L12-2 CFP Output amp 120W*2 8R

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Install a repeater between the pot and the amplifier input.
 
L12-2 Power Amp boards

I ordered a couple of these boards to use in my project that I am currently working on. The power supply uses a 300VA Hammond Toroid and is putting out 45 volts -+.I was not too sure about these boards but glad that they seem to be good for the price. I have included a couple of pics of the amp so far. The top has been sent for a redo of the white strip on the back area
Cheers Wayne
 

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Hi guys,
Let me ad my 2 cents to this fine conversation.
I have purchased a DIY set and have measured all components before soldering. I have a Ver. 4 board. Everything was okay. All components have proven to be just fine.

I have made measurements of this board fed from capacitance multiplier at 22 and 42 rails.

For load I have used three 22R/100W resistors (Arcol HS100 22R J) in parallel.

I have warmed up the amplifier for 1 hour before taking measurements.

Everything was just fine except a small detail shown on the snapshot below. The figure shows magnified initial part of response to square wave at 1KHz. Similar response can be detected at both 10Hz and 20KHz. However, at 42V rails this distorted response vanishes completely and the square wave response at 1kHz is perfect.

This indicates to me that this board was designed to run at 40-50 V rails. Also, there was no need to meddle with bias and DC drift. The both boards have consistent values without any modification whatsoever. I have decided to leave the boards without any attempt for improvements because I believe LJM knows exactly what's he doing.
 

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Hi guys,

Everything was just fine except a small detail shown on the snapshot below. The figure shows magnified initial part of response to square wave at 1KHz. Similar response can be detected at both 10Hz and 20KHz. However, at 42V rails this distorted response vanishes completely and the square wave response at 1kHz is perfect.
What is first voltage, when square wave distorted? I'm using 2x20ac and about 2x31v dc.
 
Hello mdardeniz,

Unfortunately, I cannot answer this question because I couldn't change the voltage continously - that is the nature of capacitance multiplier. There is no regulation but efficient removal of ripple.

However, there is a good news: (1) that distortion is so small that I had to magnify it by stretching the time scale. (2) you are at higher voltage and it wouldn't be audible. Sine wave response is really 'blameless'.

I have presented that result to indicate that the amplifier itself was designed for the use at higher voltages.

Regards :)