Huge Range in "Recommended Amp Power"

Quickley17

Quickley17

Audioholic
So in looking at specs for speakers, I've noticed some manufacturers provide very large ranges for recommendations. An example of this is the B&W 683.

"25W - 200W into 8Ω on unclipped programme"

From what I've learned from reading here, a 25 watt amplifier turned way up poses a serious risk of clipping to a speaker that can potentially ask for 200 (or more) watts. How do you define a safe or ideal middle ground for trying to decipher specs like this?

I'm inclined to go with the bigger is safer idea that I've heard around here a few times, and say that a 200 wpc stereo amplifier would be the best thing to drive these with to prevent clipping and allow proper "head room"? I suppose most of the time this wouldn't even pose itself as a problem with your typical 100-120 wpc reciever not being asked to provide the kind of output I'm asking about, but a 25-200 watt range leaves a lot in question, in my opinion.

(also noticed the 800D says 50-1000 which is even crazier)
 
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fredk

Audioholic General
I think that part of the idea behind those numbers is to let you know what sort of peaks the speaker can handle.

If there is a link to a power calculator in the articles Adam posted, play with it for a while to get an idea of how power requirements change as you get into bigger rooms (distance from speakers) or start listening to music with a lot of dynamic range (headroom).
 
Quickley17

Quickley17

Audioholic
Hi. The Audioholics main site has some good articles on power ratings for speakers:

There's some good reading there. How much power you'll be using/want will depend on how loud you listen to material and the sensitivity of your speakers.
Thanks for the heads up Adam, Those articles are very illuminating.

My next question is, is it possible to implement a "safety factor" when you are buying speakers/components?

By this I am refering to roomates, guests, kids, drunk self, etc. who may abuse the system and use it beyond its capabilities. It seems to me that with experience you get a feel for what your own speakers can handle by using them, but are there programs built into recievers or via some other avenue that can be implemented to protect the components from inappropriate use in order to avoid the risks associated with things like turning up the system too high?
 
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fredk

Audioholic General
On some receivers you can set the maximum volume and the default volume when you turn the receiver on.
 
J

jostenmeat

Audioholic Spartan
I'm inclined to go with the bigger is safer idea that I've heard around here a few times, and say that a 200 wpc stereo amplifier would be the best thing to drive these with to prevent clipping and allow proper "head room"? I suppose most of the time this wouldn't even pose itself as a problem with your typical 100-120 wpc reciever not being asked to provide the kind of output I'm asking about, but a 25-200 watt range leaves a lot in question, in my opinion.
While you might* be thinking of what the lowest amount of power is necessary in purchasing, I have the empirical impression from those with insane setups that (assuming a good outboard amp is in the mix) that it's the speakers that are the weak link in achieving high SPL. Just only FWIW.

(also noticed the 800D says 50-1000 which is even crazier)
And at the JTR site, the Triple 12 recommends up to 1600 watts, stating usable output to 132 db. An avid salesman at another forum typically recommends at least a kilowatt to "make them wake up". :eek:
 
Quickley17

Quickley17

Audioholic
jostenmeat, in the first part of your post, what you're saying is that most of the time with really high end equipment, the speakers cannot handle the absolute peaks that the amp can provide?

Even with not high-end equipment, this is scary for me. I am very interested in increasing the quality of what I listen to and watch, and the fact that I am not in complete control over my equipment (I have three housemates... we are young... and like to get drunk and listen to loud music) concerns me. It would really suck to spend 2-3k on a set of front speakers to have them at constant risk of damage.

wikipedia -> Threshold of Pain = 130 dB... NO THANK YOU.
 
