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RMS vs Peak
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Author:  A_Lisa65 [ Mon Dec 27, 2004 5:16 pm ]
Post subject:  RMS vs Peak
I'm having some trouble understanding exactly what RMS vs Peak power where speakers are concerned. I have been doing karaoke shows for a number of years for someone else but recently put together a system to go it alone. Why does all this technical stuff have to be so confusing? haha If someone could please explain this in simple terns so I could get a grasp of thing I would appreciate it greatly. Thank you ahead of time.
Author:  Lonman [ Mon Dec 27, 2004 9:40 pm ]
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Simply put, RMS wattage ratings are a measure of continuous power — while different manufacturers will use somewhat different methods to come up with these figures, it's usually a more "real-life" rating of your speaker's (amp output as well) capabilities. Peak power, on the other hand, doesn't try to reflect realistic operation. It's simply a measure of how much power can be generated or handled for very short bursts.
Many of the cheaper or lower quality speakers will state that they can handle higher watts to make them sound more appealing. This is usually a "peak" rating when in fact they may only be able to handle 1/4-1/2 of that on a continuous basis.
Matching speakers to amps get most people confused. They see that their speaker may say it handles 250 watts RMS power. They buy an amp that may push 250 watts per channel & they think they are set. While the mentality is ok in thinking that, this is not (efficiently speaking) enough power for the speaker. This particular speaker should be running with an amp that is capable of pushing 500 watts per channel (into the correct ohms) since the program power is right around the 500 watt rating.
You have to figure that on a regular basis that you aren't going to use full power, but as people start filling the room, sound absorsion starts so you naturally turn up the system. There may be some point that you may actually need to turn that amp up to near maximum. At this point your amp is pushing it's maximum wattage of 250 watts per channel - it isn't going to give anymore, so it will start distorting as it goes over it's rating (this is called clipping). You speakers - even though they can handle the power, they aren't going to be able handle the clipping thus speaker failure can & generally will occur. Now say you have that 500 watt per channel amp on the same speakers. Now you are in the same situation, but instead of being locked at a possible distortion scenerio, your amp is now flowing freely as you go over that 250 watt mark which will keep the distortion at a minimum & your speakers will sound cleaner - not necessarily louder, but noticeably cleaner AND fuller sounding. We already know the speaker can handle 1000 watts for short periods, but this amp is not going to push close to that either on the same token this amp is not going to be needed to turn up to maximum so you aren't going to get into the distortion situation.
Author:  Tigrr27 [ Mon Dec 27, 2004 11:08 pm ]
Post subject: 
great post lonman... learned something new myself (yes I can be taught despite what my wife says)... thanks for taking the time to answer that in english... - tig
Author:  karaokemeister [ Tue Dec 28, 2004 1:59 am ]
Post subject: 
The reason that so much of this is confusing is that there are a lot of electronic terms that have defined values to electronic engineers but are twisted by markeeting and other obfuscation.

Power is measured in watts and is computed using the power formula:

P=IxE

P=Power
I=Current
E=Volts

In DC where the voltage is constant this is easy. The problem is that in AC the voltage changes direction on a regular basis (measured in Hertz or cycles per second). Additionally AC based on a sine wave is constantly changing applitude. Because of all these variables in AC they came up with a way of determining the 'average' volatage within AC. This is done by using a formula based on 'Root Mean Squared' or RMS.

Unfortunately, where this all went terribly awry when there was a 'standard' introduced in 1978 for measuring power on amplifiers. The standard uses a purely reistive load (which a speaker is not) and is the RMS voltage times the RMS current which is referred to as RMS Power (which it isn't because of the way it's measured). But because of the way RMS is used and the actual measuring methods it's misleading.

It only gets more confusing when they refer to peak power and other terms that only mislead and confuse even more. Especially when you start using terms like 'average' which is sometimes applied to certain methods of measuring the power.

If none of this makes any sense, it's ok. But some basics:

The standard measures RMS by driving a channel to a max distortion of .1% for a period of five minutes or more using a sine wave as the input driving a purly resistive load after loading the amplifier by driving all channels for over an hour at 1/3 of it's capacity. There are more requirements but it's all spelled out in IHF A202 (the standard for measuring power output on amplifiers).

Ok... enough of the technical details.....

