Improving the musicality of my SBB4 Tempest

Discussion in 'Home Theater Projects' started by Justin Ward, Jun 4, 2003.

  1. Justin Ward

    Justin Ward Supporting Actor

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    My Tempest in an SBB4 Tempest and I love it for HT. It has all the punch I love for explosions. Although I am still powering with a minisystem it is plenty loud (for now anyway). The problem is music is a little less satisfying. Here are my observations:

    I finally have the sub calibrated to the point where it blends well with the mains and doesn't stand out as the source of bass. The problem is that when I play it louder it doesn't get more punchy per se, its just like the bass is too "thick" for lack of a better term. The bass seems to have little detail as well. At first I thought maybe the porting was responsible but I plugged it and noticed little to no difference. So I've narrowed it down to a few problems I think could be happening:

    - It is in the corner of a nearly square room, I am guesing I am getting all kinds of bad room effects. The bass is strongest in the rooms corners and weakest near the centers of walls in general.

    - I notice that reversing the phase has little to no effect so I am guessing I am roughly 90 degrees out of phase.

    - Dustin B mentioned something about a poor damping factor in minisystems ( not sure what this means but maybe it is responsible for some of these probs)

    - It is just sitting on 4 inch legs, I've heard a cement slab can improve clarity, is this a good idea?

    Yes I know the SBB4 is probably the least musical allignment but I'm sure I can improve its musical performance.
     
  2. Jonny K

    Jonny K Second Unit

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    Well I can't really help you too much, but I can suggest trying a different music source (if you haven't already). For instance, I was fighting to get my bass sounding good for a while, and finally on a hunch I hooked the sub up to a different stereo and suddenly it was awesome. It had been my receiver all along.


    Jonny K.
     
  3. Pete Mazz

    Pete Mazz Supporting Actor

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    Beg, borrow or steal a different amp, preferably one suited to a 4 ohm load.

    Pete
     
  4. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    I believe what you're hearing is the subwoofer design itself. The SBB4 is a small vented design that has some mid bass punch and impact to it. I've built a 194L 18.4hz tempest in the past, and I too noticed that it didn't sound as "musical" during some tracks than with an Adire Alignment tempest.

    If you designed the box yourself and didn't include bracing, this could be another factor that is creating "thick" of bass. Did you put in the 64oz of polyfil?

    When you combine mini stereo speakers with a high Q subwoofer, you may get a system that sounds bloated in the bass. There can even be a lack of sound in the lower midrange to upper bass which exaggerates the mid bass hump.

    If you would like your sound system to sound more integrated, I suggest getting main speakers that can easily blend in with your subwoofer through a nice crossover point around 80hz or below. If your mini mains can extend fairly deep already, then perhaps design a subwoofer that lacks a mid bass hump closer to the Adire Alignment or EBS specs.

    Maybe try a BFD parametric equalizer and reduce any of the "bloated" bass peaks in the frequency response. This should result in a smooth response that may just have a few dips.

    What can also be happening is your room has a standing wave "peak" at about 50hz where the subwoofer hump is. This can result in a bigger "boom" that doesn't go well with your mains. If your subwoofer is corner placed, it activates ALL the standing waves. The way to cancel an axial standing wave is by placing the sub in a specific location and putting the listening position in a certain location.

    Lets say your room has a 22ft distance between 2 walls. This creates a (2nd order) 50hz spike right between those 2 walls. IF you place your subwoofer 5.5 feet (1/4 distance) away from one of those walls, and the listener stays in the middle, the standing wave and peak at 50hz should be canceled. This is just another idea that might get rid of the boom.

    Good luck!
     
  5. Michael R Price

    Michael R Price Screenwriter

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    Even if the alignment dictates an underdamped in-room response, I would imagine it is capable of sounding pretty good since a 210L/19Hz Tempest has a pretty nice sound just lacking some of the "awe inspiring" depth or detail of a lower tuned one. The two immediate things to try are to play around with the placements, or (this one's probably more important) replace the amplifier. To get an idea of what the problem is, you could do a quick measurement of the frequency response.
     
  6. Justin Ward

    Justin Ward Supporting Actor

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  7. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    One more vote for trying a different amp. Its very likely that the minisystem has a built-in low-frequency filter to accomplish two goals -

    Reduce the power output at a given volume level and
    Prevent overexcursion of the small woofers in the typical minisystem speakers.

    I wouldn't be surprised if the frequency response started dropping off at 40Hz or so.
     
  8. Justin Ward

    Justin Ward Supporting Actor

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    More signs pointing to the minisystem as the source of troubles. When I play test tones the signal drops off very sharply below 50hz, with almost no output at 30hz. My parent's amp will make me feel nauseus if I play a 19hz tone really loud. I think the extra bass around 50hz is caused by a builtin eq that emphasizes that frequency(possibly the tuning frequency of the original speakers). When I play a 120hz - 15hz sweep on the minisystem it doesn't sound even at all. But with the other amp the volume seems more or less constant.
     
  9. Justin Ward

    Justin Ward Supporting Actor

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    Update: Tomorrow I am hooking up a 220 watt Technics stereo amp. I am also moving the Titans out of the corners, they are wall mounted but due to rrom restictions I couldn't mount on the front wall. The Titans are going onto my stands(check out the link in my signature). They will have way less separation which should improve the gap I hear between the two speakers. I think having three sources of bass in 3 corners of a nearly square room is just asking for troubles.
     
  10. Justin Ward

    Justin Ward Supporting Actor

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    I haven't moved the Titans onto the stands yet, but the new amp is in place. It actually had very little difference at all. It does sound clearer at extreme volumes but with music I don't notice any better extension. With movies I am getting amazing improvements though.

    Sadly I also bottomed the Tempest for the first time as well[​IMG] .

    I did this on the final scene of Fight Club, the explosions must have some intense subsonic signal because the Tempest was just flapping. Sounded like it tried to jump out of the box.

    The opening of AOTC was amazing. The exploding ship shook the entire room and no rude noises came from the sub.


    As for the music performance, I am going to move the Titans onto stands soon.

    Is there anyway to do a 90 degree phase shift? I am sure my sub is 90 degrees out of phase because reversing the polarity makes no audible difference.

    This would explain why I get awesome movie bass because the sub is the only speaker to receive the LFE therefore there is nothing to cancel it.
     

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