Confusion over Power

[Sylar]

I auditioned a pair of paradigm speakers, CT 90 & Monitor 7 (Monitor had some issues, so i could not really check out how they sounded, only fronts with no woofer).
...I had a discussion with the owner, and topic went into power. And he said something regarding power and he was adamant that I was wrong.

This is my understanding regarding power & amps..., the power that is used to drive the speakers cannot be more than the input power drawn (AC supply). It is the input power which is used to 'amplify' the weak audio signal. Average power is different to peak power (short bursts).

But, he was like, that is input power and this is audio power & hence power output can a lot more.
Just to clarify, so am 100% sure. No way it is possible to provide higher power at output (other than for short bursts). If it is possible, then everythin i read and understood of peak dynamics, headroom & clipping is

 

[TLS Guy]

I auditioned a pair of paradigm speakers, CT 90 & Monitor 7 (Monitor had some issues, so i could not really check out how they sounded, only fronts with no woofer).
...I had a discussion with the owner, and topic went into power. And he said something regarding power and he was adamant that I was wrong.

This is my understanding regarding power & amps..., the power that is used to drive the speakers cannot be more than the input power drawn (AC supply). It is the input power which is used to 'amplify' the weak audio signal. Average power is different to peak power (short bursts).

But, he was like, that is input power and this is audio power & hence power output can a lot more.
Just to clarify, so am 100% sure. No way it is possible to provide higher power at output (other than for short bursts). If it is possible, then everythin i read and understood of peak dynamics, headroom & clipping is

Unless his amp is a nuclear reactor: - Energy can neither be created nor destroyed.

Class A/B amps pass on at best 70% of the power drawn from the AC. Any heat generated in the device is power no available to the load, the speaker.

So the owner you were talking to needs to take some physics classes.

He is wrong and that's an end to it.

 

[jeffsg4mac]

Or unless his amps are powered by one of these

But yeah as said he needs to read some basic physics for sure

 

[highfigh]

I auditioned a pair of paradigm speakers, CT 90 & Monitor 7 (Monitor had some issues, so i could not really check out how they sounded, only fronts with no woofer).
...I had a discussion with the owner, and topic went into power. And he said something regarding power and he was adamant that I was wrong.

This is my understanding regarding power & amps..., the power that is used to drive the speakers cannot be more than the input power drawn (AC supply). It is the input power which is used to 'amplify' the weak audio signal. Average power is different to peak power (short bursts).

But, he was like, that is input power and this is audio power & hence power output can a lot more.
Just to clarify, so am 100% sure. No way it is possible to provide higher power at output (other than for short bursts). If it is possible, then everythin i read and understood of peak dynamics, headroom & clipping is

If he thinks output power can exceed input power, the government may want to talk to him.

Ask him how he accounts for the heat generated by the amplifier- it is wasted input power, after all. Throw him a bone- 33,000 BTU= 1HP, and 746W = 1HP, so he can divide 33K/746 to find that one Watt is lost for every 44.24 BTU of heat generated.

 

[jcmccorm]

You got it.

You're not going to get more than 120V * 15A = 1800W from a single circuit. Considering that continuous loads should be limited to 12A, you won't get more than 120V * 12A = 1440W from a single outlet. Add the efficiency of the amp (the 70% number given is probably generous) then you're down to 1008W available for your speakers. Through the magic of capacitors you could get more for peaks but not for long and the overall average won't exceed 1008W.

Cary

 

[AcuDefTechGuy]

Damn, I love physics.

 

[walter duque]

You got it.

You're not going to get more than 120V * 15A = 1800W from a single circuit. Considering that continuous loads should be limited to 12A, you won't get more than 120V * 12A = 1440W from a single outlet. Add the efficiency of the amp (the 70% number given is probably generous) then you're down to 1008W available for your speakers. Through the magic of capacitors you could get more for peaks but not for long and the overall average won't exceed 1008W.

Cary

Now this might be a stupid question. My power amp requires 5500 watts at max. power. Does that mean that I am only getting 1/3 of what the amp is capable of. Using a 15 amp breaker.

 

[highfigh]

Now this might be a stupid question. My power amp requires 5500 watts at max. power. Does that mean that I am only getting 1/3 of what the amp is capable of. Using a 15 amp breaker.

"Requires"? To do what? Is that what it shows near the power cord? If it's not designed to run on 240VAC, that can't be correct. De-rated to 80%, that comes to 18.33A @ 240VAC and 22A @ 220VAC.

 

[walter duque]

"Requires"? To do what? Is that what it shows near the power cord? If it's not designed to run on 240VAC, that can't be correct. De-rated to 80%, that comes to 18.33A @ 240VAC and 22A @ 220VAC.

Thanks, you made it clear that it was a stupid question. This is what is says in the owners manual. Would I get more out of the amp if I would use a 30 amp breaker or not?