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jostenmeat

Audioholic Spartan
jostenmeat, in the first part of your post, what you're saying is that most of the time with really high end equipment, the speakers cannot handle the absolute peaks that the amp can provide?
Not necessarily only with "high end". Just that once you add an outboard amp, or IOW get beyond what a receiver can typically provide, it's the speakers that will limit you in achieving high SPL, whether extreme peaks, or prolonged periods of high volume playback. That said, for most people, a good receiver is plenty. But I just wanted to note my impression that for the difficult-to-define-as-loud that you might be talking about . . . you might focus firstly on the speakers that can handle large amounts of power to begin with. Ya know, depending.

Even with not high-end equipment, this is scary for me. I am very interested in increasing the quality of what I listen to and watch, and the fact that I am not in complete control over my equipment (I have three housemates... we are young... and like to get drunk and listen to loud music) concerns me. It would really suck to spend 2-3k on a set of front speakers to have them at constant risk of damage.
I hear ya. It's just really hard to define loud, and how much power is needed. It will also depend on how far you sit. But if you want it cranked while you're hanging out in another room.. I dunno. It just might not sound very good either if super loud; well, in my experiences it was only after acoustically treating (and perhaps employing Audyssey) that I started to use more of my amps' capabilities. Maybe even a 6db difference, which is what 400% of the power, but I've scaled that back about halfway since making my ears ring for a couple days (on more than one occasion) with the Band of Brothers series. YMMV.
 
F

fredk

Audioholic General
Quickley17. Take a little time to play with this power calculator to get a feel for how much power you really need.

For instance. My speakers are 91db @1w @1 meter, fairly efficient. I sit 8-10' from my speakers in a relatively small room. to play at an average volume of 90db (quite loud, but not quite concert level) takes less than 10w of power. If I want lots of headroom for dynamic material like classical music (say +15db from average) I will need to have 50w total power for the highest peaks.

Most people think they need more power than they actually do. Most rock/pop, for instance, only requires 6db of headroom as the material is not very dynamic (range from quiet to loud passages).

Lets go back to the calculator. If I have very inefficient speakers, say 84db@1w@1meter, I now need 249w of power for the same classical music.

How much power you need depends very much on the efficiency of your speakers, your room size, and how loud you listen.
 
j_garcia

j_garcia

Audioholic Jedi
For instance. My speakers are 91db @1w @1 meter, fairly efficient. I sit 8-10' from my speakers in a relatively small room. to play at an average volume of 90db (quite loud, but not quite concert level) takes less than 10w of power. If I want lots of headroom for dynamic material like classical music (say +15db from average) I will need to have 50w total power for the highest peaks.
No, for a +15dB peak you would need 451W for a 105dB peak with 3dB headroom using those specs. That means you are using 10W of the total power of your receiver or amp, but the amp needs to be capable of delivering 451 during that peak to avoid clipping.

That calculator does not factor in room gain or the room size either, so your actual power requirements could actually be slightly lower or higher.

The range means that feeding the speaker with less than the lowest amount of power listed could damage the drivers, and the max rating means that is the most it can handle PEAK before something fries; in both cases, damage to the speaker is likely. The fact is, if you have sufficient power to achieve the SPL you are looking for in your room without clipping, it doesn't really matter what the ratings on the speaker are because most speakers will be OK with an unclipped signal. The amount of power actually used by the typical speaker during normal listening is likely very low, on the order of a few watts. When you clip the signal, the amount of power drawn goes up exponentially.
 
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no. 5

no. 5

Audioholic Field Marshall
That calculator does not factor in room gain or the room size either, so your actual power requirements could actually be slightly lower or higher.
Probably lower, I believe that that calculator assumes free space, so it's calculating the absolutely worst case scenario. Even in a very 'dead' room you wont be seeing 6dB/dd.
Just that once you add an outboard amp, or IOW get beyond what a receiver can typically provide, it's the speakers that will limit you in achieving high SPL, whether extreme peaks, or prolonged periods of high volume playback. That said, for most people, a good receiver is plenty.
Exactly, a loudspeaker cannot produce infinite loudness. Even with a two thousand watt amplifier there is no guarantee (without measurements) that you will have 13dB more output available compared to a one hundred watt amplifier. At some level there will be power compression decreasing output.
 
