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PA power ratings

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Does anyone know what the difference is, when referring to PA speakers, between RMS, continuous, program and peak power ratings....??

If someone says to you "I have a 5kW system"....what wattage are they talking about? My PA cabs have a continuous rating of 300W, and a peak of 1200W. That means that if I use the peak power rating, I've got a 5kW system.....but using continuous, I've only got a 1400W system.

Is there a particular convention that "people in the know" use when discussing PA?

Cheers

Neil

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continous and RMS are comparable and refer to a constant delivered signal. It means your amp can deliver 300 W of power till the cows come home without damaging the speaker.

Peak power refers to short transients like snare hits that are momenetary. Your speakers won't like this level of power continuously.

The wattage has little to do with overall loudness as this depends on how efficient your speakers are at turning wattage into sound.

Bear in mind that many manufacturers lie about their speaker ratings.

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Normally they add up the amplifier output ratings (continuous, RMS or program, not peak) for the specific ohmage (you'd be amazed how many people get that bit wrong, or maybe you wouldn't) of the cabs they are driving. As Stupot points out, the peak part is their ability to handle larger amounts of power for short periods of time (we're talking milliseconds here).

The speaker efficiency doesn't matter too much because you need a lot more power just to squeeze a few more dB out of a system, iirc double the power would be 3 dB more, which comes in as barely noticeable, you need ten times the power to be twice as loud.

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If someone says to you "I have a 5kW system"....what wattage are they talking about?

Is there a particular convention that "people in the know" use when discussing PA?

People 'in the know' wont say things like "I have a 5kW system" to each other. Quotes like that are used, in my experience, in one of two contexts.

Either a) To try and convey in terms someone uneducated in sound systems will understand, roughly how loud to expect the system to be. The actual number has no direct corelation as to how loud the system will be but "Yeah i'm running a 16 box Nexo line array" means nothing to most people. Most people only understand watts.

or b) By uneducated providers who have a (usually cheap) pa system with that number located on the power amps somewhere, in order to brag about their 'awesome' sound system. The number is often the maximum output of the amplifier under 2 ohm loads, or the peak power handling of the speakers added up, and usually bears no correlation to how much power they actually have usable in the system.

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dont think anyone said loudness was measured in watts.

Exactly but it was in topic and replies which seemed not very relevant to me.

Is there a particular convention that "people in the know" use when discussing PA?

I think my reply answered above question.

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People 'in the know' wont say things like "I have a 5kW system" to each other. Quotes like that are used, in my experience, in one of two contexts.

Either a) To try and convey in terms someone uneducated in sound systems will understand, roughly how loud to expect the system to be. The actual number has no direct corelation as to how loud the system will be but "Yeah i'm running a 16 box Nexo line array" means nothing to most people. Most people only understand watts.

or b) By uneducated providers who have a (usually cheap) pa system with that number located on the power amps somewhere, in order to brag about their 'awesome' sound system. The number is often the maximum output of the amplifier under 2 ohm loads, or the peak power handling of the speakers added up, and usually bears no correlation to how much power they actually have usable in the system.

It is used a lot and "people in the know" take it with a pinch of salt in the absence of additional information, but it's useful to make sure you're in the same ballpark. Certainly a lot easier than adding up the power ratings for 16 boxes, of which there will be at least two types. Coupled with the fact that there's a hell of a lot of different boxes out there and it's almost impossible to keep that knowledge in your head you can see why it's useful.

People who use b) should have their behringer/peavey/thomann/cheaponasty inc boxes removed from them for the public good.

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Exactly but it was in topic and replies which seemed not very relevant to me.

I think my reply answered above question.

Go back and read the question.

He doesn't want to know how loud it is, just if 5KW means peak or continuous.

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I realise this is off topic but it's an interesting subject, did a little research into when we bought our current rig 3 years ago. Can't promise what follows is 100% accurate, it's just my understanding.

Add up all our amp power at 4 ohms and it's somewhere in the region of 30KW but the speakers themselves only draw around 6KW RMS in total. Make a mathematical allowance for the speaker efficiency (and Funktion One speakers are incredibly efficient compared to just about everything else), then that 6KW will output more like what you'd expect from a 7KW rig. All those figures are from memory as I can't be arsed checking.

But that doesn't provide much to go on, the number of actual drivers makes a big impact. Using 2 speakers will move twice as much air as 1 speaker. There are many different speaker configurations. We're currently running 22 drivers of various sizes, and this will shortly increase to 28 when we add another set of delays.

Then there are other factors like the room itself and where the speakers are positioned.

