Originally Posted by edorr
This may explain why my balanced Furman reference did nothing for me (other than expensive surge protection) and the PPP was a complete revelation.
Well what exactly is the PPP doing to improve your system performance? If you have a sine wave with less than 10% distortion coming out of the wall, I don't see how a power supply would function any better from a source of pure AC.
In the case of a switch mode power supply, the first step is direct rectification of the AC input to high voltage DC. That DC feeds an power square wave oscillator in the neighborhood of 100khz who's duty cycle is varied based on load demands. That 100khz is sent through a transformer taking advantage of the size vs frequency ratio. The low voltage 100khz output is again rectified and filtered via an LC network.
Now tell me how input 60hz waveform distortion is of any importance in the above design?
In the case of an unregulated linear power supply, the input AC distortion is still of little concern. The primary effect is a distorted AC waveform will produce a slightly different DC output voltage from the supply. The engineering reasons are integration - basic calculus. In a regulated linear supply, all the distortion does is stress the regulator - not good but the DC output voltage remains the same hence I question how the clean AC input has any effect on the device performance with a re-generated AC supply.
There is one area where the AC regenerator may help. NOISE! If the AC input has significant harmonics, those can create both RFI as well as noise on the DC rails even in a linear regulated power supply. A switch mode supply is still immune to this. So a regenerator is in fact an excellent AC power filter and that's perhaps what many of you are hearing. But cleaning up residual noise does nothing to improve dynamics or frequency response.
As for injecting harmonics to deliberately alter the sonic signature of a power amp - aka "Multiwave", it's a very bad idea. Altering the AC waveform changes the integration of the AC to DC. The charging nature of the filter capacitors is altered. The end result is higher or lower DC rails. Both of which can be awesomely destructive to a high power amplifier. If a power amp was designed for a nominal +/-70 volt power supply, by distorting the AC input, you can push that up to 80 or 90 volts DC average. So yes the amp sounds birghter and more dynamic. It's also probably running out of SOA. (S
rea). That's what "Multiwave" does. Now you may like how it sounds but I would not abuse my expensive high and amps like that!