Here is a real stupid question,but I got to ask.

[Fred Mott]

When a amp reads like 500 watts RMS then 1000 watt peak, what does that mean. I am very sorry to ask such a dumb question but I am not sure. If you want go ahead and joke and have fun as long as I get the right answer. Thanks

[JimmyM]

in simple terms, rms is the amount of clean wattage available, and peak is the wattage that's available past the clean point.

[Matt Lake]

People and amp companies usually just talk in terms of the RMS ("root mean square" if I recall correctly). The peak levels are only reached occasionally when you are doing power chords to end a song. You don't usually push it that hard all the time. If you did your amp would overheat and fail or you would blow your speakers, assuming you amp and speakers are matched to begin with. I suppose some people probably run speakers that are rated for more power than their amp puts out so they can do punk rock type stuff, overloading the amp but not hurting their speakers.

[Calaverasgrande]

I would say RMS is better measure of how much an amp can actually do. I swear peak ratings are calculated by marketing, RMS ratings by engineering.

[Eric Moesle]

There is really no measurement for "peak" wattage, they just derive that term by doubling the RMS rating number. In that sense, its just a fictitious number that looks good on paper to those who don't understand.

That's why brands like Behringer only cite "peak" wattage . . .

[prd004]

RMS is kinda the average power output of an amp, peak is the maximum it can put out in short bursts without clipping. If you push the amp beyond it's peak, it will clip and/or overheat and even possibly fail if you push it too much or too long.

So match your speakers and amps, it's a good idea for the speakers RMS to be higher than the amps by a bit, but not too much! And you definately want the speakers to be able to hanle the amps peaks, but..........
You don't want under-poweerd speakers either, it's a fine line but better safe than sorry.

[seamonkey]

"RMS" means nothing. "Continuous" means nothing, It's like saying 10 Apples of taste.
"Peak" or "Music Power" are dishonest.

Look for:
EIA
FTC
EIAJ

Mainly only mainline FOH power amps or home audio sold in the US will have these ratings.

Looks these up to be an informed consumer.

[JimmyM]

Originally Posted by prd004

RMS is kinda the average power output of an amp, peak is the maximum it can put out in short bursts without clipping. If you push the amp beyond it's peak, it will clip and/or overheat and even possibly fail if you push it too much or too long.

So match your speakers and amps, it's a good idea for the speakers RMS to be higher than the amps by a bit, but not too much! And you definately want the speakers to be able to hanle the amps peaks, but..........
You don't want under-poweerd speakers either, it's a fine line but better safe than sorry.

we say this a lot around here, but it's a total myth about underpowered speakers. i've run cabs that can do 800w with a 25w amp before and they were always fine. if underpowering was real, amps wouldn't have volume knobs. also, power handling ratings, by and large, and grossly inaccurate when it comes to real world usage.

but there's a simple solution...if your cab sounds like it's struggling, turn it down.

[prd004]

Originally Posted by JimmyM

we say this a lot around here, but it's a total myth about underpowered speakers. i've run cabs that can do 800w with a 25w amp before and they were always fine. if underpowering was real, amps wouldn't have volume knobs. also, power handling ratings, by and large, and grossly inaccurate when it comes to real world usage.

but there's a simple solution...if your cab sounds like it's struggling, turn it down.

I would basically agree with everything you've said here.

You certainly can run a 25 watt amp into an 800 watt speaker. It will make sound and you can't hurt it this way. But running more closely matched amps and speakers will work better, in your scenario the speakers are barely moving and you won't get all the beatiful tone they were made to produce. Especially in the bass world, where you need to move air.

But less power is better than too much!

And I totally agree that all the power ratings on amps amps speakers these days being major fluff! Companies like to throw out big numbers to make their products sound bigger/badder/better than they are! Compare a 100 watt amp from the 70's to a 350 watt amp from today, quite often the 100 watt oldie will kick the newer ones ass!

[JimmyM]

Originally Posted by prd004

Compare a 100 watt amp from the 70's to a 350 watt amp from today, quite often the 100 watt oldie will kick the newer ones ass!

you raise an excellent point, and i have a theory about that. i believe that the oldies were often underrepresented for wattage back then because it wasn't nearly the numbers game that it is now. i think nowadays there might be more of a tendency to round numbers up instead of down.

as for cabs, most companies use the manufacturer's thermal ratings, and that's for when the voice coil burns out, but in real life, you usually get about half the thermal rating before the cab starts to fartout. so cabs are definitely overrated imho. there are a small handful of companies that rate their cabs accurately, but most don't.

[KJung]

Originally Posted by prd004

I would basically agree with everything you've said here.

You certainly can run a 25 watt amp into an 800 watt speaker. It will make sound and you can't hurt it this way. But running more closely matched amps and speakers will work better, in your scenario the speakers are barely moving and you won't get all the beatiful tone they were made to produce. Especially in the bass world, where you need to move air.

But less power is better than too much!

