Karaoke Forums

No, even with the cap, it will not help when the diff is large.

_________________
I can neither confirm nor deny ever having or knowing anything about nothing.... mrscott

???????

The answer to your question is, no you can't. If you want  18 amps from a 15 amp circuit then you need to use two 15 amps circuit separately. Thats the way I will do it,rather that risk blowing the fuse.

_________________
I can neither confirm nor deny ever having or knowing anything about nothing.... mrscott

The answer to this question is no.

As others have stated, the answer is simple no. Where you have been confusing is that the amplifier does amplify SIGNAL, not power. Your input voltage from your source, like a CD-G player, is a signal that is about 1 volt peak to peak. The amp amplifies it to where you would get 500 watts, 1000 watts or whatever it is rated at.

You can not amplify power more than you can put in to it so you can not get 20 amps out of 15 amp circuit.

_________________

Seize the day and SING!!!

Sorry, double post.

If the answer is no, then having an amplifier that puts out more watts than the circuit it's plugged into, is a waste.   Yes or no

So everyone that thinks they are putting out 3000 watts on one circuit is full of crap?    Yes or no

So then the whole PA system thing needs reevaluated.

Depends, I always try to make sure I get at least a dedicated circuit for my amps alone & run an extension cord for the rest of the system if needed.  If that's not possible then I try to get minimum 20 amp circuit for the system alone.  So far I haven't had any problems.  But yes it's true if the circuit breaker can't handle the load of the amp, it will usually shut off once it hits the max amps.  Our sound guy for my old band has a 10,000 watt set-up that needs a minimum 20 amp circuit strictly for the amps or it will blow everytime sometime during the night.

_________________
LIKE Lonman on Facebook - Lonman Productions Karaoke & my main site via my profile!

Here is a short article by Hartley Peavey That may help answer the question.

"Can an amp put out more power than a 'wall socket' can deliver?"
I have encountered this discussion numerous times. It is a fairly complex issue
that even fairly decent technicians don’t understand. The simple fact is that you cannot
get more power out of an amplifier (CONTINUOUSLY) than the wall socket can provide!
No power amp is 100% efficient, but the situation with peak and/or music power is quite
a bit different than average power or what most people refer to as RMS (root mean
square) power.
First of all, Watt’s Law dictates that the total power (P) may be obtained by
multiplying voltage (E) times current (I), i.e. P = I X E… Or 20 amps X 120 volts equals
approximately 2,400 watts. This is assuming that you a have a well regulated 120 volt
supply and a 20 amp breaker… The fact is, 20 amp breakers can rarely supply 20 amps
CONTINUOUSLY, and even at that, the VOLTAGE usually DROPS considerably from
the nominal 120 volts when you are pulling that much current. Given the 120-volts/20
amps scenario, you are pretty much stuck with an AVERAGE maximum of 2,400 watts.
Most people do the math on this and ASSUME that 2,400 watts is all you can get
out of a wall socket… At first glance, this is true, but then the amplifier itself has the
ability to STORE energy in its INTERNAL power supply CAPACITORS. If we are talking
about purely RMS (average power), we are talking about SINEWAVES and if the
discussion is limited to the amount of sinewave power, then the argument about the
amount of available power out of the wall socket has some validity.
In the real world, we usually do not encounter “sinewaves” but in fact, some kind
of “musical waveform” that is anything but a “sinewave.” There are “peaks and valleys”
in the signal that contribute to the complexity of this issue. Since our products are
designed to reproduce music, the additional headroom afforded by our amplifiers is
indeed considerably in excess (on peaks) of what is available from the wall socket on a
continuous average (RMS) basis.
A simple listening test will quickly illustrate the superiority of a higher-powered
amplifier than the supposed 2,400-watt theoretical maximum power. It is true however,
that for long term (continuous) average power you cannot exceed the power available at
the wall socket. There is a huge “differential” in musical peaks and zero power
especially considering the “time domain” of musical waveforms. It is indeed possible to
instantaneously deliver considerably in excess of the theoretical power available from
the wall socket by virtue of the stored energy in the amplifier’s power supply capacitors.
Simply put, it is possible to deliver more power on “peaks” because of the time
constants involved and because of the ability of the power supply to store considerable
energy. What we are talking about here is enough power (headroom) to handle musical
peaks without clipping. And while it is "technically correct" that you can’t get more
(continuously) out of the amp than is available at the wall socket, the additional
headroom afforded by high-powered amplifiers is readily recognizable and audible…
Otherwise, no one would ever buy (or produce) an amplifier having power rating greater
than 2,400 watts. Obviously, Peavey, Crest, and many other companies offer amplifiers
far in excess of what is “theoretically” available from the wall socket. It would seem
3
rather apparent that users of these high powered amplifiers have long recognized the
utility in having the peak power available in order to reproduce musical transients
cleanly.
I have a somewhat “gross” explanation that I have found quite effective over the
years… Here goes… When you flush a toilet, you can instantaneously achieve a short
term “massive flow” of water… FAR MORE in fact, than the small water supply pipe
feeding the toilet could deliver on a CONSTANT (continuous) basis… Why? The toilet’s
water tank stores up a considerable quantity of water and releases it on demand…
Obviously, it takes some time for the tank to “recover” given its small water supply pipe,
but the toilet’s ability to deliver a large quantity of water PERIODICALLY is quite similar
to the power amp’s internal power supply capacitors being able to store up “energy” and
deliver it instantaneously when required… The toilet (and high-powered amplifiers) can
not deliver this volume of water (energy) CONTINUOUSLY, but absolutely CAN do it
PERIODICALLY, and very reliably!
The "2,400 watt argument" is “half right and half wrong.” It is correct that you
can’t get more (continuous) power out of the amplifier than the wall socket can deliver…
The salient point here is that this is ONLY true for a CONTINUOUS average (RMS)
power basis… It is NOT true that the “theoretical limit” represents the MAXIMUM power
that can be delivered MOMENTARILY from the amplifier (i.e. by the P = I X R formula).
This is a very complex topic that most engineers understand only marginally.



