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WTF? AvP just melted my SVS!

Discussion in 'Speakers' started by chris_everett, Mar 8, 2005.

  1. chris_everett

    chris_everett Second Unit

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    So I was watching Alien vs. Predator. My SVS CS+ 20-39, powered by a crown CH2 was pounding away... It was loud, but not reference level. And then, that big explosion when the bomb goes off. Sub goes "pop-pop-pop". I reach for the volume control to turn it down, but it's too late. The driver is totally melted!!
    Anybody else ever melt one of these things? I've expected better from SVS.... I've never run the thing into distortion, I've played it loud, but not been abusive....
     
  2. Parker Clack

    Parker Clack Schizophrenic Man
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    Chris:

    I would send Ron or Tom an email and they will fix you up.

    Parker
     
  3. John S

    John S Producer

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    Do you run you sub(s) hot? Sure sounds that way. Interesting. Thanks for the post. Not many around here melting their SVS drivers. [​IMG] So yours may have been an odd exception. Not to familure with that amp, but it sounds like it could provide massive peak dynamic power for sure.

    I'm hard on subs, I'm afraid to change from my Velo 15", just because it has been so reliable. And I am brutal on them in general, I run hot to rediculously hot on my sub.

    I'm still inclined to think you got a rare lemmon driver, that made it through QC.
     
  4. AlanZ

    AlanZ Screenwriter

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    Sounds like a great excuse to upgrade to the PB12-Ultra/2 in my opinion [​IMG] Good luck melting that monster!
     
  5. William_Gravem

    William_Gravem Stunt Coordinator

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    John,

    I'm sort of a newbie around here, I'm not familiar with the term "running your sub hot." What exactly does that mean?

    Sorry for the naive question.

    ---Bill
     
  6. Ilkka R

    Ilkka R Second Unit

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    It means that you are running your subs level higher than your mains. For example with AVIA these levels (if calibrating at reference level) are 85db for mains and 82-83dB for sub (using c-weighted meter). If you calibrate your sub say at 88dB, then it's 5-6dB hot.
     
  7. chris_everett

    chris_everett Second Unit

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    I run probably 5-8 DB under reference. Yeah, I warm the things up, but that's why I bought the SVS! The CH2 is close in power output to a K1, plenty of juice, but it should not be enough to melt something on a short peak.

    I've already sent an e-mail to SVS techsupport.

    Everything is calibrated to reference.
     
  8. William_Gravem

    William_Gravem Stunt Coordinator

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    Thanks Illka! That makes sense.

    If you don't mind me asking, what are the risks? I have an SVS PB12+ paired with Axiom speakers and I tend to have the subwoofer volume turned up quite a bit (I watch a lot of movies, and I enjoy a lot of deep bass.) But I hadn't seriously considered the possibility of ruining my sub.
     
  9. WayneO

    WayneO Supporting Actor

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    I wouldn't get all up in arms about it...........one person's problem, which the cause hasn't been determined, shouldn't alarm everyone else into turning down their subs. As long as you're playing it distortion free, you should have no problems.

    I'm sure SVS will take care of things, but is "melted" an exaggeration? Or what part actually melted? Maybe the amp somehow spiked it's power output......do you have any kind of LF filter on it?
     
  10. John S

    John S Producer

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    I agree, as I stated, I think somehow the driver was a bit of a lemmon. But other causes are totally plausable as well. Nothing to get alarmed about. I run my subs by preference, if it can't take the heat, I need a different sub. I thrashed three JBL subs before getting my Velodyne.

    I would think an SVS would / could take it for sure. Gotta watch those pro audio amps a little though. They can be running along at 100 watts sustained and when a good peak comes along, the sky is the limit with them. This is a good thing from a performance angle, they can be harsh on stuff geared for home audio though for sure.

    All speculation at this point though.
     
  11. John Garcia

    John Garcia Executive Producer

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    If anything, you cooked a voice coil. This doesn't happen because of too much power, but too little, during a peak. If you are listening at -5 from ref, and you are running your sub hot, there's a good chance of this.

