Alright. Single supply preamplifiers has couple of inherent problem like turn on POP, output capacitors etc. So it is better to use symmetric design.
Found 0.33ohm resistors, biased and tested the amp.
I used c4793&a1837 drivers and c2837&a1186 outputs. These output transistors are much faster than usual p3a transistors.
Is it ok to use these?
I used c4793&a1837 drivers and c2837&a1186 outputs. These output transistors are much faster than usual p3a transistors.
Is it ok to use these?
I think it's not drivers fault. Removed and measured all drivers, all is fine.
Maybe outputs caused oscillation?
Don't have scope, so I can't be sure...
Btw, supply rails is 28vdc and speakers are 8ohm. I never listen too loud btw.
Maybe outputs caused oscillation?
Don't have scope, so I can't be sure...
Btw, supply rails is 28vdc and speakers are 8ohm. I never listen too loud btw.
Interesting thing is; sound was crystal clear with these drivers and outputs. Very very different than my other trials.
Cymbals sounds very real and female voices was silky smooth.
Pity it wasn't last long..
Cymbals sounds very real and female voices was silky smooth.
Pity it wasn't last long..
Answer to my own question;
Tried 100uf 50v Silmic II at bootstrap. Sound was dry, uninvolved, rolled of top end.
Tried to bypass 100uf 50v silmic II with 1uf wima mks4. Sound becomes unbearable.
Tried 100uf 63v old vishay. Better than silmic II with slighly rolled of top end.
Finally tried 100uf 63v panasonic eb-a. Everything changed dramatically.
Top end crystal clear, bass is gone deeper, much more detailed than other two.
Btw; I replaced drivers with bd139-140 and outputs to A1492&C3856, bias at 75mA.
Heatsink is lukewarm, after hours of listening and pushing the amp, seems like everything is ok for now.
Tried 100uf 50v Silmic II at bootstrap. Sound was dry, uninvolved, rolled of top end.
Tried to bypass 100uf 50v silmic II with 1uf wima mks4. Sound becomes unbearable.
Tried 100uf 63v old vishay. Better than silmic II with slighly rolled of top end.
Finally tried 100uf 63v panasonic eb-a. Everything changed dramatically.
Top end crystal clear, bass is gone deeper, much more detailed than other two.
Btw; I replaced drivers with bd139-140 and outputs to A1492&C3856, bias at 75mA.
Heatsink is lukewarm, after hours of listening and pushing the amp, seems like everything is ok for now.
I am sort of tempted to build another P3A. I originally built one in about 2004 using the ESP board and remember it sounding tather aggressive and ragged, but having read most of this thread maybe I got something wrong?
One probem is that none of the pcb design's are deemed adequate except for the one described in post #982 which seems to be secret (and "IT CANNOT BE DONE"??). Another probem is that VAS and driver transistors are now difficult to get and could well be fakes.
I have the following transistors available:
2SC3280/2SA1301
2SC3298/2SA1306
2SC3423
Is it worth having another go (with these transistors)?
One probem is that none of the pcb design's are deemed adequate except for the one described in post #982 which seems to be secret (and "IT CANNOT BE DONE"??). Another probem is that VAS and driver transistors are now difficult to get and could well be fakes.
I have the following transistors available:
2SC3280/2SA1301
2SC3298/2SA1306
2SC3423
Is it worth having another go (with these transistors)?
Building the 3rd one using C4468 and A1695...
having one transistor from SEC and one other from fairchild is a guarantee that things will go wrong ....
Can you share your p3a layout for diy pcbs for black and white toner transfer method
No i will not the pcbs i make i s for my own private use and have my own modifications on them
If you need a pcb talk to ESP Elliot sound products
I get it, you made it ,did some Modification with original Schematic etc.
I get that, okay.
It was something that I appreciate, thanks for sharing information anyway.
I already build a P3A amplifier.
Here is the pictures
I just love to build new project and then move on to new project, it's fun doing this audio amplifier stuff, I do it only for fun.
No commercial activity.