Power ratings don't really reveal much... except how big you electric bill would be if you cranked it right up for an our and fed through a test tone heh heh.

I subscribe to the Tony Andrews school of thought that ringing ears is caused by crap fidelity rather than too much volume. This is something you can check with a dB meter. There's little correlation between ringing ears and volume. We once maxed out at 120dB about 3-5m back from the stage front and my ears were clear afterwards. I've been to other gigs that registered a significantly lower volume and had to leave because my ears were complaining so much - I'm such a fucking anorack sometimes :(

There is a good analogy relating to amp power vs speaker requirements:

Imagine your car broke down at the side of the road and it was blocking someone drive way so you had to push it out of the way. Provide the road was reasonable flat, using all your strength you would be able to overcome the inertia of the car and roll it forward a few meters. But if you tried to roll the car forward exactly 3cm in exactly 2secs, and do it consistenly then you'd find that impossible.

Given a matchbox car you could make a much better job of the 3cm in 2secs, but you wouldn't be using anything like all your strength. Yet it's within your range of strength to move both the 1500KG car and the 25g car. The difference is that with the 25g matchbox car your latent strength is overwhelming and that's what gives you so much control, compared with the 1500KG car where your strength is being used closed to it's upper working limit.

The same applies to amps. Getting the speaker going is easy but controlling it is a lot harder. Using a big amp that is easily producing clean power well within the ranges that the speaker requires, increaes fidelity, and is less stressful to the speaker. Hence why we have so much amp power driving so little speaker requirement. Dampening factor also plays a big part in this phenomenon, so it's important to take that into account too.

If the rig is any good, then a good live gig should sound nearly as good as a good live CD of the same gig that has been mixed from the channel outputs. Just with more dynamic range.

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I realise this is off topic but it's an interesting subject, did a little research into when we bought our current rig 3 years ago. Can't promise what follows is 100% accurate, it's just my understanding.

Add up all our amp power at 4 ohms and it's somewhere in the region of 30KW but the speakers themselves only draw around 6KW RMS in total. Make a mathematical allowance for the speaker efficiency (and Funktion One speakers are incredibly efficient compared to just about everything else), then that 6KW will output more like what you'd expect from a 7KW rig. All those figures are from memory as I can't be arsed checking.

But that doesn't provide much to go on, the number of actual drivers makes a big impact. Using 2 speakers will move twice as much air as 1 speaker. There are many different speaker configurations. We're currently running 22 drivers of various sizes, and this will shortly increase to 28 when we add another set of delays.

Then there are other factors like the room itself and where the speakers are positioned.

Power ratings don't really reveal much... except how big you electric bill would be if you cranked it right up for an our and fed through a test tone heh heh.

I subscribe to the Tony Andrews school of thought that ringing ears is caused by crap fidelity rather than too much volume. This is something you can check with a dB meter. There's little correlation between ringing ears and volume. We once maxed out at 120dB about 3-5m back from the stage front and my ears were clear afterwards. I've been to other gigs that registered a significantly lower volume and had to leave because my ears were complaining so much - I'm such a fucking anorack sometimes :(

There is a good analogy relating to amp power vs speaker requirements:

Imagine your car broke down at the side of the road and it was blocking someone drive way so you had to push it out of the way. Provide the road was reasonable flat, using all your strength you would be able to overcome the inertia of the car and roll it forward a few meters. But if you tried to roll the car forward exactly 3cm in exactly 2secs, and do it consistenly then you'd find that impossible.

Given a matchbox car you could make a much better job of the 3cm in 2secs, but you wouldn't be using anything like all your strength. Yet it's within your range of strength to move both the 1500KG car and the 25g car. The difference is that with the 25g matchbox car your latent strength is overwhelming and that's what gives you so much control, compared with the 1500KG car where your strength is being used closed to it's upper working limit.

The same applies to amps. Getting the speaker going is easy but controlling it is a lot harder. Using a big amp that is easily producing clean power well within the ranges that the speaker requires, increaes fidelity, and is less stressful to the speaker. Hence why we have so much amp power driving so little speaker requirement. Dampening factor also plays a big part in this phenomenon, so it's important to take that into account too.

If the rig is any good, then a good live gig should sound nearly as good as a good live CD of the same gig that has been mixed from the channel outputs. Just with more dynamic range.

Pretty much spot on flash.

Most people try to drive speakers with power amps that are inadequate and end up with really ghastly distortion and blown tweeters.

Good hefty power amps driving effiecient speakers and not even breaking sweat while doing so is the beginning of good sound.

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Pretty much spot on flash.

