blowing eclipse subs by under powerring them?

Discussion in 'OT Technology' started by APMD, Oct 29, 2002.

  1. APMD

    APMD New Member

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    Hey guys, I have had 2 eclispe aluminum 10's for a while now and a month ago they just stopped working. So I went and test everything else out, and amps work fine.

    So i bring the subs down to a local shop and they put an ohm meter on them, one is reading 266 ohms and the other 0 ohms, so obviously something was wrong with them.

    I asked what could be the cause and this is what they said:

    could be a lot of things...blah blah..we would have to run a full diagnostic on your system balh blah..then they find out that I am pushing them with a kicker zr360, which is 400x1 at 2 ohms, which is what i was runnning at.

    they said i probably blew them from underpowering them, that 200 watts each wasnt enough and they are really sensitive, and that if i didnt give them about 400-500 watts this would happen.

    is this possible? i wasnt sure if they were just tellin me this to get money out of me (which they wont).

    I can get them repaired, I have heard that it will be a bit pricey to get eclipse speakers repaired...so now here is my dilemma....

    if they are right, i either get new subs, that my amp will power sufficiently, get them fixed and get a new amp, or get new subs and new amp.

    I dont really want to spend too much money....what do you guys thing???

    thanks!
     
  2. flynfrog

    flynfrog Cool isnt Cheap

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    first off find a differnt shop its siply not possible to blow them by under powering them

    you can get them repaired witch would not be a bad idea

    my guess that you blew them by clipping the amp you wanted more output so you turned up the gain trying to get more power out of the amp but even a good sub wont last to long with a fully clipped signal even at a modest wattage

    id recomend gettign them fixed turning down the gains then see how you like them if you want more out pu finnd a bigger amp
     
  3. APMD

    APMD New Member

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    thanks for the reply, that is what i was thinking...

    I only have the gain on the amp turned to about 3/4, and havent touched it in years.

    also what would the consequences be if my box was too small? I had the box made, supposedly to eclispe specs but that could always be messed up.

    thanks again.
     
  4. flynfrog

    flynfrog Cool isnt Cheap

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    how old were the subs ?

    they were over powered soem how if the vc are reading that low it means that they were melted id still check and see if you can find soem one to put you amp on a ocilascope and see if its clipping the signal

    have you changed any thing in the system deck line driver ect?

    also i have rarley seen a deck so weak that the gains need to be over half way ever amp is differnt but its a good rule to go buy if your not sure what your doing.
     
  5. edrox

    edrox A good man, and thorough

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    Flyn

    I think that what the shop meant was that the amp was too small for the volume levels he wanted. Then, like you said, over-cranking caused clipping, thus damaging the speakers.
     
  6. BobG

    BobG Fuchs.

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    Bingo. A DCR of 0 is a dead short and means the coil is shot. Time for a new sub.
     
  7. 04

    04 Guest

    Clipping did not kill his speaker, they died from thermal failure, or the voice coil shorting out.
     
  8. flynfrog

    flynfrog Cool isnt Cheap

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    the thermal failer could have easiy been caused by clipping as in it gets to much power does not move and all of the heat is focused on one part of the VC
     
  9. 04

    04 Guest

    Ok, the problem here is we just are wording it differently. When I see people say that clipping kills speakers it looks to me just like someone saying: "Guns kill people". Yes a gun could be used to kill a person, but without the human to pull the trigger, they are harmless.

    Same thing with speakers. Yes clipping could kill a speaker, but without the associated heating that comes with it, it wont hurt a thing.

    You need to realize though that a clipped signal does not cause the voice coil to move any less, it still moves the same amount, an could move more.

    The heat is never focused on one part of the voice coil. Heat always trys to find an equilibrium, and will move from warmer areas to cooler areas.

    If a driver's motion is halted, but power is still being fed to the coil, the heat will still spread evenly throughout the voice coil, it just will not be wicked away as fast due to the lack of motion.
     