Because the RMS measurements are the average power output at the highest distortion level you'll likely want it's in your best interest to buy an emplifier with a higher rating than speakers. This allows you to do as Lonman suggests and drive the speaker at up to near peak levels without the amplifier distorting the signal which causes the amplifier to heat up, damages speakers and sounds 'really bad' (note the technical term 'really bad').

In high end car stereo competitions I've seen as much as 1000watts per speaker which allows for exteremely clean sound at high volume levels. Keep in mind the speakers aren't rated anywhere near 1000 watts (usually closer to 200-250 watts RMS). The sound is EXTERMELY clean because the distortion levels on the amplifier are very low and the speakers are being driven cleanly. While the measurements between car audio and PA systems/home stereo are a little different (because of input voltage levels playing a role in car stereo) the same general theories still apply.



If all this is confusing you even more I'm sorry... I studied electronics for about 3 years and taught basic electronics for over a year in the military and sometimes get in a little too deep too quick.

For more information do a search on IHF A202, rms power, and some similar terms. For an explanation of why the terms aren't right you can check out this site until they delete the link:

http://www.hifi-writer.com/he/misc/rmspower.htm

Note: this site doesn't sell anything and is entirely informative in nature.
Author:  Tigrr27 [ Tue Dec 28, 2004 2:04 am ]
Post subject: 
nah it is all good KM... I am a techno-geek and can wade through most any spec sheet but it was nice to hear both renditions/explanations just the same... the problem is when some people go in to purchase speakers/amps the sales guy doesn't have a clue and is like "sure sure this amp will power these babies just FIIIINNNEEE" and after a serious party one of them goes KAPUTZ... always good to see things from different angles... thanks- tig
Author:  EElvis [ Tue Dec 28, 2004 4:55 am ]
Post subject: 
Also look at the Ac power consumption. If an amp says it is rated at 1000 watts, and uses 160 watts of power, They are full of it.

you cant get 160 watts from 1000 watts of total power consumption.
Author:  kenpat [ Tue Dec 28, 2004 7:24 am ]
Post subject:  amp clipping
while I have these pros here I have a question, heres my system, cfx12,sonic max, crown2000,peaveysp5's,and jbleon1500, jbl]s sit on top of the peaveys and are plugged into the peaveys...I run the crown wide open...when I'm into funky music, get low or some hot song whereyou need lots of volume (DJ) music also karaoke, baby get back, wild west show etc. its going pretty good but at a point the amp starts flashing red lights at me if I go any further the amp shuts off...I have the gain on the board set at about 40% .....am I doing something wrong or am I just getting all there is.........
Author:  Lonman [ Tue Dec 28, 2004 8:57 am ]
Post subject: 
Well running both sets of speakers at the same time, your load is sitting at 4 ohms. The Crown amp is pushing 660 watts into 4 ohms. It isn't really a good idea to run different brand speakers on the same amp (inline as you described - JBL plugged into Peavey) either as 1 brand is almost ALWAYS going to react & sound differently than the other. If you are running that loud that you are STILL getting clip lights & the built in shut down circuitry kicking in - I would seriously consider going with a larger bi-amp system with at least 2 amps & adding subs.
You could try spreading your speakers out more first. Put 2 in the front of the room & 2 in the back also put both Peaveys on 1 channel & both JBL's on the other channel. Other than that - turn it down.
Author:  EElvis [ Tue Dec 28, 2004 11:12 am ]
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Like loneman says, 2 in the frony & 2 in the back is the best. you won't have to run as high. you will be pushing the air (sound pressure) to the center of the room. You will get better distributed sound instead of having a loud front portion, and a rear of the room that is low.
Author:  A_Lisa65 [ Tue Dec 28, 2004 11:58 am ]
Post subject: 
Thank you all very much! I have always loved music and would be lost without it, but I do wish I understood the techical aspect of things a little more... this I do understand more than before, thank you again. I'm pretty sure the first amp went out because of not knowing what we were up against and I don't want to do the same to the replacement. Thank goodness the speakers are fine.

Just to ease my worried mind about things can I ask something else? We now have a Crate1400 amp and run Pyle speakers 400rms/800peak. They're 8ohm speakers but with having one hooked up to each channel that breaks the ohms down to 4... am I correct in this? I read that if you connect two 8 ohm speakers to the same amp the load halves into 4. If so that makes this particular amp sending 425watts to each side. (possible goofy question coming here) Will these speakers hold up to the extra 25 watts?

