Audio Power Amplifier AD2

I designed this principle in 1990 when I needed lots of power amplifiers for a large air show in Norway.

I have converted some of my blue towers to AD2 design. It is described in my video on YouTube.

As you can see, distortion is very good. Output power is 100 Watt.

This is based on my previous designs which I called AD1.
I will come up with a description of this later.
This new design is possible to build stereo vesion.
AD1 could only be used as a mono design.

The change from AD1 to AD2 is located on the small brown circuit board.
This is essentially the entire amplifier.
What is on the green is only a gain amplifier.

This is the entire amplifier.
By using this connection we get a very large gain which gives us a swing of +/- 50 volts.
The power to the opamp is connected to the audio out terminal. In this way,
the opamp will never get too high voltages, neither out nor in.
This amplifier should be operated at low impedance. Therefore, it is an input amplifier that also has some gain.
I use the AD797 which is one of the best audio amplifiers ever made.

This is a very special amplifier.
The opamp on the left has a normal power supply of +/- 15 volts and functions as a gain amplifier. It also acts as a low-impedance source for the next stage.
The output MOSFETs are connected in series.
It is just as well to connect several in parallel.

Here we see the driver stage's "GND" is connected to the amplifier's output terminal.

The two opamps have identical power.
Only a drop resistor and a zener diode of 15 volts and a capacitor.
The difference is GND. The first has GND as GND,
and the second has "GND" as audio output.