PA100 GC - 100W per channel, 2x LM3886 in parallel power amplifier

The power supply used is a regulated power supply. I used 10000uF per rail before the LT1083 regulator. After the regulator, I have 100uF on the regulator board. The advantage of using regulator is that the power supply ripple voltage is removed. If power regulation is not used, I can hear very little 50/100Hz hum from the speaker.


Power Supply Schematic :


The high current MUR860 diode is used to ensure high current flow.


The voltage regulator used is LT1083, it can provide about 8A of current.

Transformer used here is a 500VA 2x 25V. The power supply is then regulated by 2 LT1083, after the regulation, the voltage is 30V.




Will consider to use this supply circuit instead, the TIP2955 is capable of providing 15A of current:

I did some DC measurement and the result is quite good, I got 7 mV of DC offset at the speaker terminal. The voltage difference between the output of the 2 chips is less then 1 mV.


The sound of this amplifier is similar to my LM3875 amplifier, which is very clean and detail. It has no hum, no hiss and no noise. Compared to the LM3875 Gainclone, this amp can deliver twice the power to my 4-ohm speaker, and it improves the dynamics and bass punch a lot.


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(Also check out my 300W LM3886 mono block amplifier)




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