Power Conditioning / Surge Protection

I chose the following option: power amplifiers - Isotek Super Titan, then added SR PowerCell Two. (An early choice was - Isotek Titan.)
Sources-PS Audio P10 - > SR PowerCell SX (primarily-PS Audio).
PS. Regenerators always killed my power amplifiers (Classe).
I've heard a lot of good things about Niagara from audiophiles, but I haven't tested it in my system.
I strongly recommend testing High Fidelity Cables MC and Bybee iQSE. I didn't return it.

I only stated that when charge time gets higher - ripple is higher (capacitor is charged from the bottom of the ripple to the next peak)

Which is wrong. The next peak (voltage) will get smaller, and the total ripple will be lower. The high frequency ripple (which most impacts THD) in most amplifiers and can induct IMD will get much lower. Don’t believe me then feel free to build an amp and test it and/or simulate one.

I only argue that at the moment when net capacitor current is zero (peak of the wave) voltage on capacitor depends on source voltage and source impedance. That’s the peak supply voltage for the output stage. How much it will drop depends on total source impedance including house wiring, power cord, fuse, transformer windings resistance and added impedance of the filter in conditioner.

Here you are totally ignoring the load the is not synchronous to the source. You can’t do that. That is where the error in your logic is. This only applies, to some degree, at much less than 2x line voltage. Dynamics we tend to associate with mid-bass.

If this filter is poor then voltage drop, especially on inductive reactance, can be high. Even if we assume only 10% it will result in 20% loss of max power - equivalent to about 6% of drop in perceived loudness.

You are treating the "inductor" as a resistor effectively, and the load as a constant current load, both in the DC domain with this argument. Again, that is incorrect logic. Even with 0 resistance, any frequency beyond 2x line frequency in the load (and effectively less depending on timing) mostly eliminates any benefit of charging in the short term.

Large linear supplies have a lot of filter capacitance reducing voltage ripple to very small resulting in even narrower and higher charging current pulses and much higher voltage drops on conditioner’s filter impedance.

And again, if you add resistance or inductance, the size of those charging currents gets less, meaning the high frequency harmonics in them gets less (less noise / THD and potentially less IMD), and the length of time of charging gets longer.

I use Furman Elite 20PFi. They call it "Power Factor Correction", but in reality it is huge inductor in series with large capacitor (in parallel to load) that stores energy delivering up to 55A current for spikes (it presents resistive load to mains).

Let’s look at your Furman. Do you really think it delivers 55A peak currents from that capacitor in your system with a linear supply? It does not, not practically at least. The only time it can supply anything into a linear supply is when the voltage on that capacitor is above the transformer reflected voltage on your linear power supply capacitors. The problem is the voltage on the cap in the Furman and the reflected voltage of the capacitors in the linear supply in the amplifier will be exactly the same as it progresses through the charge (AC) cycle. Effectively, the capacitor in the Furman ends up in parallel to the capacitors in the linear supply (reflected through the transformer) once the diodes start conducting and it does not end up transferring any power at the start of the charge cycle, and only a small amount at the end of the charge cycle when the AC voltage decays. It is likely a film capacitor and hence able to store much less energy than the caps in the amplifier power supply. The only time it will supply a large peak current (very short duration and not much energy), is if the amplifier has a large load right after peak of the AC cycle.


For an LC PFC to be effective as PFC, it must be exactly tuned to the load including the reactive components in the load (i.e. capacitors). Odds are your Furman is rarely presenting something that looks like a resistor to the mains. The inductor does improve power factor and reduce THD on the AC lines, but effectively the capacitor is doing very little to help that due to the nature of the load.


I will guarantee you that under peak loading, due to the inductor in the Furman, the rail voltage on your supply is slightly dropping, and that is a good thing, means the ripple/noise is being kept under control. I would expect taking out the AC capacitor in the Furman would have almost 0 impact on the DC rail voltage in the amplifier under loading but I would not suggest it. What it will be good at is suppressing high frequency noise coming in from the AC line.

We agree to disagree.

It is not a matter of disagreeing of agreeing. This is objective engineering, not subjective listening.  Everything in what I wrote is easily verified through simulations or building and testing.  I will absolutely agree that added resistance whether real resistance or AC impedance will limit /reduce the maximum rail voltage and hence the peak volume, but I cannot agree as it simply is not true, that the effect and operation is as you described and to the to the level you described as that is simply not the case, no more than the real world performance of the Furman will be as they describe. I am not making that statement because "I believe" it to be true, I am making that statement as I know it to be true both from a fundamental engineering standpoint, and a practical, having done it, implemented it, tested it. measured it standpoint.


There may be something perceived as lack of dynamics with some filters and some amplifiers, but any real world loss of peak power using real music is going to be fairly small, and unless you are driving into clipping, loss of dynamics should not be an issue with any competently design amplifier. Instead of just taking the easy answer, which means the problem is never solved, it is better to find out what is really behind the perceived difference.

I'm just tired of arguing, especially most of people don't follow the subject.  I also don't understand some of your statements.  Capacitor is charged only from the bottom of the ripple to next peak.  Bigger ripple means longer charging time - ALWAYS!, but you disagree with this.

Ripple is a function of capacitance and load current.  At constant load current when capacitors get larger (big capacitance) voltage ripple gets smaller hence current charges will be narrower (and usually of higher amplitude because of lower ESR).  Yes, additional impedance will make charging pulses smaller, because they depend on source voltage divided by impedance in the charging circuit - but charging time will not get longer!  It will be charged exactly the same amount of time - from the bottom of the ripple to next peak. Additional impedance in the charging circuit will only result in the voltage drop and the lower voltage on capacitors. It does not affect charging time within each cycle.

Yes, Furman's output capacitor appears to be connected in parallel to electrolytic caps, but is not.  It is on the the other side of the rectifier on the AC side.  Voltage on this capacitor follows AC voltage cycle but any loss of charge caused by PS charging pulse is replenished from energy stored in the inductor thru the whole cycle.  In addition this (huge!) capacitor has very low ESR.  That way during narrow charging pulses current comes from this capacitor and not from the inductor.  Removing this capacitor would have huge effect on the amp.  Just connect big inductor in series with mains and you will see results.  There are power supplies that charge/discharge capacitors during whole cycle because they have big choke in series but then capacitors' voltage is an average and not the peak of the waveform.

Perhaps we're hijacking this thread?