What makes for a blown speaker???

Discussion in 'Archived Threads 2001-2004' started by Kirk Mango, Aug 25, 2002.

  1. Kirk Mango

    Kirk Mango Stunt Coordinator

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    There have been several threads recently, especially since LOTR, regarding bottoming out or blown speakers. I was wondering, from those who really know, what bappens when a speaker gets damaged. Is it a Black or White issue where the speaker either works or does not give any sound? When a speaker is taken to its limits does it immediately get damaged? Most importantly, does the speaker slowly degrade over time when played at higher levels? What I mean by this is or does the speaker slowly lose its sonic quality or ability until it does not work properly? Does it make funny sounds like crackling or mild distortion which continues until it becomes obvious or does it just stop working altogether? I am familiar with the idea of clipping and how an amp, if driven improperly, can start to clip the waveform which sends a distorted signal to the speaker which the speaker tries to reproduce and this process can damage the dfiver. The question is, what really happens to a tweeter, midgange, or woofer when this occurs. Can just plain loud volumes, say, wear out a speaker like hard cornering on a tire wears out tires faster. Can a speaker get slightly damaged without the user knowing? Just wondering the physics behind this based on some recent posts.

    KM
     
  2. Kevin P

    Kevin P Screenwriter

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    The most common form of speaker damage due to amp clipping is overheated voice coils in the drivers. Slight overheating can cause the coil to warp, and then the speaker may sound odd or distorted. More severe overheating can "blow" the coil, resulting in an open circuit and a completely dead driver.

    Bottoming out speakers (most commonly in woofers/subwoofers) can also cause coil, spider, or cone damage but this doesn't happen as often unless you really slam the thing hard.

    Other than overheating or damage due to overdriving, speakers don't really "wear out" from use. Most people upgrade speakers long before they "wear out".

    KJP
     
  3. John F. Palacio

    John F. Palacio Supporting Actor

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    To add to what Kevin P. wrote.

    The "surround" or cone suspension of some speakers, mainly woofers, can chemically degrade over time also.

    I've seen what can be honestly considered "vintage" speakers still working very well.
     
  4. TedO

    TedO Stunt Coordinator

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    I once blew a subwoofer driver, the voice coil was damaged. It would play fine at lower volumes, but once you started to turn it up, the driver would start to distort. The driver then deteriorated very rapidly (sound wise) until I replaced it. Moving the cone in and out by hand, I could feel the drag of the windings, it was like they warped and started rubbing.
     
  5. John Royster

    John Royster Screenwriter

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    think I've had my fair share of blown speakers...
    tweeters - melting, audible/visible distortion.
    crossovers - melted
    Woofers of the 10 and 12 inch variety - simply shattered voice coil and torn to bits spider. Those were' 400 buck a piece woofers that I managed to smash to smithereens. poor woof-woofs. [​IMG]
    The best advice is...if it sounds bad or looses any clarity - turn it down. over time you can wear down a speaker.
    What really happens to a driver? voicecoil melts or breaks and creates a short or open circuit. That means driver no worky no more. Or over time the surround/voicecoil is warped and the speaker doesn't perform as it should. Both kinds of wear/abuse can damage a speaker...slow or immediate.
     
  6. Dave_Whiting

    Dave_Whiting Stunt Coordinator

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    So if you damage your tweeter you are going to know about it? i.e. will it be pretty obvious
     
  7. John Royster

    John Royster Screenwriter

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    Dave,

    It all depends on how much damage has occured. It it sounds good, then you're fine.
     
  8. Richard Harvey

    Richard Harvey Stunt Coordinator

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    When my brother toasted my old Cerwin-Vegas, they started getting a "buzz" in them. It was like listening to AM radio, even when a CD was being played. From there, it deteriorated quickly until most of the audio was inaudible. All of this from cranking a no-brand cheapo 50W stereo receiver through my beautiful speakers. Like others have said, you should be able to notice problems by ear -- if the sound is distorted, grainy, or otherwise abnormal, you may be on the road to a new pair of speakers.

    Rich
     
  9. EdwinL

    EdwinL Stunt Coordinator

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    Well, it's quite simple.... If it sounds like some of Cher's recent stuff (with the horrible computer/distored effects) then it's BROKE!....
    It's hard not to tell, I mean, it just doesn't sound right! [​IMG]
     
  10. Mike_Ch

    Mike_Ch Stunt Coordinator

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    I have a pair of Tannoy speakers. A couple months ago, my friend sat on the remote, jacked the gain up on the preamp to *full* (+16db or something)... with my 200W power amp, well the results were pretty frightening. The dustcaps of the bass drivers blew out halfway across the room, the spider was torn, and the glue on the cone backing "spat" thorugh the cracks in the cone itself. Needless to say, replacing 6 drivers was a very very expensive process. The crossover however was fine. To answer the original poster's question, I think with bass drivers it is pretty obvious when you've blown a driver. The sound will be very wrong (missing out entire low frequencies). However, with a tweeter I am not so sure. Will the perceived balance be favoured to the speaker with a non-blown tweeter? That is, will the image be skewed to one side?

    Cheers,
    Mike
     
  11. John Royster

    John Royster Screenwriter

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    Mike,

    In my experience with blown and even marginal tweeters is you can hear it. Pretty obvious. If you sit down to enjoy some music and the sound is continously shifted to on side then maybe one should investigate.

    DISCLAIMER - this "soundstage shifted to one side" can very well have something to do with the room so my advice is not absolute. But for the most part your soundstage and vocals should be front and center. Even then "should be front and center" will vary somewhat between recordings, tracks, etc.

    BUT - if it is overly exagerrated on most/all recordings then check out your drivers.
     
  12. Mike_Ch

    Mike_Ch Stunt Coordinator

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    John,
    Yeah, I am getting paranoid these days and won't run my speakers too loud cos I'm worried about facing another massive repair bill hehe [​IMG]. I have a large cabinet on the right side that causes some reflection and perceived increase in sound which I compensate with the balance adjustment. However, on some tracks it feels like the vocals are still shifted slightly to one side, especially on Norah Jones' cd. I don't think its a tweeter problem though, cos its brand new! I should check with some test tones just to make sure I guess [​IMG].
    Cheers,
    Mike
     
  13. Jon Cheung

    Jon Cheung Stunt Coordinator

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    There are pretty much 2 ways to blow a driver, too much power or too much excursion. When the driver is blown it is definetly audible, when you push the cone down, it makes sort of a popping noise and when playing it, it sounds scratchy. If it's a dual coil, it will sound a lot less quietier cuz one of the coils is blown. Hope that helps!
     
  14. Brett DiMichele

    Brett DiMichele Producer

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    Types of Damage Cause
    • Voice Coil Burnt: Too little power, Too much power,Too much Impedance.
    • Damage to Diaphram/Cone: Bottoming out the speaker, children "poking" at the speakers.
    • Damage to Motor/ Suspension StructureL: Over excurting a woofer will cause torn tinsel leads, ripped spiders, mangled voice coils (from slamming the back plate/T-Yoke)
     
  15. Patrick Sun

    Patrick Sun Studio Mogul

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    "Too much impedance"? I can't co-sign on that one.
     
  16. Brett DiMichele

    Brett DiMichele Producer

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    Too little even.. Ahh hey like I said before I work steady
    midnight, I don't even know what I mean, I don't expect
    anyone else to.. [​IMG]
     

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