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#1
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Damping Material Question
I always thought the purpose for damping material was to keep sound
waves from bouncing off of the back/sides of the enclosure and back into the driver causing distortion. What is the deal with using damping material to fool the enclosure into thinking it is bigger? If you add something to a box, doesn't it make it smaller? LOL |
#2
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Damping Material Question
"Ron" wrote in message ... I always thought the purpose for damping material was to keep sound waves from bouncing off of the back/sides of the enclosure and back into the driver causing distortion. Its purpose is to reduce standing waves within the enclosure that would affect the frequency response. This applies to mid-to-high range of the audio spectrum. I don't think distortion is an issue. What is the deal with using damping material to fool the enclosure into thinking it is bigger? If you add something to a box, doesn't it make it smaller? LOL At lower frequencies where standing waves and reflections aren't an issue because the enclosure dimensions prevent them anyway, the addition of damping material will increase the enclosures effective size |
#3
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Damping Material Question
Ron wrote:
I always thought the purpose for damping material was to keep sound waves from bouncing off of the back/sides of the enclosure and back into the driver causing distortion. What is the deal with using damping material to fool the enclosure into thinking it is bigger? If you add something to a box, doesn't it make it smaller? LOL The idea is that the thermal insulation aspect of "stuffing" (usually polyfill, though fiberglass insulation has been used in some home speakers I've seen - not hot on the idea of glass fibers being propelled into my atmosphere) absorbs some of the acoustic output of the speaker in the same way the air in a larger enclosure would. In theory, it ads 15-25%. In actual practice...well...you can make up your own mind, but I've never measured any actual noticable change that couldn't also be accounted for by other factors. -- thelizman "I didn't steal the FAQ either" Before you ask a question, check the FAQs for this newsgroup at http://www.mobileaudio.com/rac-faq. It contains over a decade and a half of knowledge. teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/ teamROCS Car Audio News http://www.teamrocs.com/news/ "It's about the music, stupid" This post is Copyright (C) 2004. Reproduction of its content anywhere other than usenet without the express written permission of the author is forbidden. |
#4
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Damping Material Question
Fred wrote:
Its purpose is to reduce standing waves within the enclosure that would affect the frequency response. This applies to mid-to-high range of the audio spectrum. I don't think distortion is an issue. At lower frequencies where standing waves and reflections aren't an issue because the enclosure dimensions prevent them anyway, the addition of damping material will increase the enclosures effective size How many 15 foot subwoofer boxes have you ever seen? It's not about "standing waves", unless you're building a full range box. -- thelizman "I didn't steal the FAQ either" Before you ask a question, check the FAQs for this newsgroup at http://www.mobileaudio.com/rac-faq. It contains over a decade and a half of knowledge. teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/ teamROCS Car Audio News http://www.teamrocs.com/news/ "It's about the music, stupid" This post is Copyright (C) 2004. Reproduction of its content anywhere other than usenet without the express written permission of the author is forbidden. |
#5
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Damping Material Question
"thelizman" wrote in message ... Fred wrote: Its purpose is to reduce standing waves within the enclosure that would affect the frequency response. This applies to mid-to-high range of the audio spectrum. I don't think distortion is an issue. At lower frequencies where standing waves and reflections aren't an issue because the enclosure dimensions prevent them anyway, the addition of damping material will increase the enclosures effective size How many 15 foot subwoofer boxes have you ever seen? It's not about "standing waves", unless you're building a full range box. You wanna read my post again? See the part about mid-to-high range of the audio spectrum? |
#6
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Damping Material Question
In article ,
thelizman wrote: In theory, it ads 15-25%. In actual practice...well...you can make up your own mind, but I've never measured any actual noticable change that couldn't also be accounted for by other factors. Actually, if you use the right density of stuffing, you do get about 15 to 25% effective size increase. The stuffing slows down the propagation of the sound waves within the enclosure. The effect is more commonly used to advantage in "transmission line" style home enclosures, allowing the use of a shorter line for a given bass extension. I've got a technical paper somewhere here with suggested densities for various types of stuffing. I expect there'll be useful information on web sites that discuss home construction of hi-fi speakers, too. -- Don Hills (dmhills at attglobaldotnet) Wellington, New Zealand |
#7
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Damping Material Question
Fred wrote:
