Circuit power requirements when A-B'ing systems

[KEW]

When A-B'ing two pairs of speakers (stereo), I have two full systems (worst case - with external amps and dual subs on each system) all fed from a single circuit. I have 2 questions:

1) I feel comfortable running either system alone on the circuit, but wonder if I should be concerned about running two systems on the same circuit...given only one system is playing at any given moment (the other is muted).
2) On occasion I have both systems playing at the same time (usually briefly between switching systems). Assuming that this does begin to tax the circuit, is there any risk of damage?

 

[mtrycrafts]

When A-B'ing two pairs of speakers (stereo), I have two full systems (worst case - with external amps and dual subs on each system) all fed from a single circuit. I have 2 questions:

1) I feel comfortable running either system alone on the circuit, but wonder if I should be concerned about running two systems on the same circuit...given only one system is playing at any given moment (the other is muted).
2) On occasion I have both systems playing at the same time (usually briefly between switching systems). Assuming that this does begin to tax the circuit, is there any risk of damage?

Muting the system doesn't take its idle load off the circuit.
My system shows a 4A load at idle, not including the projector as it bypasses the load meter.
I tried ton see the load amp at loud passages but I didn't see much change as I think the filter caps do a good job.

So, I would not hesitate to double up especially if you don't do reference comparisons with both.

 

[PENG]

When A-B'ing two pairs of speakers (stereo), I have two full systems (worst case - with external amps and dual subs on each system) all fed from a single circuit. I have 2 questions:

1) I feel comfortable running either system alone on the circuit, but wonder if I should be concerned about running two systems on the same circuit...given only one system is playing at any given moment (the other is muted).
2) On occasion I have both systems playing at the same time (usually briefly between switching systems). Assuming that this does begin to tax the circuit, is there any risk of damage?

No risk of damaging anything as long as the combined load don't overload your circuit. So do your math by adding the average load of each system and see if they come close to the capacity of the circuit. I would think that even a dedicated 15A circuit should be plenty for just two pairs of speakers. If the combined average load is close enough to the circuit capacity (whatever that may be), then if you have two systems on and if both have hit a huge dynamic peak moment at exactly the same time (day 15 to 20 dB peaks), then in theory it is possible to result in an instantaneous voltage dip high enough to cause sound degradation for that very short duration, depending on the design of the amp's power supply design.

 

[KEW]

No risk of damaging anything as long as the combined load don't overload your circuit. So do your math by adding the average load of each system and see if they come close to the capacity of the circuit. I would think that even a dedicated 15A circuit should be plenty for just two pairs of speakers. If the combined average load is close enough to the circuit capacity (whatever that may be), then if you have two systems on and if both have hit a huge dynamic peak moment at exactly the same time (day 15 to 20 dB peaks), then in theory it is possible to result in an instantaneous voltage dip high enough to cause sound degradation for that very short duration, depending on the design of the amp's power supply design.

How do I determine or measure the average load?
Looking at MTrycrafts system, I think I am under his 4 - 5 Amp level.

 

[Alex2507]

How do I determine or measure the average load?
Looking at MTrycrafts system, I think I am under his 4 - 5 Amp level.

I've seen one system shut down because of the protection circuitry in the AVR and I saw Walter's system shut down because of a tripped breaker. Nothing was damaged except maybe my ears. I say you crank both systems up to past any sane SPL to demonstrate that you can go there and then be secure in playing both systems at reasonable levels from there on in. This is no time for math.

 

[PENG]

How do I determine or measure the average load?
Looking at MTrycrafts system, I think I am under his 4 - 5 Amp level.

I would base it on the speaker's ratings. Example: speaker specs say recommended amp power 25-200W, so base it on the worse case of 200W. 200WX4 (you said two pairs) = 800W, a 15A dedicated circuit is rated for 1800W so one circuit can handle 800W of amp power draw even if the amps are of the class AB type. Obviously this is just a rough, cheap and dirty example but I think that's good enough for a quick estimate that is based on the side of worst scenario.

