Secrets of Amplifier and Speaker Power Requirements Revealed - AVS Forum
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Bob Hetherington's Avatar Bob Hetherington 11:43 AM 10-22-2010
Secrets of Amplifier and Speaker Power Requirements Revealed
Author: Alan Lofft


As audio/video hobbyists, most of us grew up thinking that if we have an amplifier with 50 watts of rated output power into 8-ohm speakers, and that combination produces reasonably clean and loud music, then by doubling the amplifier power to 100 watts per channel, the system would then play twice as loud. Many readers likely still believe that. Not so.

Although it's not the easiest thing to comprehend, doubling the amplifier power does not double the loudness. In the above example, the sound from the speakers would not be "twice as loud"; it would only be "a little louder," an increase of 3 decibels. How loud is that? Hearing tests with large groups of people have revealed that a one-decibel (1 dB) change in loudness is approximately the smallest audible step that the average listener can detect, so an increase of 3 dB most listeners term "slightly louder."

Read the complete article in the latest issue of our eMagazine at HomeToys.com

bbell_'s Avatar bbell_ 11:48 AM 10-22-2010
Its always been more like 10x the power to sound twice as loud.

So try 500W.
Ralarcon's Avatar Ralarcon 12:02 PM 10-22-2010
Excellent article thanks.

Cheers
punahou80's Avatar punahou80 12:34 PM 10-22-2010
"The lesson in all this is that you can never have too much power, and that big amplifiers rarely damage speakers."

That's a great line - he could be an honorary Texan

I also like the way he handles "logarithmic" with kid gloves. A good read from a true expert without any audiophile 'Tude....
Big Lag's Avatar Big Lag 01:13 PM 10-22-2010
What speakers are those in the accompanying photo?
Pure-Evil's Avatar Pure-Evil 01:17 PM 10-22-2010
wow. what a great article. so basically, i'd be much farther ahead to power all my speakers (or at least the front 3) with BIG amps such as Behringer EP4000's? More power gives more headroom with equals less distortion at higher volumes. I tend to listen to my movies quite loudly, so I think this would be a good thing.

and since many are telling me there is no audible sound quality difference between much more expensive amplifiers and less expensive commerical amps such as the Behringer, I see no need to spend thousands of $$$ on those amps when I can get 3 Behringers EP4000 for less than $1000.00

do i have this correct then?
durckelg's Avatar durckelg 01:26 PM 10-22-2010
Quote:
Originally Posted by punahou80 View Post

"The lesson in all this is that you can never have too much power, and that big amplifiers rarely damage speakers."

That's a great line - he could be an honorary Texan

I also like the way he handles "logarithmic" with kid gloves. A good read from a true expert without any audiophile 'Tude....

So true however......

Knowing this, back in the day I decide to run run my two old Pioneer Impp subs which I believe were rated at 150-250 watts rms each, with a my new Fosgate amp at 500 watts rms to each sub. They sounded clean with all music. I then ran a bass test CD which sounded great until the bass stopped with a little magical smoke.

Be careful when you fry a voice coil due to too much amplifier power, you get little warning. I knew this would eventually happen. I needed an excuse for new subs.
javanpohl's Avatar javanpohl 01:47 PM 10-22-2010
Nice to see that the audio world is favoring subjective assessments over objective ones. I have always considered an increase of three decibels to mean "twice as loud" since it does indeed use twice the power. Obviously, to the subjective ear, that increase doesn't sound twice as loud, but I favor empirical ratings over what my ear thinks.
bwilberg266's Avatar bwilberg266 02:45 PM 10-22-2010
So basically we are re-writing articles from the current issue of Sound & Vision?

Hm...
stepyourgameup's Avatar stepyourgameup 03:06 PM 10-22-2010
If you want to play a 90db sensitive speaker at 90dbs, then you need to give it 1 watt of power. If you want to play it at 93dbs, you need to give it 2 watts of power, 96dbs = 4 watts and so on right?
desertdome's Avatar desertdome 03:39 PM 10-22-2010
Quote:
Originally Posted by stepyourgameup View Post

If you want to play a 90db sensitive speaker at 90dbs, then you need to give it 1 watt of power. If you want to play it at 93dbs, you need to give it 2 watts of power, 96dbs = 4 watts and so on right?

Yes, you are correct. Getting further up in loudness, 128 watts are needed for 111 dB and 256 watts for 114 dB.

Where do you live in Kansas?

Edit: I guess about 30 miles from Newton.
SuperDaveAPK's Avatar SuperDaveAPK 03:41 PM 10-22-2010
Correct. Speaker efficiency is measured in db with 1 watt of input from 1 meter away.
stepyourgameup's Avatar stepyourgameup 03:51 PM 10-22-2010
Quote:
Originally Posted by desertdome View Post

Yes, you are correct. Getting further up in loudness, 128 watts are needed for 111 dB and 256 watts for 114 dB.

Where do you live in Kansas?

Edit: I guess about 30 miles from Newton.

Hutchinson, KS. Home of the Kansas Cosmosphere and Kansas State Fair!
poolboyclay's Avatar poolboyclay 06:46 PM 10-22-2010
Very well written article!
David Susilo's Avatar David Susilo 07:20 PM 10-22-2010
the article itself is old news that's been discussed in various magazine even way back when in late early 80's when I began my foray into home theatre.

What I want to know is where can I buy those speakers shown above. They look cool for my dresser.
blue_z's Avatar blue_z 08:23 PM 10-22-2010
Quote:


Or they may have very efficient speakers ..., the trade-off being a very large degradation in tonal accuracy, a definite harshness, and a complete loss of off-axis performance that accompanies horn-loaded designs.

