Clear Image

This is a wonderful phono MM pre-amp made by Colin Farch !!

MM-1

The Clear Image MM-1 moving magnet phono stage is designed to amplify your MM cartridge to

line level output voltage. Gain is 42db at 1kHz.
 

You can connect a MM or high output MC cartridge directly to it; or to use your low output MC

cartridge you should first use an active pre-preamp or a transformer to step up its output voltage.

The Clear Image MC-1 is an active pre-preamp.
 

The MM-1 incorporates the RIAA equalisation necessary for vinyl record replay via a magnetic

cartridge. It uses the Sonic Imagery Labs studio grade discrete op amps which have very high

output drive capability. This op amp is one of only a very few that can properly drive the low

impedance of the RIAA equalisation network accurately and with low distortion. The circuit is

deceptively simple and evolved after many hours (years!) of listening.
 

You can vary the cartridge loading impedance to suit your particular MM cartridge with the control

on the rear panel. Frequency response measurements have shown that the value of MM cartridge

loading impedance has an influence on the treble response of the cartridge. On the MM-1 it can be

set to a value between 10k to 110k. Standard is 47k but most MM cartridges work best with the

control adjusted to whichever impedance results in the best treble response. You can adjust it to

your liking while listening. Measurements have also shown that the less capacitance for cartridge

loading, the better to get both a flat and extended frequency response from the MM cartridge. So

the MM-1 phono stage has minimal, non-adjustable, input capacitance (22pf) to achieve this goal.

It is also good to use short, low capacitance (under 80pf), shielded cables from your turntable to

the phono preamp. That helps to minimise radio frequency (RF) interference and extend high

frequency response.
 

The MM-1 runs from a 16V AC-only wall plug transformer to keep its magnetic hum radiation away

from sensitive circuitry. (Note that accidentally connecting a DC power supply under 24V will not

allow the MM-1 to work, but will not damage it.)