Maximum Average Power....
Ummm, 115V x 15A = 1725W maximum (legally) continuous allowable power, before branch wire overheating or breaker drop-out I suppose, and this is assuming unity power factor (pure resistive load).
Reactive loads will lessen this maximum rating.
Seeing as audio is not continuous level, this max power consumption can be well exceeded intermittently, or periodically, without significant penalty, except for IR losses of the branch circuit.
It is worthy to note that some high power PA amplifiers claim power factor correction, and this would be important in multiple high power amplifier applications.
I have Pro-audio guys telling me that high power PA amps with SMPS are wonderfull with a very clean power feed, but go to pieces when hanging off a dirty power circuit. (lose power, lose bass power and punch, and get dirty).
Many SMPS exhibit lousy power factor, so multiple such amplifiers all hanging off a lousy supply, would likely pollute each other's supplies badly.
It also worthy to note amplifiers with 3000W rating hanging off a 10 amp plug (240V).
Eric.
Ummm, 115V x 15A = 1725W maximum (legally) continuous allowable power, before branch wire overheating or breaker drop-out I suppose, and this is assuming unity power factor (pure resistive load).
Reactive loads will lessen this maximum rating.
Seeing as audio is not continuous level, this max power consumption can be well exceeded intermittently, or periodically, without significant penalty, except for IR losses of the branch circuit.
It is worthy to note that some high power PA amplifiers claim power factor correction, and this would be important in multiple high power amplifier applications.
I have Pro-audio guys telling me that high power PA amps with SMPS are wonderfull with a very clean power feed, but go to pieces when hanging off a dirty power circuit. (lose power, lose bass power and punch, and get dirty).
Many SMPS exhibit lousy power factor, so multiple such amplifiers all hanging off a lousy supply, would likely pollute each other's supplies badly.
It also worthy to note amplifiers with 3000W rating hanging off a 10 amp plug (240V).
Eric.
Re: Maximum Average Power....
Our data centre here has a 225KVA 600/208 step-down transformer... Add a 6-pulse rectifier to the secondary, and it would make one hell of a power supply!
mrfeedback said:Ummm, 115V x 15A = 1725W maximum (legally) continuous allowable power, before branch wire overheating or breaker drop-out I suppose, and this is assuming unity power factor (pure resistive load).
Reactive loads will lessen this maximum rating.
Perhaps you should have specified 1725VA, rather than 1725W. If we want to extract maximum useable power, our power supply should definitely be power-factor corrected.
fcel's value of 1380 comes from the fact that a normal 15A breaker is not supposed to be continuously loaded at more than 80% of its rating. 1725 x .8 = 1380VA.
Seeing as audio is not continuous level, this max power consumption can be well exceeded intermittently, or periodically, without significant penalty, except for IR losses of the branch circuit.
Granted, assuming we're not talking class A, which of course we aren't. So what is a reasonable figure? Let's say 150%, which would give us 2588VA of peak power (not accounting for voltage drop, but then, most of use are closer to 120V anyway).
This is fine for specifying "peak music power", but the amp would have to carry a much lower RMS rating, since a sine wave pumped through it would pop the breaker, and also violate code.
But why are we limiting ourselves to a 15A circuit? If we're really concerned about power, we should be willing to run a separate 20A or greater feed. As Nelson would say, "Woahahahaha...."
Our data centre here has a 225KVA 600/208 step-down transformer... Add a 6-pulse rectifier to the secondary, and it would make one hell of a power supply!
"Perhaps you should have specified 1725VA, rather than 1725W....."
Quoting VA does not specify power factor, and I did say "assuming unity power factor" - you're sort of right.
"fcel's value of 1380 comes from the fact that a normal 15A breaker is not supposed to be continuously loaded at more than 80% of its rating. 1725 x .8 = 1380VA."
Thanks that clears that up - I wondered how he got that figure.
"but the amp would have to carry a much lower RMS rating....and also violate code...."
Sure, but I have seen amps like Amcron VZ-5000 (5000W rms/1 ohm) hanging off a factory fitted 15 amp plug, and no breaker trips on live music.
Ditto multiple 3000W amps hanging off a 10 amp circuit - the deal is that for class A/B amplifiers, the average power on music (fortunately) is rather lower than what the rms ratings may suggest.
"Our data centre here has a 225KVA 600/208 step-down transformer... "
Yeah, but what kind of power plug are you going to put on it ?
Eric.
Quoting VA does not specify power factor, and I did say "assuming unity power factor" - you're sort of right.
"fcel's value of 1380 comes from the fact that a normal 15A breaker is not supposed to be continuously loaded at more than 80% of its rating. 1725 x .8 = 1380VA."
Thanks that clears that up - I wondered how he got that figure.
"but the amp would have to carry a much lower RMS rating....and also violate code...."
Sure, but I have seen amps like Amcron VZ-5000 (5000W rms/1 ohm) hanging off a factory fitted 15 amp plug, and no breaker trips on live music.
Ditto multiple 3000W amps hanging off a 10 amp circuit - the deal is that for class A/B amplifiers, the average power on music (fortunately) is rather lower than what the rms ratings may suggest.
"Our data centre here has a 225KVA 600/208 step-down transformer... "
Yeah, but what kind of power plug are you going to put on it ?
Eric.
mrfeedback said:Quoting VA does not specify power factor, and I did say "assuming unity power factor" - you're sort of right.
I missed the fact that you had specified a unity power factor. In that case, we were saying exactly the same thing.
Sure, but I have seen amps like Amcron VZ-5000 (5000W rms/1 ohm) hanging off a factory fitted 15 amp plug, and no breaker trips on live music. Ditto multiple 3000W amps hanging off a 10 amp circuit - the deal is that for class A/B amplifiers, the average power on music (fortunately) is rather lower than what the rms ratings may suggest.
