Dynamic Power Watts vss Power Supply Watts

I have a total dynamic peak power output of 4,650 watts from nine amplifiers (@ 8 ohms each); does that mean I need the same amount from the wall? Seeing as it is only possible to get 1800 watts from any given 15 amp circuit or 2400 watts from a 20 amp circuit; correct me if I am off.

Perhaps you electricians out there can enlighten. The reason I ask is that I have not yet decided to run dedicated lines. Thank you in advance.
If all 9 amplifiers might at times be putting out their peak dynamic power simultaneously, you would actually need considerably more than 4650 watts, because amplifiers are not 100% efficient (more power has to go into them than the amount of power coming out of them). Class D has fairly high efficiency, Class A has extremely low efficiency, and Class AB is somewhere in between.

But I VERY much doubt that in any living room type of situation you would ever be feeding 4650 watts into your speakers, even for an instant. Let us know what kind of amps they are, how they are hooked up (bi-amp'd, tri-amp'd, bridged etc.), and the type of speakers, and we'll be able to help more specifically.

-- Al
Al, they are all shown in my virtual system. But here is the break down:

1 Sunfire Signature 600-two, 600 watts per channel stereo biwired to B&W 803D

1 Sunfire Signature EQ True Subwoofer, 2700 watts

3 Mackie HR824MKII THX Active Monitors each w/ 150W for LF / 100W for HF

I too very much doubt that I would ever drive that much peak power at any given moment. But I am interested in knowing the technological explanation of the difference, if any, of power required from the wall and power output as expressed in watts per channel. I seem to remember someone saying that the difference is 10 to 1. But I don't know exactly what that means.
Even at a Very hi 200v, 4600 watts is 23 amps. This would represent the total output current of all 9 amps.
Some more info, please. How many output devices per amp? How much PS capacitance?...A couple of cans about the size of a 5lb coffee can would 'bout do it, per channel.
Not to mention the output devices for this kind of demand.
Outlaw makes a 7ch amp which requires 2 sep'd 20 amp circuits.
This is an A/B design of probably no higher than 55 or 60% efficiency.

Under any circumstances where you tap into that kind of power, I'm sure you are dimming the lights, in the neighborhood.
Magfan, I am not certain of the output devices on the subwoofer or the active monitors but I do know there are, if memory serves, 18 output devices per channel on the power amp with a peak current output of somewhere around 80 amps per channel, if memory serves.

It's hard to provide a precise answer, for a number of reasons.

First, there are very wide variations in the efficiency of different amplifier designs.

Second, depending on the type of music there may or may not be wide variation between the amplitude of short-term peaks and the average (long-term) amplitude of the music. Typically the power required for short-term peaks comes from energy which has previously (during periods of low demand) been stored in the large capacitors in the power supply section of the amplifiers. So short-term peak power output does not directly translate into the need for equivalent power from the wall.

And their are considerable differences between amplifiers in the amount of energy storage their power supplies provide.

Fortunately, as you are probably aware, the Sunfire/Carver designs use innovative technology that provides high efficiency. Also, your main speakers are moderately efficient (90db).

I looked at the manual for the Mackie's, and they indicate 135 watt typical ac line consumption under "loud musical program" conditions.

The subwoofer manual indicates 800 watt average ac line consumption at its maximum continuous rated output. Strangely, though, it indicates 2700 watts max ac consumption on short-term peaks, which I find hard to believe especially considering that its literature emphasizes how back-emf from its driver significantly limits the amount of current it's amplifier has to put out.

I couldn't find data on the Sunfire 600's, but as I say they should be highly efficient. As a conservative rough guess, let's say that the most power they would be putting out that would last long enough to not be supply-able from capacitively stored energy might be 300 watts per side, and let's assume 50% efficiency. That would be 1200 watts for the two amps.

So as a very rough ballpark, on loud musical program I would expect your total ac requirements to be around 1200 + 800 + 135*3 = 2405 watts. That is 20 amps at 120 volts, so it seems clear that 2 dedicated 20 amp runs are the right answer, in terms of power capability. You may want to consider having more than 2 to provide isolation between digital and analog components, between power amps and low-level components, etc.

-- Al
Thank you for a most comprehensive explanation. Are you an electrician? In any case, I think I now have more to go on to making a better informed decision to run dedicated lines. It would seem a most prudent course.
Thanks again.
You're welcome! No, I'm not an electrician. I'm a recently retired electronics design engineer and manager, primarily in digital circuit design (unrelated to audio).

-- Al
Good discussion - your amps are not like a hair dryer or a toaster - they do
not require continuous power - so you are fine. Remember that music is
dynamic and not continuous.

Think of it like a river feeding a large reservoir (amp power supply) - the
utility can let out more water than is actually feeding the reservoir during dry
summer periods and during peak demand without constricting the output
(provided the reservoir is big enough). So the issue is more likely down to
how well and over engineered are your amp power supplies rather than your
house wiring. (analogy - small reservoir means more likely for the output to
run dry)

The other issue is how well designed are your speakers - are there any nasty
phase isues that cause demand for extremely high instantaneous output from
your amp - do they have extremely low impedance like Infinity - that is as
much a consideration as how beefy your amp is. (In this case, once again, the
house wiring will not be the bottle neck.)
Interesting analogy. The capacitance factor would seem to be one of the most important. I hadn't understood their importance until now. That brings up the question of whether many small capacitors or few large capacitors are desirable in a given amplifier design. I have seen both and it would seem the many small ones would provide for better speed, while few larger ones may provide for better dynamics? I wonder?

There is some interesting discussion of that very question in this thread, including comments by a couple of distinguished amplifier designers:


Just to make sure it's clear to everyone, this pertains to capacitors that are used for energy storage (and ripple-filtering) in an amplifier's power supply section; obviously many small capacitors are required elsewhere for other purposes.

-- Al
I beleive what you want to look at is the "Power Consumption" from your owners manual or the sticker/tag on the equipment you are using, not the output power. Both are different. For instance my Krell 300cx uses (max)1700 watts from the wall & has an output that does not corespond at all to input. All electrical equipment has the power use printed somewhere and most has it stamped on a sticker on the equipment you are using. For instance a toaster may say; 125 watts max @ 120 volts AC. This is the power it draws form the wall. I hope this helps, John
eric buy your self one or two monster pro3500s then you can see what you are realy drawing in amps from the wall outlet i use them i never draw more then two amps and i am running two big mac amps i allways thaught that i needed dedicated lines witch i have but now moved my system to a nother part of the room and am just useing a 15 amp outlet
Ammeters have differing "ballistics," and you have to be careful interpreting what they indicate. What would be needed in this case is a meter that has very fast "attack," so that it can capture brief current peaks, and much slower "decay," so that the reading will be held long enough to be visible to the user. I took a look at the Pro3500 specs and manual at Monster's site, and they do not indicate what its attack, decay, and/or averaging characteristics are.

-- Al