You wanna read my post again? See the part about mid-to-high range of the audio spectrum? You wanna explain to me where mid to high frequencies occur in a subwoofer system, ya moron? -- thelizman "I didn't steal the FAQ either" Before you ask a question, check the FAQs for this newsgroup at http://www.mobileaudio.com/rac-faq. It contains over a decade and a half of knowledge. teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/ teamROCS Car Audio News http://www.teamrocs.com/news/ "It's about the music, stupid" This post is Copyright (C) 2004. Reproduction of its content anywhere other than usenet without the express written permission of the author is forbidden. |
#8
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Damping Material Question
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#9
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Damping Material Question
"thelizman" wrote in message ... Fred wrote: You wanna read my post again? See the part about mid-to-high range of the audio spectrum? You wanna explain to me where mid to high frequencies occur in a subwoofer system, ya moron? When you show me where the original post mentioned a subwoofer you totally stupid ****wit. He said "enclosure" not subwoofer! |
#10
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Damping Material Question
"Fred" wrote in message You wanna read my post again? See the part about mid-to-high range of the audio spectrum? You wanna explain to me where mid to high frequencies occur in a subwoofer system, ya moron? When you show me where the original post mentioned a subwoofer you totally stupid ****wit. He said "enclosure" not subwoofer! He does not have to say subwoofer, it is implied. It is called reading comprehension skills. Do they not teach that anymore? Therefore high frequencies really have nothing to do with the question posed. Les |
#11
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Damping Material Question
"Les" wrote in message ... "Fred" wrote in message You wanna read my post again? See the part about mid-to-high range of the audio spectrum? You wanna explain to me where mid to high frequencies occur in a subwoofer system, ya moron? When you show me where the original post mentioned a subwoofer you totally stupid ****wit. He said "enclosure" not subwoofer! He does not have to say subwoofer, it is implied. It is called reading comprehension skills. Do they not teach that anymore? Therefore high frequencies really have nothing to do with the question posed. Les No implication in the original post at all. You have interpreted your way and I have interpreted it as it was written. It has nothing to do with comprehension at all. If **** was electricity you'd be a walking, talking power station. |
#12
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Damping Material Question
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#13
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Damping Material Question
Fred wrote:
No implication in the original post at all. You have interpreted your way and I have interpreted it as it was written. It has nothing to do with comprehension at all. If **** was electricity you'd be a walking, talking power station. You're an idiot. Just admit it. Anyone who starts talking about standing waves in a box for a car is an idiot for multiple reasons. Be quiet now. -- thelizman "I didn't steal the FAQ either" Before you ask a question, check the FAQs for this newsgroup at http://www.mobileaudio.com/rac-faq. It contains over a decade and a half of knowledge. teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/ teamROCS Car Audio News http://www.teamrocs.com/news/ "It's about the music, stupid" This post is Copyright (C) 2004. Reproduction of its content anywhere other than usenet without the express written permission of the author is forbidden. |
#14
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Damping Material Question
Don Hills wrote:
As the man with a wooden leg said, "That's a matter of a pinion." grin Isn't that also the same man who said "har, whars th' cabin boyee, aye need t'sheath me sword"? -- thelizman "I didn't steal the FAQ either" Before you ask a question, check the FAQs for this newsgroup at http://www.mobileaudio.com/rac-faq. It contains over a decade and a half of knowledge. teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/ teamROCS Car Audio News http://www.teamrocs.com/news/ "It's about the music, stupid" This post is Copyright (C) 2004. Reproduction of its content anywhere other than usenet without the express written permission of the author is forbidden. |
#17
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Damping Material Question
"Fred" wrote in message No implication in the original post at all. You have interpreted your way and I have interpreted it as it was written. It has nothing to do with comprehension at all. If **** was electricity you'd be a walking, talking power station. So what do you think the OP is talking about? A box for his tweeters? He mentioned a box and an enclosure, ie things you would normally place a subwoofer in. He also mentions 2 phenomenoms that are associated with subwoofers. So there are 4 things associated with a subwoofer system. Now I can stretch one, maybe two of those things to include midbass drivers. But how can you stretch it that much to think he is talking mid/high drivers? You need to take a reading for comprehension class. BTW: OP, you should just google for this topic as it has been discussed many times here. Les |
#18
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Damping Material Question
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#19
