Power Ratings

[Revelationroadshow 0]

An old chestnut this one....

 

Is there any definative answer on the power handling of a passive speaker?

 

Lets take this as an example:

 

Power handling: 500w

Peek Power: 2000w

 

So will the speaker run all day and all night somewhere in the middle? Say 1000w?

 

How do you know and how do you work it out?

Edited November 21, 2007 by Revelationroadshow

[DJ Marky Marc 0]

500w RMS

 

so a 500 watt sine wave all day and night..

 

 

1000w program... basicly normal music so short term power handeling all the ups and downs of normal music wave form...

 

2000w peak.. very short term peak music output... you dont want punish your gear with this sort of power for long...

 

a 500w speaker should have an amp that can handle the 1000w program power so that the amp does not hit the clip point before you hit the program power..

 

 

[spinner 0]

Good quality manufacturers - Turbosound is an example - will recommend an amp with twice the RMS rating of the speaker.

 

I doubt very much that this can be applied to all speakers. Depends on the quality of individual drivers.

 

Remember also that driver efficiency is particularly important.

[Revelationroadshow 0]

500w RMS

 

so a 500 watt sine wave all day and night..

1000w program... basicly normal music so short term power handeling all the ups and downs of normal music wave form...

 

2000w peak.. very short term peak music output... you dont want punish your gear with this sort of power for long...

 

a 500w speaker should have an amp that can handle the 1000w program power so that the amp does not hit the clip point before you hit the program power..

 

So from that can I assume - a 500w RMS rated speaker should be run by aprox a 1200w amp?

[cmj 0]

RMS = 500w

Program Power = 1000w

PMPO(Peak) = 2000w

 

Personally i would use an amp at 650 - 750w/ch.

 

I tend to use rated power x 1.5.

 

For subs, tend to double it when spec'ing an amp

[eazy 0]

in most cases its not watts that blows speakers its distortion you are just as likely to blow speakers with less powerful amps and pushing it to hard still cant believe how many " djs " dont understand that red on your mixer isnt good

[Andy Westcott 0]

Quote:

"in most cases its not watts that blows speakers"

 

Yes it is - watts input equate directly (disallowing inductance and so-on) to heat produced, and therefore thermal damage. Over-excursion is a different thing, and shouldn't concern you if the drivers have been properly cabinetted.

 

This idea of distortion buring out speakers is simply that a clipped waveform contains far more energy, or wattage, than an undistorted sine wave of the same peak value so this is where the excessive wattage comes from.

 

Any amp can deliver way above its rated power if you allow it to clip very hard, but if you are in the habit of allowing this kind of distortion you would be better off with an amp rated considerably below the speakers simply to give the speakers some chance of survival. A good practical example might be a valve amp for an electic guitar, where the player has decided that he likes the sound of a highly overdriven output stage rather than clipping earlier on th the chain.

 

You could run the 500W driver off a 10KW amp, as long as you kept the output within the limits of what the driver could dissipate - you just have to be aware of the power levels.

 

All comes down to knowing the limitations of your equipment - if you aren't sure on this, select an amp power similar to the rating of the speakers - that way you won't go far wrong, and although you won't be making the best use of your drivers' power handling capacity, you will be reasonably safe against burnout.

[DJH 0]

 

 

All comes down to knowing the limitations of your equipment - if you aren't sure on this, select an amp power similar to the rating of the speakers - that way you won't go far wrong, and although you won't be making the best use of your drivers' power handling capacity, you will be reasonably safe against burnout.

 

 

now this thread has interested me but also confused me,

my amp is a 1200 and i run 4x 500watt speakers off it,

is this ok or could this blow my speakers?

blew my old ones on new year eve 2 years ago, dont want to happen again

cheers

Haydn

[eazy 0]

All comes down to knowing the limitations of your equipment - if you aren't sure on this, select an amp power similar to the rating of the speakers - that way you won't go far wrong, and although you won't be making the best use of your drivers' power handling capacity, you will be reasonably safe against burnout.

now this thread has interested me but also confused me,

my amp is a 1200 and i run 4x 500watt speakers off it,

is this ok or could this blow my speakers?

