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Understanding peak current in amplifiers and AC power distributors

My goal here is to understand. I want to understand how my electronics work. 

So, onwards.

Is there anyway to figure out an amp's max delivery (to speakers) and max draw (from the wall) knowing a few basic factors, like watts RMS per channel and speaker impedance?

Carrying on from that, I'm trying to assess PS Audio's P20, since it's built like an amplifier for AC. The specs say 3600 watts and 35 amps peak current. What does this mean? Does these number describe accurately the peak power delivery/draw? If a component needs to draw 70 amps of instantaneous power from the P20 over the course of a few milliseconds, is the 35 amp spec a hard cap or not? How can the deliverable peak current be 35 amps when the P20 can only connect to a 20 amp receptacle? What is the relationship between peak delivery and draw?

Where did I get the 70 amp figure from? Garth Powell's presentation on Audioquest's Niagara 7000 (listen at 31min:33sec). It was part of his reasoning for why he developed a peak transient reservoir within the Niagara 7000.

Shunyata's Hydra v3 can supposedly deliver over 100 amps peak instantaneous current, while the figure for the Typhon QR is over 1000 amps. And all of this is supposed to come from the wall, i.e., 15 amps or 20 amps. 

Neither Shunyata nor Audioquest power distributors regulate voltage output.  

For reference, I have: two active monitors (Adam S2Vs) rated as consuming 230 watts max each (internal amps are PWM Class AB), a PS Audio Stellar Gain Cell DAC at 20 watts and a PC with 650 watt EVGA power supply running on the same circuit, currently plugged into a Brick Wall PW8R15AUD. I can't install dedicated lines where I currently live, unfortunately. That gives a total of 1130 watts (but let's say 1200 watts for ease of calculation) or 10 amps (1200w/120v). I don't understand how to apply power factors within the calculation, although I know that they will greatly affect the final numbers. I would guess actual consumption to be around half that, around 5 amps.

I don't know how my components draw power instantaneously rather than over time. Frankly, I don't even understand how my components draw power over time in terms of the electrical mechanics. Powell drives a hard line between amplifiers and other components, for example, and I wish I knew why.

I'd be very grateful to anyone who would take the time to help me with these questions. I can easily summarize the answers as we go, as well. 
goropozz
3 responses Add your response
teo_audio
2,197 posts
 
Very short transients, in time, is what it is all about.

Eg, dynaudio used to rate it's drivers in peak transient ratings, 1000 watts, was typical. For 10 milliseconds, that is.

Look at the time frames they speak of. One might say 1000 amps, but for how long? the guess is only a few milliseconds. Which can be enough, depending, to stop coloration from appearing via blunted transients.


For a morel 6" mid-woofer. Look at the transient power handling. Not unusual for well built drivers.

https://www.madisoundspeakerstore.com/morel-woofers-6-7/morel-tiw-638ft-titanium-6-woofer-double-fer...
erik_squires
16,041 posts
 
OP:
For the most part these are all about bragging, which in the end only matters to a smidgen of speakers. Your ears and wallet should be the biggest reasons to pick an amplifier, not current specs per se. 

The relationship between peak, rated amplifier power vs. AC power is not by any means standard. There are requirements to rate an amp a certain wattage, like preheating at 1/3 power, and then measuring, but not about peak power or efficiency.

Class D/H amplifiers are among the most efficient, so generally speaking, they convert 80% or more of power drawn into what the speaker sees, with the lowest idle power. Class-A is least efficient, they draw their rated output at idle!

The next thing to understand is power reserves. All sorts of ways to give amplifiers extra headroom in voltage or power. This is a useful thing since music is transitory and not really like the FTC testing mentioned above.

It may help you a little to understand that amplifiers rely on capacitors to store energy. They act like fast batteries. So instantaneously they can deliver more power than the wall outlets can, and then recharge slowly. 

There are also some resonant tank circuits (using coils and caps)  that can store energy for AC circuits. Richard Grey relied heavily on this to increase current delivery for his AC conditioners. Not sure why but his products have fallen out of favor.

Personally based on listening, and cost, I use Furman products with series mode surge suppression, LiFT noise canceling and occasionally voltage regulation.

Best,
E

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