Question on power handling

Silver Member

Username: Scubasteve

Annapolis, MD

Post Number: 316
Registered: May-05

Posted on Friday, July 29, 2005 - 09:09 pm:

I'm new to home audio, and I had a question concerning the power that companies recommend that people give their loudspeakers. It seems like most speakers you see, even if they have dual 8s and multiple midrange and tweeters will only recommend a few hundred watts RMS (if that), when the raw drivers can handle much much more power than that. Is it because the crossovers can't handle all that power, or they don't want to scare consumers off thinking that they will need to buy multi-kilowatt amplifier to run the speakers or what?

Bronze Member

Username: Devils_advocate

Post Number: 89
Registered: Jul-05

Posted on Friday, July 29, 2005 - 09:15 pm:

Power handling numbers are all but meaningless in the real world.

Silver Member

Username: Scubasteve

Annapolis, MD

Post Number: 317
Registered: May-05

Posted on Friday, July 29, 2005 - 09:27 pm:

would you care to explain that one?

Bronze Member

Username: Devils_advocate

Post Number: 91
Registered: Jul-05

Posted on Friday, July 29, 2005 - 09:52 pm:

How detailed of an explanation do you want? There are a lot of reasons.

Bronze Member

Username: Devils_advocate

Post Number: 92
Registered: Jul-05

Posted on Friday, July 29, 2005 - 10:06 pm:

Heres a short list.

1. Receiver manufacturers lie about power ratings.
2. Speaker manufacturers give the power handling characteristics as a guideline, it is by no means set in stone.
3. You are much more likely to destroy your speakers buy underpowering them (causing your receiver to go into clipping) than overpowering them (if you purchased some Bose cubes and Mark Levinson amplifiers).

Silver Member

Username: Scubasteve

Annapolis, MD

Post Number: 318
Registered: May-05

Posted on Friday, July 29, 2005 - 10:10 pm:

Any time anyone could take out their schedule would be just fine. I'm not a complete audio newb who doesn't know the difference between true RMS handling, peak handling, true thermal dissipation abilites, etc. My background is in car audio where you usually attempt to have an amp (or a channel of an amp) for each component that can supply the RMS handling of the driver, assuming you believe this is a truthful claim by the speaker company. I was just wondering why this is (seemingly) different in home audio.

Silver Member

Username: Scubasteve

Annapolis, MD

Post Number: 319
Registered: May-05

Posted on Friday, July 29, 2005 - 10:16 pm:

"You are much more likely to destroy your speakers buy underpowering them (causing your receiver to go into clipping) than overpowering them"

I agree with that statement, but it doesn't explain why loudspeaker companies would suggest using LESS power than the drivers can handle. That means an owner is garunteed to be underpowering them, which will make him more likely to drive the amp into clipping.

Gold Member

Username: Petergalbraith

Rimouski, Quebec
Canada

Post Number: 1048
Registered: Feb-04

Posted on Friday, July 29, 2005 - 10:16 pm:

For another thing, power output capability and power input capability varies with frequency. If you can safely pump 100W of 100 Hz into a speaker, I wouldn't try pumping 100W at 10kHz.

For another, since power works on a log scale it's difficult to accurately know whether you are pumping 100W or 150W since the difference in dB is so small.

Since the scale is logarithmic, you may most often require less than 1W rather than 100W.

Bronze Member

Username: Devils_advocate

Post Number: 93
Registered: Jul-05

Posted on Friday, July 29, 2005 - 10:18 pm:

How many amps do you know that can deliver a couple hundred watts RMS?

Gold Member

Username: Petergalbraith

Rimouski, Quebec
Canada

Post Number: 1049
Registered: Feb-04

Posted on Friday, July 29, 2005 - 10:21 pm:

I don't know that's it's true if drivers are over-spec'ed. But judging from the dainty PC-board type of crossovers often used today I wouldn't be surprised if they were the limiting factor.

