High current negative voltage supply from 10vDC+?

Thread Starter

NameET

Joined Jun 4, 2018
12
Hello everyone,

After having built quite a few amplifiers (most class A), I wanted to decide to take on a class AB amplifier. My issue lies with the output stage. I've drawnup a basic design (I'll attach below) that allows for a 4 volt swing across an 8 ohm load for 2 watts of output power. The only issue I've got is the power supply. I need a +10 and -10 supply, and I've only got a 10v 2A wall wart. I've heard of splitting the supply with a divider, but that didn't work for me (the emulated ground's potential kept changing), and the classic 555 negative voltage rail simply couldn't supply the ~400mA of current needed for the 8 ohm load.

TL;DR: does anyone know of a schematic that could produce a -10v, 400mA rail from a +10V, 2A rail?
ppfollower.PNG
 

ebp

Joined Feb 8, 2018
2,332
The least expensive solution is an inverting switcher, often called "buck-boost" though it neither bucks nor boosts. Switchers aren't ideal for audio because of noise that can fall in the audio spectrum.
 

Audioguru

Joined Dec 20, 2007
11,251
Instead of making a negative supply voltage, why not make a bridged amplifier that has two amplifier outputs like you show but powered from your +10v supply?
Each amplifier output drives one of the two speaker wires then the voltage swing across the speaker is almost doubled and it will work with your single +10V supply. Since both amplifier outputs are identical then they will each have the same DC voltage at about +5V then an output coupling capacitor to feed the speaker is not needed. Of course one of the amplifiers needs an inverting stage so that the signal swings are opposite.
 
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