Will this Tempest rock the house?

Discussion in 'Archived Threads 2001-2004' started by PaulDF, Sep 19, 2002.

  1. PaulDF

    PaulDF Second Unit

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    I am in the process of planning my first DIY subwoofer. I want to know how will it compare to comercial subs... I want to build a 214L ported box with a 15" Tempest. Adire alignment same as on the Adire site. For now I plan to power it with a 100w/ch two channel amp. 1 channel per voice coil. What subs out there might this compare to?? Also, is this the optimum box for overall performance? 60% music 40% HT. Size of box no object...
    (I figure I can do this for $350-$400C) [​IMG]
     
  2. Andrew Pratt

    Andrew Pratt Producer

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    Paul I just built two of those subs and yes it will kick ass. As far as comercial units to compare it to...try a couple of Paradigm PW2200's or Servo 15's.
     
  3. PaulDF

    PaulDF Second Unit

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    Ok, but even a single Tempest running off my old receiver? Am I on the right track with the box?
    Thanks
     
  4. Mark Fitzsimmons

    Mark Fitzsimmons Supporting Actor

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    214L is huge!
    I built a 122L sealed tempest, and it's amazing, and flat down to the low 20's in room. Plus sealed designs are cheaper and easier to make. The way I look at it, I have the tighter sound which will help for music, and I have some very good extention for home cinema.
    www.markfitzsimmons.com/pics/responce.jpg
     
  5. Dustin B

    Dustin B Producer

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    Yep, in larger boxes 250W can push a Tempest to it's linear excursion limits (you'll be 1dB or so off that putting 100W to each VC). Small boxes need lots of power to produce big bass, big ones don't.

    If size isn't an issue I'd up the volume a bit (some where up over 240L) and go to a 6" diameter port.

    I've got one in a 260L sonotube with a 6" port tuned to just over 16hz. I've tried plugging the port (which should make it very similar to the low Q sealed allignment) and listening sealed. They sounded extremely similar listening to one of my Kodo CDs (really nicely recorded traditional Japanese drums). I thought I could maybe hear a slight difference, but I wasn't doing this blind. Blind I'm almost positive I wouldn't be able to tell them appart on music.

    But when I did the same thing on big bass scenes in movies, the story changes. I'm positive I could tell them appart. The sealed allignments just can't keep up down in the last octave.
     
  6. also remember that recievers doesn't have a subsonic filter (most likely), so the driver will unload if he goes ported.
     
  7. Darren_T

    Darren_T Second Unit

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    On the initial advice of Dustin followed by many others I built the exact sub you are considering...214L Adire Alignment Tempest. Kick ass you ask? How many asses do you want kicked? This monster will kick many asses and then some [​IMG]
    I listen to HT 60% and Music the remainder and I must say it performs beautifully for both. I'm no audiophile but I can tell you I am quite picky. For fun I take a low frequency sweep that begins below 20Hz and play it for friends. They don't know what I'm playing but when the house begins to rattle they perk up, then from nowhere the house shakes violently but still no audible sound from the sub... few more seconds into the sweep and your eyes start to vibrate and your voice oscillates. Now you get into the 35 - 40hz range and your chest is vibrating and your ears start to panic. Get the picture?
    [​IMG]
    People that I've done the frequency sweep for think that the beginnings of an earthquake occur until I tell them that's what sub 20hz tones feel like.
    For home theater the Tempest gives new meaning to LFE when watching Lord of the Rings. I had a Velodyne CT100 which is a 10" ported sub with I believe 150watts. It was quite a sub for it's size. I was going to upgrade to a Paradigm 2200 but wasn't impressed for the money. I went on blind faith in the people of this forum and haven't regretted it.
    How's that? [​IMG]
    Darren
     
  8. Mike Strassburg

    Mike Strassburg Second Unit

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    You could build half of the 480L dual Tempest I built. I also second the 6" port size....no noise.
    With 250 watts per sub I hit 127+ dB @ 31.5Hz. It sounds very good for music and LFE is AMAZING!!!
    This was a Dan W design and I couldn't be happier...he's the man [​IMG]
     
  9. Joe Tilley

    Joe Tilley Supporting Actor

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    I recently built a 270liter sono with a 15" Dayton DVC & it is just amazing to hear. Every time someone comes the first reaction I get is [​IMG] WHAT THE HELL IS THAT THING [​IMG] Than I throw in a couple of my favorite demo disks & get [​IMG] DAAAMMMN I WONT ONE OF THOSE!!!
     
