"Peter Wieck" <pfjw@aol.com> wrote in message
news:fvo34901act@news1.newsguy.com...
> On May 4, 10:43 pm, dpierce.cartchunk....@gmail.com wrote:
>> On May 4, 3:31 pm, luvpoc...@hotmail.com wrote:
>>
>> > Hi, I just started reading Daniel Levitin's book, "This is Your Brain
>> > on Music" and in the introduction he says that in his college days he
>> > listened to music at such high volumes that: "I actually set my
>> > loudspeakers on fire by cranking the volume too high." Is this
>> > hyperbole, or can this really happen? Has anybody here ever
>> > experienced this?
>>
>> The short answer is no, it can't happen.
>>
>> The long answer is still no.
>>
>> I have, for a variety of clients, done extreme stress testing
>> of loudspeakers to the point of irrecoverable failure under
>> a wide variety of circumstances. I have driven voice coils
>> to the point of melting the attached domes, to beyond the
>> point of boiling the ferrofluid out of the gap, and so on.
>>
>> In THOUSANDS of cases, there does not exist a single
>> case of ANY of them coming remotely close to catching
>> fire. In all cases, the electrical system simply opened
>> up first.
>>
>> There was once a high-end store in Harvard Square
>> which had a pair of EPI 100 speakers where the center
>> of the cone was charred and burned through, and the
>> store's claim was that their McIntosh amplifiers were
>> so powerful that they set the speakers on fire. A friend
>> bought the speakers for $5 as a curiosity and brought
>> them buy. The burn pattern was VERY curious, indeed.
>> While the cone was indeed burned, as in fire, the voice
>> coil itself was perfectly intact and had NO signs of
>> ANY thermal stress whatsoever. Further, the speakers
>> had their grills, and there was no sign of soot or ash
>> in the backside of the grill cloth, even thoughthe cones
>> were extensively damaged.
>>
>> The conclusion was simple: the single case that I was
>> able to examine where there was visual evidence of a
>> fire was deliberately burned with a torch as a sales
>> gimmick.
>>
>> The reasons it can't happen are many. In most cases,
>> the voice coil or the solder joints for the flex leads or
>> the power supply caps give up LONG before there's
>> enough heat generated to raise the temperature to
>> the ignition point of the cone. The voice coil is buried
>> in a steel structure that conducts a LOT of the heat
>> away. The speakers at that point are sounding SO
>> awful by being so several overdriven that they are
>> beyond intolerable to listen to. And so on.
>>
>> It's urban legend, short and sweet.
>>
>> Now, you want STUPID loud? I once knew a kid
>> who would brag about the fact that he would take
>> his Phase Linear 700 and hook it to his Bose 901's
>> and set them up almost like giant headphones
>> and play it SO loud his ears would bleed. He
>> though it was WAY cool.
>>
>> I met him about 5-8 years later and he was a sorry
>> young man in his mid 20's who was almost completely
>> deaf.
>
> Oh, I dunno...
>
> You are assuming well-made, well-designed speakers that would
> generally fail as you describe from being over-driven.
>
> However, here are a few designed-to-fail situations:
>
> http://www.youtube.com/watch?v=TSqy7p--O2c
>
> http://www.youtube.com/watch?v=oNBdWfBgqXk
>
> Sub-woofers are strange beasts - and those designed for vehicles yet
> stranger. One needs suspend assumptions when dealing with such
> animals. Catching fire from being over-drive would not surprise me at
> at all given that the are designed simply _not_ to fail from whatever
> abuse as might be thrown at them.
>
> I do remember one "legend" - an AR rep stating that their AR-9
> speakers could be plugged into a wall and not sustain damage for at
> least ten full minutes. Yeah... right... Imagine that warranty claim.
>
> Peter Wieck
> Melrose Park, PA
When I was a student in the late 60s, I occasionally did discos for parties.
I once needed a long 'speaker extension, there wasn't time to do it properly
so decided to use a 25 metre mains extension, live was left, neutral was
right and earth was the common ground. I wired a mains socket to banana
plugs to go in the back of the amplifier. At one point, for reasons that may
have had something to do with the amount of social intoxicants consumed, I
ended up plugging the 'speaker extension into the mains. The right hand
'speaker just hummed quietly, but the left hand went BANG. It was probably
the loudest noise I've ever heard. The cone (a 12" "full range" speaker)
actually flew out of the cabinet and landed on the floor with small flames
coming from the coil and former. Consequently, I can say that 'speakers CAN
catch fire if you plug them into the 240 volt mains.
S.
--
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