Most people try to drive speakers with power amps that are inadequate and end up with really ghastly distortion and blown tweeters.

Good hefty power amps driving effiecient speakers and not even breaking sweat while doing so is the beginning of good sound.

Overamping in a non-controlled environment (e.g. live) is also another way to get a pile of blown tweeters unless you have really good and extremely fast limiters to catch things like dodgy cables carrying phantom power or the DC shunts when people unplug from DI's without giving the operator a chance to close down the channels.

Having enough headroom in the system is what you need but not necessarily in the amps.

If the rig is any good' date=' then a good live gig should sound nearly as good as a good live CD of the same gig that has been mixed from the channel outputs. Just with more dynamic range.[/quote']

...if the band's backline is quiet enough/far enough away to not be heard acoustically at the mixing position.

Nah, even then I don't agree completely. Certain genres benefit from a different treatment live than they do recorded.

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Overamping in a non-controlled environment (e.g. live) is also another way to get a pile of blown tweeters unless you have really good and extremely fast limiters to catch things like dodgy cables carrying phantom power or the DC shunts when people unplug from DI's without giving the operator a chance to close down the channels.

Having enough headroom in the system is what you need but not necessarily in the amps.

There are ways around this. In our system all inputs are initially routed through AD convertors in the desk at 96KHz. From there on everything remains in the digital domain and is sent at 96KHz to a digital crossover. The digital crossover incorporates limiters (in addition to EQ) and again all this is handled by digital processing. Afterwards the signal is separated for each driver and only converted back into analogue just prior to being delivered to the poweramps. The power amps also contain some last resort circuit protection features.

We still hear bangs when things are unplugged, especially if phantom power is involved, but it's fairly obvious that these are within the safe working envelope.

Most engineers still prefer analogue, and would claim that analogue sound is superior (it probably is in ultimate terms). But a rig is the sum of it's parts, and if the least impressive part is an A->D convertor then any downside is more than made up for by the extra flexibility and convenience that digital brings to the party... plus an astonishingly low noise floor. I certainly wouldn't go back to an analogue desk and XOs, and in my experience the digital XOs produce noticably improved fidelity with a digital feed.

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There are ways around this. In our system all inputs are initially routed through AD convertors in the desk at 96KHz. From there on everything remains in the digital domain and is sent at 96KHz to a digital crossover. The digital crossover incorporates limiters (in addition to EQ) and again all this is handled by digital processing. Afterwards the signal is separated for each driver and only converted back into analogue just prior to being delivered to the poweramps. The power amps also contain some last resort circuit protection features.

We still hear bangs when things are unplugged, especially if phantom power is involved, but it's fairly obvious that these are within the safe working envelope.

Most engineers still prefer analogue, and would claim that analogue sound is superior (it probably is in ultimate terms). But a rig is the sum of it's parts, and if the least impressive part is an A->D convertor then any downside is more than made up for by the extra flexibility and convenience that digital brings to the party... plus an astonishingly low noise floor. I certainly wouldn't go back to an analogue desk and XOs, and in my experience the digital XOs produce noticably improved fidelity with a digital feed.

I think most live engineers don't like digital mainly because the work surface is shit (reliability is another reason, we've seen too many lampies pulling their hair out when their digi desks crash mid gig). Give me a desk with the features of digital, such as onboard dynamic processing, scene recall etc and the work surface of an analogue with all EQ and faders immediately accessible and I'd be a happy bunny. If it didn't ever crash.

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I think most live engineers don't like digital mainly because the work surface is shit (reliability is another reason, we've seen too many lampies pulling their hair out when their digi desks crash mid gig). Give me a desk with the features of digital, such as onboard dynamic processing, scene recall etc and the work surface of an analogue with all EQ and faders immediately accessible and I'd be a happy bunny. If it didn't ever crash.

My Sony DMX R100 comes pretty close to that ideal. 48 channels of dynamics and EQ. You have to press a touch screen to access the dynamics and EQ screens but once there it actually has real knobs to turn and real buttons to press!

It has never crashed, but, on the other hand it lives in a nice clean studio and doesn't get carted around the country and abused by people who believe themselves to be sound engineers. I'd happily use it live and speaking to people who have, it appears to be reliable.

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My Sony DMX R100 comes pretty close to that ideal. 48 channels of dynamics and EQ. You have to press a touch screen to access the dynamics and EQ screens but once there it actually has real knobs to turn and real buttons to press!

It has never crashed, but, on the other hand it lives in a nice clean studio and doesn't get carted around the country and abused by people who believe themselves to be sound engineers. I'd happily use it live and speaking to people who have, it appears to be reliable.

