Reconfiguring an existing Power Supply using PSUD2 - could use some second opinions :-)

[tonescout]

The simulation does not match what actually happens. After 6s the voltage in the real amplifer is still zero base the rectifiers haven't warmed up, and they give a much slower and steadier rise than the simulation shows. The assertion that this has anything to do with steady state behaviour remains unsubstantiated.

I have been away for a few days, but just turned the amp on and measured B+ at the valve socket and it was up to voltage ~ 1000v in a couple of seconds from cold? (This is with the current CLCLCLC circuit obviously)

 

[tonescout]

Reason that CLC version ‘sounds better’ could be because transient response is much better with three capacitor cells in parallel, providing lower output impedance across the frequency range.

My view on power supply for audio is:

• Amplifier is an extension of its power supply. There can’t be an excellent amplifier with bad power supply.
• Ripple level is important (overrated) . Transient response is neglected, but even more important.
• Power supply, even simplest CRC or CLC, is a nonlinear circuit that produces distortion (harmonics).
• Operation of power supply is indeed ruled by physics laws, but different components with their properties like ESR, ESL, dielectric absorption, inductance over frequency and current, hysteresis, parasitic capacitance and so on, will introduce some ‘voodoo’ factor, as PS circuit linearity and transient response will change.
• Different power supplies can, by small measure, change sound of an amplifier, especially one with low or nonexistent PSRR.

Thanks for your insight, and the transient response is something I am not sure how or if PSUD2 is capable of predicting or guiding, other than the (already challenged here on the thread) POV that the ability of the simulation to control a sudden change in current load quickly and without obvious ringing.

Example of rail harmonics of CRC power supply with 1 A DC load. Example is from low voltage supply for a solid state amplifier, but same rules apply to HV supplies.

View attachment 1104134


CRC under 1 A DC + 1 kHz 1.75 A rms load. PS under AC load produces harmonics. H2 harmonic is 30 dB below rail modulation caused by load from the amplifier and H3 is another 10 dB lower.

View attachment 1104135

Someone should compare rails of CLCLCLC vs. CLC under load, for harmonics and transient response.
Example of clean transient response of regulated PS under hard conditions. There should be small voltage variation and no ringing:

View attachment 1104136

 

[tombo56]

I am not sure how or if PSUD2 is capable of predicting or guiding, other than the (already challenged here on the thread) POV that the ability of the simulation to control a sudden change in current load quickly and without obvious ringing.

Stepped load is in fact simple transient response simulation, as transient response is power supply reaction to sudden load changes. I don’t know how close to reality is PSUD2’s stepped load simulation.

On real circuit, it could be measured with oscilloscope and active rail load driven by signal generator or by feeding amplifier with large square wave input signal and observing supply rail with oscilloscope. Dummy load at amp. output is required. In this specific case, very high rail voltage makes such measurements a hard task.