I want to point out that with any siwtched mode power supply or switching step up or down regulators. Any circuit that dosen't have high frequency compensation built in will have parasitic osscliations.
I had built a zero negative feedback amp with gret scope results, zero compensation required.
However I built a newer model involving a switching ste up module, with the same topnology my amp started oscilatting under a proper scope that has bandwith of 50mhz.
The class a head amp irf610 dosen't have any high frequency/parasitic compensation built in, it will osscilate when a smps is used. A computer scope cannot detect osscilations becuase its sampled and has a filter cutting off 20+khz. Parasitic Osscilations are typically in 1+mhz range.
Typicalkly because parasitic oscillations are well above 20khz range in theory the oscillations cannot be heard. However in my real world testing, getting rid of oscillations will improve sound quality.
A lm317 typically has poor ripple rejection in mhz range, therefore I reckon smps+317 regulator will not solve parasitic osscilations, however realworld testing is required to prove this.
acomeau wrote:
thinkbrown wrote:
I have an old PSU from a computer somewhere. I believe it supplies 85ish watts at 12volt. Would that do it?
A power supply is not a power supply..........that is just because the rating is the same does NOT mean its performance is the same.
SPSU [switching power supplies] are notorious for noise and IMHO should be avoided entirely for audio circuits. Would be experts claim SPSUs are more efficient - and that is usually but Not always true - but they fail to understand that SPSUs are noisy and can be less stable [in some conditions] and have other problems.
I Never use a SPSU in development work, nor in audio circuits.In addition, SPSUs can fail with terrible results - destroying what the circuit they supply. I had that happen twice.
In summary then never use an old SPSU for a circuit you care about, and never use for audio circuits.I've used a duall 24v switch mode supply for my class a amp no plorbems
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