Our desk has never crashed, but the interface between the desk and the PC remote controlling it goes down from time to time, this entails rebooting the PC. The control interface of the Yamaha is horrible, and it's much easier to folloow what's going on from the PC interface, so we just rackmounted the desk where it's safe, and only really touch the gains (which cannot be remote controlled).

The big downside is that you don't get to rest your fingers across a bunch of faders.

The upside is that you get 48 channels plus a 16 channel master bus to play with, and EVERYTHING is routable anywhere, even to several places at once. The flexibility is immense.

The built in processing is adequate for live music, but wouldn't cut the mustard for recordings, to this end we direct out 17 channels from the desk, plus another 8 froma separate digital preamp. The outputs are all digital and go direct to our 24-track Sydec recorder.

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My Sony DMX R100 comes pretty close to that ideal. 48 channels of dynamics and EQ. You have to press a touch screen to access the dynamics and EQ screens but once there it actually has real knobs to turn and real buttons to press!

It has never crashed, but, on the other hand it lives in a nice clean studio and doesn't get carted around the country and abused by people who believe themselves to be sound engineers. I'd happily use it live and speaking to people who have, it appears to be reliable.

here's someone putting it better than I can.

"As one would expect from an experienced engineer, Kay has mixed on all the digital desks currently on the market. Ive always found digital consoles a bit fiddly and a bit slow. Its like mixing with one hand tied behind your back! My reservation is not the sound of digital desks, its the speed of operation. Most consoles are hampered by the interface, which can be too complicated and slow you down to the point where it starts to interfere with the creative process. "

Soundcraft - Professional Audio Equipment

Fortunately manufacturers seem to have cottoned on to the fact that most live engineers think this way and a quick scan of this here interweb reveals a few newly released digi consoles designed specifically for live use.

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here's someone putting it better than I can.

"As one would expect from an experienced engineer, Kay has mixed on all the digital desks currently on the market. Ive always found digital consoles a bit fiddly and a bit slow. Its like mixing with one hand tied behind your back! My reservation is not the sound of digital desks, its the speed of operation. Most consoles are hampered by the interface, which can be too complicated and slow you down to the point where it starts to interfere with the creative process. "

Soundcraft - Professional Audio Equipment

Fortunately manufacturers seem to have cottoned on to the fact that most live engineers think this way and a quick scan of this here interweb reveals a few newly released digi consoles designed specifically for live use.

Know what you mean. My desk's biggest bugbear is it's fiddly to set up the aux sends and returns as it's done through two different menus. Once it's set up, you can change the levels using the motorised faders by just pressing one button to switch the faders to the aux buss. It's not quite the same as having a yard long channel strip but not too bad all the same. I had to use a yamaha digital desk at a live gig once and it was horrendous.

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Know what you mean. My desk's biggest bugbear is it's fiddly to set up the aux sends and returns as it's done through two different menus. Once it's set up, you can change the levels using the motorised faders by just pressing one button to switch the faders to the aux buss. It's not quite the same as having a yard long channel strip but not too bad all the same. I had to use a yamaha digital desk at a live gig once and it was horrendous.

The Yamaha interface is also full of traps. Note the cunning location of the cursor keys only 2" away from the identically shaped save & recall settings keys. The desk will gaily recall last weeks settings at single touch of the recall key as this is the default, unless the engineer has had to foresight to read the manual, enter the setup menu, and tell it to ask "Are you sure <Yes> / <No>"! How many engineers have instantly recalled last weeks settings mid gig?

And the controls are horrible to boot.

The DM1000 does offer a big advantage for us, which is that is can be mounted into a standard rack, which keeps it clean safe, and enables us to use it as a preamp for jukebox, DJ's, movies etc.

In an ideal world they would make a desk like the DM1000 that can be rack mounted into a standard rack... AND they would then separately market various analogue like interface modules ranging from 16 fader through to 60 fader that you could go out and attach via a special lead. If that were possible then our laptop could still be used by the bar staff to set jukebox volumes, and the DM's built in interface is ideal for DJ's provided they don't fuck with the bank select, but the engineer could benefit from a more user friendly interface during gigs. Give it 5 years, if not sooner...

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Does anyone know what the difference is, when referring to PA speakers, between RMS, continuous, program and peak power ratings....??

If someone says to you "I have a 5kW system"....what wattage are they talking about? My PA cabs have a continuous rating of 300W, and a peak of 1200W. That means that if I use the peak power rating, I've got a 5kW system.....but using continuous, I've only got a 1400W system.

Is there a particular convention that "people in the know" use when discussing PA?

