Hi
From what I know, going below 250k is not needed, even if for subs. I find that 250k freq. is very good ecause of lower output noise(what LC filter don't stops) and still has very high efficiency, way more then 90%. And best thing is you are not limited for sub use, you don't have to change anything to use it as full range.
Switching losses can be high =>400kHz, so you have to start thinking about that too
From what I know, going below 250k is not needed, even if for subs. I find that 250k freq. is very good ecause of lower output noise(what LC filter don't stops) and still has very high efficiency, way more then 90%. And best thing is you are not limited for sub use, you don't have to change anything to use it as full range.
Switching losses can be high =>400kHz, so you have to start thinking about that too
lumanauw said:
I tried this too. 100n is low value. It should be 470n or more. Q1-Q2 output is much better, but current trough zeners is much higher ( maybe too much for them ). Also there is a little cross conduction, so this might be bad idea.
@RX5
I'm using 120VA transformer ( caps are 4700uf ).
I know it' old thread...
After few weeks amp still working.
Today I finished new version of amp - all smd components ( single sided pcb ). Same component values as first version, except driver transistors. It's powered from same supply as first version, but have some problems.
1. Amp won't start oscillating at power up ! It powers up when short -9V ( supplied via 7909 ) to ground !
2. IRF530 runs warm, IRF9530N is warmer. Driver transistors ( BCP53 and BCP56 ) are hot ( 60C - is this too much ).
Where is the problem ? I have no scope right now, so can't see any waveforms.
After few weeks amp still working.
Today I finished new version of amp - all smd components ( single sided pcb ). Same component values as first version, except driver transistors. It's powered from same supply as first version, but have some problems.
1. Amp won't start oscillating at power up ! It powers up when short -9V ( supplied via 7909 ) to ground !
2. IRF530 runs warm, IRF9530N is warmer. Driver transistors ( BCP53 and BCP56 ) are hot ( 60C - is this too much ).
Where is the problem ? I have no scope right now, so can't see any waveforms.
m-tech said:
Hi,
I'm considering to build this amp just for experiment, but is interesting to know before:
- The output power of this amp
- If there is possible to run at higher voltage PSU and increase the power
- How it really sounds?
- Can I use a switching power supply?
- Is possible to feed two channels with the same PSU without interference between the channels?
Thank you very much!!!
i'm a newbie on classD amps...
I built a ucd-style amp using capacitive coupling to the output stage right back when I first saw the ucd design. It is possible for the design not to start oscillating as there is no dc path through the amp. You can add an NPN and a PNP transistor in a push-pull common-base configuration in parallel with the capacitors to ensure it will always oscillate.
I know it' old thread...
After few weeks amp still working.
Today I finished new version of amp - all smd components ( single sided pcb ). Same component values as first version, except driver transistors. It's powered from same supply as first version, but have some problems.
1. Amp won't start oscillating at power up ! It powers up when short -9V ( supplied via 7909 ) to ground !
2. IRF530 runs warm, IRF9530N is warmer. Driver transistors ( BCP53 and BCP56 ) are hot ( 60C - is this too much ).
Where is the problem ? I have no scope right now, so can't see any waveforms.
was that the problem with new layout? or smd that leads problem for this frequency and voltage. would snubber recommended for IRF Mosfets?
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