How much gain is needed in a Phono Preamp for a 0.2 to 0.3mv low output moving coil?

Thanks, Analogluvr.  Good to know.  What I was recalling may have been the second of the two posts dated 4-22-2013 by member Czbbcl in this thread.  Apparently he was wrong.

Best regards,
-- Al
 

With the Herron  you have the added advantage of being able to easily switch from 64 to 69 Db of gain just by swapping out two tubes.

I'm not sure that is true, Analogluvr.  I believe I recall someone stating in a thread some time ago that he was told by Keith Herron that there are circuit differences between the two gain configurations, in addition to the differences in tubes.

In any event, as you, I, and just about everyone else who has heard it and posted about it has found, it is a remarkable performer.

Best regards,
-- Al
 

As usual Larryi makes an excellent point, in this case about the relevance of line stage gain and amplifier sensitivity. I see in one of the OP’s recent posts that he has recently purchased an ARC REF 5SE line stage (12 db gain for its balanced outputs) and a REF 75 amplifier (1.4 volt sensitivity).

Based on the relation...

db = 20 x logarithm(Vout/Vin)

it can be calculated that 60 db of gain corresponds to a voltage multiplication of 1000 times, and 12 db of gain corresponds to a voltage multiplication of about 4 times. Therefore 0.2 mv into a 60 db phono stage and a 12 db line stage will provide an input to the amplifier of 0.2 mv x 1000 x 4 = 0.8 volts, ***when the volume control on the line stage is turned up all the way.***

Since the amp requires 1.4 volts to be driven to full power, with a 0.2 mv cartridge and a 60 db phono stage you would therefore only be able to drive the amp to full power on particularly high volume peaks that are present on some recordings, that exceed the standard test conditions upon which cartridge output ratings are based. And even then you would find yourself turning the volume control up to close to the top of its range, especially on recordings having wide dynamic range. With excessive hiss possibly also resulting.

FWIW, I use a 0.5 mv cartridge (the Audio Technica AT-ART9) with a 64 db phono stage (the Herron VTPH-2, which is also offered in a 69 db version BTW), in a system having particularly high gains and sensitivities further downstream, and that works out well.

Finally, I suggest caution in using the KAB calculator. Note the following statement in the text above the calculator:

The optimum gain is based on achieving 325mV rms output at 5 cm/s. For the current crop of CD recorders, 300mV is required for 0dB recording level with the recorder’s level control set at max. Aiming for 325mV gives a little margin.

325 mv multiplied by the 4x gain of your line stage would result in 1.3 volts into your power amp when the volume control is at max, which would still not be enough to drive the amp to full power.

Good luck. Regards,
-- Al