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Author Topic: Here's a pretty good article on how NOT to destroy your speakers  (Read 17477 times)

Branko Pucekovic

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Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #10 on: February 24, 2014, 01:10:45 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.

I like number 3
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g'bye, Dick Rees

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Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #11 on: February 24, 2014, 01:12:53 pm »

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.

Scott...

It's not the thing itself, but the OE involved in persisting to abuse the gear until it fails.

Square waves do not kill speakers.  Idiots kill speakers.
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Scott Carneval

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Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #12 on: February 24, 2014, 01:20:16 pm »

Scott...

It's not the thing itself, but the OE involved in persisting to abuse the gear until it fails.

Square waves do not kill speakers.  Idiots kill speakers.

I agree with that.  And I further add to it that if you're going to run a 500 watt amp into severe clipping, you're probably going to run a 2000 watt amp into severe clipping as well, so you're going to destroy the speaker regardless of how much power you send to it.  But the overall article is accurate, especially as it relates to over-excursion and overheating.
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Taylor Hall

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Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #13 on: February 24, 2014, 01:24:54 pm »

The problem is that to the layman reading the article they think "oh dear, if my speakers are rated for 500W, then I need a 500W amp or I'll destroy them!" Which, in turn, sells Crutchfield more high-dollar amps because of customers misunderstanding half-truths. If they didn't wait to explain that using a smaller amp than what your speakers are rated is perfectly fine until the last couple sentences it would add much more credibility to the article and not make it smack of up-selling hijinks.

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 500 watt amp CAN be worse for a 1000wrms subwoofer than running a 2000 watt amp cleanly.  It all depends on the content of the signal.

"Not giving your speaker or subwoofer enough power can be even worse that giving it too much."

If I were someone that knew nothing about sound reinforcement that pretty much says to me that I need an amp that exactly matches my speaker's specs or I'm going to blow it. This again highlights the tactics the article is using to try and up-sell customers. Scare them up front into thinking they need something, then bury the fact that it's not really necessary in a later portion after they've already stopped paying attention and made up their minds.

Seems like it's just business as usual for crutchfield.
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Scott Carneval

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Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #14 on: February 24, 2014, 01:37:02 pm »

The problem is that to the layman reading the article they think "oh dear, if my speakers are rated for 500W, then I need a 500W amp or I'll destroy them!"

Which may or may not be unreasonable.  If someone buys a '500 watt speaker' chances are they expect '500 watt performance' and therefore need about a 500-1000 watt amp.  I believe thats what the author was trying to convey.
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TJ (Tom) Cornish

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Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #15 on: February 24, 2014, 02:29:18 pm »

I'd rather recommend this article: http://www.bennettprescott.com/downloads/LoudspeakerFundamentals.pdf which is actually accurate, instead of sort of accurate.
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Lyle Williams

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Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #16 on: February 24, 2014, 02:30:51 pm »

I like number 3

You like Nickelback?  OK....
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Tim McCulloch

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Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #17 on: February 24, 2014, 03:07:51 pm »


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

If wishing could make it so...

edit ps.  Canada gave us Nickelback AND Bieber.  How hostile does Canada have to get before we invade to return both acts to their homeland? /satire
« Last Edit: February 24, 2014, 03:10:16 pm by Tim McCulloch »
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Chuck Simon

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Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #18 on: February 24, 2014, 03:23:06 pm »

If wishing could make it so...

edit ps.  Canada gave us Nickelback AND Bieber.  How hostile does Canada have to get before we invade to return both acts to their homeland? /satire

Cut Canada a break, they gave us Neil Young, too ;)
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Ray Aberle

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Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #19 on: February 24, 2014, 03:24:55 pm »

If wishing could make it so...

edit ps.  Canada gave us Nickelback AND Bieber.  How hostile does Canada have to get before we invade to return both acts to their homeland? /satire
And Bryan Adams, but I heard they've already apologised for that one...

Ray
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Re: Here's a pretty good article on how clipped waveforms destroy speakers
« Reply #19 on: February 24, 2014, 03:24:55 pm »


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