taken from http://www.peavey.com/support/technotes ... pter_4.pdf

_________________
I can neither confirm nor deny ever having or knowing anything about nothing.... mrscott

Let's make it simple.....I believe(correct me if I'm wrong, it won't be the first time)....Newton said "energy can not be created or destroyed, it can only be transformed from one form to another".......amps can not create energy, that is not there, and when the energy allowed by the breaker is reached.......time for a short break........

Where all this theory is wrong is you are all talking RMS rather than peak to peak.

in reality a 120v ac circuit is 120v rms. Peak to peak ot the same 120v is 360volts.

360v X 15 amps = 5400 watts. Remember audio is peak to peak sinewave, and not DC. In a cycle power goes from neutral to top peak back to neutral to bottom peak to neutral. the peak to peak here is 360 volts.

the 120volt figure is from the neutral position to the peak figured rms.

_________________
______________________________________
I'm Not Dead yet...... But every day Im getting Closer !

True, I retract my earlier post. This is a really good reason for me not to offer to help people.

Huh? You lost me there. First of all, the AC means altenating current, not voltage. It happens that since the line resistance is constant per distance, the voltage swings with the current in phase.

If my memory is correct, the Vrms is 0.7 times Vpeak or Peak voltage is 1.4 times the RMS voltage. So 120 volts AC, which is RMS, the peak would be 120 times 1.4, which is 168 volts peak to peak. So, the 168Vpeak x 15amps = 2520 Watts max, not 5400 watts.

I had to get my electrical engineering books out to make sure this was correct.  LOL

(It's been over 20 years since my college but I am always surprise at the crap I still remember from then).

_________________

Seize the day and SING!!!

Jian, great info.    :worship:    Now if I read that correctly and understand the interpretation, any amp over say 26-2700 watts (i.e. 2400 watts plus some amp headroom) is about all that can be used on one circuit.   Bi amping would require two seperate circuits.    Thank to all for digging up some really good info.     This was a very meaningful, and helpful post.   I hope everyone learned something about/from this topic.  

Sorry but the Peak to Peak voltage on a 120 volt outlet is 360 volts.




http://www.ferret.com.au/articles/3b/0c03933b.asp        read this article this is the first one I could find, but the consensus is 360 volts. This was fresh in my mind it was a question on the amateur Extra test I took a couple of months ago.

_________________
______________________________________
I'm Not Dead yet...... But every day Im getting Closer !

I think I know what a difference is. I was referring to the peak power, not peak to peak. If you take peak to peak, which is from top of the wave to bottom of the wave, it should be 2x peak voltage, which is about 2.8 times the RMS voltage, which at 120 volts, is about 336 volts. That still does not equal to 360 but close.

Check out this article: http://www.kpsec.freeuk.com/acdc.htm at the bottom and it explains the RMS versus Peak voltage. Maybe there is a different definition between engineering and music but this is what I was taught when I attended university.

Also, from my understanding, you don't use peak to peak voltage when calculating how much an amp can take, you use the peak voltage.  Check out this article http://www.rocketroberts.com/techart/powerart_a.htm and read the middle of the article called Peak Power and RMS Power. The maximum voltage an amp can take without clipping is peak voltage not peak to peak. So, again. My calculation is right from before. Peak to peak voltage is NOT the way to check out if the amp can take the signal.

_________________

Seize the day and SING!!!

It is better to be on the safe side; use 2 or more circuits if the house have them.

_________________
I can neither confirm nor deny ever having or knowing anything about nothing.... mrscott

I think the problem is everyone is talking in different terms here. apples and oranges.

You refering to the maximum voltage an amp can take without clipping is input voltage into the 1st stage of the amp.

I am refering to the power factor of an amp. and depending on the configuration of the capacitor bank in the power supply of the amp. I think this is too deep a discussion here for most to get into.

I am running 2-2600 watt class H amps on a 20 amp circuit in my rack. I have had it maxed out many times, and have never tripped a circuit. But peak power will not trip a circuit, it has to be maintained long enough to heat up the thermal trip inside the breaker.

_________________
______________________________________
I'm Not Dead yet...... But every day Im getting Closer !

This is so interesting - I read it all twice. I'm such a junkie for
this stuff. Cool topic.

_________________
[shadow=pink][glow=deepskyblue]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
[updown]~*~ MONKEY BUSINESS KARAOKE~*~ [/shadow][/updown][/glow]

If you want to know about watts, you stick the red and black long metal thingies, into the wall slots.... and look at the meter and the red arm and the numbers....and turn that little nobby thing..


Any other questions,  I'll have to charge you for my expertise !


Here's a hint.... you can take the red plastic thingy off the amp.. and look on that tiny little lighbulb too.


I'd ask how the tech room is doing without my presence,  but I'm afraid the answer I'd get would make me feel quite guilty for abandoning them with my vast wealth of knowledge.

_________________
Northeast United States runner up for the "Singing Hall of Shame".