Watts RMS, Program, Peak

TravTrav · #1 07-09-2011, 08:47 PM

I apologize if this has been discussed before, but had a hard time searching for it, and it was not in the FAQs.

So, when reading a speakers specs what does RMS, Program, and Peak mean? Example: 200 watts RMS, 400 watts Program, and 800 watts peak.

I don't understand how much power I can put into the speaker without hurting it...

T-Bird · #2 07-09-2011, 10:44 PM

Hi.

By themselves, none of the figures tell pretty much anything.

RMS (Root Mean Square) is the most comparable, but still only tell the thermal power handling of the voice coil.

Program = BS
Peak = ES ( E as in an elephant)

Regards
Sam

TravTrav · #3 07-09-2011, 11:53 PM

^^ BA HA HAHA!

bongomania · #4 07-10-2011, 12:20 AM

In addition to T-Bird's excellent analysis, you can look at RMS as the "safest" of the three, in terms of power handling. The actual wattage a speaker can handle depends on the frequencies it's being fed, the envelope of the notes (percussive vs. smooth), and how much of the time the speaker is up near its maximum abilities, and other factors.

So you can look at the RMS rating as the most general guideline of what to expect from the cab without having to think about it too much. With knowledge and caution it is possible to use a 1000 W amp with a cab rated for only 200 W, and there's nothing wrong with connecting a 200 W amp to a cab rated for 1000 W; so the numbers don't mean very much at all, except again as a rough guide for when you need a quick idea of what the cab is supposed to do.

**B-string** · #5 07-10-2011, 12:35 AM

If I may add? You may have an amp that will put out 1500 watts RMS, on stage you may only use 100 to 250 watts of that rating without blowing everyone else off the stage. Depends on the cabs used and the venue.

TravTrav · #6 07-10-2011, 12:58 AM

Right on. Thanks, guys.

Jerrold Tiers · #7 07-10-2011, 09:42 AM

They SHOULD NOT be BS..... they often are.......

"RMS" is probably the LEAST useful...... it tells you (maybe) the thermal limit of the speakers..... but if you trust in it, you will buy more speakers...... because it gives such a low estimate of the "use with" power.

"program" power should be the best, it ought to (but often does not) correspond to a "use with" power.... that is more-or less what we used it for... you would be OK to use an amp of that power, pretty much regardless.

"Peak" is where the marketing folks really like to play...... it doesn't come into the running for useful, because you can essentially laugh it off..... it exists to put a big number on the spec sheet......

**B-string** · #8 07-10-2011, 11:54 AM

Was there ever an EIA standard mandated for "Program" to make it somewhat reliable JT?

anderbass · #9 07-10-2011, 12:44 PM

Quote:

Originally Posted by Jerrold Tiers

"Peak" is where the marketing folks really like to play...... it doesn't come into the running for useful, because you can essentially laugh it off..... it exists to put a big number on the spec sheet......

I agree and realise you were talking about cabs there, but dont you think a 'Peak output' rating might be some useful info for tube powered amps?

For big tube powered amps like the SVT, I think manufactures also including the max-peak output would be totally useful info for customers that might assume they have absolutely no need to purchase a cab that will handle over 300 watt.

Lots of tube amp users (like me) crank their tube-amps way up to overdrive the power sections, and you posted that tube power sections can actually achieve nearly twice the clean-rated output level here in this thread/quote:

Tube Amp Peak Ratings?

Quote:

Originally Posted by Jerrold Tiers

Theoretically, since the peak and RMS of a square wave are equal, if you measured the power at "hard clipping" you could get "up to" a number of double the power at onset of clipping.

For various reasons you won't quite get double...... and does it really matter? Save it for the lead guitar..... bass usually sounds kinda bad if severely clipped..... unless you are a Pink Floyd / Soft Machine tribute band.......in the studio with lots-o-effects to add.

So If a tube powered amp is capable of much higher peak output-levels, why not publish those ratings along with the conventional clean-output ratings?

Jerrold Tiers · #10 07-10-2011, 01:53 PM

ANY amp inherently can produce peaks of twice RMS...... it's in the definition.

Square wave is as I said, but most tube amps don't produce good square waves, and don't like to do it for long anyway. Some are OK.

If you play real music, you'll never get close to the rms or continuous square wave..... even 6 string heavy distortion rarely gets over 80% "duty".... with bass, it is really really hard to get over half power without basically being in "thrash" territory.

And, that's why "program" power exists..... to give a realistic 'average power" capability. use with an amp of the program rating and you will use the speaker to it's capability. Stick with RMS and you will not.

that assumes the makers are not liars.

it all changes if you tune down, or like to shake the place..... but you probably have speakers capable of it... in any case, speakers have a "cone movement limit" and at lows you can run into it if you push far over "RMS" at that frequency range.

