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MM vs. MC phono stage???

Jayrosc

Jayrosc

Super Member
I just picked up a nice amp at a garage sale. It is a British Fidelity B200. Thing is it has a switch on the back for either "MM" or "MC" and the booklet says it is so the amp works with whatever cartridge a turntable has. Wording is muddy though, as it implies it is only a matter of taste as to which setting one can use. It says the magnetic coil (MC) setting is high gain and the moving magnet (MM) setting is low gain mode. I am tempted to just try the switch in both positions but fear doing damage to something.
It is here where I once again turn to those at AudioKarma for advice.
I can post pics if need be, but this seems more of a general tech talk kind of thing rather than a brand specific issue.
 
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What kind of cartridge (make/model) do you have?
Some moving coil (MC) cartridges have very low output & require more gain than other (so-called "High output") moving coil and most moving magnet (MM) cartridges.

Chances are, MM is right for you. If the output of the preamp seems too soft for you at reasonable volume settings on your "linestage" preamp, integrated amp, or receiver, though, you might need the additional gain of the MC setting.

You can certainly try MC but the result may be "over-amplified"; too loud (so to speak) at any given volume setting and it's also likely to be distorted in louder passages from a record.

PS: The instructions are misleading: MM is high gain, MC is higher :-)
 
You don't just "try the switch in both positions" just for the hell of it.

MC is moving coil, not magnetic coil.

You use MM if you have a MM (moving-magnet) cartridge OR a high-output MC (moving-coil). DO NOT use the MC setting for any MM cartridge....you will overload (and possibly damage) the preamp.

Use the MC setting for low-output MC cartridges ONLY.

It is NOT simply a matter of taste. You have to use the correct setting with whatever cartridge you're using.

mhardy is right....the instructions are misleading. The MC setting has much higher gain than the MM setting.
 
thanks for the quick response. Two turntables. One, a sansui sr-525, has an audio technica cartridge but not sure which one. The other table, a technics sl-d20, has the original cartridge on it and I have no clue what it is. I want to try both with this british unit.
 
Chances are they are MM cartridges, as those are most common. To be safe, use the MM setting on the amp. If you do in fact have an MC cartridge, running it through the MM setting will just produce very low sound. Best to check, though. Check the underside of the carts to see if there are any markings, or maybe remove them to check.
 
Go for MM -- the latter tt certainly has an MM cartridge with (relatively) high output (several millivolts). Most (although not all!) A-T cartridges you're likely to stumble across will be MM with output of a few millivolts, too.

Just to make things a little weirder -- there are a few MM cartridges with low output levels (less than 1 millivolt) similar to the low output MC cartridges. One example: Grado's best cartridges are available in "low" and "high" output versions. Actually, just to make matters a little weirder still, the Grados are not technically MM cartridges, but are actually so-called moving iron (MI) or 'variable reluctance' cartridges.

Stick with MM....

:-)
 
MM it is. I look forward to finding out if this Brit machine even works. Setback number 1: speaker outputs are banana plug only......
 
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