MC cart, can I use MM phono preamp?

Doug, I'm curious what that $125MM cart is.

Just curious, anyone know if frequency response is affected when mismatching a MC cart to a MM pre stage? Can help think the impedance of a coil used in an MC cart is going to be inherently different from one used in an MM. Or is a coil is a coil is a coil?

Opaceo,

Your supposition is correct. If you compare several manufacturers' recommended phono input impedance settings for their LOMC's, you'll notice two things:
- recommended values are all over the map (ranging from 10 ohms up to 47k)
- recommended values are often a range, not a single number

All MM's and most HOMC's are optimized for 47k ohms. LOMC's are all over the place. Each manufacturer uses what they believe is best for a particular price point, desired output, desired frequency response, etc.

Frequency response is one characteristic that changes, particularly at the top end. Further, the optimal impedance may vary from one system to another, which is why many LOMC manufacturers recommend a range (ie, experimentation) rather than a specific value.

To address this, many MC phono stages include adjustable input impedance, which allows user optimization with different cartridges. An MC stage that doesn't somehow allow for this is inherently limited, in that it won't necessarily optimize with all LOMCs.

Impedance matching for an LOMC is even more critical and complex when using step up transformers, as suggested by some of the posts above.

Not to take issue with the fundamental sense of Doug's post, it is in fact also true that MM cartridges are affected by loading perhaps even more so than MC types. Most importantly, because of their much higher inductance compared to an MC, MM cartridges are sensitive to capacitance. Also, I and many others have found that for really getting the most out of a top of the line MM, increasing the load R to 100K or some value in between, along with varying C, is worth the effort. If you take a look at vintage MM-only phono stages from the era prior to the obsession with MC cartridges uber alles (late 1970s to early 1980s), you will find that the best of them had adjustable loading for both R and C. It's just that the loading issues are electrically different for the two types of cartridge.