How dangerous is bottoming your sub?

Discussion in 'Archived Threads 2001-2004' started by Jon D, Jan 2, 2002.

  1. Jon D

    Jon D Stunt Coordinator

    Joined:
    Sep 29, 2000
    Messages:
    166
    Likes Received:
    0
    Recently I was able to upgrade my receiver. Unfortunately, the now correct LFE on movies such as the Haunting and Titan AE is bottoming my sub. It's not a loud clapping, but on heavy bass effects I can hear a noticeable muddy distortion. Is this minor bottoming okay? Or am I slowly shredding my sub until it explodes?
     
  2. Dustin B

    Dustin B Producer

    Joined:
    Mar 10, 2001
    Messages:
    3,126
    Likes Received:
    0
    Bottoming your sub means you have pushed the driver to the end of its mechanical excurions limits. When this happens what you hear is one solid object hitting another solid object (I forget the names of the two parts of the driver that hit each other). I have never heard a sub bottom, but others describe it as sounding like a gun shot. Sounds like you are just pushing your sub to where the distortion starts to get noticable not bottoming it. This shouldn't hurt your sub any.

    Unless what is happening is your amp is clipping and not that your driver is working a little harder than it likes too. This could burn the voice coil out.

    This sucks, I know what bottoming, distortion and clipping are, but I don't know how to distinguish dirstortion and clipping audiably becuase I don't have any first hand experience with either.

    Hopefully someone who can will read this thread. All I can recommend is if you aren't happy with how your sub sounds with your new receiver, either turn the bass down so it doesn't distort any more, or buy a bigger sub. Personally I'd build a bigger sub :p)
     
  3. NicholasF

    NicholasF Auditioning

    Joined:
    Jan 1, 2002
    Messages:
    11
    Likes Received:
    0
    Jon, what kind of sub is it? Do you have a SPL meter? (don't know where you live, but available at Radio Shack) If not, they are not too expensive, I think $50-$90 depending on analog or digital display. By telling us the type of sub and how loud the SPL meter registers (C wieghted, taken from a distance of 1 meter from the sub) we could probably tell you if it is bottoming or not. (and if you can, disable the mains & center while measuring the sub) Most subs should be able to play < 85db fairly easily, which is a comfortable range. Some smaller subs may begin to struggle somewhere between 85db and 100db. But if you are really blasting, 100db and greater, depending on the sub, could cause it to produce unintended sounds.
    Also, you might be hearing other ambient sounds caused by the sub. In my situation the floors, walls, and windows all shake like crazy and start producing all kinds of additional noise that pollutes the clarity of the original recording. In effect these large vibrating surfaces become "speakers" themselves... very poor quality ones! Wood floors & drywall will sound worse than carpeted concrete floors & cinderblock walls.
    I haven't had time to work on this yet, but anchoring the sub to a heavy plate and isolating the plate from the floor by using three spikes should help out a lot. Unfortunately I have wood floors, so I'm going to have to come up with something to prevent the spikes from damaging the floor (I suppose I could mount them upside-down, and drive the points into the plate.) It is important to use only three points to isolate the sub from the floor, because it is very difficult to get four (or more points) to be perfectly coplanar.
    Good luck, -Nicholas
    [edit: I just scanned some of your other posts. Sorry, I should have done this before writing my book long reply. Is this sub the 10" JBL w/ 150 watt amp? And your interests include listening to Titan AE at reference levels? [​IMG] ]
     
  4. Jon D

    Jon D Stunt Coordinator

    Joined:
    Sep 29, 2000
    Messages:
    166
    Likes Received:
    0
     

Share This Page