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Damping Material Question
In article ,
Eddie Runner wrote: give him hell Don! Why? I'm aware of his history, and he does appear to be what many claim him to be, but he's made his reputation and now he has to live with it. As you well know, I generally confine myself to gently pointing out the misconceptions some people expound from time to time. Have you figured out how a bridged amp works yet? big grin And notice how the "should I fasten down my sub box" thread went quiet? bigger grin I could see the light bulbs lighting up from way over here... Toms not a bad guy, he is just a little overzealous in his embelishing of facts so he can publish his own papers in largely non technical magazines for profit... Thanks for the concise potted history. Google Groups filled in the gaps. I saw some of the arguments that Tom has been in while I was looking for clues as to the title of the paper I can't find. (I did find an on-topic post by Dick Pierce from 1985...) -- Don Hills (dmhills at attglobaldotnet) Wellington, New Zealand "I don't use Linux. I prefer to use an OS supported by a large multi- national vendor, with a good office suite, excellent network/internet software and decent hardware support." |
#20
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Damping Material Question
Don Hills wrote:
Have you figured out how a bridged amp works yet? big grin Please notice that thanks to my persistance it is now VERY RARE to find someone saying that bridging halves the resistance.... And notice how the "should I fasten down my sub box" thread went quiet? bigger grin I dont remember that thread was I in that one..?? Eddie |
#21
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Damping Material Question
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#22
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Damping Material Question
In article ,
Eddie Runner wrote: Please notice that thanks to my persistance it is now VERY RARE to find someone saying that bridging halves the resistance.... Ah, but that doesn't mean you're right. just kidding I dont remember that thread was I in that one..?? Nope. Sancho and Lizard were. Look in Google for "How to secure a sub enclosure", started 2 weeks ago. -- Don Hills (dmhills at attglobaldotnet) Wellington, New Zealand |
#23
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Damping Material Question
Don Hills wrote: In article , Eddie Runner wrote: Please notice that thanks to my persistance it is now VERY RARE to find someone saying that bridging halves the resistance.... Ah, but that doesn't mean you're right. just kidding a few years back everyone said bridging halves speakers impedance.. it was on tech websites, manufacturers web sites, (some of my best argueing was with some of the JL techs) and even in amp install manuals.... Thanks to my persistance none of that is there anymore, folks have learned the truth... Damn I am good.... ;-) I dont remember that thread was I in that one..?? Nope. Sancho and Lizard were. Look in Google for "How to secure a sub enclosure", started 2 weeks ago. Ahhh... I try not to argue with morons... Eddie |
#24
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Damping Material Question
In article , Eddie Runner wrote:
Don Hills wrote: In article , Eddie Runner wrote: Please notice that thanks to my persistance it is now VERY RARE to find someone saying that bridging halves the resistance.... Ah, but that doesn't mean you're right. just kidding a few years back everyone said bridging halves speakers impedance.. it was on tech websites, manufacturers web sites, (some of my best argueing was with some of the JL techs) and even in amp install manuals.... Thanks to my persistance none of that is there anymore, folks have learned the truth... Damn I am good.... ;-) Aw but you rarely hear what bridging really does.It doubles the voltage! greg |
#26
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Physics of bridging an amplifier - was: Damping Material Question
True, and I've always wondered why it's not explained that way more often in the first place. I used to see that "halving the impedance" crap all the time too, when the correct explanation is so much simpler - you double the voltage swing, which quadruples the output power. (Obviously, the *total* power only doubles, since you're going from two channels to only one when you bridge the amp.) Liz - I'm saddened to hear that the JL techs were arguing with you about how amp bridging works. I can understand it if the marketing types were confused, and maybe even the manual writers, but the techs and engineers should know better. How hard is it to understand that power equals voltage squared divided by impedance? Scott Gardner Power does not equal voltage squared divided by impedance..... sorry, but power equalss voltage squared divided by resistance... impedance and resistances are different... If you wanna be talking about impedences...you gotta take into account PF angles... which means you arent really dealing with Power anymore, your dealing V-A (volt-amps). Just what i gathered at Electrical eng. school. Never did understand why speakers are rated in WATTS and impedences. Can anyone explain this to me? Or is the 5 text books i spent ,which seems to be, unlimited hours reading...wrong? |
#27
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Physics of bridging an amplifier - was: Damping MaterialQuestion
Scott Gardner wrote:
