Dual + auxiliary Power supply for MOSFET amplifier ACTRK600 Actrk400 amplifier. Analog audio circuit power supplies can impact listening tests audibly and can be measured quantitatively in bench tests. There are three common types of power supply designs that operate from the power mains: Switch mode (SMPS), regulated, and unregulated power supplies.

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Amplifier Actrk400 ACTRK600 circuit Mosfet IRFP460 600W

Switch mode power supplies, or SMPS, have gained popularity due to their widespread availability and affordability. They are commonly used in computer hardware for their efficient regulation and compact size. However, one drawback of SMPS is the generation of electromagnetic interference (EMI) and radio frequency interference (RFI), as well as electrical noise on the power supply rails. This can be problematic for small signal analog circuits, which are more sensitive to noise. Despite this, certain amplifier classes like Class G and Class H can benefit from the fast response of SMPS for full audio bandwidth signals. Designing audio circuits with SMPS poses additional challenges compared to non-audio circuits.

A regulated power supply can come in the form of a basic linear regulator IC utilizing the rectified voltage from a transformer and a few external components, or a more complex and high-performance design. Various factors such as complexity, cost, space, thermal design, reliability, and protection need to be considered when choosing a regulated design. Regulated supplies are often used for analog small signal portions and sensitive circuits to ensure optimal performance. In the case of an audio power amplifier, regulated supplies with high bandwidth are necessary for good audio quality. However, the complexity and cost of such a power supply design may not always be feasible. Many linear regulator ICs lack the necessary bandwidth and are slower compared to audio signals, which can result in reduced audio performance.

The most common power supply option for audio power amplifiers is an unregulated supply, which is chosen for its simplicity, good performance, and reasonable cost. This type of supply typically includes a transformer, a bridge rectifier, and various rail capacitors. However, a drawback of the unregulated supply is its susceptibility to voltage fluctuations with load and power mains fluctuations. To account for this, a design should be able to handle a minimum 10% high line condition on the power mains. Unlike more sophisticated regulated designs, unregulated supplies usually only have a fuse in the power mains input to protect against excessive current. In some cases, inline fuses may be added to the power supply voltage rails for additional protection.

Schematic Power supply for ACTRK600 ACTRk400 amplifier

Characteristic Power supply for ACTRK600 Actrk400 amplifier

• AC IN: 42 + 42V to 64 + 64V, dual
• DC out: +-60V to +-90V
• Power of transformer: at least 40% higher than output power.
• Auxiliary Power supply: 62VAC
• C6 and C12 are low value, ceramic capacitors to filter higher frequency noise right at the DC output of the diode bridge.
• C13 to C20 are the large reservoir capacitors to supply large current demands and stabilize the supply rails to minimize low frequency fluctuations. These are very large value electrolytic capacitors. Four capacitors are used for ACTRk400 and Eight to ACTRK600, normally 10000UF. The values for the different capacitors were not chosen based on extensive bench work or research. The values were chosen based on general guidelines and commonly used values. Additional performance may be obtained through refinement of the capacitor values.
• Additionally, the supply rails have bleeder resistors, R1 and R2, to drain the large reservoir capacitors. Two footprints per rail were placed on the PCB to allow for lower power resistors to be used and a wide range of bleeder current.

Connections:

• U10: AC 62VAC
• U1: AC 42 to 64V
• U2: GND
• U3: AC 42 to 64V
• U11: DC +85V 27mA
• U6, U7: DC +85V
• U5, U8: GND
• U4, U9: DC -85V

See the amplifier here:
Amplifier Actrk400 ACTRK600 circuit Mosfet IRFP460 600W

BOM Power supply for ACTRK600 Actrk400 amplifier

*For voltage greater than 85V use 120V capacitors

Download files, links, and notes

• Download PCB in Gerber + BOM + Centroid file + PDF 
• Mirror
• BUY Amplifier power supply
• PDF datasheet KBPC3510
• PDF datasheet 1N4004

Source: https://oshwlab.com/cmircea2006/supply-for-actrk600