  10. flynfrog

    flynfrog Cool isnt Cheap

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    it is still focused on part of the vc and yes it will dissapte to other parts but if it cant do it fast enough you get a nice meting with magic green smoke
     
  11. 04

    04 Guest

    flyn, the only time that I have ever heard of something like that is when a loudspeaker was hit with a super ultrasonic in the mhz range signal. Quoting Richard Clark:

    "concerning your reply-----a spectral analysis of virtually any amp clipping shows no RF power spectrum-------when i get a chance to do it i will post a measurement of several amps---------concerning the EXTREMELY rare condition of RF voicecoil burnout-------it manifests itself in a easy to diagnose way-----the coil will show excessive temperature discoloration near the center windings only-----the windings near the ends of the coil will be normal appearing.........RC"

    If the heat was focused on one part of the coil and not others, several things could be said about that loudspeaker. The conductor material would have to either change halfway through from copper to steel for instance, or the wire would have to get thicker and thinner. I have never heard of this happening. A certain length of copper is going to have the same resistance throughout as an exactly same sized length of copper.

    Or the incredibly rare situation of ultrasonic overpowering as shown above happened.
     
  12. flynfrog

    flynfrog Cool isnt Cheap

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    ok a low freqency sin wave is going to resemb dc votage for a time perid therefo focusing energy on the ends of teh vc

    have you ever seen a clipped wave in a scope see those flats spots where signal is staying at the top and bottom that is power focusing its self on teh ends of the vc teh vc cant disipate the heat fast enough there for a burnt vc

    you can quote richard clark all you want but i spend most of my day in electronics class discussing theroys and showing examples

    if the sub died of thermal failer where did this sudden boots in poewr come form if he had bveen running the same setup for years
     
  13. 04

    04 Guest

    Yes, but that does not mean the speaker moves any less. Look at an amplifiers maximum clean sine output. Then look at it producing a near square wave. Look at the voltage, peaks are both at the same maximum, only the clipped signal "holds" longer at the peak, meaning more power being disapated.

    I dont understand why you think one part of the coil will be heated more than another part, there is no logical sense behind it. It has nothing to do with the fact the signal input is dc, square or sine. The heat generated will be the same throughout the coil, one part will not have more than another.

    There was no sudden boost in power, you just had it turned up too loud for too long. Lets say for 2 years you had a sub and cranked it up for a bit every day to show off. No problems. but, after those two years, one day you crank it up for 2 hours straight as loud as it goes and it blows. Why? Because the voice coil got super hot, and there was no time for it to cool in those two hours.

    What electronics class instructor told you that a coil of wire would have more heat disapated at the ends when a square wave input is applied? :ugh:
     
  14. flynfrog

    flynfrog Cool isnt Cheap

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    i never said that it moves the coil any more than normal but it is focusing more energy at one part that the other feed your subs dc at teh same amprage as your amp will be producing and lets see how well it can dicipate the heat
     
  15. APMD

    APMD New Member

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    woah, I am EE senior at UT and am only picking up a few things you guys are saying.

    I guess I am hearing two things. It is the clipping of the amp, the subs are overheating, or both? Am I getting that right? So if i get the subs repaired, turn the gain down on my amp, should I be ok, or are the subs going to get blown again?

    042801 pretty much described my situation in that, I played my system not full blast, but relatively loud, not showing off, just like listening to my music loud. Then one day I was driving home to visit my parents which is about a 3 hour drive, and 2/3 the way through the trip the subs gave up.

    what can i do to prevent this from happening again?

    thanks for your help guys
     
  16. 04

    04 Guest

    Clipping of the amplifier is inconsequential. It has nothing to do with the failure of the subwoofers except that more power is output.

    The subs got blown because you played them too loud too long. You could feed them a super clean signal with .000000001%thd and still blow them. You just surpassed the thermal limits of your speaker(s).

    Yes, if you get the subs repaired, they will likely be fine, as long as you are carefull with the volume knob.
     