Cirk · #11 07-10-2011, 02:14 PM

So the 1000's watt 6x9 inch 7 way speakers in the JC Whitney catalog are better at power handling that my Boogie 4x10 flight case? Who'd have thunk it? - Just kidding!

My personal favorite has always been ILS - If Lightning Strikes

If would be nice if all manufacturers would use one standard for power ratings, but it seems that marketing won't let them. Kinda takes away from the smoke and mirrors.

Sundogue · #12 07-10-2011, 02:20 PM

Two words to do a search on...

displacement limitation.

THAT will tell you all you need to know.

The rest is pretty much useless.

Jerrold Tiers · #13 07-10-2011, 08:00 PM

Displacement limit is, as I mentioned, ONLY good as a limit below a certain frequency.....

And it can be modified by cabinet design, ported takes a big chunk out of the limit, and a horn can virtually do away with the limit. Both within a particular range, of course.

the true displacement limit based on size and Xmax / X damage is directly relevant in an infinite baffle.

Seal the cab, and the power handling is modified, because the available power input isn't directly related to movement by output acoustic power..... the cab limits output, and also limits movement. it can take more power in, and puts out less sound, at lower frequencies.

Ports reflect a high impedance back, and limit movement, but teh limit "has limits", it goes away at much lower frequencies, and there can be a range above the port tuning where movement limits power also.

Horns, within their effective range, drastically limit movement, and totally "distort" the relation between movement and sound power output.

Any decent manufacturer will use all these facts to arrive at a real power handling number. And it SHOULD be assumed to cover only the usable (quoted) frequency range.

if marketing "made the unit specs competitive", then it's a "pants on fire" situation, and who knows what the real number is.......

Sorry.... displacement limitation is NOT "all you need to know".

JimmyM · #14 07-10-2011, 08:22 PM

Hey Jerrold, sault to you folks at SLM and Ampeg for keeping your quoted power handling specs within reality. I wish all companies did that.

Jerrold Tiers · #15 07-10-2011, 10:43 PM

The marketing folks always wanted to have big numbers....That's what they do.

But we had support from the ownership level to keep Ampeg specs truthful...... so that's what they were.

nemmind... I was gonna say something "clever", but whatever

JimmyM · #16 07-11-2011, 12:09 AM

Aw, bummer! I'm always up for a clever jab!

Thermal handling quotes are a big pet peeve of mine, especially with these tiny cabs these days. I don't think it's so much to ask that you should be able to operate your gear within the parameters they give you. A kid gets a tiny little combo they say handles 400w or 500w, I don't think it should sound like it's going to explode when powered by a 300w micro head operating within its clean range. How's that kid supposed to know? Common sense? RIIIIGHT! He blows the speaker and it's not his fault...he's just doing what they told him he could do.

JimmyM · #17 07-11-2011, 02:55 PM

I see everyone's as up in arms about it as I am.

Russell L · #18 07-11-2011, 02:59 PM

But, the manufacturers will never listen, I guess. There'll never be a way for the average joe to know what he's getting, unless he knows a ton of stuff. Even then, there's no guarantee. The last cab I bought, I just took a chance that it would sound good and be serviceable. It is, on both counts, but, I'm jes sayin'...

BogeyBass · #19 07-11-2011, 03:15 PM

To figure out the Max Power Handling of your Speaker Cab is real easy.

1. Keep turning up the volume till the speakers Blow

2. Make a Mark on the volume knob where they blew

3. Replace all speakers

4. Never go past the Mark on your volume knob

Easy.

or as a general rule of thumb whatever the manufacture says it can handle....divide that in half

will33 · #20 07-11-2011, 03:26 PM

Ampeg hasn't been one to play fast and loose with their claims and that's a good thing. I get the kid analogy but you also can't foolproof everything or it wouldn't work right for those who aren't fools. Designing a combo amp where you could dime every knob all night and not hurt anything would leave no headroom and no expandability. The user also wouldn't learn anything about their equipment....there'd be no need to.

That said I really don't like all these fudged high numbers either but if I called up every president of every company that makes these things I really doubt anything would happen.

So we post about it here and hopefully folks will catch on.

I still think a very basic explanation of how equipment works should be in every beginners lesson plan. Don't need to inundate the kids with a lot of charts and graphs but some real world examples of use vs. abuse would be nice.

Of course this is coming from a guy who thinks you shouldn't be licensed to drive if can't at least change a tire or know how to check your oil or hookup jumper cables without breaking anything. You don't have to be a mechanic but you shouldn't be so completely clueless you're entirely dependent on everybody else for every little thing and thus easily bamboozled by folks who do know a thing or 2.

The salesman who sees a youngster walk in the music store and the one who sees a confused woman walk in the mechanics shop have the same dollar signs flashing in their eyes.