Stereo Preamp Kit for Magnetic Vinyl Cartridge / Stylus

RIAA Preamplifier for Moving Magnet Pickups

Build:

The components needed to assemble the amplifier are divided into several groups:

1. Resistors

2. Capacitors

3. Transistors.

In this order, the components must be mounted and soldered to the printed circuit board. Use high-quality solder (eg Sn60Pb) with a sufficient amount flux (rosin). At the end, check the correctness of the soldering of the components. If everything is in order, we clean the board of residues of soldering with alcohol

Commissioning:

A stabilized, well-filtered 12V power source and DMM, are required for commissioning.

Connect the supply voltage. The current draw should be 5 to 7mA. Connect an input signal and connect the output to the amplifier.

If you followed the instructions correctly, the preamplifier will work on the first connection. If hum could be heard, the preamplifier should be placed as far as possible from mains transformer, turntable motor, or place the whole thing in a screened box.

Technical specifications :

Supply voltage - 12V

Current Draw - 5-7mA

Output impedance at f=1kHz - 200ohm

Input impedance at f=1kHz - 47kohm

Minimum load resistance - 2kohm

Recommended load resistance - 10kohm

Frequency characteristic - RIAA

Max. output voltage at no load - 3V

Parts breakdown: (parts are identical for both channels)

R1, R8 - 100k

R2 - 220r

R3, R4 - 27k

R5 - 120k

R6 - 6k8

R7 - 180r

R9 - 220r

R10 - 2k2

R11 - 47k

C1 - 2u2

C2 - 22u

C3 - 68p

C4, C5 - 47u

C6 - 47n

C7 - 6n8

T1, T2 - KC238

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