New P20 ..... more details please?

[jvvita]

And I always put to mute before turning off. I experienced nasty noises turning off the preamp before the amps

[darrenv1070]

Great tip! Thank you

[John_H]

Hi Paul, and everyone! I’ve been a regular poster on this PSAudio forum, but there are so many unique topics which pop up like mushrooms that my contributions have been extremely fragmented, having been posted all over the place. THIS thread is the longest and richest of the P20 threads, so I’m back!

I’ve been a very happy owner of two beastly black P20s since late 2018, and here’s a low-Rez photo of my setup:

I have a question - is the P20 essentially a PWM (Class D) amplifier, whose output waveform is shaped by a DSD-like process of multi-MHz pulsed voltages?

Here’s a very informative primer on Class D amps from Infineon from the year 2005 which clearly describes the difference between linear power amps and PWM amps:

an-1071.pdf

[John_H]

Also, on the topic of balanced AC toroidal transformers (Equi=tech, PLiXiR, Torus, etc.) - has anyone tried connecting one between the output duplex of a PowerPlant and a source component (not power-hungry amplifiers) as an additional power conditioner?

My two P20s “regenerate” wall duplex AC into low-distortion, low output-impedance AC to feed my system, but the source components are still extremely sensitive to the quality of the input AC. So why not use multiple small balanced toroidal transformers (150W, 400W, or 1,000W - depending on the needs) to further filter out the residual DC and noise? This will further silence imbalances in the DC ground potential, as well a broad range of broadband noise, both common mode, as well as uncorrelated ultrasonic noise.

I have these 230V 400W units in mind:
https://www.plixirpower.com/products/elite-bac-400

Some details on my source components on another PS Audio forum thread:

PS10 hum when Lyngdorf RP1 connected

As my 230V P20s are rated for 2,000VA, a toroidal with adequate overhead will be the equivalent of 3,000VA and above. Such a unit would be over 110 lbs. in weight and of substantial size. Rather than two such units in my already cramped audio setup, I believe that it would be far more effective to place balanced toroidals AFTER the P20’s duplex outlet, as my source components a much more modest amount of power. The most critical components (and the power consumption in watts) are: MSB Technol…

“Powering” AC through an extra high-quality external bifilar toroidal isolation transformer should be just a matter of single-digit impedance (with the inefficiencies manifesting itself in heat being dissipated naturally), minimal inductance, and almost no capacitance - much like the load of any component which has a built-in toroidal transformer, which the P20 would have absolutely no problems with, would it not?

[John_H]

Finally, last but not least, a third question regarding discrepancies in the P20s display data screen which has really bugged me, since the problem appears to a faulty “calculator” algorithm:

P20 calibration question

Under very similar output loads of ~175W the current output amperages between my two P20s are significantly different. Can anyone explain why the discrepancy (over 20%) is so large? I thought the relationship between wattage and amperage was straight-forward math. Is there something else which needs to be calibrated for my two P20s? [image] [image]

[Paul]

Wow. What a gorgeous room. I am jealous! The P20 are not Class D, they are pure Class AB amps

[John_H]

Thanks Paul, for the compliments! So here’s the balanced bifilar-wound toroidal isolation transformer, that which I’d like to use to further reduce any of the P20’s residual DC and ultrasonic noise (both common mode and uncorrelated high frequency spectral) at the output duplexes of the regenerated AC power. I have some concerns that the inrush current upon turning on may overtax the P20, so I intend to connect them to the HC output duplexes (intended for amplifiers).

PLiXiR Elite BAC 400 Power Conditioner Review

Have others had any experience with using balanced toroidal isolation transformers with their Powerplants, plugging in the former AFTER the regenerated AC duplexes? I’ve been asking around, but it seems no one else in this planet has done this…