blew my old ones on new year eve 2 years ago, dont want to happen again

cheers

Haydn

well the short answer is yes but thats based on the fact that you can blow speakers with whatever power you have but as long as you careful and sensible with your levels you should be fine . in my earlier post as i mentioned its not usually watts !!! what i meant was if you are running say 800w speakers with an amp that only gives you 400w the speakers do not respond great as they are being underpowered so you can be tempted to try and push that volume on your mixer up just another lil bit then before you know it your driving your mixer into the red and putting out a distorted signal which then can burn out your speakers

 

just out of intrest what is your 1200w amp rated at ohm's? 2,4 or 8 also your speakers are they 4 or 8 and if they are 8 im guessing you link them to reduce the load to 4 ohms ??? just getting nosey now lol

 

but anyway my advise to anyone is you are always better having more power than too little as long as you use it responsably ie no red lights i quite often as in at least once a week runn 800w speakers with 1000w going to them never blown one yet (touch wood) ps this dosent mean it cant its just a case of using it properly

[norty303 0]

just out of intrest what is your 1200w amp rated at ohm's? 2,4 or 8 also your speakers are they 4 or 8 and if they are 8 im guessing you link them to reduce the load to 4 ohms ??? just getting nosey now lol

 

It's not being nosey.

 

You can't possibly answer his question without knowing the answers to those questions.

 

 

Describing an amp as '1200w' is like me asking if my car will drive up a mountain. It might do, depending on if its 4x4, got a big enough engine, etc, etc.

 

What power does your amp give at 4R and 8R per side? If it will do 2R loads, what power does it give at those loads PER SIDE?

 

well the short answer is yes but thats based on the fact that you can blow speakers with whatever power you have

 

I'll give you £50 if you can blow my subs with a 100w rated amp.

 

in my earlier post as i mentioned its not usually watts

 

As Andy said, it's ALWAYS watts.

 

For example, a small amp of say (rated power) 250w will give 250w at 20hz -20khz with 0.01%THD

Thats not to say that it can't do more than 250w, its just that it gets a higher percentage of THD as the power goes up, a combination of both of these is what causes the energy to be so high - distorted signal in excess of the maximum rating of the amp. An amp doesn't just get to its rated limit and stop putting out any more power - it doesn't know it's got a max power rating. It just keeps going in a less and less pleasant manner as the level rises.

 

A 250w amp might do 500w but with 50% THD and blow speakers

A 500w amp will do it with 0.01% THD and not blow speakers. Overall its still the watts that do it.

 

Is there any definative answer on the power handling of a passive speaker?

 

Lets take this as an example:

 

Power handling: 500w

Peek Power: 2000w

 

So will the speaker run all day and all night somewhere in the middle? Say 1000w?

 

The only figure you need to know is the RMS rating and impedance. Peak level will be double this. If you only have peak level then halve it for RMS.

 

You should be able to drive your 500w rms speaker with 1000w of clean amp power (playing music) all day and night with no ill effects providing you run the speaker as guided by the manufacturer. For most subs and full range speakers this will require using a high pass filter to cut the very low frequencies (40hz will do for most subs, 50 or 55hz for a lot of 15" loaded full range cabs).

 

Not only is it wasting power trying to play notes you won't hear, it is also stressing the drivers by causing over excursion. This happens because most DJ speakers are reflex loaded and will have a port tuned to the low note that they are designed to play. Once you drop below this frequency the driver becomes unloaded (i.e. it meets no or significantly reduced air resistance) and will flap around. As low frequency music also contains the most energy it'll also be generating a lot more heat. One other side effect is that the impedance of the speaker can change dramatically once unloaded meaning the power the amp feeds it can go up or down significantly.

[eazy 0]

 

I'll give you £50 if you can blow my subs with a 100w rated amp.

 

well it would be good crack trying lol not but obviously if you are dramatically underpowering then it could be difficult but maybe after about 3weeks of constant running maybe burn out the coil lol

 

i'll explane again my answer about watts just ment alot of people just look at an amp say a peavey PV2600 and think thats 1300 watts a side ans say have 1000w 8ohm speakers and are worried that would be to powerful and blow there speakers but really thats not enough watts as the amp is rated ay 2600w at 2ohms

so at best probably gives 400w at 8 ohms ( But still could blow there speakers )anyways im no expert i only know what i taught myself and picked up along the years and still learning

[deejaymitch 0]

im no expert

 

Ladies and gentlemen of DJU - THANK-YOU!!!! I've been trying for years to get a statement like this out of 'Eazy' and now it's here for eternity!!! Thank-you so much!!!