Now this is a crossover :
http://cgi.ebay.com/New-Replacement-Crossover-Klipsch-Type-AA-PR-Cedar_W0QQitemZ 5792679238QQcategoryZ14993QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

:-)

Silver Member

Username: Scubasteve

Annapolis, MD

Post Number: 320
Registered: May-05

Posted on Friday, July 29, 2005 - 10:26 pm:

since when is power on a logrithmic scale? SPL is measured on a logrithmic scale but thats a different story. Dainty crossovers was my first thought though...

Bronze Member

Username: Devils_advocate

Post Number: 94
Registered: Jul-05

Posted on Friday, July 29, 2005 - 10:30 pm:

Either way, whether you have a amplifier that is too powerful or too weak, if you hear distortion, just turn the thing down....

As for SPL vrs power, it is somewhat important. Every doubling of power only results in a 3dB gain. So from 100 to 200 watts is 3dB. From 100 to 400 is 6dB. Not that much in the grand scheme of things.

Gold Member

Username: Petergalbraith

Rimouski, Quebec
Canada

Post Number: 1050
Registered: Feb-04

Posted on Friday, July 29, 2005 - 10:32 pm:

sigh. That's what I meant. How would you have phrased it?

Start at 1W, turn the volume dial up 10dB and you are at 10W, turn it up another 10dB and you are at 100W, turn it up another mere 3dB and opps you're at 200W and you've blown something.

Gold Member

Username: Petergalbraith

Rimouski, Quebec
Canada

Post Number: 1051
Registered: Feb-04

Posted on Friday, July 29, 2005 - 10:34 pm:

Not that much in the grand scheme of things.

Exactly my point. Not much SPL gain but a whole lot of Watts more required!

Gold Member

Username: Petergalbraith

Rimouski, Quebec
Canada

Post Number: 1052
Registered: Feb-04

Posted on Friday, July 29, 2005 - 10:34 pm:

Hey DA, a few more and you turn silver!

Silver Member

Username: Scubasteve

Annapolis, MD

Post Number: 321
Registered: May-05

Posted on Friday, July 29, 2005 - 10:36 pm:

ahh, sorry about that, Peter. Now that I re-read, I see what you were getting at.

Gold Member

Username: Petergalbraith

Rimouski, Quebec
Canada

Post Number: 1053
Registered: Feb-04

Posted on Friday, July 29, 2005 - 10:40 pm:

No harm done.

But have we convinced you of anything yet? ;-)

Bronze Member

Username: Devils_advocate

Post Number: 95
Registered: Jul-05

Posted on Friday, July 29, 2005 - 10:41 pm:

Yes indeed Peter. Then just a few more weeks till gold if I keep going at this rate!

Bronze Member

Username: Devils_advocate

Post Number: 96
Registered: Jul-05

Posted on Friday, July 29, 2005 - 10:42 pm:

Its just way too much information to write down coherently without spending a lot of time to formulate all my thoughts, etc.

Gold Member

Username: Petergalbraith

Rimouski, Quebec
Canada

Post Number: 1054
Registered: Feb-04

Posted on Friday, July 29, 2005 - 10:44 pm:

yeah, you registered this month so it's going up fast!

Then there's Art, Paul and Jan. Boy are their counts going up quickly!

Bronze Member

Username: Devils_advocate

Post Number: 97
Registered: Jul-05

Posted on Friday, July 29, 2005 - 10:46 pm:

It helps to be able to sit on here all day at work with nothing better to do.

Gold Member

Username: Petergalbraith

Rimouski, Quebec
Canada

Post Number: 1056
Registered: Feb-04

Posted on Friday, July 29, 2005 - 10:54 pm:

I've been on vacation for the last few weeks so my count went up. But the pattern won't hold...

Silver Member

Username: Scubasteve

Annapolis, MD

Post Number: 322
Registered: May-05

Posted on Friday, July 29, 2005 - 10:57 pm:

"Not much SPL gain but a whole lot of Watts more required!"

Isn't a 3 dB increase in SPL considered twice the audible level?

