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Current Draw

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jharmon

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Current Draw

PostThu May 06, 2010 6:52 pm

I would like to add channels to my Hauptwerk project. Currently I have three stereo amps powering three stereo channels. How do I determine how much wattage I can power off the typical 15 amp circuit breaker knowing that that the amps are not consuming a continuous amount of power? I would like to get to the 10-14 channel range. Thanks for any input.

John
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wurlitzerwilly

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Re: Current Draw

PostThu May 06, 2010 7:41 pm

jharmon wrote:I would like to add channels to my Hauptwerk project. Currently I have three stereo amps powering three stereo channels. How do I determine how much wattage I can power off the typical 15 amp circuit breaker knowing that that the amps are not consuming a continuous amount of power? I would like to get to the 10-14 channel range. Thanks for any input.

John

The current consumption of an amplifier is not directly related to the audio output power.
The easiest way to check is by looking at the rating plate of all the amplifiers for either current in Amps or power consumption in Watts.
If it's given in Watts, just divide the figure by the supply voltage to obtain the current in Amps.
Add all the current (Amps) figures together to obtain the final load.
It's worth remembering that often when first switched on, devices exhibit a 'surge' in current and it may be better (if code allows) to have a delayed circuit breaker if you are getting close to the maximum 15Amps.
Regards,

Alan.
(Paramount Organ Works)
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Eric Sagmuller

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Re: Current Draw

PostThu May 06, 2010 9:43 pm

As Alan mentions, the turn on surge can be the biggest problem. Most speakers at normal listening levels never come close to drawing their nameplate rating. As the decibel output is logarithmic, in other words it takes 10x power increase for 2x volume increase, most speaker drivers will be drawing less than or equal to 1 watt at a normal listening level, 80- 90db ~ 1 meter away,. and if there are more speakers the power gets shared even more. This of course doesn't take into account efficiency loss in the amplifier. Basically the only way to really know how many can be connected to a 15 or 20A circuit, would be to play one or two at the expected maximum volume level and measure the current draw. I've noticed recently some monitors give a wattage draw spec at an average listening level, and it is just a fraction of what is rated for full output.

Eric
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Grant_Youngman

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Re: Current Draw

PostFri May 07, 2010 12:13 pm

jharmon wrote:I would like to add channels to my Hauptwerk project. Currently I have three stereo amps powering three stereo channels. How do I determine how much wattage I can power off the typical 15 amp circuit breaker knowing that that the amps are not consuming a continuous amount of power? I would like to get to the 10-14 channel range. Thanks for any input.

John


You're probably fine into that range. I have 12 Behringer 2031A's on a single 20A breaker. They are split 6/6 across two power strips. Works fine, no surge problem, no problem period. As others pointed out, the "average" power draw is well below nameplate spec. If you're on a 15A circuit, you shouldn't have a problem, unless you plan on going deaf in your youth :-)
Grant

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