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Author Topic: Here's a pretty good article on how NOT to destroy your speakers  (Read 17476 times)

Scott Carneval

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Here's a pretty good article on how NOT to destroy your speakers
« on: February 24, 2014, 10:19:00 am »

Ironically enough, it came from Crutchfield, but it's well written, easy to understand, and fairly accurate. 

http://www.crutchfield.com/S-ofaNUv4FAuT/learn/why-subs-blow.html?utm_source=taboola&utm_medium=referral
« Last Edit: February 24, 2014, 01:50:21 pm by Scott Carneval »
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Chuck Simon

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Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #1 on: February 24, 2014, 10:54:41 am »

Well this should be the start of an interesting conversation!  Much of the stuff in that article has been "debunked" here by people who know a lot more than I. For example, quoted from the article:

"Not giving your speaker or subwoofer enough power can be even worse that giving it too much. The sub tries to do what you're asking it to do, but it doesn't have the power to keep up with your demands."

Huh?  if you are not giving your subwoofer "enough" power, how does it know "what you're asking it to do"?
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Paul G. OBrien

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Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #2 on: February 24, 2014, 11:02:31 am »

it's well written, easy to understand, and fairly accurate. 

Nope.. its full of misinformation and poorly written. Do not recommend.
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John Roberts {JR}

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Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #3 on: February 24, 2014, 11:07:13 am »

Ironically enough, it came from Crutchfield, but it's well written, easy to understand, and fairly accurate. 

http://www.crutchfield.com/S-ofaNUv4FAuT/learn/why-subs-blow.html?utm_source=taboola&utm_medium=referral

No, just repeating old mis-information.

Please do a search of this site for past discussions where every one of these false points were inspected and explained in detail.

JR
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David Parker

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Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #4 on: February 24, 2014, 11:32:58 am »

Well this should be the start of an interesting conversation!  Much of the stuff in that article has been "debunked" here by people who know a lot more than I. For example, quoted from the article:

"Not giving your speaker or subwoofer enough power can be even worse that giving it too much. The sub tries to do what you're asking it to do, but it doesn't have the power to keep up with your demands."

Huh?  if you are not giving your subwoofer "enough" power, how does it know "what you're asking it to do"?
if giving a speaker too little power would blow it, every time you stopped the music the speaker would blow! At idle the amp isn't sending any power to the speaker!
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Ray Aberle

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Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #5 on: February 24, 2014, 11:43:44 am »

No, just repeating old mis-information.

Please do a search of this site for past discussions where every one of these false points were inspected and explained in detail.

JR
At the bottom of the article's page, there is a little box:
Quote from: Bill Crutchfield
About Crutchfield
For over 40 years, I've worked hard to make sure you get the best possible shopping experience. I look forward to hearing your comments.
- Bill Crutchfield
Founder and CEO
Maybe we should send a flurry of messages... "Why your article is carp." Heh.

-Ray
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Geoff Doane

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Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #6 on: February 24, 2014, 11:47:55 am »

To be fair, the first two points the article makes are correct.  Too much excursion in either direction will tear things apart.  But they completely forgot about simply melting things with too much long term power.  And it went quickly downhill when they got to the part about clipping killing speakers.

GTD
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John Roberts {JR}

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Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #7 on: February 24, 2014, 12:28:49 pm »

At the bottom of the article's page, there is a little box:Maybe we should send a flurry of messages... "Why your article is carp." Heh.

-Ray
Good luck stamping out misinformation. The information highway does not discriminate against information based on veracity, and the OP thought he was doing a service by repeating this.

I used to write a column back in the early '80s called audio mythology and I routinely see the same myths reappear years later even after being well beaten down.

Some of these myths sound plausible (like the square wave causing drivers to stand still) and are easier for uninformed consumers to grasp than the real physics surrounding how drivers actually move in response to input voltage.