[DJH 0]

Very interesting read, you have asked me some very technical questions, and i aint got a clue, so i m not answering,,,,,,lol

so after reading the replies to this thread, i see i could if i wanted to downsize my amp,

as long as i get sound and my mixer aint hitting red i should be ok. i hope,

Haydn :shrug:

[norty303 0]

so after reading the replies to this thread, i see i could if i wanted to downsize my amp,

as long as i get sound and my mixer aint hitting red i should be ok. i hope,

 

NO!

 

The critical piece in all of this is the amp and if it's clipping or not. Having a mixer hitting some red lights is not going to be damaging (it might sound poo) unless you're really caning the amp as well and then its normally the HF that goes.

 

Don't forget its possible to have amixer showing red lights constantly without an amp even being connected so you know from that, that the correlation between mixer output and amp output are not exclusively tied together.

 

So your statement would be correct if it said.....

 

so after reading the replies to this thread, i see i could if i wanted to downsize my amp,

as long as i get sound and my amp aint hitting red i should be ok. i hope,

Edited December 5, 2007 by norty303

[shakermaker 0]

Wierd!

My mixer often hits the red and it doesn't sound distorted and my speakers haven't blown as yet (fingers crossed).

 

I'm using a Crown XLS602 to run 2 x 300 rms Peavey Pro Subs and a Peavey CS3000 to run 2 x JBL JRX125 full range.

 

 

[Andy Westcott 0]

But that's because the VU meters on mixers are telling you something different to the clip light on an amp.

 

Mixers are designed with a lot of headroom - they have to be, given the muppets that occasionally get their hands on them, so the red lights will come on way before the mixer reaches true clipping level. The lights are to indicate to you a safe working area, consistent with supplying an output in line with industry standards - the 0dB point. +6db is considered acceptable, although better to set levels to occasionally pip the first red. (+3db) Thoughts on this vary, of course.

 

The clip light on an amp shows when the amp has run out of headroom - the waveform has been clipped. Small amounts of this clipping will be inaudible, especially with the atrocious recording quality prevelent today (Don't get me started!!) and will also cause no problems, but take note of the fact that you have reached that limit and work with it rather than ignoring it.

 

OK;

I've even prepared a couple of waveforms for those not familiar with this 'clipping' idea:

 

This first one represents the output from an amplifier, with the peaks of the waveform right at the clipping point, represented by the white lines. Note the clean, rounded shape of the curve.

 

http://myweb.tiscali.co.uk/andyspatch/hosting/wavenorm.gif

 

This next one represents a situation where the mixer outut has been increased by 3dB, causing the amplifier to clip the top of the waveform off - it has no choice, as it cannot physically develop an output voltage any higher than its internal power supply voltage, indicated as before by those white lines.

 

http://myweb.tiscali.co.uk/andyspatch/hosting/waveclip.gif

 

This flat-topping of the waveform is the bit that makes music sound distorted - the more of the waveform that is missing, the worse it will sound. It will also get louder, and the speakers will get hotter.

 

Now the power dissipation bit for those interested: (In Easyspeak)

Although the peak level of the second signal hasn't increased, you may notice that if you measured the area enclosed within one half of a wave, it would be greater in the clipped wave than in the unclipped one. This allows you to understand why a clipped waveform contains more power than an unclipped one of the same peak value.

 

So who's confused now?? tongue out icon

[norty303 0]

And to put that into a real world context about distortion, here's some 100hz sine waves I ran through a DJM600 with different levels of gain. The first is within normal operating levels (a couple of red lights on the input channels, none on the output side).

 

The second is with everything at full, both the input channel leds and master output leds were on permanently and all the way up. You can see the physical shape of the wave changes.

 

http://myweb.tiscali.co.uk/substance/allmaxatthalf.jpg

 

http://myweb.tiscali.co.uk/substance/allmax.jpg