Under powering speakers

Aaron McQueen

Aaron McQueen

Freshman
Dec 23, 2011
99
2
0
I've seen quite a few posts on other forums and facebook groups where people are claiming that under powering a speaker is very dangerous and can damage the speaker more than overpowering it. The explanation is added that under powering leads to clipping the amp and that will create a square wave that basically destroys the speaker. Something doesn't sound right to me, so I came here to ask the experts. Is this true? What's the whole story? What really destroys the speaker? I've personally under powered speakers before and haven't experienced any problems, but I've also kept things out of the red.
 
Re: Under powering speakers

"Under powering" is misplacing blame. The problem is from pushing an amp beyond its ability, because one didn't bring enough rig for the gig.

As long as you're not pushing the amp onto clipping, under sized will never be a problem (destroying speakers).
 
Re: Under powering speakers

Mitch Miller said:
"Under powering" is misplacing blame. The problem is from pushing an amp beyond its ability, because one didn't bring enough rig for the gig.

As long as you're not pushing the amp onto clipping, under sized will never be a problem (destroying speakers).
Click to expand...

So what's actually happening when you push the amp into clipping? What destroys the speaker?
 
Re: Under powering speakers

Also there's mention of distortion being the cause of the damage. If that's the case then I need to have a talk with our electric guitar player.
 
Re: Under powering speakers

Aaron McQueen said:
So what's actually happening when you push the amp into clipping? What destroys the speaker?
Click to expand...

The AVERAGE amount of power (heat) that the voice coil has dissipate increases when you are clipping the amp. However, if that amount of voltage is still under what the speaker can tolerate you could do that all day long. It just turns your voice coil into tiny space heaters.


By using larger amps you can supply (maybe over supply) enough voltage for the peaks in the music, but the average amount of power will be far less. Basically it will hit harder and sound cleaner, right up until you launch the cones into orbit.

And this is the great balancing act we all face.
 
Re: Under powering speakers

Aaron McQueen said:
Also there's mention of distortion being the cause of the damage. If that's the case then I need to have a talk with our electric guitar player.
Click to expand...

Any speaker is happy to play any distorted signal all day long. As long as it is within it's power handling window.

This also goes for square waves, saw tooth, triangle, And even DC. All no problem as long as the speaker's power handling, long term and short term, are not exceeded.
 
Re: Under powering speakers

Aaron McQueen said:
I've seen quite a few posts on other forums and facebook groups where people are claiming that under powering a speaker is very dangerous and can damage the speaker more than overpowering it. The explanation is added that under powering leads to clipping the amp and that will create a square wave that basically destroys the speaker. Something doesn't sound right to me, so I came here to ask the experts. Is this true? What's the whole story? What really destroys the speaker? I've personally under powered speakers before and haven't experienced any problems, but I've also kept things out of the red.
Click to expand...

STOP the madness... Do a search. This has been discussed ad nasuem here and at prosound web.

Speakers are damaged by too much power plain and simple... really...

JR
 
Re: Under powering speakers

John Roberts said:
STOP the madness... Do a search. This has been discussed ad nasuem here and at prosound web.

Speakers are damaged by too much power plain and simple... really...

JR
Click to expand...

You're right. I should know better. I've been around here and PSW long enough to know these things. I just second guessed myself since there was so many people saying the same thing.
 
Re: Under powering speakers

Aaron McQueen said:
I've seen quite a few posts on other forums and facebook groups where people are claiming that under powering a speaker is very dangerous and can damage the speaker more than overpowering it. The explanation is added that under powering leads to clipping the amp and that will create a square wave that basically destroys the speaker. Something doesn't sound right to me, so I came here to ask the experts. Is this true? What's the whole story? What really destroys the speaker? I've personally under powered speakers before and haven't experienced any problems, but I've also kept things out of the red.
Click to expand...

Hey Aaron,

http://bennettprescott.com/downloads/LoudspeakerFundamentals.pdf
 
Re: Under powering speakers

John Roberts said:
STOP the madness... Do a search. This has been discussed ad nasuem here and at prosound web.

Speakers are damaged by too much power plain and simple... really...

JR
Click to expand...

Speakers are damaged by too much power, or physically moving beyond their ability. It is possible that a signal can contain the right harmonics to cause a speaker to move beyond it's physical limits and cause damage without overdriving the speaker.

As far as why square waves cause damage, it's because a square wave is twice the actual power of a sine wave. Even though the max voltage is the same, if you clip your amp, you could be providing up to twice the rated power of the amp to the speaker.

The answer is never clip your amp and you should be fine.
 
Re: Under powering speakers

Aaron McQueen said:
You're right. I should know better. I've been around here and PSW long enough to know these things. I just second guessed myself since there was so many people saying the same thing.
Click to expand...

You were right to post here. I don't care how much it's been discussed, I still gained some info and so did you.
 
Re: Under powering speakers

Aaron McQueen said:
Follow up question to the article. What is needed to do the RMS limiter? Does the device need to know some information about the speaker? Does it need to be able to sense the output of the amplifier?
Click to expand...
To do it well, destructive testing. Peak and RMS limiters are two tools in your toolbox. By setting both limiters very conservatively you can make it pretty much impossible to kill your speaker. You will sacrifice significant performance though. Finding the balance between performance and safety is complicated, and while you can make some guesses, manufacturers do it by smoking some stuff to find the limits.

For those of us who don't have a large reconing budget, you can start with the peak limiter set per the manufacturer's specs (may have to convert watts to volts), and for RMS, start at something like 25% of program power with a 2 second delay. From there, use your ears, eyes, and nose to determine how stressed the box is, and you can refine from there.
 
Re: Under powering speakers

TJ Cornish said:
To do it well, destructive testing. Peak and RMS limiters are two tools in your toolbox. By setting both limiters very conservatively you can make it pretty much impossible to kill your speaker. You will sacrifice significant performance though. Finding the balance between performance and safety is complicated, and while you can make some guesses, manufacturers do it by smoking some stuff to find the limits.

For those of us who don't have a large reconing budget, you can start with the peak limiter set per the manufacturer's specs (may have to convert watts to volts), and for RMS, start at something like 25% of program power with a 2 second delay. From there, use your ears, eyes, and nose to determine how stressed the box is, and you can refine from there.
Click to expand...

I guess this is why powered speakers are so appealing.
 
Re: Under powering speakers

Aaron McQueen said:
I guess this is why powered speakers are so appealing.
Click to expand...

Ding ding ding... give the man a cigar. :)

Besides average (heat power) management, and peak (excursion) management, speaker excursion is not a simple peak voltage consideration but a voltage @ frequency situation, so best managed with dedicated processing set with knowledge about the box tuning and driver.

I prefer to let the loudspeaker design engineers manage this stuff.

JR
 
Top Bottom