Electron Engine ™
Printed Circuit Boards by Emissionlabs ®

EE21 Board V6.5, MC Applications

    1. Overview
    2. MC Applications (you are here)
    3. MC Tuning
    4. All Connection Schemes, Complete Overview
    5. Unsorted Application Information

Moving Coil

Input Board
Gain Low
Gain High
Core Characteristic
LL1681 EE21
8x
16x
Amorphous Iron Studio Favorite. What goes in, it what comes out.
LL1931 EE21
8x
16x
Amorphous Cobalt Best Sound of Amorphous, 6N 'Cardas' wire.
LL1933 EE21
8x
16x
Nickel Clean sound, Low Distortion, 6N 'Cardas' wire.
LL1971 EE21
12x
24x
Amorphous Cobalt Best Sound of Amorphous, 6N 'Cardas' wire.
LL1941 EE21
1:16
1:32
Amorphous Cobalt Best Sound of Amorphous, 6N 'Cardas' wire.
LL1943 EE21
16x
32x
Nickel Clean sound, Low Distortion, 6N 'Cardas' wire.

 

A good beginning, with a good end.

The output signal of an MC is only 0.5mV. Then, if we say residual hum is 1%, this would be audible and nobody would accept it. Yet what does it mean at 1% if 0.5mV? We talk about 0.005mV and this can not be meausured without special equipment.

This is why people sometimes say: 'I tried everything, but I can not find the reason for the hum', and they you get stuck at that point. For this reason, AVOIDING things which cause hum, is the better way to go. A hum free amplifier is the result of the right concept from the beginning. It is hardly possible to de-hum an amplifier which is hand-wired and there is some mistake somewhere. So yes, the mistake is in the wiring, but there is no way to measure it.

Some tips and tricks.

These boards should be placed close to the signal source. When possible, lay the wiring on the metal of the chassis, because electric and magnetic hum fields are lower there. Keep the wiring minimum 10cm away from mains transformers, power supply parts, and cabling to those.

For unbalanced inputs, if inside a metal cage, shielding is not strictly needed, but it is better. Using a wooden case is also possible, but then coaxial cable should be used always. If inside an amplifier, balanced MC signals need no shielding, but drilled cables only.

If in a metal housing, the EE21 board is grounded via the screw holes. PCB screws always tend to get a bit loose over the years. So solder a short ground wire in addition, to one of the 'G' connections, and screw this wire on the chassis.


Moving Coil, Grounded Type RCA (Cinch) Connector

not recommended

We often see people use this wiring. It may work satisfactory. The next schematic below here is better.


An floating ground RCA (Cinch) connector has a balanced input, and the turntable chassis serves as ground reference.

This is an isolated ground RCA (Cinch) Connector by Yamamoto Soundcraft Japan. This preserves the balanced character of the transformer input.

Connect L+ and L- directly to the RCA (Cinch) plug, Since the board is now floating, it needs a ground reference. One of the 'G' connections is attached to the chassis.

Turntable ground. There is normally a screw or a connector, for chassis ground of the turntable. Through this wire flows no current, but it prevents a voltage difference between turntable chassis and the chassis of the next device in the chain. This is connected with just a loose wire to the device where the MC transformer is mounted. If this is a wooden box, it still needs a connection! This is screw connector or banana plug, which internally gets connected to the ground plane, 'G' of the EE21, EE23 Board V6.5. If the MC transformer is in a metal housing, this wire is connected this wire to the metal. WIth a wooden MC box, the 'G' is of course connected to the output in whatever way it is done, and so the ground references of the record player is passed on to the RIAA amplifier metal housing.


An XLR input works almost the same like the above floating ground RCA connector, but an XLR cable is better balanced, and the cable shield is not used for signal, but only for shielding. So any hum current trough the shield can not generate electric signal, which is what makes XLR better. Such current may sometimes exist, because we connect two apparatus with each other via the ground of the cable. That is the reason for using XLR, and such current doesn't matter.

Turntable ground. This is by definition connected to the XLR cable shield inside the turntable, at XLR-1. The manufacturer already did so. A loose wire from the turn table may be connected still as additional security, and the idea is that the ideal ground connection is not 'plugged' but 'screwed'.

The XLR cable shield coming from the turn table, one way or another needs to be connected to RIAA amplifier Chassis. If we use a wooden MC box, it is passed on via the EE21 board. So, at the output side, the 'G' is connected to XLR-1, and the outgoing XLR cable will make the connection to the RIAA amplifier chassis. With a metal MC box, it works the same, but the metal of the box becomes part of it.

If the EE21 board is build into an amplifier, it is best to ground the XLR-1 directly at the connector inputs.

Gain Selection

Gain can be choosen from two variations. Choose to use solder Jumpers (J1, J2, J3,) or instead connectd the extermal switch board EE22, to 1,2,3,4,G. (See Introduction and gain setting)

Part2. Damping of the Cartridge

This comes all in the end as a final adjustment. First the board has to be set up and make it work. Then, electrical damping of the cartridge can be adjusted. The cartridge is already damped more or less correct by the load of the phono amplifier. Yet not extremely perfect. So fine tuning is a good thing to do, when everything is finished and working. Read more about this