity refer to something less than maximum cartridge output?
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Showing 1 response by almarg

The phono stage is spec’d as having a gain of 650 (which btw corresponds to a gain of 56.26 db), and as having a maximum output capability of 3.2 volts.

3.2 volts/650 = 4.9 mv.

So an output from the cartridge of 4.9 mv or more would overload the phono stage, assuming the specs on the phono stage are accurate.

Cartridge output specs are based on certain standard test conditions, which can be exceeded by the peaks of some recordings. The margin ("headroom") you would have is:

4.9 mv/1.6 mv = 3.06, which corresponds to 9.7 db.

That amount of headroom is within reason but is a little on the light side. There may be a few recordings on which brief dynamic peaks might cause it to be exceeded, but I suspect that on the great majority of recordings you would be ok.

This assumes, again, that all of the relevant specs are accurate.

BTW, I would expect that the fact that the phono preamp has a specified input impedance of 470 ohms, slightly less than the 500 ohm minimum value you indicated is recommended by the cartridge manufacturer, will **not** be a significant issue.

Good luck. Regards,
-- Al