Let me thank you all again for your comments about the previous question and once again thank you ahead of time for this new question.
Author:  Lonman [ Tue Dec 28, 2004 1:25 pm ]
Post subject: 
A_Lisa65 wrote:
Just to ease my worried mind about things can I ask something else? We now have a Crate1400 amp and run Pyle speakers 400rms/800peak. They're 8ohm speakers but with having one hooked up to each channel that breaks the ohms down to 4... am I correct in this? I read that if you connect two 8 ohm speakers to the same amp the load halves into 4. If so that makes this particular amp sending 425watts to each side. (possible goofy question coming here) Will these speakers hold up to the extra 25 watts?


You have 2 8 ohm speakers & a stereo amp that pushes 260 watts per channel into 8 ohms. This means if you are hooking each speaker up to an individual channel, then they are sitting at 8 ohms & receiving 260 watts (under rated for the RMS rating of the Pyle speakers). If you connected BOTH speakers to 1 channel, THEN the load drops to 4 ohms & the speakers will see the 425 watts which is better overall. In doing this you will no longer be able to run in stereo (in medium-large clubs stereo isn't needed anyway), but in smaller clubs & home party situations, you may want that stereo imaging as most all karaoke discs are recorded in stereo.
WIll those handle the extra 25 watts, well they should! Since most sound engineers will recommend an amp that pushes double the RMS power. I am not familiar with Pyle speakers reliability & power handling capabilities though. If you are running the speaker & hear distortion, turn down the system. If it isn't loud enough at that point or you are still getting distortion at the desired listening level, then you may need a higher power amp or a more quality speaker.
Author:  karaokemeister [ Tue Dec 28, 2004 2:32 pm ]
Post subject: 
To learn more about this stuff I recommend picking up the 'Basic' series by Paul White. They're easy to understand, very straightforward, and not overly technical without introducing the specifics first.

Another pretty good book is 'Live Music for Musicians'. It covers live music specifics but avoids any use of mathematics. It covers the basics like sound waves from different speaker set ups, etc.

The Yamaha Sound Handbook is an excellent book but gets VERY technical in a short period of time with lots of math. If you get comfortable with dealing with acoutics as a science then you might want to move up to this book but I'd start with the others if you don't have a background in acoustics.
Author:  marley rules [ Tue Dec 28, 2004 3:02 pm ]
Post subject: 
A good aproach to matching an amp with speakers is to buy powered speakers. You eliminate any guesswork and do not have to worry if the RMS ratings from one manufacturer are accurate or measured the same as another. Think about surround sound receivers. You can buy an inexpensive receiver that claims to output 100 watts/channel for about $300.. You can then shop the higher end receivers that cost five times as much (or more) but are rated at 80 watts/channel. Play both units and it becomes clear which manufacturer is accurately reporting wattage ratings.
Author:  bowfishn [ Tue Dec 28, 2004 8:06 pm ]
Post subject: 
The spec on your Amp are as follows I take it:
Power Stereo Mode:
260 watts / channel @ 8 ohms
425 watts / channel @ 4 ohms
660 watts / channel @ 2 ohms
Power Bridged Mono Mode:
520 watts / channel @ 16 ohms
850 watts / channel @ 8 ohms
1320 watts / channel @ 4 ohms
If so you should Bridge the amp and run the speakers in paralel so they will be 4ohm rating and a total of 800 watts RMS and 1600 watts Peak for the pair. The amp is able to deliver 1320 watts into 4ohms, that should be more than enough to opperate the speakers and still not go over the peak rating.
Lonman if your talking about using only one channel of his two channels o at 425 watts 4ohm it would only have 425 watts to split between the two speakers. That would be 212.5 watts per speaker, so he would need to bridge to get the speakers working out of the amp clipping.
Author:  Lonman [ Wed Dec 29, 2004 10:42 am ]
Post subject: 
bowfishn wrote:
Lonman if your talking about using only one channel of his two channels o at 425 watts 4ohm it would only have 425 watts to split between the two speakers. That would be 212.5 watts per speaker, so he would need to bridge to get the speakers working out of the amp clipping.


The amp sees the load as a whole, so while both speakers may technically see less wattage individually, both as a unit (as they would be) would see the higher wattage.