P

PENG

Audioholic Slumlord
That calculator does not factor in room gain or the room size either, so your actual power requirements could actually be slightly lower or higher.
I agree, but I dare say it will most likely be much lower than "slightly", and almost never higher. I would think that room gains are rarely negative.
 
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PENG

Audioholic Slumlord
From what I've learned from reading here, a 25 watt amplifier turned way up poses a serious risk of clipping to a speaker that can potentially ask for 200 (or more) watts.
Speakers do not ask.... It is you, the listener, and the source media that do the asking, then the amp has to amplify the signal to the level that can drive the speakers to deliver the SPL you, and the souce material "ask" for.

I agree if the range of the speaker is 25W to 200W, it will be safer to get a 200W or more powerful amp. Higher is good but lower is not, unless everyone in your room can discipline themselves.
 
KEW

KEW

Audioholic Overlord
FWIW - With college and room mates I went through 3 tweeters and one woofer. I paid for one tweeter (the first to blow) and room mates bought the other three drivers. In my case I had more amp than the speakers could handle.

If you are deciding on a receiver, I think Fredk had your answer with:
"On some receivers you can set the maximum volume"
 
Quickley17

Quickley17

Audioholic
Speakers do not ask.... It is you, the listener, and the source media that do the asking, then the amp has to amplify the signal to the level that can drive the speakers to deliver the SPL you, and the souce material "ask" for.

I agree if the range of the speaker is 25W to 200W, it will be safer to get a 200W or more powerful amp. Higher is good but lower is not, unless everyone in your room can discipline themselves.
Peng, I agree, and that's what I was trying to imply by saying "ask"... that me, or someone else in the house could potentially push the speakers to that kind of output, which I hope doesn't happen... I am not confident in the self discipline of the people around me. (Edit: or me at 3 am)
 
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fredk

Audioholic General
No, for a +15dB peak you would need 451W for a 105dB peak with 3dB headroom using those specs. That means you are using 10W of the total power of your receiver or amp, but the amp needs to be capable of delivering 451 during that peak to avoid clipping.

That calculator does not factor in room gain or the room size either, so your actual power requirements could actually be slightly lower or higher.
I was factoring room gain into my numbers. I neglected to mention that.

The numbers are, of course, not accurate as room gain will be slightly different for each room, but are good enough to get a reasonable idea of power requirements. I am willing to bet that for most people, most of the time, it will show that you don't need gobs of power.

Edit: Being pedantic, I ran the numbers through the calculator again. If I plug in 2.5m for distance, 91db for sensitivity, 90db for desired level and 15db for headroom (assuming no room gain) I come up with a power requirement of 157w for that 105db peak. As Peng pointed out, room gain reduces the power requirement a lot, but not that much.
 
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JerryLove

JerryLove

Audioholic Samurai
This conversation really re-enforces my on-going move to clipping-protected amps (like my McIntosh).

But my limited knowledge repeats much of what is said here:
-Peak power can be orders of magnitude more than sustained.
-loads add up fast as dB increases.
-Don't forget the added db on certain frequencies if you are using equalization.
 
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jostenmeat

Audioholic Spartan
Peng, I agree, and that's what I was trying to imply by saying "ask"... that me, or someone else in the house could potentially push the speakers to that kind of output, which I hope doesn't happen... I am not confident in the self discipline of the people around me. (Edit: or me at 3 am)
mmmmhowabout some JTR Triple 8s with a pro amp? No worries at that point, ok, outside of getting too familiar with the local police.
 
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Jeff Permanian

Enthusiast
mmmmhowabout some JTR Triple 8s with a pro amp? No worries at that point, ok, outside of getting too familiar with the local police.
You can send your neighbors a turkey on thanksgiving or invite them over for movies:D
 
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