Liz - I'm saddened to hear that the JL techs were arguing with you about how amp bridging works. Liz..???????????? No Scott, it was me! Eddie Runner! In the old days EVERYONE said inpedance halves when bridging an amplifier (thats how bridging works)... Many amp manuals said so.. Many web sites said so. Most all installers said so... And RAC said so every day! Anyone that was around back then will remember my relentless debates and arguements over why it was not so... It is doubling the voltage, not halving the impedance! If youve been around to see me in some big arguements here then let me tell you the recent arguements are nothing compared to the size and length of the arguements over bridging that we used to have, those were the whoppers!! Since EVERYONE was against me, I sometimes argued against 5 or 6 guys at the same time, it was overwhelming but I stuck it out and eventually won just about everyone over to the truth.... Alot of folks back then called me the bridging guy. After a while when someone would come on and say bridging halves the impedence, someone would say DONT LET EDDIE SEE YOU SAY THAT!! ha ha ha Nowdays I almost never hear that anymore... For a while I know folks were afraid I would jump on them if they said it... ;-) Now, it may just be because amps arent bridged that much anymore, the class D amps are so common...... Get it right in the history books, it was Eddie Runner, not Liz! Eddie |
#28
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Physics of bridging an amplifier - was: Damping MaterialQuestion
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#29
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Physics of bridging an amplifier - was: Damping Material Question
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#30
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Damping Material Question
"thelizman" wrote in message
... Fred wrote: You wanna read my post again? See the part about mid-to-high range of the audio spectrum? You wanna explain to me where mid to high frequencies occur in a subwoofer system, ya moron? if you have a metal cone sub there can be hi-freq content. look at the lab graphs, so he's not a moron you may be. |
#31
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Damping Material Question
"thelizman" wrote in message
... Fred wrote: No implication in the original post at all. You have interpreted your way and I have interpreted it as it was written. It has nothing to do with comprehension at all. If **** was electricity you'd be a walking, talking power station. You're an idiot. Just admit it. Anyone who starts talking about standing waves in a box for a car is an idiot for multiple reasons. Be quiet now. are you saying there are no standing waves in sub encs.?? |
#32
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Physics of bridging an amplifier - was: Damping Material Question
Speakers are rated in watts in order to tell you how much electrical power they
can dissipate. Over 95% of the power delivered to a loudspeaker is dissipated as heat by it's resistive element and can quickly barbecue the voice coil. Reactive power (V-A) is what does all the work in a speaker. Since the reactive power is not converted to heat, the maximum V-A delivered to a speaker will vary depending on several things such as enclosure type, signal frequency, and driver x-max among others. In this case the driver will reach it's excursion limit and mechanically destroy itself. Since your average loudspeaker is only about 5% efficient at best, it's satisfactory to only provide it's maximum power rating in watts. If a speaker bottoms out it will sound like crap and the listener will turn down the volume. This inherent "built-in protection" protects the speaker from mechanical damage resulting from excessive V-A. Kevin Murray wrote in message ... True, and I've always wondered why it's not explained that way more often in the first place. I used to see that "halving the impedance" crap all the time too, when the correct explanation is so much simpler - you double the voltage swing, which quadruples the output power. (Obviously, the *total* power only doubles, since you're going from two channels to only one when you bridge the amp.) Liz - I'm saddened to hear that the JL techs were arguing with you about how amp bridging works. I can understand it if the marketing types were confused, and maybe even the manual writers, but the techs and engineers should know better. How hard is it to understand that power equals voltage squared divided by impedance? Scott Gardner Power does not equal voltage squared divided by impedance..... sorry, but power equalss voltage squared divided by resistance... impedance and resistances are different... If you wanna be talking about impedences...you gotta take into account PF angles... which means you arent really dealing with Power anymore, your dealing V-A (volt-amps). Just what i gathered at Electrical eng. school. Never did understand why speakers are rated in WATTS and impedences. Can anyone explain this to me? Or is the 5 text books i spent ,which seems to be, unlimited hours reading...wrong? |
#33
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Damping Material Question
Tha Ghee wrote:
"thelizman" wrote in message ... are you saying there are no standing waves in sub encs.?? Not at subwoofer frequencies. Prove me wrong. -- thelizman "I didn't steal the FAQ either" Before you ask a question, check the FAQs for this newsgroup at http://www.mobileaudio.com/rac-faq. It contains over a decade and a half of knowledge. teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/ teamROCS Car Audio News http://www.teamrocs.com/news/ "It's about the music, stupid" This post is Copyright (C) 2004. Reproduction of its content anywhere other than usenet without the express written permission of the author is forbidden. |