Cheers

Neil

In answer to the original question -

RMS stands for Root-Mean-Square and is a type of travelling average used for electrical power (amongst other things) and is the only measurement that you need worry about when it comes to power ratings.

The word 'continuous' is pretty much meaningless and is a typical method used by some manufacturers to obfuscate the issue and confuse some into believing that it refers to RMS.

Peak power is even more meaningless, because that peak could come at about the time the object being described blows up!

Remember that power ratings are just that, power ratings. They tell you how much power the object in question is using or supplying. Nothing else. Not loudness, not quality. Just the amount of power the speaker (in this case) can soak up.

To be meaningful, the RMS rating has to be accompanied by a THD (Total Harmonic Distortion) figure. It would then look like this -

200 Watts RMS (<2% THD) - meaning that the speaker is capable of handling 200 Watts, at which point less than 2% of that signal is distortion.

_____________________________________________________________________

Loudness is measured in decibels (dB) which is a logarithmic comparative value. In other words, we are comparing values as a power of ten. Because of that, a difference of 10dB means a doubling of volume.

Also, in order to get double the volume, you need ten times the power.

So a 1kW (1,000 Watt) system is twice as loud as a 100 Watt system, but half as loud as a 10kW system.

_____________________________________________________________________

Effectivity

Effectivity is the volume generated by a speaker system for a given power and is expressed in dB-phones and is the level given for one Watt at one meter distance. A typical value for a hi-fi speaker is 90dB. A typical value for a PA speaker would be 100dB. Therefore, for those two values, the PA speaker will be twice as loud as the hi-fi speaker.

_____________________________________________________________________

And now to all that stuff Flash was talking about -

Possibly without realising it, he is describing response rate. Response rate is the ability of the speaker to respond to the incoming signal. Measuring this requires several different tests and a reasonable explanation is not within the scope of a forum posting!

The nasty and cheap stuff responds poorly and response rate deteriorates as the power is increased. High quality speakers such as the JBL Line Array series maintain their faster response rates to a higher power rating before deterioration of the signal sets in. Typically, you can drive a good quality speaker twice as hard for a given power level, compared to something cheaper. That is to say, not only will you have a better response rate from the better speaker, but that better response rate can be maintained over double the power range, compared to, say, a Behringer PA system.

What Flash says about hearing damage and quality is 100% correct. Volume alone can damage your hearing, but add distortion to that volume and damage occurs far sooner. I do not have the exact values in my head, but this phenomena has been studied in depth by many acoustics experts. It varies with frequency and is most noticeable at about 1.2kHz.

_____________________________________________________________________

From all the above, we can deduce that if we had to supply a club or a festival with a given volume of music, a high-quality PA speaker system, such as a JBL line-array with an effectivity of 106dB (1W-1m) could produce that volume with a cleaner signal (i.e. better response rate) and would be able to do so with just one-twentieth of the power required by a cheap system such as the Behringer PA series of speakers with 96dB (1W-1m).

I hope you have all been paying attention and making notes, there will be written test!

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In an ideal world they would make a desk like the DM1000 that can be rack mounted into a standard rack... AND they would then separately market various analogue like interface modules ranging from 16 fader through to 60 fader that you could go out and attach via a special lead.

I haven't investigated this properly but the way they seem to be doing live digi consoles now is to have an input and processing unit ( rackable but with no controls) linked to a "user friendly" control surface.

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Here's a question for you then. How much power would an average gigging rock band need? Would they need 5K, 1K or just a 300w type thing? Would they need bass bins etc

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Here's a question for you then. How much power would an average gigging rock band need? Would they need 5K, 1K or just a 300w type thing? Would they need bass bins etc

What size of venues are said rock band playing?

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Here's a question for you then. How much power would an average gigging rock band need? Would they need 5K, 1K or just a 300w type thing? Would they need bass bins etc

Depends on how efficient the speakers are, size/shape of the room and how willing the guitarist is ready to be to turn down his stack. Do you reckon an average rock band has their own transit-style van? If not then the maximum loudness of the rig will be limited by how many speakers the band can carry in the back of their car(s).

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Here's a question for you then. How much power would an average gigging rock band need? Would they need 5K, 1K or just a 300w type thing? Would they need bass bins etc

My advice would be to go for a 1K vocal rig, and only run the vocal through it, otherwise the average size rock band will be there all day setting it up. They'll need monitor too, but in-ear might be the easiest option. In the scenario it's the drums that'll suffer most depending on the material make up of the room. Just ensure that the guitarists and bassist have big powerful amp heads.

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