This has been well discussed numerous times here and I don't care to repeat myself this morning, while I don't expect my wishes to stop people from testing their personal understanding by sharing.

Please if you have questions do a search. A lot has been posted here about this subject. This is pretty basic sound reinforcement knowledge.. 


JR
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Brian Jojade

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Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #8 on: February 24, 2014, 12:35:13 pm »

Sending a square wave to the speaker will try to get it to move infinitely fast.  Thank god nobody has actually done that, because if the cone is moving infinitely fast, it would be moving faster than the speed of light, and create a black hole, and we'd all cease to exist.

The article does try to make sense of why under powering your speakers is bad, but does a horrible job explaining it.  Distortion alone does NOT kill speakers. However, distorted audio changes the waveform pattern in ways that could make an otherwise well operating system damage speakers.

There are 3 things that kill speakers. 
1. Asking the speaker to move beyond its physical limits.  Usually, a well designed speaker in a properly tuned cabinet will operate up to its power rating without issue.  However, if for example, you send subharmonic frequencies to a driver, it could try and move too far, even at rated power.  The distortion created by the speaker should be quite noticeable when this happens.  This can happen with a very clean sine wave as well as with distorted signal, so again, distortion isn't the cause.

2. Asking the speaker to dissipate more heat than it is capable of. Pretty simple.  The speaker coil can safely dissipate a specific amount of heat over time.  As long as you're below that threshold, you're safe. Now where it gets tricky is actually measuring the power used.  Music is not a constant. level or frequency.  It would be pretty boring if it was.  So because of this, you can get away with using an amplifier larger than the long term power rating of the speaker to handle the short bursts of power needed.  But beware that if you ask the speaker for too many short bursts, it's going to get hotter and hotter until it melts.  Now, here is where clipped signals come into play.  At the same voltage, a square wave represents double the power of a sine wave.  That means that the speaker has to dissipate twice the amount of heat.  Amplifiers are rated at the power they can provide with a sine wave type signal.  When that signal is pushed into a square wave, the amplifier can often output more than its rated power.  How much depends on other design factors.  Old school amps used to have power supplies big enough to do this forever.  Newer amps, not so much.   In any case, because the clipped square wave signal represents more power that the speaker has to dissipate, an amplifier listed with an output of half of the RMS rating of the speaker could potentially deliver enough power to destroy the speaker from overheating.  But only a DJ would be dumb enough to keep driving the speaker at that level for that long because it would sound horrible.  If your amplifier is less than half of the RMS rating of the speaker, you're not likely to be able to blow it up from overheating.  You could still cause damage though by exceeding the physical excursion properties of the driver.

 3. Asking the speaker to play Nickelback. The speaker will then commit suicide, at any power level.
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Brian Jojade

Scott Carneval

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Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #9 on: February 24, 2014, 01:03:11 pm »

Well this should be the start of an interesting conversation!  Much of the stuff in that article has been "debunked" here by people who know a lot more than I. For example, quoted from the article:

"Not giving your speaker or subwoofer enough power can be even worse that giving it too much. The sub tries to do what you're asking it to do, but it doesn't have the power to keep up with your demands."

Huh?  if you are not giving your subwoofer "enough" power, how does it know "what you're asking it to do"?

Pick it apart if you want, but the overall point of the article (and my intention behind posting it here) is to help beginners understand that over-excursion, overheating, and clipping can and will destroy speakers and/or subwoofers. This is posted in the lounge (beginner section) for a reason. 

The article doesn't say 'too small of an amp will kill your sub' it says that 'not giving your speaker enough power CAN be worse than giving it too much'.  While that statement might be misleading to some, it's not entirely inaccurate.   Hard clipping a smaller amp CAN result more long-term power, and therefore thermal damage.  It all depends on the content of the signal. 
« Last Edit: February 24, 2014, 01:07:32 pm by Scott Carneval »
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ProSoundWeb Community

Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #9 on: February 24, 2014, 01:03:11 pm »


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