#34
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Physics of bridging an amplifier - was: Damping MaterialQuestion
Kevin Murray wrote:
If a speaker bottoms out it will sound like crap and the listener will turn down the volume. This inherent "built-in protection" protects the speaker from mechanical damage resulting from excessive V-A. You would think, anyway. What most often happens is the listener ignores it, thinks its part of the source, or because the subs are in the trunk they don't even notice. Thats why as an installer I was such a fan of Alpine's (or was it JBL's?)old soft-clip design. The speaker never bottomed out per-se, it just got harder to push. It's also worth pointing out that IME 75% of the time a speaker blows, its not the voice coil that went bad, but the mechanical portion of the speaker which couldn't handle the abuse. Spiders and surrounds come unglued, get worn out, or the cone itself becomes warped. I've even seen some speakers where the leads get ripped out of the speaker terminal in subs that have high Xmax, but don't cut the leads long enough. Power handling in a voice coil is rarely a problem. Thats why I tell people not to worry about an amp thats too big, you can always turn it down when things start to go "thwack!". -- thelizman "I didn't steal the FAQ either" Before you ask a question, check the FAQs for this newsgroup at http://www.mobileaudio.com/rac-faq. It contains over a decade and a half of knowledge. teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/ teamROCS Car Audio News http://www.teamrocs.com/news/ "It's about the music, stupid" This post is Copyright (C) 2004. Reproduction of its content anywhere other than usenet without the express written permission of the author is forbidden. |
#35
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Damping Material Question
"Tha Ghee" wrote in message if you have a metal cone sub there can be hi-freq content. look at the lab graphs, so he's not a moron you may be. No Ghee, you and Fred are morons. Do you not run a crossover on a sub? Are you that dumb? Let's say you run your crossover unusually high at 140Hz, do you consider that high frequency? We are talking application here, not what a sub could potentially do in a lab if the conditions are right. Les |
#36
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Physics of bridging an amplifier - was: Damping Material
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#37
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Physics of bridging an amplifier - was: Damping Material
Nousaine wrote:
Not saying that it doesn't happen; I'd just like to know more about the circumstance. Tom, I think Liz, and maybe other installers may be mistaken here.. As installers working in the bay we do see alot of speakers with worn out surrounds and alot of problems other than burned VCs. But I think your right this time Tom, the things other than burned VCs like surrounds coming apart are usually just bad (cheap or badly engineered) speakers... Or where an installer put a screw threw it or where the outside (where the cork would be but they dont use cork anymore) is coming off so badly that the speaker is coming apart from the basket. The ones where the customer just play the damn things too loud are typicly burned coils, but we probably see (in the bays) way more of other types of abuse on the drivers as well.... I see what Liz is saying, and you work in a lab more than a bay so you may not see what real installers see... But what we see isnt really what Liz thinks it is (IMO)..... Eddie Runner |
#38
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Physics of bridging an amplifier - was: Damping Material
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#39
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Physics of bridging an amplifier - was: Damping Material
Nousaine wrote:
thelizman FWIW; in speaker testing the most common failure mode is melting voice coil glue. I drive every woofer to its maximum SPL capability using a ramped sine wave ( a demanding but non-purposfully threatening) that has characteristics similar to musical programs. snip Not saying that it doesn't happen; I'd just like to know more about the circumstance. Yeah, in your LAB, where you don't deal with seasonal swings in temperature and humidity. Woofers should be designed for real world conditions, not to satisfy lab tests. -- thelizman "I didn't steal the FAQ either" Before you ask a question, check the FAQs for this newsgroup at http://www.mobileaudio.com/rac-faq. It contains over a decade and a half of knowledge. teamROCS Car Audio Forums http://www.teamrocs.com/caraudio/ teamROCS Car Audio News http://www.teamrocs.com/news/ "It's about the music, stupid" This post is Copyright (C) 2004. Reproduction of its content anywhere other than usenet without the express written permission of the author is forbidden. |
#40
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Physics of bridging an amplifier - was: Damping Material
"Nousaine" wrote: snip If the speaker "bottoms" meaning striking some part of the basket it is often already damaged. snip What do you mean by "striking some part of the basket?" I was referring to the motor assembly. I'm sure it's possible but I've yet to see a woofer damaged from a few whacks against the pole piece. I would think that if the diaphragm itself were to strike the basket, the damage would be assured and catastrophic. |
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