Description.

A preamplifier for magnetic pickups of record players is shown here.The uA 741 is used as an AC coupled non-inverting amplifier operating on a single supply.The amplifier gain is decided by the feedback components in which C2 controls the low frequency roll-off characteristics while C4 reduces the gain at high frequency end to compensate for the pickup characteristics.R3,R4 and R5 form a voltage divider to give a bias of about half the supply voltage to the non-inverting of uA741.The output at pin6 therefore stands at half the supply voltage.R5 and C3 form a supply line filter to reduce the hum level ans also to eliminate “growling” in case the preamplifier circuit is operated on a common supply with other circuits.

Circuit diagram with Parts list.

magnetic-pickup-preamplifier.JPG

Notes.

Assemble the circuit on a good quality PCB or common board.

Mount the IC1 on an IC base .

The circuit can be powered from a 12V battery or 12V DC power supply.

Up to 24 V DC can be given to power the circuit.I prefer 12 V DC.

Mono sockets can be used to connect the input and output.

Author

3 Comments

  1. Would you better analyze the circuit? The formula shows the frequency dependence of the value of the capacitors C2 and C4. I’d like to know how to calculate a circuit design to pre-am for my subwoofer.

  2. benjamin mulwa

    am looking for amplifier for double sub-woofer,2chanel using 12volts

  3. balamuugan.k

    we have magnetic pickups are there,it is frequent failure due to starter hitting. please send alternate solution for that.