You are kidding? Sorry, but who needs support for a per design unstable amplifier? The designer or the rebuilder?
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You are kidding? Sorry, but who needs support for a per design unstable amplifier? The designer or the rebuilder?
I wouldn't jump to conclusions so fast. Me and my colleagues already have a few preamps and amps designed by dadod and they are super stable are they sound superb.
I'll build this CFA with Exicon lateral mosfets, I already bought PCB's but don't have time to do it so fast. In a few months.
It's great that you are a part of this thread, but until the source of oscillation is found it not good that you automaticaly blame someone.
Regards
The source of oscillation is the cherry component. I have done a VFA lateral using TMC + a small cherry cap. Simulation always showed stability but never the real amplifier using Lateral MOSFET. Removing the cherry component and redesign the TMC stabilized the 3 pairs double die laterals ECW20(N|P)20 even with using lower gate resistor values (270R n-chan., 180R p-chan.).
This amp has been tested up to +/- 62V - VAS anti saturation diode and over current protection in situ, measurement bandwidth 80kHz:
The resulting TMC only amp has then been successful rebuilt by AndrewT (RIP - missing him).
BR, Toni
This amp has been tested up to +/- 62V - VAS anti saturation diode and over current protection in situ, measurement bandwidth 80kHz:
- THD20k+N@200W@8R: 0.0052%
- This measurement was taken with sagging rail voltages from power supply (~ +/-58V) just before power supply current limit: THD20k+N@320W@4R: 0.008%
The resulting TMC only amp has then been successful rebuilt by AndrewT (RIP - missing him).
BR, Toni
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mounting issues
Hello Damir,
started to build the BSA two days ago and found some issues
- drilling holes for Q9 and Q10 not fit for KAS1381/KSC3503
- left drilling hole R40 to small (different diameter for both holes of R40)
- drilling holes for capacitors >=220µF, for resistors >= 2W and for D5,D6 are very tight.
Keep me informed about the actual issue from thimios. I still have power mosfets from Hitachi, Renesas and Exicon, so i am not quite sure, which one to use.
BR
Günni
Hello Damir,
started to build the BSA two days ago and found some issues
- drilling holes for Q9 and Q10 not fit for KAS1381/KSC3503
- left drilling hole R40 to small (different diameter for both holes of R40)
- drilling holes for capacitors >=220µF, for resistors >= 2W and for D5,D6 are very tight.
Keep me informed about the actual issue from thimios. I still have power mosfets from Hitachi, Renesas and Exicon, so i am not quite sure, which one to use.
BR
Günni
I see now heatsinks on drivers.
No, no, see more carefully.
Heatshinks are placed always when 50v used.
The problem are the 1uf C8, C11
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I see now heatsinks on drivers.
I found my amps more DC stable with heat sinks on drivers.
No, no, see more carefully.
Heatshinks are placed always when 50v used.
The problem are the 1uf C8, C11
C8 and C11 increased PM (in simulation), here is LG without those caps.
Thimios you can try with lower values as 330nF or 470nF (that one I used in my amp).
Attachments
Lets stay without those for a little, i want to be sure that is absolutely stable now(running an fft test)and i want to listen.
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Yes, that's correct, but in case of enhanced VAS when is essential, but here with simple VAS not so.
