Simply build the thing and test the mentioned step by step. It takes a bit of effort, but it is audio engineering, diy, because these steps have different influences on the sound - which cannot be determined by peek-measurement methods;-)
You need to write down your own specification first.
I assume you want the amp to be a simple Class A like you have been experimenting with.
What is the amp to be used with? Speaker or headphones?
If it is to drive a speaker how much power do you want? That will determine the supply voltage.
If a speaker would you consider Class AB which runs much cooler?
I assume you want the amp to be a simple Class A like you have been experimenting with.
What is the amp to be used with? Speaker or headphones?
If it is to drive a speaker how much power do you want? That will determine the supply voltage.
If a speaker would you consider Class AB which runs much cooler?
If you consider two separate PSU for low and high voltage is that parts count. What if you drive the first stage from a voltage doubler instead, then the bootstrap does not even needed or the second PSU.
Second thing I will do is replace bottom FET with LM317 in constant current mode, only one resistor and LM317, lower parts count even more.
One more resistor and one TO-92. Problem with the LM317 is the dropout voltage. It needs that to stay in constant current, too. With a 15 volt supply you can ill afford to lose another two volts. Losing one vbe plus Rds(on)*Idq is a little more palatable. And if the FETs are already on hand and the 317 isn’t, it a no brainer which to use,
Okay did not realize that you did not have a LM317 on hand. Why would the same drop over the LM317 than across the FET be troublesome, it is what you need. Why not run the whole thing off 30V you have it available.
May I suggest a circuit like:
Source: https://www.diyaudio.com/community/threads/hybrid-zen-amplifier-lm317-efficient-and-simple.402477/
Source: https://www.diyaudio.com/community/threads/hybrid-zen-amplifier-lm317-efficient-and-simple.402477/
is that what you meant by "direct couple into the gate"? it seems to have the reverse efect
It's a trap. How do these different types of distortion compare in real life?:
1) A 'raw' BC546 gain stage with no constant current source, with high voltage swings so it has lots of modulation, connected to a MOSFET follower.
2) With the BC546 connected to the lower MOSFET (common source), so its collector voltage modulation is 20-30x less, but/and the MOSFET is now a gain stage. Feedback could be used to reduce the total gain, or
3) connect the BC546 as a follower. Something also has to be done with the upper MOSFET. It could be reconfigured as a CCS and it's probably easier to use a P-channel for that.
More ideas:
Could a PTC thermistor be used in a resistor divider network controlling the gate voltage of the MOSFET CCS? So if the MOSFET gets hot, reduced gate voltage compensates the reduced on-resistance of the IRF.
almost you can see some cutting on the bottom. i also realised i have way too much of these "40321" transistors laying around.
so here comes my millionth amplifier project
so here comes my millionth amplifier project
No, what I meant was what you did in #34. Then split R8, and boot strap back to the output. That will give you the largest possible output of anything you’ve tried so far, and all off a single 15 volt supply. To get the most gate drive possible, make the upper half a diode (1N4148). That could however, add audible artifacts that two resistors won’t, and a maximum drain current of say 4A (2X IdQ) you only need about 3 or 4 volts above the source to fully turn the FET on. At higher currents you might want more, but not here.
i could also increase the voltage to 18V or 17V and make r2 biggger, the transformer i have will output a voltage slightly above 15V after rectification.