True. And I suppose it doesn't technically violate the electrical code, since the amp itself is fused at 15A, likely with a slow-blow type. But it's pretty lame from a design perspective. A 5KW amp, even though running on a 15A fuse internally, should really have a 50A stove plug, if only to lower voltage drop.
Yeah, but what kind of power plug are you going to put on it ?
This amp wouldn't be very portable. It would require a sizeable forklift to move, so hardwiring isn't such a limitation.
Assuming a decent power factor, and an efficient amp design, this puppy could put out something on the order of 45,000W into 8 ohms.
(Actually, that might require 2 of these transformers, for a +/- supply...)
Well I see most of you get my point about the limits of true RMS power ratings of amplifier technology. The law of physics states you can not create or destroy energy, only change it's state, then how could you possibly get a better than 1:1 power conversion. This has to restrict any real power output from the amp to the input power, at 1725VA. Power is simply a factor of Voltage times current, so how do some manufacturers claim such ludicrous power factors from thier amps with a straight face.
I think there should be warning labels like on cartons of cigarettes: "Caution, manufacturers claims of power output defies the law of physics".
Anthony
I think there should be warning labels like on cartons of cigarettes: "Caution, manufacturers claims of power output defies the law of physics".
Anthony
Coulomb said:Well I see most of you get my point about the limits of true RMS power ratings of amplifier technology. The law of physics states you can not create or destroy energy, only change it's state, then how could you possibly get a better than 1:1 power conversion. This has to restrict any real power output from the amp to the input power, at 1725VA. Power is simply a factor of Voltage times current, so how do some manufacturers claim such ludicrous power factors from thier amps with a straight face.
Anthony
As mrfeedback noted previously, you can pull much more than 1725VA from a 15A outlet, when you're talking about actual music. That 15A is not a hard limit; you can pull much higher currents for brief intervals. It takes a sustained current > 15A to actually trip the breaker. When you turn on a vacuum cleaner or such, it usually draws 20-30 amps for the first instant.
What really makes me laugh, thogh, are the ratings on some of those cheap little computer speakers. 120W from a 12V / 1A wall wort...
Sparhawk said:
Ahh, but I did say my argument is regarding True RMS, not instantaneous current at extremly short intervals. I would argue that can a speaker really react that fast in any significant way? I am not a speaker expert so I can only speculate.
I also do not want to be guilty of thread piracy, but as we were poking Mr Pass with a stick, like children would poke a bear to see if he really is asleep, about a monster amp I felt it was on topic.
Regards
Stated ratings....
Anthony, the PA amplifier ratings are accurate, for an unlimited 240V (110V) supply, and make no claims wrt the supply spur capability.
On sinewave test, these power amplifiers will draw more than standard rated breaker capability, but of course this level will never be achieved on audio programme content.
There are no laws being broken here, and the only limitation is the rating of the mains supply breaker.
"I would argue that can a speaker really react that fast in any significant way? I am not a speaker expert so I can only speculate" - I am not quite sure what you mean by this ?.
Sparhawk, those PMPO ratings astound me too.
I had a Sony surround shelf system in the shop recently, and the front panel display decal quoted 2800W pmpo total, and 120Wrms x 6 channels, all out of a transformer of about 250VA or so in size.
I still have no real idea of how they get these sorts of ratings, pmpo or rms.
Yes, those $30.00 PC speakers take the cake for overstating ratings.
Did you notice also that they are all rated 20Hz - 20kHz too - yeah right, sure thing.
Anthony, the PA amplifier ratings are accurate, for an unlimited 240V (110V) supply, and make no claims wrt the supply spur capability.
On sinewave test, these power amplifiers will draw more than standard rated breaker capability, but of course this level will never be achieved on audio programme content.
There are no laws being broken here, and the only limitation is the rating of the mains supply breaker.
"I would argue that can a speaker really react that fast in any significant way? I am not a speaker expert so I can only speculate" - I am not quite sure what you mean by this ?.
Sparhawk, those PMPO ratings astound me too.
I had a Sony surround shelf system in the shop recently, and the front panel display decal quoted 2800W pmpo total, and 120Wrms x 6 channels, all out of a transformer of about 250VA or so in size.
I still have no real idea of how they get these sorts of ratings, pmpo or rms.
Yes, those $30.00 PC speakers take the cake for overstating ratings.
Did you notice also that they are all rated 20Hz - 20kHz too - yeah right, sure thing.
Nelson, thanks so much. Couldn't have asked for a better Christmas gift. Merry Christmas to you and your loved ones and a BIG GOD BLESS.
(Last night I almost thought I'd make the amp Nelson is to publish on Christmas Eve, before New Year's Eve and play 4 Bass Bins with EV 18" and P.Audio 18" (2 each) in a big New Year bash. Each EV handles 400 watts RMS and the P.Audios 600 watts RMS. But I don't know how complex the design would be! So I'll make it for the next event.)
Merry Christmas to everyone else in the Forum. This is a great and pleasant place to be.
Last but not the least - Jason thank you very much for making all of this possible. By the way, the site looks great with the Christmas decorations on.
(Last night I almost thought I'd make the amp Nelson is to publish on Christmas Eve, before New Year's Eve and play 4 Bass Bins with EV 18" and P.Audio 18" (2 each) in a big New Year bash. Each EV handles 400 watts RMS and the P.Audios 600 watts RMS. But I don't know how complex the design would be! So I'll make it for the next event.)
Merry Christmas to everyone else in the Forum. This is a great and pleasant place to be.
Last but not the least - Jason thank you very much for making all of this possible. By the way, the site looks great with the Christmas decorations on.
