Watts per channel, RMS... overrated?

Judas Priest said:

My QSC GX5 puts out 500W/ch. I know when I get there when the clip LEDs start to flicker

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And, as big as 500wpc sounds, it's not all that difficult to make 'em flicker is it. It certainly was an eye-opening experience when I started playing with amps that had/have clipping indicators.

titanstats.... it was your comment about the "not-so-efficient speakers" that I replied about.

It seemed like a "dig" at the moment. But hey I'm cool with all this... I love this forum and the knowledge shared. I still maintain that the EPI 150s are plenty efficient given that my 12wpc Realistic receiver drives them beautifully. To even turn it up to their "efficiency" ... 87-88dB @ 1 watt @ 1 meter... drives me out of the room. And it sure seems that I have plenty of headroom... power to spare. That's what led me to initiate this discussion. Seems as if I have all the headroom I need, again... given my listening habits.

Cheers to all! Keep on listening!

Back in college an amp was big enough if it made the room lights dim on the drum hits of the first Emerson Lake & Palmer album.

@whoareyou: I REALLY have to crank it before the clip LEDs start to flicker. I mean WAY,WAY,WAY louder than normal LOUD. My Cerwin Vegas are pretty efficient, so at 500 w/ch it´s LOUD.

I think I have posted this video already; turn it down before watching

There was no audible distortion, but my cell phone can´t handle that volume.

https://www.youtube.com/watch?v=hQruUWrI0fQ

hnash53 said:

I still maintain that the EPI 150s are plenty efficient given that my 12wpc Realistic receiver drives them beautifully. To even turn it up to their "efficiency" ... 87-88dB @ 1 watt @ 1 meter... drives me out of the room. And it sure seems that I have plenty of headroom... power to spare. That's what led me to initiate this discussion. Seems as if I have all the headroom I need, again... given my listening habits.

Cheers to all! Keep on listening!

Click to expand...

I concur!

12 wpc with 87 db/w speakers, which is about average, will produce 97 db on a SPL meter 10' away in your chair. Thats pretty darn loud, considering most of us, according to a survey taken here on AK like our music best in the 80 - 90 db range. Generally speaking if you can get to 100 db's in your chair, that is plenty loud for most situations, which would require about 25 wpc for the EPI's.

The wide discrepancy is peoples perceptions of enough power isn't surprising. In my younger years, If I wanted to crank up some rock, I might want 110 db's. That would require 250 wpc to be feed into a speaker with 87 db/w sensitivity. Just 3 more db's, which is more felt than heard at these SPL's would require the 500 wpc suggested in some posts.

Far more important than power, is getting the first watt right. No amount of power/headroom will matter otherwise. That is why there are many people using low power vintage amps and receivers with average speakers that are more than satisfied with the results.

My Realistic System 7 receiver with just 10 wpc drives my palm size Minimus 7's speakers, even with an sensitivity of just 80 db/w with the EQ on, to about 90 db's in a smallish room with enough bass to not need a sub. Thats louder than I normally listen to music anyway. If I want to rock, I have 2 other systems for that.

Let's circle back to the original question by the OP:

Yes, the calculation of 4-5 watts to average 80dB SPL at 4 meters with your EPI's while allowing 3dB of headroom seems to be about right. And if you are convinced that this is plenty of headroom, as you have mentioned several times, so be it.

I think most recommendations as regards headroom for transient peaks would stipulate 9dB as the minimum. Many would recommend 12-15dB, and some would say even higher.

To meet the 9dB minimum you need an amp capable of 16-20 watts before clipping. For 12dB, its 32-40 watts, and for 15dB its 64-80 watts. And of course it you just want to play it just a very bit louder than 80dB on occasion, you'll need to double all of these numbers!

But if you are happy with the performance of your existing amp with your existing speakers, use them and and be happy!

charles 1973... what calculation did you use to come up with 97dB from 10' away?

"... getting the first watt right." I like that. That seems to be the key... very well said!

Speaker watts, loudness, and sound quality explained: http://hubpages.com/hub/Speaker-Watt

Get the first two watts right and you've got 93dB. Every 3 dB above that requires a doubling of necessary watts.

hnash53 said:

charles 1973... what calculation did you use to come up with 97dB from 10' away?

"... getting the first watt right." I like that. That seems to be the key... very well said!

Speaker watts, loudness, and sound quality explained: http://hubpages.com/hub/Speaker-Watt

Get the first two watts right and you've got 93dB. Every 3 dB above that requires a doubling of necessary watts.

Click to expand...

Nope. At your listening distance, the first two watts gets you to an average/nominal SPL of 82-84dB (or thereabouts).

EDIT: The article you linked has factual errors and important omissions. There is no basis for the contention that better speakers have high sensitivities. And it would seem to me that any useful discussion of the topic would include an explanation of crest factor and headroom. And while the platitude-like notion of getting the first watt right sounds appealing, upon reflection I have no idea what this really means. Does it imply that each successive watt of output is inherently not quite as good? Or maybe that the first watt defines the quality of all the successive watts?

"charles 1973... what calculation did you use to come up with 97dB from 10' away?"

http://www.google.ca/url?sa=t&rct=j...4IDYBw&usg=AFQjCNHVV0Er33AolqsD4iMky1kgMHROLA

97 db's @ 12 wpc is with the speakers in a corner, subtract 3 db if they are just near a wall.

Use of Tone controls, or an EQ can significantly change power requirements when boosted. Loudness is typically calibrated to the volume control, So by the time we get to full power, it has no effect.

kcbluesman said:

Let's circle back to the original question by the OP:

Yes, the calculation of 4-5 watts to average 80dB SPL at 4 meters with your EPI's while allowing 3dB of headroom seems to be about right. And if you are convinced that this is plenty of headroom, as you have mentioned several times, so be it.

I think most recommendations as regards headroom for transient peaks would stipulate 9dB as the minimum. Many would recommend 12-15dB, and some would say even higher.

To meet the 9dB minimum you need an amp capable of 16-20 watts before clipping. For 12dB, its 32-40 watts, and for 15dB its 64-80 watts. And of course it you just want to play it just a very bit louder than 80dB on occasion, you'll need to double all of these numbers!

But if you are happy with the performance of your existing amp with your existing speakers, use them and and be happy!

Click to expand...

I think you're talking different headroom here though. I think the Crown calculator is geared more to just having twice as many watts for good measure, not really factoring in the crest factor of the music.

whoaru99 said:

I think you're talking different headroom here though. I think the Crown calculator is geared more to just having twice as many watts for good measure, not really factoring in the crest factor of the music.

Click to expand...

That certainly may be the case...but from a practical usage standpoint, I think we would agree that to minimize the potential for clipping, one's amp should have enough power to provide a reserve of at least 9dB (and more ideally, 12-15dB) above the highest average SPL one wants to be able to achieve on a sustained basis?

Yeah, I usually use 10dB as a good all-around average, and it's easy to calc. But, sure, if one knows they have very high needs in that regard they should adjust accordingly.