Mismatch - between SUT and MC cartridge.

Most cartridges that have an extremely low source impedance, such as the 3-4 ohms you mentioned, are quite low in output (fewer coil turns mean low impedance and low output), and therefore also need more gain. The transformers that "match" to such cartridges typically have higher turn ratios and gain. But, if excessive gain is not a big issue, you can use such transformers with cartridges with a higher source impedance and the result should be fine.

I believe Art Dudley, in a series of articles in Stereophile about SUTs, said that, not withstanding supposed compatibility criteria, he has not heard problems with mismatches.

I have personally never experienced compatibility issues except for not having enough gain. Most SUT with enough gain have worked well, and personal favorites seem to remain favorites with a wide variety of cartridges.

Thanks for your response.
It is good to know that the voltage level matching is much more important than the impedance level matching.
I've listened to many more LPs in more serious manner, and I guess I would like it, even though I cannot say that MC100 (on my system) is much better than MC20.

Say your cartridge is 10 ohms and the SUT was designed to load a 2.5 ohm cartridge. This means that the low end bandwidth will be two octaves less due to the fixed inductance. Depending on the design choices and system matching this could be a good or a bad thing.

So if the SUT designer chose to put the -1dB point at 10hz for a 2.5 ohm cartridge, it will be -1dB @ 40hz if fed from a 10 ohm cartridge which might be an issue. If however the design were to be -1dB @ 3hz with the 2.5 ohm cartridge, the 10 ohm source will move the -1dB point to 12hz.

dave

Thanks.
I guess I need to spend more time to understand your explanation. Overall, it seems to work fine to my ears.