Actually why not just do what Alex said and forget about the math.

 

[KEW]

I would base it on the speaker's ratings. Example: speaker specs say recommended amp power 25-200W, so base it on the worse case of 200W. 200WX4 (you said two pairs) = 800W, a 15A dedicated circuit is rated for 1800W so one circuit can handle 800W of amp power draw even if the amps are of the class AB type. Obviously this is just a rough, cheap and dirty example but I think that's good enough for a quick estimate that is based on the side of worst scenario.

Actually why not just do what Alex said and forget about the math.

Also running subs (potentially two pairs). My Rythmik E15HP amps are, I think, 600 Watts each.

 

[KEW]

I've seen one system shut down because of the protection circuitry in the AVR and I saw Walter's system shut down because of a tripped breaker. Nothing was damaged except maybe my ears. I say you crank both systems up to past any sane SPL to demonstrate that you can go there and then be secure in playing both systems at reasonable levels from there on in. This is no time for math.

Man, I'm sitting here getting into some good mental masturbation and you go and ruin the moment with a stupid-simple practical solution.


Thanks!

 

[Alex2507]

a 15A dedicated circuit is rated for 1800W

... and then there are weird rules for peaks and duration of current draw that all basically add up to the breaker not being that quick to trip regardless of exceeding the rated 1800 watt spec.

Edit: I think, IMO, YMMV, Buy a fire extinguisher.

 

[Alex2507]

Also running subs (potentially two pairs). My Rythmik E15HP amps are, I think, 600 Watts each.

That might be what it takes to trip that breaker. I still think it would be painfully loud before the breaker tripped.

 

[Rickster71]

Man, I'm sitting here getting into some good mental masturbation and you go and ruin the moment with a stupid-simple practical solution.


Thanks!

That it exactly.
If I may add to what's already been said.
A large part of the issue is the type of load that's presented to the breaker.
It's a much easier load, than say, the linear load of a toaster or heater.

Trying to do the math on something so variable, is exactly what's quoted above.

Let the breaker do it's job.
Note: Unless you have old Federal Pacific breakers. They're notorious for not tripping.

 

[TheWarrior]

Load= Two subwoofers, two powered monitors, two 200w @8ohm mono block amps, two mid-high end receivers, and an Oppo.

I fear amps and undercurrent. I haven't had time to run another line for the amps, but if we only listen, I can use the separate circuit I ran for the TV, and it has APC protection.

Oh, bring your speaker stands! (just thought of that)

 

[PENG]

... and then there are weird rules for peaks and duration of current draw that all basically add up to the breaker not being that quick to trip regardless of exceeding the rated 1800 watt spec.

In fact, if he exceeds the 1800W by less than 10-15% it may never trip. My concern is not tripping the breaker or damaging his gear, just the voltage dips during the highest coincidental peaks affecting sound quality. The chance of that happening should be just next to 0 and most decent amps would have large enough caps to help dealing with those moments. He's worrying about nothing really.

 

[Speedskater]

For measuring line voltage, current or power a little 'Kill-a-Watt' meter does a great job.
Some home theater people run amps that are capable of well over 2000 total Watts on one circuit.
If you draw too much current the circuit breaker will trip, if it doesn't trip then you're not drawing too much current.
Low line voltage will not damage hi-fi equipment.

 

[Rickster71]

For those interested.
Here's an article about Voltage Sags, Overvoltage and electronics failures:
http://ecmweb.com/sagsswellsinterruptions/when-does-poor-power-quality-cause-electronics-failures

 

[fuzz092888]

If Walter's apartment hasn't burst into a fiery inferno, I think you'll probably be ok

I've cranked my system once or twice while all on a single breaker with no harm to anything in 3 different residences so I can't imagine that even two systems played at moderate volume would cause any harm or breaker tripping.

I guess I should also add that my system is run through two APC voltage regulators so that may also play into why nothing bad has every happened, but I've never tripped the breakers on those either.