Nominal - 2,700w, Test conditions - 5,550w
20/30amp@ 100-120vac, 20amp@ 220-240vac

 

[PENG]

You got it.

You're not going to get more than 120V * 15A = 1800W from a single circuit. Considering that continuous loads should be limited to 12A, you won't get more than 120V * 12A = 1440W from a single outlet. Add the efficiency of the amp (the 70% number given is probably generous) then you're down to 1008W available for your speakers. Through the magic of capacitors you could get more for peaks but not for long and the overall average won't exceed 1008W.

Cary

We have been through with this many times before in this forum. You will not get 1800W from 120V 15A unless the load current is in phase with the voltage and that only happens if the load is 100% resistive such as a resistor with no inherent inductance and/or capacitance and if there is no voltage drop that depends on the length and size of the cable. An amplifier is not a resistive load and its current draw is not going to be in phase with the voltage

 

[jeffsg4mac]

Thanks, you made it clear that it was a stupid question. This is what is says in the owners manual. Would I get more out of the amp if I would use a 30 amp breaker or not?

Nominal - 2,700w, Test conditions - 5,550w
20/30amp@ 100-120vac, 20amp@ 220-240vac

Unless you have been tripping the breaker I would not worry. You obviously have not exceeded the limits of it.

 

[TLS Guy]

Thanks, you made it clear that it was a stupid question. This is what is says in the owners manual. Would I get more out of the amp if I would use a 30 amp breaker or not?

Nominal - 2,700w, Test conditions - 5,550w
20/30amp@ 100-120vac, 20amp@ 220-240vac

If you really did draw full power you would trip the breaker.

 

[walter duque]

Unless you have been tripping the breaker I would not worry. You obviously have not exceeded the limits of it.

It does trip the breaker once I start getting near the top. +5db is the safe zone, after that it's pop, and it seems to me the amp still got more to give.

 

[TLS Guy]

It does trip the breaker once I start getting near the top. +5db is the safe zone, after that it's pop, and it seems to me the amp still got more to give.

Then you need a bigger circuit. Ask your electrician what can be done. May be the 15 amp breaker will stop you going deaf! It is a crude limiter.

 

[highfigh]

Thanks, you made it clear that it was a stupid question. This is what is says in the owners manual. Would I get more out of the amp if I would use a 30 amp breaker or not?

Nominal - 2,700w, Test conditions - 5,550w
20/30amp@ 100-120vac, 20amp@ 220-240vac

I never said or implied it was a stupid question (you brought that up) but at 120VAC, that 2700 W calculates to 22.5A and if it's continuous output, you would need a 30A circuit. The 15A breaker isn't the only thing that limits the current- the wire will cause voltage drop if too much current passes through it constantly. You could change the breaker and still limit the current/voltage to the amp so, to answer your question, yes, you're getting less than full power from the amp if it's on a 15A circuit. Even if you ran it on 220/240, 14ga Romex isn't heavy enough.

 

[walter duque]

I never said or implied it was a stupid question (you brought that up) but at 120VAC, that 2700 W calculates to 22.5A and if it's continuous output, you would need a 30A circuit. The 15A breaker isn't the only thing that limits the current- the wire will cause voltage drop if too much current passes through it constantly. You could change the breaker and still limit the current/voltage to the amp so, to answer your question, yes, you're getting less than full power from the amp if it's on a 15A circuit. Even if you ran it on 220/240, 14ga Romex isn't heavy enough.

Thanks for the info, I think am catching on. Sometimes it take me a while. Amp runs almost as hot as an iron. Besides I don't know anything about wiring, but it makes sense.

 

[AcuDefTechGuy]

I thought a 30A circuit was only used for ovens/stoves/washer/dryer?

I have a 20A cirucit for my ATI amps.

 

[walter duque]

I thought a 30A circuit was only used for ovens/stoves/washer/dryer?

I have a 20A cirucit for my ATI amps.

My amp is multi purpose. First amp then heater, bbq grill etc. This thing runs major hot.

 

[PENG]

Walter, I thought amps like that sometimes come with two power cords so you can plug one each into an outlet of separate 15A circuits. If the nominal rated power outpt is 2700 W, it probably needs to draw about 28 to 30A at 120V. If you run it on 220V you could draw not quite, but almost 2700W.

I assume you wear hearing protection with this amp if and when you push it anywhere near its limit, unless you are sitting like 30 feet away from your speakers or your speakers has <80 dB/2.83V sensitivity.

 

[Alex2507]

My amp [] runs major hot.

You know I never saw where your circuit breakers were but adding a breaker and then getting a dedicated line over to your amp and sub via surface mounted Wiremold from Home Depot might be worth looking into.

... or you could just turn it down.