  10. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    I guess you could say I'm pleased with the Tempest driver, I do have 3 of them.
    I decided to put one in my 4runner with a 1 farad cap and 600 watts RMS @ 4 ohms (parallel VC).
    My SUV can fit Dual tempest adire alignments (214L! EA) but I plan on using a single sealed 139L tempest for all practical reasons for a smooth response with a 3db downpoint at 34hz.
    What I plan to do for fun is use a 6th order bandpass enclosure tuned to produce an insane spike at the cabin resonance frequency of my 4runner. After playing around with some programs I concluded I might reach volumes as high as 150db though the response would be anything but smooth.
    My other "fun" option was to try and use 2 of them in a horn loaded enclosure powered by my single 1500 watt amp. The gigantic bass horn would likely take up the entire back of my SUV (including the folded down backrow of seats). The sole purpose of the horn would be to amplify bass so that everyone outside (open windows) can hear bass. Think it'll work?
    As for the Tumult, my calculations indicated that it's a bit smoother down to 20hz than the tempest but also at a lower volume which means it's more power hungry. A 250 watt plate amp ain't gonna do squat for a tumult, a 500 watt suits it better to match a tempest in output. The other advantage I guess is the Tumult able to operate better in smaller boxes. But since this is the DIY forum, size isn't a problem. [​IMG]
     
  11. PaulDF

    PaulDF Second Unit

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    Darren, that was awesome... How many watts are you driving it with??
    Can anyone explain the "unloading" that Anthony was talking about? My prepro is a Pioneer 850s.
     
  12. Andrew Pratt

    Andrew Pratt Producer

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    Paul think of a ported box as a sealed box from the highest note it can play down to the tuning freq. While playing a freq withing this range there's a back pressure on the cone due to the air that's trapped inside the box. This is why large box's are more efficent since there's more air available to compress vs a small box where there's more resistance. Now what happens at and below the tuning point is that more air will move out the port and the back pressure drops off dramatically so there's nothing stopping the driver from moving back and forth which if given enough of a signal can cause it to bottom out.
     
  13. Dustin B

    Dustin B Producer

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    Here is a screen shot of an Adire Dharman being modelled in LspCAD. Bottom graph is driver excursion.
    http://dustin.bunnyhug.net/pics/forum/dharman.jpg
    Tuning frequency is 22hz. Notice how quickly excursion rises below the tuning point. This is unloading. Well above tuning excursion isn't high. The port starts to take over output just above 30hz which is why you see the drop in excursion. This continues untill 22hz, the tuning point. Below this the term used is unloading and the port is no longer protecting the driver from over excusrion and starts to rapidly drop in the amount of output it's handling. As a result the driver excursion sky rockets.
     
  14. Darren_T

    Darren_T Second Unit

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  15. PaulDF

    PaulDF Second Unit

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    Okay, if my processor has a "low frequency cut" option, will that help do the trick? What about tuning 16-20 hz? Would a sealed box be better for me in this case then?? According to my graphs, the sealed box has higher spls and lower hz than the vented. Even over a wide box size range... Is this right?
     
  16. Andrew Pratt

    Andrew Pratt Producer

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    Paul if the processor has a low freq option then yes that will help. As for the sealed having more SPL that shouldn't be the case...esp down low. Typically ported designs have a flat curve down to the tuning freq where they'll drop off sharply. Sealed subs on the other hand start dropping off much earlier but don't roll off as quickly so they can still provide lots of SPL down low due to room gain etc.
     
  17. PaulDF

    PaulDF Second Unit

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    Yeah, I thought something looked wrong there. I probably enetered a wrong figure somewhere... So then, the ported box is still my way to go? Around 250L (mother huge!) And a 6" port about 24" long(to tune to 18hz or so)?
    Thanks again!
     

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