Hi Micah. Here is the explanation I got when I asked one of the lead engineers at Peavey about what some of the ratings on one of their new amps meant.

Keep in mind that pro amps are usually driven harder than consumer equipment.
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Hi Fred

Normal use is 1/8 power. That means uncompressed music up to but not exceeding clip. Clipping will compress the material. Safety agency requirements are that the amplifier does not thermal at 1/8 power while at 10% high line (132VAC) at the minimum rated impedance. The 1/8 power is based on what the manufacturer rates the amp for, or whatever UL measures, whichever is higher. Their concern is that there is no nuisance tripping to encourage a consumer to go into the amp and defeat the thermal protection.

The current draw figures in the spec sheet represent current consumption at normal (1/8) and severe (1/3) duty cycles. The consumption is stated for the three rated load impedances.

Hope that helps

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The question came about when he talked about UL tests where they are required to draw maximum rated power for x seconds before they trip the protection circuitry.

Here is the thread the post came from. If you want to learn a little more about amps and amp design, its a great thread to read. It does have the obligatory multiple pages of troll posts that show up in most interesting threads at avs, but its worth wading through those for the info the thread contains.

Oh yeah. On RMS power, I think this is more a marketing invention than anything else. Amp ratings in the car audio world are not subjected to the same level of regulation as consumer audio.

No doubt Johnk will be along shortly to correct my on my mistakes.

Wow, so an amp rated at 1000 RMS could only put out roughly 130 watts of continuous power? There certainly are some dubious marketing techniques in use if that's the case. In all the research I have done (and one of my favorite hobbies since I was a teenager has been car/home audio, so I have done quite a bit of looking up on the subject) the RMS rating was how much power an amp could continuously produce. Most car audio amps would list two ratings, their RMS rating for example might be 500 watts, and their peak power rating might be 1000 watts or more, but it was understood those peak bursts were short lived, perhaps a second or two at the longest.

That was why we bought and installed capasitors... Which were basically batteries that were kept charged in reserve to help boost musical peaks that an amp might not be able to reach, or run out of power while trying to do so.

I greatly appreciate your continued efforts to help clear up some of these misunderstandings. I know there are many people out there that have those same beliefs I had before coming on here. And we still continue to see people with that mind set come on here and get their opinions corrected by those who know more about the way things have evolved. There are certainly many ignorances about these things floating around out there. As it seems that has a lot to do with questionable information given out by the majority of car audio companies.

My intentions are not to prove that those people who still believe in the age old theory of 'sealed = clean, ported = louder' are right. I'm only attempting to explain why they believe that. I know it took me a long time to come around to even believe what was being said on here because after havng built dozens of sub box's for my own cars as well as my friends, I was pretty sure I knew what I was talking about. It wasn't a 'myth' that sealed box's sounded cleaner, the sealed box's we put together did sound cleaner because the ported box's we made were far from perfectly engineered. They put out loads and loads of bass, but that bass wasn't so intelligable as it was just simply... LOUD!!!

I only hope that understanding where all of these myths got their roots can help the members of this board understand why so many people come on here with those beliefs firmly embedded into their brains. Simply telling them they don't know what they're talking about probably won't change their minds if they have a similar background as I have.

We just have to make it clear that the world of home audio is on an entirely different level. The difference is night and day really, looking back on the subwoofers we put in our cars back then, they were VERY crude! Nothing even close to what is available these days for your living room. There is very little comparison between the two worlds (a 1980's trunk subwoofer vs an EP800), besides them both being instruments that are here to serve in satisfying our cravings for bass.

Car audio amps are also rated with much more THD, many with as much as 10%, take that same amp and try to get the RMS at 1% or less and it most likely falls well short of most of the avr's we mention here.

I'm still hopping that Johnk will drop by and correct anything I got wrong. My understanding of amps and power is far from solid.

Having spent a little time on a car audio forum recently trying to figure out what to do about the not so good sound in my car, I get the impression that car audio has stepped out if its 'loud and proud' roots to at least partially embrace sound quality.

The spl folks seem to understand what they are doing does not involve sound quality. I also understand there is a sound quality category at competitions now.

Actually there has always been two camps in car audio. Way back in 1991 when I went to the IASCA Championships they had both 'SQ' (sound quality) and 'SPL' (sound pressure) catagories. While we didn't know exactly what we were doing, some of us really did try to make our rides sound as good as we possibly could. While most of my friends were out spending $80 bucks on a 1000 watt Pyramid amplifier that sounded like crap, I invested hundreds of dollars in Precision Power amps (PPI) that were rated at 4 x 50 watts at .002 THD.

Sure I had friends that you could hear 10 blocks down the road, but you didn't want to actually be in their car. My car on the other hand may not have shaken the neighbors windows when I drove by, but those sweet MB Quart's sounded like heaven (at least to me), and were plenty loud from where I sat.

exactly

Yea.

Mm.

Yahtzee!!

Look Everyone! It's Sean!!!

::applause::