Thinking about 15" Dayton DIY (not a kit) subwoofer:

Discussion in 'Home Theater Projects' started by Kenneth Harden, Jan 22, 2004.

  1. Kenneth Harden

    Kenneth Harden Screenwriter

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    I downloaded WinISD last night, and after reading the tutorial, I pretty much figured it out. I am considering either the Dayton 15" Quatro ($85 295-560) or the 15" Titanic MkIII ($200 295-420)

    As a theoretical box, I did 18" X 24" X 24" inside measurements and a 20 Hz. tuning frequency. A single 4" port is also included. They both show ~22 Hz. @ -3dB., but the Titanic, at RMS, had a max output of ~120 dB. while the Quatro was at ~115 dB. - I am in a pretty small room, and that is a small difference, and that $120 difference would be enought to do the project (wood, compoenets, etc.)

    What do you think? Am I using the software correctly? Am I in the sort of mindset I should be? Any advice? I have a pretty good understanding of audio, but I am still a novice in DIY.

    ALSO: whenever I do a sealed box design, my -3 dB. point seems to be in the upper 30's, is that about right?

    Thanks!

    Also, when I get some $$$ taken care of, I will probably order a pro Crown amp and a Art 351 EQ, so that will be enough to drive it.
     
  2. keoni

    keoni Agent

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    I am glad you figured out the WinISD. I downloaded and for the most part know what it means. I am totally lost on the graph though.
     
  3. Kenneth Harden

    Kenneth Harden Screenwriter

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    I understand the 'GAIN' graph - it shows the responce curve for the speaker/cabinet, and the goal is to have the line (the green line that curves) pretty flat, and you also know where your bass starts to fall off when it crosses that purple line (-3 dB) so you can 'see/hear' your speaker. The SPL graph lets you put in a certain amount of power, and it shows you, at what frequency, what your levels will be.

    The other two, don't know, but I am sure they are not THAT important [​IMG]
     
  4. Aaron Gilbert

    Aaron Gilbert Second Unit

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    I think in a medium sized room or less, the Quatro 15" will be more than enough. All the Titanic will get you is more maximum output and less distortion above say, maybe 114 dB or so. To my mind, that's definitely not worth more than double the price. It sounds like you are using the software correctly, by the way. Just to throw out a few numbers, I happened to measure my subwoofer's maximum output at several frequencies, a few nights ago. I have a Quatro 15" in a giant enclosure tuned to 11Hz. As you are tuning to 20Hz, your numbers from about 18Hz and up will actually be higher than mine, all else being equal. Granted, all else is rarely equal, but the potential would be there. [​IMG] My room I consider medium sized, it's roughly 21' x 23' x 7.5' I have approximately 400 watts available to the subwoofer.

    Anyhow, this was measured at my listening position in the center of the room - the subwoofer is the front right corner, 3.2m away. Naturally this includes room gain, so levels at the subwoofer are less (that's what WinISD is showing you). My SPL meter was set to C weighting.

    50Hz = 112dB
    40Hz = 113dB
    30Hz = 114dB
    20Hz = 112dB
    18Hz = 115dB
    15Hz = 107dB
    10Hz = 103dB

    I think a few of these may actually be low because I was too chicken to turn it up all the way (house was falling apart).

    If you are used to car audio SPL, these sound really really low, but trust me, 115dB at 18Hz is intense when it's your entire living room. Oh, and most of the time I listen to movies at 10-20dB lower than the volume settings required to produce these output levels.


    Aaron Gilbert
     
  5. Kenneth Harden

    Kenneth Harden Screenwriter

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    Aaron:

    Awesome info!!! [​IMG]

    My room (bedroom, I'm 18, living at home, in college, and working, too) is 13' X 13'6 X 9' and fully sealable (as in, I can close the door) So that is definetly a 'small' room [​IMG]

    Does my box size sound OK? I would plan on 24" tall and deep, and 18" wide.

    I have no idea what I would do to the box. If I can find some industrial self-adhesive black finish, I would do that. I am just looking for a simple covering.
     
  6. Jack Keck

    Jack Keck Second Unit

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    Wanna get REAL confused? Download WinISD Pro. It has even more graphs to not be able to understand. I think I'm starting to figure some of it out. I'm grateful for the vets on this forum, though. Otherwise,I'd be totally lost.
     
  7. Aaron Gilbert

    Aaron Gilbert Second Unit

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    That room isn't tiny, but you definitely should have a good amount of gain. You might want to try the sub in a sealed box first, as ported may give you too much boom. That box size is actually a bit smaller than ideal for the 15" Quatro ported, but it certainly can be made to work just fine. Assuming 1/2 a cubic foot for bracing/driver/etc, tune it to 15-20Hz and you will have tons of output but still very accurate. Lower tuning should make it sound more like a sealed box.

    Aaron Gilbert
     
  8. perry web

    perry web Stunt Coordinator

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    how about the temptest 15"?
    It is 150 shipped.
    I am in the process of looking for a driver also. i was looking at 12"'ers but this 15" is not much more.
     
  9. Kenneth Harden

    Kenneth Harden Screenwriter

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    Also, if you have the room, why would you NOT want a 15 or 18 inch driver? It will make more bass, deeper bass, do it easier, and have less distortion.

    I am also looking into building a 8" subwoofer just for fun using the 8" Quatro (Parts Express) sub driver - it looks like it can do 30 Hz. with decent output.
     

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