And I totally agree that all the power ratings on amps amps speakers these days being major fluff! Companies like to throw out big numbers to make their products sound bigger/badder/better than they are! Compare a 100 watt amp from the 70's to a 350 watt amp from today, quite often the 100 watt oldie will kick the newer ones ass!

Disagree with most of the above. Matching amp output to the 'maximum thermal power rating' of a cab is meaningless. The power rating of a cab has nothing to do with sensitivity, nor does it have anything to do with how much power it needs (even the 'concept' of underpowering makes no sense, since a cab power rating is only a loose suggesting regarding the maximum power a cab will take prior to the voice coils being damaged... it gives you absolutely NO information on 'how much power a cab needs', whatever that even means). Better to totally ignore cab power rating, and use your ears.

Also, the idea that 'older amps' are louder is about the biggest myth out there. As one who was there 'back in the day', and also one who has recently done quite a few A/B tests with a variety of newer amps, and a bunch of old Acoustics and GKs', your memory is not quite accurate. Yes, those older solid state amps were VERY loud, but that was primarily due to a brutally mid range voicing, and very little true deep low end. When you plug in a 370 and compare it to, for example, a Markbass LMII, the Acoustic 370 does sound louder, but that loudness is totally in the midrange (which is also dirty as heck). When you somewhat match the deeper, more even voicing of a typical modern head by greatly increasing the low end EQ of a head like the Acoustic 370, and cutting the mids, guess what happens to the headroom and volume

The master volume tapers on those older amps were also brutal, with the amps reaching what seemed to be full output at about the first 40% of the master taper. This was a clever 'marketing way' to make the amps seem louder ('man, my GK kicks total a** with the master only at 10 o'clock!). Eden was the king of this.

That doesn't mean that the old GK's or Acoustics or Sunns don't sound good for what they are, and if you want the super midrange aggressive snarly solid state grind, they are great and loud as heck... but they can't compare to what is out there now if you want a clean, full sound with real low end.

The other thing that impacts all of this is that many cabs today are MUCH more full range than the old, nasal, midrangy boxes. This, of course, impacts sensitivity (takes more power to pump out 45 hz than 100hz). So, guess what happens to the perception of amplifier wattage? That's why those who say 'I only need 100 watts, or I need 1000 watts, etc. can only meaningfully comment when (along with absolute volume), cab voicing and sensitivity are included in the discussion. Some midrange voiced cabs can kill with 200 watts. Other cabs don't reach the same volume with 600 watts.

IMO and IME!

[gary mitchell]

Do any of the amp company,s have a standard to go by. I know when I played guitar, my tube amps were louder then most transistor amps of the same wattage. I am 60 years old and in the old days, I replace a lot of speakers. Speakers were not made as well as they are to day.

[KJung]

Originally Posted by gary mitchell

Do any of the amp company,s have a standard to go by. I know when I played guitar, my tube amps were louder then most transistor amps of the same wattage. I am 60 years old and in the old days, I replace a lot of speakers. Speakers were not made as well as they are to day.

Most solid state amps these days perform reasonably close to what you would expect based on their published wattage spec. For example, when you compare the 450 to 600 watt offerings by Aguilar, Genz, Markbass, GK, Ashdown, Thunderfunk, Eden, Carvin, etc., etc., etc., they are all IMO and IME in the same absolute volume range. There are differences in power amp limiting and low end voice that impact the absolute volume a bit between all of them, but it is more of a tonal thing than an absolute volume thing. There are some exceptions... the 600 watt Mesa M6 sounds huge relative to other amps in its power class, for example, but the typical RMS power spec is pretty useful and 'representative' IMO.

The tube amp versus solid state thing is much discussed, and the general feeling is tube amps, when pushed to distortion, still can sound pretty nice, and hence often can perform quite a bit above their wattage spec ratings versus solid state amps (which sound nasty when pushed to high distortion), that are typically 'electronically limited' to their published wattage spec at a particular THD. So, better to keep tube and solid state amps in their own sort of universes or a small war will break out

The thing that makes this all difficult IMO is more the vast difference in cab voicing and sensitivity today, which can really impact how a head will perform. The nice thing is, wattage has gotten really inexpensive, and even most micro amps now have enough juice to power even deeply voiced, low sensitivity cabs to suprisingly loud volumes.

[T-Bird]

Hi.

Originally Posted by Fred Mott

When a amp reads like 500 watts RMS then 1000 watt peak, what does that mean. I am very sorry to ask such a dumb question but I am not sure. If you want go ahead and joke and have fun as long as I get the right answer. Thanks

Without going into the age old debates of beaten to death subjects, RMS is the easily measurable figure anyone can measure approximately with minimal equipment, ie. PC, a few leads and a dummy load.

By itself RMS doesn't mean much either, only when the standards Seamonkey listed are followed.

Peak power can be measured, but requires special equipment and the figure given is next to useless, telling mainly the state of the PS capacitors.

