Phono stage overload margin ??

Smoffatt, I have a 2002 model ARC Phono Ref (69db MC gain) and the Manual suggests not using MCs of more than 0.30mV, and from using various carts over the years I now know that it tends to sound better with carts of around 0.25mV that with those at 0.30mV and more. I am not that technical but I believe that some designs will have a sweet spot input voltage and resistance/capacitance. Maybe thats why some designs have a switch for multiple gain settings? If a manufacturer doesn't even mention overload margin in the specs/manual then I would stick to .25mV-.32mV on a valve stage with 66db gain, and .22mV-.32mV on a solid state one.

In my earlier post I mentioned that the description of the Ref Phono 2 at the ARC website does not indicate which gain setting the 250mv maximum input spec corresponds to. As might be expected, looking at the gain numbers and the specs for maximum output makes it clear that it only applies to the low gain setting. The maximum input for the high gain setting can be calculated based on the gain and maximum output numbers, and works out to be 15.9mv.

Good comments by the others above. I should clarify that my earlier post was just intended to address the question that was asked, about phono stage overload margins. Selection of gains which are optimal for a particular cartridge and system obviously calls other factors into play, including preventing overload of the front end circuits in the line stage, avoiding having to operate the volume control near the bottom of its range, avoiding the increase in distortion which may occur as the overload point is approached, and optimizing noise levels.

Regards,
-- Al

KAB USA has a phono overload calculator along with an "ideal gain range" calculator on their website. I've used it in the past and it helped. I believe it is at the bottom of their phono stage page.