Hi all, I thought I would add some capacitance to my cheap SMPS to see what happens!
I have 3 low ESR 10,000uf caps. Each rated about 7A ripple at 50 Hz. Well, the 8.3A rated supply current limit says No!
So I found a simple anti-spark circuit using an FET, a couple resistors and a cap. It works really well using a parallel resistor as a capacitor pre charge circuit. Does it make any difference having 30,000uf of power caps feeding a class D amp? I don't know yet.
I have 3 low ESR 10,000uf caps. Each rated about 7A ripple at 50 Hz. Well, the 8.3A rated supply current limit says No!
So I found a simple anti-spark circuit using an FET, a couple resistors and a cap. It works really well using a parallel resistor as a capacitor pre charge circuit. Does it make any difference having 30,000uf of power caps feeding a class D amp? I don't know yet.
I found with my irs2092 based class d amp too much smoothing caused power down problems.
On power down I would get a siren type noise then a huge thump through the speaker.
I had a chat with International Rectifier about it and they said with too much smoothing I need a reset circuit to hold the 2092 in reset if VCC goes too low.
On power down I would get a siren type noise then a huge thump through the speaker.
I had a chat with International Rectifier about it and they said with too much smoothing I need a reset circuit to hold the 2092 in reset if VCC goes too low.
The tas5630s I'm using shut down quietly from 48v. The PSU holds up a couple seconds longer with the caps and a low or no signal, but she turns off smartly and does not go bonkers 🙂
TPA 3116 I have on 24V does not go off as cleanly. I think it would also do something nasty with a very slow supply decay.
I don't have enough bass speaker load to see if this actually makes any difference yet. Full load on a pair of 97db 10" bass mids is loud, but not really testing the supply. They don't do anything below 50hz or more.
TPA 3116 I have on 24V does not go off as cleanly. I think it would also do something nasty with a very slow supply decay.
I don't have enough bass speaker load to see if this actually makes any difference yet. Full load on a pair of 97db 10" bass mids is loud, but not really testing the supply. They don't do anything below 50hz or more.
Adding caps could make things worse. Regulated supplies, including SMPS, often have output impedances which are inductive. Adding caps to this could raise output impedance, thus reducing amplifier performance. You need to measure the PSU output impedance with, and without, the added caps. The frequency range from about 2Hz up to 200Hz is probably sufficient. All you need to do this is an oscilloscope (or audio millivoltmeter), AF sig gen, another power amp and an 8ohm power resistor.
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