Musical power = Peavey (= BS)

Regards
Sam

[gary mitchell]

I use to be a real power buff,but not so much anymore. I was running a SWR 700 with a Aguilar,210 and Peavey Lowrider 18. Both 8ohm cabs,then run a small 12 cab to the drummer. By the time we got done I was only running maybe 400 watts maybe,and playing outside gigs without going tru the P.A. and still be heard pretty good. Then I got rid of those cabs and started using my Schroeder 310212 4ohm. Then I just put my rig beside the drummer. So how much power do you need. I am into sound now. What would be decent around RMS are wattage. Rather your inside playing for 2 to 300 people are outside. Without going tru a P.A. I don't know.

[GRAHAM SG1]

I dont think your question is stupid OP, I find Ohms and all that stuff confusing, we cant all be electrical wizards
I always thought that the best way to truly measure output is with decibels but even that can vary with different pick ups I believe, its like comparing guitar amps where a 25 watt valve amp can own a 100 watt transistor amp, I will stick to mechanical engineering and leave electrics to those who are good at it !!

[BluesBear]

After the enlightening Theile/Small study was published it really caused a shakeup (wakeup).
One good thing was that speaker manufacturers started listing standardized SPL (sound pressure level) ratings.
For example: 93db 1w@1m (93 decibels from a 1 watt white noise signal measured at 1 meter)

One company offered musicial instrument speakers in a single size with sensitivities from 91 to 95 db. That means that one speaker was over twice as loud, acoustically, as another.

The 95db speaker would appear louder connected to a 50 watt amp than the 01db speaker would when connected to a 100w amp.

However there's more than raw volume involved. Frequency response is also very important. A speaker that is twice as loud at 40-80Hz isn't much of an advantage to a guitarist. And while flat response amps/speakers are often desired by bassists, guitarists usually dislike super flat response amps/speakers.

[BluesBear]

Originally Posted by KJung

Also, the idea that 'older amps' are louder is about the biggest myth out there. As one who was there 'back in the day', and also one who has recently done quite a few A/B tests with a variety of newer amps, and a bunch of old Acoustics and GKs', your memory is not quite accurate. Yes, those older solid state amps were VERY loud, but that was primarily due to a brutally mid range voicing, and very little true deep low end. When you plug in a 370 and compare it to, for example, a Markbass LMII, the Acoustic 370 does sound louder, but that loudness is totally in the midrange (which is also dirty as heck). When you somewhat match the deeper, more even voicing of a typical modern head by greatly increasing the low end EQ of a head like the Acoustic 370, and cutting the mids, guess what happens to the headroom and volume

IMO and IME!

AMEN!
As another who was there i can attest to the accuracy of his statements.
There was a huge Watts War going on.
Fender took the RMS rating on their amos and doubled them to determine their Peak Watts numbers for their tube amps.
However when Fender released their Solid State line in the middle 1960s the peaks were suddenly TRIPLE the RMS rating! Transistors were magical even back then. Did anyine notice that the Fender dual 6L6 amps started out at 40 watts and through the years, with little or no circuit changes became 60 watt amps?

Sunn often only advertised their peak ratings. I have owned several Sunn Coliseum amps and they are nowhere near 800 watts even at 2 ohms. Another problem was that many of the most Sunn cabs of that era were 8 or 16 ohms.

And speaking of that, it wan't until the late 1970s that most manufacturers listed ANY ohmage rating for their speaker cabinents.

I was a Traynor endorser in the 1970s and for a time Traynor didn't list ANY wattage rating for their amps. they simply chose to say compare our Mark 1 to a Fender Bassman or our Mark III to a Dual Showman Reverb and decide for yourself.

Another variable was preamp gain.
I recall reading an advertisment in Rolling Stone (back when it was more like a newspaper) and seeing the original ad for the Electro-Harmonix LPB-1 Linear Power Booster. It clamed it would make ANY amp four times louder. And for only $20!!! MAN I HAD to have one. Know what. It worked. it was nothing more than a 9v battery operated gain stage. The EH ads stated that 'modern amps are desigbned to work with the loudest pickups possible' and that since no major manufacturer was using such critters, their booster too advantage of your amp's capability for increased input.
I may have been over simplified junk science but remember this was the day of amps with Volume, Treble, Bass circuits (with the occasion Middle control).

As for replacing speakers back in the day, it wasn't until the late '70s that it became common to find speakers that could handle more than 100 watts. The Altec Lansing 421A and the JBL D140 were the top of the line, gold standards and they were only 100 watt motors.

[Orph]

Originally Posted by Calaverasgrande

I would say RMS is better measure of how much an amp can actually do. I swear peak ratings are calculated by marketing, RMS ratings by engineering.

RMS is a better measure of baloney. It doesn't mean anything without more information available.

[billfitzmaurice]

Originally Posted by Fred Mott

When a amp reads like 500 watts RMS then 1000 watt peak, what does that mean.

500 watts is what engineers will quote as its rated power, 1000 watts is what marketeers will quote.