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DIY Stereo Amplifier LM1875 2 x 20W + Preamp + PSU

Hello guys, in this post I will make a stereo power amplifier using a gainclone LM1875 chip, using components that are quite an audio grade. Which has a power of 20W per mono. Here's the PCB, PCB for the PSU circuit,

PCB Power Supply LM1875

PCB of the stereo preamplifier circuit. All of these PCBs are printed in JLCPCB, the PCBs are very high quality and low price, and fast delivery.

PCB Preamp LM1875

And finally, for the Gainclone LM1875 power amplifier PCB, you can visit this link: LM1875 Gainclone Chip Amplifier

Friends, you can download the PCB design for free at the link at the end of the post. All my PCB designs are single-point grounding, or commonly called star grounding, its function is to minimize hum and noise. And the path I use uses a 45-degree arc angle. All PCBs I order via JLCPCB use the Gerber file that I have shared.

Assemble the amplifier circuit first, here are the components I use, the resistor I use is a Vishay Dale RN60 resistor. And my R Zobel is using Vishay Dale 2 W 1ohm.

PCB Stereo LM1875

For the LM1875 IC, I put it under the PCB, so I bend the IC leg forward like this.

Original LM1875 IC

Continue assembling the stereo preamp, for the resistor I used a Vishay resistor. Install the components according to the label on the PCB. For this rectifier diode, you can use a 1N4007 diode, in this case, I use a BYV27 diode.

Diode BYV27

For the opamp IC I use OPA2277, this IC can also be replaced with other dual opamp ICs, for example, JRC4558, NE5532, and others.

Dual OpAmp Preamplifier

Stereo potentiometer using Original ALPS RK16 50K

Stereo Potentiometer RK16

Continue assembling the PSU circuit, here are the components I use, for Capacitor bank Elco I use 2200uF 35VELNA RE3 18 pieces and Nichicon FW 6 pieces, install the components according to the label on the PCB again. 

Capacitor Bank

For diodes, you can install a heatsink like this, I took the heatsink from the PC PSUThe diode I use is MUR860 diode.

Diode MUR1560

All kits are ready, it's time to put them in the box, I used BOX DIY AMPLIFIER 0914 FULL ALUMINUM

If you are interested in making this super detailed amplifier, you can see the video of its manufacture at the following link: Build Stereo Amplifier LM1875

You can check the sound test in this video:

and this:


Schematic, PCB Layout, BoM Files PSU and Stereo Preamp

PCB Schematic LM1875 Amplifier

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