This article is not that well written since it repeats an incorrect generalization of horn-loaded speakers. A well-designed Tractrix horn system is not at all distorted like a (conical) megaphone. Besides being efficient, horn-loaded speakers usually have very good dynamics. The real trade-off is size.
Zax1108's Avatar Zax1108 08:23 PM 10-22-2010
I would really really like to know what they of speakers are shown in this image.

Think you
Bob Hetherington's Avatar Bob Hetherington 12:12 AM 10-23-2010
Here's more info on the speakers. It was a short story we ran back in August of 2009. They are cool and apparently very good sound quality too.

Designer Joey Roth's Ceramic Speakers boast only 10 watts of output per channel, though each 4-inch full-range driver is housed in an acoustically dead porcelain and cork chamber that should do quite a lot with quite a little. Made from porcelain, wood and cork, Roth chose the materials not only for the aesthetic appeal they add to desktops, but also because porcelain's density and "acoustical deadness" rivals that of wood or plastic enabling the cone shape. Due out in October, Roth will be accepting pre-orders via his site starting September. No official word on pricing yet, but Roth expects they will be in the $400-500 range.

Update from that --- here is a link to the site where you can buy them for $495
http://joeyroth.com/ceramic-speakers/

Enjoy!
Optica's Avatar Optica 12:13 AM 10-23-2010
The speakers shown in the photo are from www.joeyroth.com They are small ipod or laptop speakers. Somewhere around $495. ouch!
poolboyclay's Avatar poolboyclay 08:32 AM 10-23-2010
Quote:
Originally Posted by blue_z View Post

This article is not that well written since it repeats an incorrect generalization of horn-loaded speakers. A well-designed Tractrix horn system is not at all distorted like a (conical) megaphone. Besides being efficient, horn-loaded speakers usually have very good dynamics. The real trade-off is size.

Since the article was about power consumption and the understanding of such, in that context it was well written. Yes there were some inaccuracies.

Clay
Big Lag's Avatar Big Lag 10:57 PM 10-23-2010
1kW per channel, that's all we ask.
EJ's Avatar EJ 01:56 AM 10-24-2010
I have tried to explain that to SO many of my friends over the years! I actually started learning about this as a kud. I was into my dad's sound system more than he was. His Onkyo receiver had VU meter needles . In watts it started at .001, then .01, 1, 5, 50 (something like that)
bmwracer's Avatar bmwracer 07:53 AM 10-25-2010
Quote:
Originally Posted by Optica View Post

The speakers shown in the photo are from www.joeyroth.com They are small ipod or laptop speakers. Somewhere around $495. ouch!

Isn't everything Apple-related priced to kill?
gingus's Avatar gingus 12:34 PM 10-25-2010
Nice article without all the esoteric lingo that doesn't confuse.
spivonious's Avatar spivonious 10:51 AM 10-27-2010
Well-written article that puts a subject most people have trouble understanding in layman's terms.

It's all about the headroom.
SabreWulf69's Avatar SabreWulf69 06:04 AM 10-29-2010
Excellent article, I would also like to submit a personal extension to it so people don't go ahead doing something as exaggerated and silly as trying to pump 2000W RMS into a 15W speaker LOL. According to this excellent article I have read over at Audio Junkies called "Overpowering, Underpowering, Distortion, Clipping, and Everything in Between", you can overpower something, just don't overdrive it, if you want to hear the maximum fidelity and loudness from a speaker, make sure it is amplified properly, have your gains set correctly among other things, then you can't go wrong. I have always said music no matter what it is can't kill a system, people, incorrect configurations, and poorly made components kill systems. The general science is --> 3 things kill speakers 1) Exceding thermal limits. 2) Exceding mechanical limits. 3) Material degradation. "Generally, amplifiers use the formula V1=G*V2. To power the amplifying device, you usually need two reference points, +Vcc and -Vcc. For symetrical reasons, they usually have the same absolute value. If these values are not high enough, the amplified peak value may exceed +-Vcc, causing clipping". Clipping can = harsh and distorted sounding speakers. As mentioned in the article, for perceived loudness everything power wise will have to be upped substantially for a considerable increase in loudness. Happy listening :-)
spivonious's Avatar spivonious 06:58 AM 10-29-2010
Quote:
Originally Posted by SabreWulf69 View Post

Excellent article, I would also like to submit a personal extension to it so people don't go ahead doing something as exaggerated and silly as trying to pump 2000W RMS into a 15W speaker LOL.

My hope is much smaller: that people stop thinking speakers generate watts. "My speaker has 100W. Is it okay if I run it with a 50W amplifier?" :facepalm:
David Susilo's Avatar David Susilo 10:59 PM 10-30-2010
Behringer amps? Uuuuugh. You get what you pay for and Behrinver amps are cheap amd cheaply designed. You do the math.
spivonious's Avatar spivonious 08:34 AM 10-31-2010
Quote:
Originally Posted by David Susilo View Post

Behringer amps? Uuuuugh. You get what you pay for and Behrinver amps are cheap amd cheaply designed. You do the math.

At least in the guitar world, Behringer's products are a good value. The EP4000 gets good reviews at Musician's Friend.
David Susilo's Avatar David Susilo 08:37 AM 10-31-2010
good value does not equal good sound. Especially it's good value for guitar-amp.

I used to own lots of Behringer amps, mixer, effects... yeah, I got rid of them all. Even a Mackie is better than anything Behringer and only for a fraction more.
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