I blew my first sub!

Discussion in 'Speakers & Subwoofers' started by Justin_D, Jan 16, 2004.

  1. Justin_D

    Justin_D Stunt Coordinator

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    My CHT-12 got blown yesterday! I couldn't post it because I was cramming for finals after running to Circuit City. It was an X-Mas present (but I kinda payed for some of it) so they exchanged it. I was running a 20hz test tone just to hear what it sounded like, and I guess I turned it up too high [​IMG]

    The volume was ~1/2 way up on the sub and about 45 on the receiver (Onkyo TX-SR501 which goes up to 80 on the redundant-o-meter).

    How common is this?
     
  2. JamesCB

    JamesCB Second Unit

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    You may have only blown a fuse.
     
  3. Justin_D

    Justin_D Stunt Coordinator

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    I'll add what was going on...

    I was running a test tone, and I turned the volume up, and heard a pop.

    The amp and lights stayed on, but it would NOT play a single note. I tried turning it off and everything, but nothing...
     
  4. Chu Gai

    Chu Gai Lead Actor

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    If you mean how common is it that people abuse their speakers with test tones...it happens. Now don't go and do something foolish like playing a 15 kHz test tone to see what that sounds like or else you'll fry your tweeter. Speakers are designed for playing back audio which has a complex distribution of signals of varying frequencies. I'd imagine your test tone caused the speaker to exceed its xmax. Frankly, you were fortunate to get a replacement sub.
     
  5. Dan Hine

    Dan Hine Screenwriter

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    Did you calibrate your sub that way or just set it that way arbitrarily?
     
  6. steve nn

    steve nn Cinematographer

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    Justin thats to much!!! You need to calibrate first and then turn things down to -30 or so. I'll let the more knowledgable members explain it. Lets just say those test tones on the bass disks are very hotttttt and a extended tone is very hard on a woof![​IMG]
     
  7. Justin_D

    Justin_D Stunt Coordinator

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    How would I know its too much?


    As you can tell I'm still learning the hard way....[​IMG]
     
  8. JakubH

    JakubH Stunt Coordinator

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    If you sub is ported, you should figure out the tuning frequency of the port. Below this frequency, the driver becomes unloaded, that is to say the excursion is no longer controlled by the box. If you feed a ported subwoofer frequencies below the tuning frequency at any sort of decent volume, it is very easy to blow the driver. Aside from that, a ported subwoofer will not really be capable of significant output below its tuning frequency, so you won't really be able to see what these frequencies 'sound like'.

    If your subwoofer is sealed, it is much harder to blow, as the box keeps the excursion under better control all the way down. This does not mean that you'll have better output all the way down, just that the driver will not be flailing around as much as the ported driver below tuning. Also, a sealed woofer should will usually make audible bottoming noises before blowing (unless it reaches its thermal limit before its excursion limit), these noises are hard to miss and are quite disconcerting - if you hear them, turn it down!

    So the short solution - if you sub is ported, find the tuning frequency and don't feed it tones lower than that. If its sealed... you've either fried the driver or blown something on the amp.. no real solution, just be very careful with test tones below 30hz, and an eye on the excursion, this will help tell how hard the driver is playing. You can't go by loudness, as for example a room mode could give you a response thats 10db down at 20hz, so you might not hear(feel) much energy from the sub, but it could be playing like crazy trying to reproduce these frequencies.

    Hopefully this is useful, I'm sure there are others who can provide better or more succint info, hopefully they will.
     
  9. steve nn

    steve nn Cinematographer

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    Don't feel bad Justin. Thats how many of us learn anyway (the hard way). I run three 25-31CS+'s and I still blew a driver one night:b . Please don't tell! No excuse for me. I knew better, but I just wanted to see? My ears hurt for two weeks after running close to 130 db output! Never again I assure you.

    You have a new sub now so all is good. If you can? Make the investment necessary to calibrate. You will be glad you did and remember those bass disks are very hotttt.[​IMG]
     
  10. Garrett Lundy

    Garrett Lundy Producer

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    Ahh the memories...It seems like only yesterday I destroyed my Kenwood HTiB "subwoofer" with the "ring drop" from Lord of the Rings: The Fellowship of the Ring.

    Now I'm saving my pennies for a SVS[​IMG]
     
  11. John S

    John S Producer

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    I've blown every 12" Sub I ever had.

    I finally moved up to 15" Subs, and have been good ever since.
     
  12. Ralph B

    Ralph B Supporting Actor

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    I tried to blow my HTIB JVC 12" and it wouldnt blow. well I mean I could have played it forever until it did but I gave it 25 sec on a 16hz tone and it still works perfectly. reference level and my system is calibrated. I have a SVS 25-31PC+ so I was playing with my old sub to see what can happen. well nothing did! lol, it was going like crazy like it was gonna come out the box but it took it. the funniest thing I have ever seen. what a brut to take that. it deserves to live on so I put it away after that. played the pod race after that though and played it fine. in my experience , maybe I have been lucky but it seems to me it would take an awful amount to blow a sub that is built average.

    how can a 15hz tone blow your tweeter ? I though thats what crossovers are for. doesnt anything under say 80hz if set correctly suppose to goto the sub ?
     
  13. Roger Q

    Roger Q Stunt Coordinator

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    He said 15 kHz (15,000 Hz) not 15 Hz. That's why it would trash the tweeter.
     
  14. steve nn

    steve nn Cinematographer

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    ..
     
  15. Ralph B

    Ralph B Supporting Actor

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    sorry roger. [​IMG]

    missed that 'K' lol

    to add to that though, dont most speakers goto 20khz anyway ? I can see at reference level but it wouldnt mean it would be a sure thing at 15khz that it would die. right ?

    im learning so just trying to add by asking. [​IMG]
     
  16. Justin_D

    Justin_D Stunt Coordinator

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    Thats what I thought. I know my Polks go up to 23khz...
     
  17. Greg-ST

    Greg-ST Stunt Coordinator

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    My 8" 100 watt passive subwoofer from my original Kenwood HTiB (HTB-205) is still going strong even after plenty of what I would consider "abuse". I'm actually surprised at how well it performs considering it's a relatively lowend sub.

    I just got paid so now I'm going to upgrade to the Dayton sub [​IMG]
     
  18. Brian Bunge

    Brian Bunge Producer

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    You could blow a tweeter with a 10KHz sine wave just as easily as a 15KHz sine wave. It doesn't really matter that you are within the driver's bandwidth, it's the fact that the amplitude of the signal is too high. Sine waves played for any real length of time at high output levels cause the driver's voice coil to get extremely hot and melt, which kills the driver.

    BTW, I've never killed a 12" driver with 12mm of Xmax while running 800W through, but I did kill a huge 15" driver with 34mm of Xmax while running 2500W through it. So driver size alone means nothing. It's just that most 15's move more air than most 12's so you don't have to push the 15 as hard to get the same SPL levels as a 12.
     
  19. jonathan_little

    jonathan_little Stunt Coordinator

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    I played "Monster Mash" (the 1962 song) a few months ago and that was enough to blow my SA-WM40. At the time, the speaker was three months off of its one year warranty. I'm still in the process of communicating with Sony to see if they will do anything for me, but I'm not keeping my hopes up.

    Watch out for those 1960s tunes, evidently they've got wicked deep response. [​IMG]
     
  20. Brian Bunge

    Brian Bunge Producer

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    Jonathan,

    Was this from an LP or 45? They're notorious for subsonic noise and can easily damage speakers.
     

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