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Sub project....

Discussion in 'Archived Threads 2001-2004' started by Jordan Tracey, Jun 29, 2002.

  1. Jordan Tracey

    Jordan Tracey Stunt Coordinator

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    Well instead of buying a shiva or a tempest I am going to us a sub I bought for car use. An Eclipse 8600 series 12. A dvc, 4 ohm coils. Fs is 28hz, RMS is 170w. Xmax one way is .99". I am going to try it in the 8 cubic foot box that I was planning on putting a tempest it. But the question for today is...How many ports should I use? 2 4" round? Bigger? Smaller? I plan on tuning to the good old 20hz. Oh, if this sub doesn't work out, I plan on buying a tempest and putting it in the same box.
     
  2. Mark_E_Smith

    Mark_E_Smith Second Unit

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    Well I punched that speaker into BassBox pro and you might want to save your money. It has a rather NASTY 12 db peak at about 35 Hz in that 8 cft ported box and you get a horible group delay about that time. Plus 180 deg phase change from 30 Hz to 40 Hz
    8 cft, 2 - 4" X 3" round ports.
    This speaker would be best in a 1.1 cft closed box, BUT its max spl is only 102 db @170 watts [​IMG]
     
  3. Mark_E_Smith

    Mark_E_Smith Second Unit

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    Also a Tempest needs a big box and it looks like it might be better in a closed 8 cft box that would have a QTc of .8 How big is your room?
     
  4. Jordan Tracey

    Jordan Tracey Stunt Coordinator

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    The room is 18x25x8. Pretty decent sized room. I was going to go with vented with the tempest in the 8 cubic foot box too, or ould it do better sealed?
     
  5. Mark_E_Smith

    Mark_E_Smith Second Unit

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    I would start with a closed box @ 8 cft you could add the vents latter if the bottom end was weak but if you have any room rise at all it might sound boomy. also you might want to stuff the box, as the ideal size for the tempest for a Q of .7 is 16 cft
     
  6. Pete Mazz

    Pete Mazz Supporting Actor

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    Better re-check your calcs. A sealed Tempest enclosure will have a Qtc of .58 in 8 cu ft and .49 in 16 cu ft.

    Pete
     
  7. Mark_E_Smith

    Mark_E_Smith Second Unit

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    I keep coming up with the previously posted results, maybe the t-s specs are off in the BassBox pro[​IMG]
    Went and checked the specs and they were off, but still comes up with near same results. The white paper at Adire audio tends to agree with you.
     
  8. Mark_E_Smith

    Mark_E_Smith Second Unit

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    Ok, Pete found the setting for box leakage was very high, and set it near very low and the numbers started to agree with Adire. Any way same suggestion except he can have a smaller box if he wants. If it is ported I think it might have to much below 50 Hz if his room even has a 6 db rise below 50 Hz But I like music more than earth shaking bass at least at this point in my life as my HT and my music are in the same system.

    Mark
     
  9. Pete Mazz

    Pete Mazz Supporting Actor

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    I hear ya! My dual sealed Tempest gives me all the bass I could want, as well as being exceptional for music. [​IMG]
    Are you an Aggie, BTW? My brother is.
    Pete
     
  10. Mark_E_Smith

    Mark_E_Smith Second Unit

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    Went there for 2 years for an ME degree got into business and quit, now I own my own small business. My wife is the curator for the Corps of Cadets Center.
    I am thinking about building 2 shiva's for a project to replace my mains with 2 subs and pair of speakers with mid/bass Audax drivers and Hi-Vi ribbon tweeters to match my center channel I am building now.
    I am still a little concerned about the BassBox Pro calculations as the factor I changed made the box leakier instead of tighter.[​IMG]
     

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