Power supply with noise filter for the modular high end audio amplifier system

Project presentation


The power supply presented here is part of my modular audio amplifier system. This is an improved version of the medium power supply for the modular high end audio system. The power supply presented here is cost and performance optimized.

Design presentation

The design is mostly the same like the medium power supply for the modular high end audio system, but with rectifier diodes rating adjusted and performance improved by adding inductors, which form a low pass filter with low cut off frequency.


Not shown in the schematic are 50mΩ resistors in series with the inductors implemented by the PCB design. The extra resistance is required to avoid resonance of the filter.



Here is the cost breakdown of the module:

Part Quantity Cost p.p. [€] Cost total [€]
Storage capacitors 4 13.00 52.00
PCB 1 10.00 10.00
Rectifier diodes 8 1.00 8.00
Cage clamp terminals 24 0.25 6.00
Small capacitors 14 0.50 7.00
Inductors 2 2.00 4.00
Heat sinks 8 0.375 3.00
Resistors 14 0.15 2.00
92€ incl. VAT

The calculation shows that the module cost is roughly 20% lower than the previous power supply design. The main factors for cost saving are the heat sinks, which procured from China instead from a reputable German company drop from 20€ to roughly 3€. The Chinese heat sinks are compatible in terms of PCB footprint, but not really suitable for mounting TO-247 packages. Therefore the diodes were downgraded to TO-220 package and power rating adjusted to suit the lower output power of this medium sized power supply.


This revision of the power supply can be built with lower cost and yet offers lower output noise. This is a reasonable sized power supply targeted towards medium power applications in the range of up to 500W. For higher power applications, the large power supply for the modular high end audio system would be more suitable.