My first subwoofer, a DIY tempest

Discussion in 'Archived Threads 2001-2004' started by Chris Tsutsui, May 13, 2002.

  1. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    Ok now that I have my tempest up and running, (though the legs arn't attached and there isn't a finish yet), I have a few questions.
    In what order do I adjust the settings to tune the sub? placement, then volume, crossover, and phase?
    Next, I was wondering if I chose the wrong enclosure because the sub is able to produce very fast and accurate musical notes when I sorta wanted a sub that would knock the wind out of me. The bass is clean, easy on the ears and able to rumble the floor, but I don't get that "hit" feeling. I thought the Adire alignment would have both hit and audiophile bass but I guess I was wrong.
    I am beginning to think I should have chosen audiophile or boom box and not adire alignment so at least I'd have one advantage.
    My sub can play 20hz and below test tones but it sounds like a consistant wave pattern (I can see the driver move up and down as it vibrates). Is this supposed to happen with frequencies this low? In other words, it sounds a lot different than say 50hz or 100hz which is a smooth constant tone.
    This is my very first subwoofer and it just so happened to be a DIY. [​IMG] My parents told me it was like a movie theater and I agree. I do hear some distortion and occasional signal jumble during fast bass scenes but I think it's due to my 17ft unshielded interconnect.
    I will say this about the tempest: It gives accurate bass reproduction with very low note capabilities. It doesn't move the air around in the room but rather fills it with bass. Even when right next to the enclosure I heard no port air noise. I am very pleased with its total cost $400 and the performance.
     
  2. Greg_R

    Greg_R Screenwriter

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    That 'hit' feeling is typically caused by harmonic distortion in the upper bass frequencies (like boomy car subs).

    You want to get a test tone generator (free on Internet) or a test tone CD and measure your frequency response in your room (you'll need a SPL meter). Start with the sub in the corner and keep moving / testing it until the response is reasonably smooth. Once that is done, calibrate the output level. Set the phase to '0' and the crossover to max (if you are using your receiver as the crossover).
     
  3. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    Ah I see, thanks.

    I have many test tones and the tempest is a part of my home theater PC. I have a radio shack SPL meter, tripod setup and various test tones already.

    I am still unable to get a response from about 20-100hz that's within 3db though. More like 6db. My pre-pro PC sound card doesn't have any crossover settings, just an equilizer that adds some distortion when turned on, and volume controls for each channel.

    I may have to add some bass boost to the lower frequencies of my Parts express amp, but I'll leave that as a last resort.

    How do I tune the phase knob on the sub? It feels like the focus of bass seems to shift around when I change it and sometimes it sounds like it competes with my mains.
     
  4. ling_w

    ling_w Second Unit

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    That hit by the truck feeling is usually generated by freq in the 30-45hz range. So if you don't care about accuracy, put your sub in a spot where that freq range is boosted the most. Or put the sub as close to you as possible, so you feel more of the direct sound from the sub instead of the room reverb.
     

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