    "Hot" does not refer to actual temperature, it means calibrated higher than reference, and when listening at or near ref levels, that means a sudden peak like the one you are talking about could demand more power than is available.
     
  12. chris_everett

    chris_everett Second Unit

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    Well, SVS sells the crown K1 amp as an option, so I think that the sub should be able handle the power that's there, and by the same note, the amp that I have should be plenty for it. I'm well aware that the main cause of trashed drivers is too little power, and that's why I have the crown (I was actually planning to buy a K2, the CH2 is borrowed)

    After thinking about it some more, I think I calabrated my sub hot by a couple of dB, but I was still running 5-8dB under reference when it went.

    My guess (hope) is it's just a single bad driver.

    Wayne, the Voice coil is melted. You can see it when you look through the side of the basket. All crown's (I think) have a subsonic filter in them. Regardless, one peak should not have caused this kind of damage.
     
  13. Tom Vodhanel

    Tom Vodhanel Screenwriter

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    Hi Chris,

    Chances are the VC isn't "melted" but is it deformed. If you "melted it"...you would have a terrible odor in your home as the adhesives that hold the VC together are really what "melts" in those cases. The VC will deform if it is repeated "bottomed out" against another (metal) part of the driver assembly. In this case...probably the back plate. At this point, the driver will have to be moving well in excess of 2" peak to peak.

    If you are at 5dB under reference...with the bass say...3dB hot...then the subwoofer may be required to produce peaks in the 119-123dB range. A single CS+ will be very hard pressed to approach those levels.

    How large is the listening room and does it have any large openings to other areas of the home?

    BTW---if a crown(or any "pro" amp) does include a subsonic filter, they are typically in the 6-10hz range. Which won't really be of use in this context.

    Tom V.
    SVS
     
  14. John S

    John S Producer

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    I actually do not know the SVS product line well enough, to even know what sort of level of sub this one is. I think I will go educate myself a little on their products.
     
  15. Ilkka R

    Ilkka R Second Unit

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    It's their Plus-series, so one step better than the basic ISD-series. CS means it's passive.
     
  16. John S

    John S Producer

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    I just spent some time on their website.

    I'm a little surprised it wouldn't be able to hit those peeks within it's operating comfort though. Maybe a place where a 15" or larger driver sort of hangs in there a little better perhaps??

    It will be interesting to see how it works out for him.
     
  17. Tom Vodhanel

    Tom Vodhanel Screenwriter

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    >>>I just spent some time on their website.

    I'm a little surprised it wouldn't be able to hit those peeks within it's operating comfort though.
     
  18. John S

    John S Producer

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    Thanks for the additional information Tom. I watch movies at reference type levels often. I don't think I am in tune with most of the real world on this. [​IMG]

    Extension down low has a lot to do with it as well. I've never tried to really test below 20hz, which is where the roll off really starts to get steep with my Velo, but my peaks while watching real content have gone well into the 120's, but this is obviously not testing what frequencies those peaks are actually happening at by any means. This is again, me knowing I am running the sub quite hot.

    I do understand the demand being place on the sub, I would still think in a moderate sized room, that would still not be totally out of the relhm of the sub in question. At the far end of it's capability yes, but I'd still bet 99 times out of 100, that sub handles it. [​IMG]

    He'll probably get a new driver, and be pleased as punch for years to come I'd suspect.
     
  19. chris_everett

    chris_everett Second Unit

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    My room is small, only 10'x15'x9' (about), and has no opening into the rest of the house. (save for the HVAC vents) When I called SVS to order it, I described my room, and asked if that sub could handle reference. They said it could.

    It could have very well hit the back plate (the pop-pop-pop I heard when it went). Looking through the basket shows black "gunk" on the side of the voice coil, hence my assumption it melted something.

    Tom, What freq/rolloff do you suggest a subsonic filter be set at? Is that amp too much?
     
  20. brentl

    brentl Screenwriter

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    That scene is killer on my sub too, I using a DPL12, made a few funky sounds and it felt great but no damage.

    Brent
     

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