old design seems to have a higher voltage swing, i also ditched the 1Meg resistor, the input capacitor could be reduced in capacity to 100n or 1u.
This LTspice file, message #283 is more for example. For me those are only one tool, which I don't use very often. Best thing with these is Bode-plots and possibility to check gain- and phase margin. To do these calculations without computer is 'mission impossible' for me.
Actual circuit will be little bit different and is still under construction.
Actual circuit will be little bit different and is still under construction.
Built the circuit from post 287 and used mje3055 transistors due to their higher current out and high gain. Im going to mount everything else properly tommorow. It works fine and dosent go into flames, the amplifier is runnig for around an hour and the pre capacitor voltage is constant at 6V. I didnt bother connecting it to any serious speakers (becuse its fragille and a few components are on the bottom of the pcb for ease of replacement and i would have to carry it to the other side of the room) so i cant speak much about the sound.
Have now working 4-transistor proto and after more than 24h continuos power on it still works well. It is like amp from post#283, but with adjustable LED CCS. Only half-watt max power 😑
Schema later when ready...there is also a fet-bjt preamp by 'lineup' from Sweden.
Schema later when ready...there is also a fet-bjt preamp by 'lineup' from Sweden.
increased the feedback resistors to 180k. almost rail to rail voltage swing at 12V, the issue is that adjusting the current here is done by settig the output voltage to 6.2V and that the results wont be repairable.
It has current feedback.
That means when the speaker impedance goes up there will be more output signal-
That means when the speaker impedance goes up there will be more output signal-
cutting transistors isnt the best idea it seems, i think a zen circuit is the way for low transistor count circuits, zca+ccs is thw ay i will be going becuse i recently got these 2 heatsinks that should be enough for the 15W dissipated by each transistor with enough headroom.
There is MJ340, just bought some BD139-16 which are better choice here and also some bigger heatsinks.