  17. 04

    04 Guest

    flyn: DC or AC it doesnt matter, the same potential will remain throughout the inductor in its passband. Since the potential is the same, the resistance has to be the same, so the power being lost throughout the inductor must be the same.

    APMD: you should know this better than anyone, being an EE student. Am I not correct in saying that when DC, AC, SQuare, Sawtooth, etc waves are passed through an inductor (the speakers voice coil) The resistance will remain the same throuhout the inductor, and one magical point will not be of higher resistance than another?
     
  18. APMD

    APMD New Member

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    I am uncertain of the mechanics and internals of a speaker, but as for your question. An inductors impedence varies with frequency. Z=1/jwL. So as long as the frequency of the siganl does not change, then the impedence should stay constant.

    I took my circuit theory a few years ago so I am kinda rusty on it, and I am no expert in the making of subs and audio equipment, that is why I ask you guys! haha.
     
  19. 04

    04 Guest

    Yes, I realize that the impedence varies with frequency.

    However, flynfrog says that passing a square wave of the same frequency as a sine wave through an inductor will cause heating of the wire(assuming the signal is quite high amplitude) in different places, and different regions will be heated more than others. However, he says this does not occur with a sine wave. What is he talking about?
     
  20. flynfrog

    flynfrog Cool isnt Cheap

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    ok simple example a speaker is basicly a glorified electro magnet changing the frequency at wich the power is deliverd changes how fast teh spaker moves in and out thus providing sound. once the amp if the signal is starting to becaome a square wave its now holding the speaker at one pole longer assuming its getting the speaker there fast enough to hold it if the sub cant move fast enough it will simply be wasting energy of the amp so i a sin wave you dont get this holding in one position its a contunus change where square wave is not depending on the thermal efficncy of the coil it may or may not be able to dissipate the heat focused on one end of the coil to the rest of it.

    I have a pretty good knoldge of this area we did a ring thorwer as a project. We did alot with heat build up ect.
     
  21. 04

    04 Guest

    Yes I know it is an electromagnet. But the voice coil is also an inductor. The resistance is constant throughout the windings, it doesnt change!!!! The resistance DOES change, but with frequency, not power type.

    It doesnt matter that the speaker is held at one pole longer, The ENTIRE coil still has the same resistance, and will heat consistantly throughout. Are you talking about EMF backwave? That does not heat the coil at all.

    [​IMG]
     
  22. flynfrog

    flynfrog Cool isnt Cheap

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    lol i was goign to draw he same paint drawing but didnt casue i was lazy ok i could be wrong about the coil not heating up in the a certain spot but you also have to account for the spaker holing at the poles onger and not moving as much air

    i thoung back to our ring thower taht we did with elctro magnets if you hold the ring on tehre it gets verry hot verry quickly and teh shaft in the middle fo the coil will will also get hot

    but if you turned on the coil wiht out the ring it heats up much slower
     
  23. DSHR

    DSHR Well-Known Member

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    My friend just called me a little a while ago, he blew his 3 10' MTX 6000's w/a 8100D :rofl: I asked him how long did they take to blow he told me 30mins he actually saw smoke comming from his box, he had them cranked to hell. Now I actually understand this whole thread from reading "basic car audio electronic" :bigthumb:
     
  24. 04

    04 Guest

    Ok, yes the speaker holds at the ends longer, but the driver still moves as much if not more air.

    Ok, your ring thrower seems to be doing the same thing as a voice coil, why do you say that it heats up differently throughout? FYI, the voicecoil is ONLY the wire, the FORMER is the aluminum or kapton that the wire is wound upon.

    Could you draw a picture, it is very hard to visualize! :bigthumb:
     
  25. lsondubz

    lsondubz Guest

    i have 2 10" eclipse aluminum 88100dvc subs.. im running them off a mtx 6500d (775 watts) amp... the guy at the shop has the same setup in his car.. dont know if this will help out
     

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