Boomy bass?

Discussion in 'Archived Threads 2001-2004' started by SteveF, Apr 8, 2002.

  1. SteveF

    SteveF Extra

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    I just finished building a sealed cube subwoofer. Here are basic bits of info on it:

    [*]Internal volume of enclosure: 3.9 cuft (20"x20"x20" external)[*]Internal volume of enclosure after subtracting amp, bracing and driver: 2.8 cuft[*]Driver: Shiva Mk 1[*]Amp: RCM Akustik Detonator 110 Mk II (>150W RMS, No bass boost, etc. 182 KB PDF: here)[/list]I have heavily braced this box, and have done everything I can to ensure it is sealed. The box seems very tight, and pushing the driver in reveals no leaks and seems to feel quite different than when the top was open.



    I have also elevated the box on spikes.



    The problem is that the bass feels boomier than my previous 6 cuft ported sonosub, when I would have expected a smaller, sealed low-Q sub to be tighter if anything. Another difference with this sub is that I have wired the dual voice coils (correctly, as specified in the Adire spec sheet) rather than gone with a single voice coil in the sonosub.



    The boominess seems to be exacerbated by some specific types of music. The worst occurence occurs with a song that has a very periodic deep bass. The bass will literally travel in and out of sync with the mains sometimes being delayed by up to half a second!



    I have used approximately 2.5 lbs of polyfill - I experimented with other amounts and that does not seem to be contributing much. I also experimented with phase and reduced the problem somewhat.



    Any suggestions?
     
  2. Mike Dr

    Mike Dr Stunt Coordinator

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    I had something similar happen to me with a car audio setup and in there it was the amp that was to blame. It could also be a phase adjustment, room acoustics or room placement I suppose...
     
  3. SteveF

    SteveF Extra

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  4. Robert_Gaither

    Robert_Gaither Screenwriter

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    The same placement might be the problem as most subs usually need to be positioned slightly different from one another simply because of the way some of them fire in the room (most Sonosubs are bottom firing and I assume your current one is front firing). If this one is bottom firing it might be that your driver is mounted too close to the floor and might need to be raised somewhat higher (I like at least 3" or more personally).
     
  5. SteveF

    SteveF Extra

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  6. Michael R Price

    Michael R Price Screenwriter

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    Are they in the same place? You could be exciting a serious room resonance.
     
  7. SteveF

    SteveF Extra

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    I sorted things out. Two things helped immensely:
    1. Tweaking the crossover, amp gain, phase and subwoofer position
    2. Getting rid of a couple of songs from the test set
    Item #2 was quite interesting and definitely the much bigger factor. There were a couple of songs with steady deep bass pulses at approximately 2 Hz that were doing something strange. I'm not sure if I was getting interactions with my subfloor or the room acoustics, but the bass line in these two songs had me hunting all over for my problems. For the first 5-10 seconds of these deep beats, everything was fine, but then things would slowly drift out of sync between my mains and the sub.



    Problem solved in any case. Definitely a different sound than my previous sonosub - I'm much happier with music, and HT is good. However, there is no chance that the Matrix helicopter explosion scene is anywhere near as impressive.
     

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