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Anthony_Gomez
Ya brian! respect your elders!!!! 
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What damages a driver? (1 Viewer)
- Thread starter PaulDF
- Start date
Will Orth
Stunt Coordinator
- Joined
- Sep 14, 2002
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- 80
In Anthony_Gomez's Post is right on the money!
over drive the amp - then it Clips and turns in to DC
and drivers dont like that- it is almost like shorting out your voice coil. that is the heart-piston of your woofer. keep levels matched check amp gains and just keep an eye on whats going on for a few hours, what i do is do a sub-woofer break-in test 24 hours @ half output and see how it goes..
hope tghat helps...
Will
over drive the amp - then it Clips and turns in to DC
and drivers dont like that- it is almost like shorting out your voice coil. that is the heart-piston of your woofer. keep levels matched check amp gains and just keep an eye on whats going on for a few hours, what i do is do a sub-woofer break-in test 24 hours @ half output and see how it goes..
hope tghat helps...
Will
Griff
Stunt Coordinator
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- Jul 6, 2002
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Kicking it
Jerry Parker
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- Jan 15, 2001
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Uh, guys the fact that the amplifier is producing a clipped signal does not mean that it will hurt the driver. The fact is, when you have an amplifier that can produce a "clean" 100 watts, when completely clipped, the output will be 200 watts. Thats 2x the power of a clean sine wave, and your giving your driver 2x the power than you thought you were. The clipped signal does not mean that the woofer will have an "irregular" movement, because the suspension filters out the fact that the driver stays at peaks anyways. It wont hurt the driver as long as it hasnt surpased the drivers thermal or mechanical limits.
I know this from experience. With a dayton dvc 15" I have a 150w amplifier attached, and can play it extremely clipped without hurting it. Now, I do that for short times, if I were to do that for a long amount of time, the driver would probably suffer from thermal overload.
http://www.eatel.net/~amptech/elecdisc/caraudio.htm
He talks about the fact that a clipped signal will produce less cooling effects than an unclipped one, but for the most part, i disagree, because the driver will still be moving to the crest and trough just as fast, but the driver WILL be getting 2x the power.
I know this from experience. With a dayton dvc 15" I have a 150w amplifier attached, and can play it extremely clipped without hurting it. Now, I do that for short times, if I were to do that for a long amount of time, the driver would probably suffer from thermal overload.
http://www.eatel.net/~amptech/elecdisc/caraudio.htm
He talks about the fact that a clipped signal will produce less cooling effects than an unclipped one, but for the most part, i disagree, because the driver will still be moving to the crest and trough just as fast, but the driver WILL be getting 2x the power.
Jerry Parker
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Paul Stiles
Agent
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- Oct 4, 2002
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When the amplifier is "clipping", it is producing harmonics of the input waveform. It is not valid to look at the clipped part of the waveform as DC. If the amplifier's response goes down to DC, then the clipped part may be flat for the time of the clipping. If the amp does not have response down to DC, then the clipped part of the amp's output will have a decreasing amplitude slope. A Fourier analysis will show the fundamental frequency(ies) and a series of harmonics (mostly, if not entirely, odd harmonics) of decreasing amplitude as frequency increases. The only DC present will be whatever DC offset the amp is producing, usually in the low millivolt range or less. Depending on the input fundamental frequency, these harmonics may or may not be reproduced by the driver. They will contribute to the thermal stress on the voice coil and its surrounding thermal sink. However, due to the voice coil inductance (and any other passive crossover components that may be involved), the higher harmonics will see a higher inductive reactance and their thermal contributions will be even less.
When an amplifier that is driving a speaker with a tweeter and perhaps a midrange driver (a multi-way speaker system) clips, the speaker's crossover sends the clipping products (harmonics) to the midrange and/or the tweeter, depending on the frequencies involved. Beings midranges and especially tweeters have voice coils that are much more delicate that that big 'ol beefy woofer, they are more likely to be damaged, especially when given a extra big helping of amplifier clipping products. This is where the idea (valid in many cases) that it is better to drive a speaker with an amplifier that is more powerful (so that it won't clip) than what is recommended for the speaker than an amp that is underrated for the speaker (which will then be more likely overdriven, producing clipping products that may wipe out the tweeter and/or midrange). This does not apply to a stand-alone subwoofer, in my guestimation.
I would GUESS that repeated bottoming out of the voice coil would be bad, placing a great mechanical stress on the voice coil system, especially if the woofer is being hugely overdriven. If, due to prior mechanical or thermal stress, an epoxy bond had been weakened, bottoming of the voice coil may be the final straw that broke the woofer's back.
This is all conjecture on my part beings I am not a woofer design engineer.
Paul
When an amplifier that is driving a speaker with a tweeter and perhaps a midrange driver (a multi-way speaker system) clips, the speaker's crossover sends the clipping products (harmonics) to the midrange and/or the tweeter, depending on the frequencies involved. Beings midranges and especially tweeters have voice coils that are much more delicate that that big 'ol beefy woofer, they are more likely to be damaged, especially when given a extra big helping of amplifier clipping products. This is where the idea (valid in many cases) that it is better to drive a speaker with an amplifier that is more powerful (so that it won't clip) than what is recommended for the speaker than an amp that is underrated for the speaker (which will then be more likely overdriven, producing clipping products that may wipe out the tweeter and/or midrange). This does not apply to a stand-alone subwoofer, in my guestimation.
I would GUESS that repeated bottoming out of the voice coil would be bad, placing a great mechanical stress on the voice coil system, especially if the woofer is being hugely overdriven. If, due to prior mechanical or thermal stress, an epoxy bond had been weakened, bottoming of the voice coil may be the final straw that broke the woofer's back.
This is all conjecture on my part beings I am not a woofer design engineer.
Paul
Patrick Sun
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Just to add to what Jerry and Paul stated, clipped waveforms approximate square waves, and the principle of superposition applies when describing waveforms, and how to produce them mathematically.
This means to get a clipped or square waveform, you have to add in numerous harmonics of the frequency for the output. You have to go a lot higher in frequency than the usual limits of audio frequency (around 20KHz) to "add" together to produce that clipped waveform. So as you have higher and higher frequencies at the input to create a clipped signal, the clipped signal is asking the driver to produce sound/frequencies outside of its capabilities at an unhealthy amplitude level (loudness, in this case).
So, it's much easier to fry a tweeter with a clipped input because the input is trying to make the tweeter play higher frequencies than it's designed for, and when the amplitude of the higher frequencies is large enough, that is what fries the tweeter.
Woofer drivers are more susceptible to mechanical failure (where the input causes the travel of the cone to exceed its mechanical limits, which causes distortion, grinding noises or pops at high input levels). And of course, too much power for a long duration can cause thermal failure of the voice coil as well.
This means to get a clipped or square waveform, you have to add in numerous harmonics of the frequency for the output. You have to go a lot higher in frequency than the usual limits of audio frequency (around 20KHz) to "add" together to produce that clipped waveform. So as you have higher and higher frequencies at the input to create a clipped signal, the clipped signal is asking the driver to produce sound/frequencies outside of its capabilities at an unhealthy amplitude level (loudness, in this case).
So, it's much easier to fry a tweeter with a clipped input because the input is trying to make the tweeter play higher frequencies than it's designed for, and when the amplitude of the higher frequencies is large enough, that is what fries the tweeter.
Woofer drivers are more susceptible to mechanical failure (where the input causes the travel of the cone to exceed its mechanical limits, which causes distortion, grinding noises or pops at high input levels). And of course, too much power for a long duration can cause thermal failure of the voice coil as well.
