I saw a simple amplifier but thought maybe I can do it better without to many components.
Here is the result. Its not very temperature stable but in class A it gets less hot the louder you play.
So it is just to measure the current in the output transistors = voltage over R8 or R9 and adjust it with P1 to
a little more than Feed voltage / 4 * R speaker. But take half an Hour for the heat to be stable after the last adjustment.
It is easily adapted to other voltages and speaker impedances. Distortion is about 0,1% which maybe some people don't hear.
Noise is extremely low under 5 uv 20 - 20k. Common mode rejection is determined by C2. Frequency response is good 25 Hz to 95kHz -3dB.
View attachment 1418335
But looking at the results it is possible to do it much better. Faster and much lower distortion but a little more noise.
The problem now is that the P1 is very sensitive in adjusting the current.
Now the anti thump + radio interference filter on the input is included. But still pretty simple.
I changed the R12 to 0,82 ohm because I believe the IRF 540 has about 5S at about 1A.
View attachment 1418382
Here is the result. Its not very temperature stable but in class A it gets less hot the louder you play.
So it is just to measure the current in the output transistors = voltage over R8 or R9 and adjust it with P1 to
a little more than Feed voltage / 4 * R speaker. But take half an Hour for the heat to be stable after the last adjustment.
It is easily adapted to other voltages and speaker impedances. Distortion is about 0,1% which maybe some people don't hear.
Noise is extremely low under 5 uv 20 - 20k. Common mode rejection is determined by C2. Frequency response is good 25 Hz to 95kHz -3dB.
View attachment 1418335
But looking at the results it is possible to do it much better. Faster and much lower distortion but a little more noise.
The problem now is that the P1 is very sensitive in adjusting the current.
Now the anti thump + radio interference filter on the input is included. But still pretty simple.
I changed the R12 to 0,82 ohm because I believe the IRF 540 has about 5S at about 1A.
View attachment 1418382
