How to deal with a 1.0mV LOMC or is it HOMC


I have a vintage cartridge on its way to me and despite being very excited, I am also very curious as to how I should load it into a standard MM stage. It is spec'd at 1.0mV and 60ohms.

For my current LOMC's I use a step up transformer that has a 15x, 20x and 50x step up ratios. I calculated if I use the lowest setting of 15x and based on the load impedance of 60ohms, the MM stage of my amplifier would see an output of 11mV which would seem very high.

Alternatively if I took the step up transformer out of the chain the MM stage would only see 1.0mV which is way too low.

Can anyone advise how they have dealt with carts which have such an unusual output.
ateal

Showing 1 response by ateal

Update !!! Cartridge arrived earlier in the week and I installed it through the SUT at 1:14 (23bB gain). Apart from having to reduce the volume knob from my usual level of -28dB to a lower level of -40dB, it all sounded great. I also checked with my amplifier manufacturer "Copland" and they confirmed it would be OK for the phono stage to see an 11mV load as they designed the amp with plenty of headroom.

Based on this set up the cart is seeing a 240 Ohms load impedance from the SUT which is 4x the carts internal impedance of 60 Ohms. In my book this is ideal and provides a very smooth full bodied sound. If I wanted it to sound brighter (which I don’t) I could use a step up of 1:10 which would result in a 470 Ohms load or 7.8x the carts internal impedance.

Out of curiosity I also tried it directly into my MM stage to see what that sounded like. I gotta say there wasn’t that much difference apart from the fact I had to crank the volume up to -22dB. I didn’t notice any real difference in treble or bass response.

I decided I will keep using it through the SUT.

Thanks for all the input.