Bronze Member

Username: Devils_advocate

Post Number: 98
Registered: Jul-05

Posted on Friday, July 29, 2005 - 10:59 pm:

No, 3dB is double the power. 10dB increase is considered twice the audible level.

Bronze Member

Username: Devils_advocate

Post Number: 99
Registered: Jul-05

Posted on Friday, July 29, 2005 - 11:01 pm:

Also, keep in mind that most program material consists of peaks and dips. It is only those peaks that come anywhere close to maximum power; most loudspeakers of decent make can handle such peaks.

Silver Member

Username: Scubasteve

Annapolis, MD

Post Number: 323
Registered: May-05

Posted on Friday, July 29, 2005 - 11:32 pm:

right...but the power for the peaks won't be there if you're chronically underpowering your speakers...trying to use 1 or 2 channels of a receiver at most to power at tower speaker with 4 of 5 drivers. Thanks for being patient with my questions. I'm trying to make my break into home audio now that I acutally have a place where I can put some speakers.

Bronze Member

Username: Devils_advocate

Post Number: 100
Registered: Jul-05

Posted on Friday, July 29, 2005 - 11:45 pm:

Unless you're really pushing it hard enough to cause yourself to go deaf in a couple years, you aren't chronically underpowering your speakers. The average loudspeaker can manage somewhere on the order of 90dB with 1 watt of input. 90dB is pretty darned loud.

Silver Member

Username: Devils_advocate

Post Number: 101
Registered: Jul-05

Posted on Friday, July 29, 2005 - 11:47 pm:

http://www.moultonlabs.com/articles/93aboutloud.htm

This looks like some good info about sound levels...

Silver Member

Username: Devils_advocate

Post Number: 102
Registered: Jul-05

Posted on Friday, July 29, 2005 - 11:55 pm:

Ohh and the tower speaker being less efficient isn't really accurate. For example, Peter's mains play at 104dB with one watt of input power.

Silver Member

Username: Devils_advocate

Post Number: 103
Registered: Jul-05

Posted on Saturday, July 30, 2005 - 12:00 am:

Anyways, have a good night Steve. I'm out for the evening. I'm sure the good people of ecoustics will have more to say on the matter.

Gold Member

Username: Petergalbraith

Rimouski, Quebec
Canada

Post Number: 1059
Registered: Feb-04

Posted on Saturday, July 30, 2005 - 12:34 am:

Hey DA, you made it to silver on this very thread!

scuba steve, I think you worry too much about pushing speakers to their very limit. There's more to audio than SPL. Have a good night!

Silver Member

Username: Scubasteve

Annapolis, MD

Post Number: 324
Registered: May-05

Posted on Saturday, July 30, 2005 - 04:13 am:

yes!! truly there is peter, it is just always my experience that speakers preform better when their full RMS power is available to them, even if you're listening to them at low levels. Thank you both for your help.

Gold Member

Username: Petergalbraith

Rimouski, Quebec
Canada

Post Number: 1063
Registered: Feb-04

Posted on Saturday, July 30, 2005 - 10:43 am:

it is just always my experience that speakers preform better when their full RMS power is available to them, even if you're listening to them at low levels.

How would it know?

There are lots of recordings that I like to listen to at 90 dB or so (light trio jazz) because the instruments are more realistic at that level. That's at -30 dB on my volume dial, so 1/1000th of full power. Should the speakers care what that full power could be if they are only being fed 0.1 W peaks?

Silver Member

Username: Scubasteve

Annapolis, MD

Post Number: 325
Registered: May-05

Posted on Saturday, July 30, 2005 - 11:32 am:

Well Peter, me saying that speakers sound better when powered by an amp that has the ability to produce the full RMS handling of the speaker is true in my experience. This probably has something to do with the fact that if you're listening at low volume levels, the amp is producing a signal with .0003% THD. For an example from car audio, if you power a set of focal components with your head unit, its going to sound terrible no matter what volume level you listen on.