But you are right. I think the amp bridged would be a little much for those speakers though. I've been talking to a couple friends of mine that work at Guitar center & they said Pyle is notorious for overstating their power handling capacity & that the 400 RMS/800 PEAK is probably closer to 200/400. Again I have no direct experience with their stuff.
Author:  bowfishn [ Wed Dec 29, 2004 11:15 am ]
Post subject: 
I was just looking up the Pyle Speakers and your friends are probably right about the power handling of the Pyle Speakers. There price is extremely low for the stated wattage, less than $100.00 per speaker and that would make me wonder if they could really handle 400/800 watts RMS/Peak. Even though I am not that sure about them I would still run them on the amp bridged if they were mine but would limit how far I turned up the amp.
I am useing Behringer 1520 Cabs with B1800X subs and these are concidered by many to be bottom end speakers they still cost twice as much for half the wattage. They never let me turn them up all the way, always complain there too loud turned up less than halfway. This is in a venue that holds 300 to 400 people. (it is the owner that complains and not the customers by the way they wouldn't care if they were run to max.)
Author:  EElvis [ Wed Dec 29, 2004 12:01 pm ]
Post subject: 
The Pyle 2000 amp claims 1000 watts rms......... then later in the manual it states 160 watts per channel @ 4 ohms . Yep, I would say they overstate power. I guess if you use their speakers with their amps, you would be safe, otherwise it is guessing.
Author:  A_Lisa65 [ Wed Dec 29, 2004 2:48 pm ]
Post subject: 
There's this little voice saying to me... "Alisa, as soon as possible see about investing in some better speakers." LOL True these Pyle speakers are VERY inexpensive, and even though I wondered about the quality at the time, I couldn't pass up the buy. (spend and learn, the story of my life) :roll:

With it being that this company has a rep for hyping up their products, I'm thinking to keep trouble from happening with any of the other equipment I should just taker it as easy as possible until a time when money is flowing better and I can upgrade to a better brand name.

With all the comments you have given I have gained (no pun intended *g*) a better understanding of this part of the technical aspects of sound. I'm sure I will return one day with other questions as well as joining in on discussions. Thank you all for your time! It is greatly appreciated!!
Author:  CyprusSam [ Tue Feb 22, 2005 7:49 pm ]
Post subject:  Re: RMS vs Peak
Just another thing to bear in mind.....

If you want a system to be louder, don't think that (for example) a 200watt RMS amp is gonna be twice as loud as a 100watt RMS amp - it ain't.

If you want a system that will DOUBLE the decibel level, you need TEN TIMES the wattage.  I.E.   A 1000watt RMS amp will be twice as loud as a 100watt RMS amp.

IN THEORY  :shock:

Most transistor amps have a minimum ohmage of 4ohms per channel. I used to have a 150watt bassamp in my bassplayer days. Through an 8ohm 4x12 cab it was pretty loud, but not loud enough for me even when run at full beans. So I bought a 400watt amp and a bigger cab.....   Still not much louder.

I then had 4 cabs custom built totalling 2000watts of speakers consisting of 6x15" speakers and 4x10" and wired up with a total impedance of 4ohms. The four cabs were spread across the stage and powered by.... yes... my original 150watt amp. The sound was crystal clear and loud enough to blow the nodgers off a charging rhino at 150 paces. To achieve that kind of decibel level only involved turning the master volume knob a quarter of the way up!

My point here, is that if you do the mathematics and the wiring right, so the amp is working into the optimum load, AND use more speakers to spread the sound, it's gonna sound cleaner and louder.

The last option is to knock up a spurious fugigator, wire it quadraphonically to the triple-rotary crapshaft, engage warp factor 3, then listen to it through organic headphones. Make sure you're not wearing odd socks at the time though.
Author:  pelicaninflight [ Wed Feb 23, 2005 9:01 am ]
Post subject:  Re: RMS vs Peak
A couple of more things to keep in mind...

Speaker efficiencies... Typically measured at 1 watt of power at 1 meter of the speaker in decibels. If you have a speaker with an efficiency of 98 decibels at 1 meter at 1 watt and another one which is 101 decibels at 1 meter at 1 watt... the second speaker will sound twice as loud as the first one, because with this measurement sound level doubles every 3 db increase.

When speaking of amps... one must consider the ohms at which a particular set of speakers are going to be driven with an amp. Typically if the amp can handle the lower loads, it will push more power at 4 ohms than at 8 ohms. But the most important aspect is that at the same efficiency in order to double your sound output from 100 watts you would need a 1000 watt amp. In other words, in order to double the sound level, one needs to multiply X10 the watt requirement.

Just my two cents...
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