Hifi Preamps for your Record Player

Moving Coil with the Muffsy Phono Preamp and MC Head Amp

A low output Moving Coil (LOMC) cartridge needs, in addition to the RIAA equalization, 20 to 30 times as much gain as a Moving Magnet (MM) cartridge.

Two Important Facts on LOMC and MM Cartridges

  • The MM cartridge is most sensitive to current noise
  • The LOMC cartridge is most sensitive to voltage noise

To get low current noise, a FET input stage is needed. To get low voltage noise, a BJT (ordinary transistor) input stage is needed.

Given that LOMC and MM cartridges need different input stage technology, you can't just add more gain to your MM phono stage and call it a day. 

The output from a LOMC cartridge is so miniscule that just adding more gain would be detrimental to the sound quality. (Yet, this is what most DIY projects do, and surprisingly many commercial offerings as well...)

How to Connect the Muffsy MC Head Amp to Your Existing Setup

To get excellent sound quality from your LOMC cartridge, use the Muffsy MC Head Amp in front of your MM phono stage.:

If you have the Muffsy Phono Preamp and MC Head Amp built in the recommended enclosure, or you're using another MM phono stage, you can connect them like this:

Connecting the Muffsy MC Head Amp

Switching Between MM and MC

You can build the Muffsy Phono Preamp and the MC Head amp into the same enclosure (only one Muffsy Power Supply is needed for this), and switch between them. This requires your build to be in a larger enclosure, so you won't be able to use the Muffsy Back Panel.

You'll need two sets of RCA inputs, and a ground screw, to switch between MM and MC. Use a 3PDT (three pole, dual throw) switch to select between the two inputs, and one set of RCA outputs.

3PDT switch between MM and MC

  • MC INPUT: Connect one set of RCA inputs to the MC Head Amp (left of the picture)
  • MM INPUT: Connect one set of RCA inputs to the 3PDT switch (middle of the picture)
  • Connect Muffsy Phono Preamp and MC Head Amp to the 3PDT switch
  • Connect the output of the Muffsy Phono Preamp to the output RCA connectors
  • Add a ground screw, and connect all the RCA grounds and ground screw together