Tempest Sub "Quality" Question

Discussion in 'Archived Threads 2001-2004' started by Patrick D, Mar 21, 2003.

  1. Patrick D

    Patrick D Stunt Coordinator

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    After finishing my Tempest sub (Adire Alignment - Vented) some time ago I finally got around to giving it a little bit of a good workout.

    I was unimpressed by the output, and decided hook up my car subwoofer (Kenwood 10" DB+ in a sealed 1 cu. ft. box) to a spare amp for comparison. I unhooked the main speakers and ran the LFE output only, and ran some listening tests.

    The 10" sub is definately wanting in the volume department, but it sounds so much better. On Chapter 32 of the Matrix (about 15 seconds in), you can distinctly hear helicopter blades whooshing on the Kenwood, while on the Tempest they were not even audible (just a loud rumble). When I plugged the ports on the Tempest, the blade "whooshing" became audible but was very messy and not at all clear and punchy like on the Kenwood. I've sealed everything on both boxes and there are no air leaks I can see on the Tempest sub.

    My question is this: Am I asking too much from a 15" woofer? Would it sound better if I moved the Tempest to the mid-Q sealed design? Or did I just goof up the Tempest box and I have either bad bracing or air holes still (either is possible, the box is fairly resonant)? I'm more concerned right now with detail than with loud.
     
  2. TimForman

    TimForman Supporting Actor

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    I'm running a Tempest in a sealed MidQ design and it shakes the house. No problem handling The Matrix LFE. The Tempest can be power hungry at lower frequencies. What are you feeding it? Also, what crossover are you using?
     
  3. Patrick D

    Patrick D Stunt Coordinator

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    I'm using a Parts Express 250W plate amp (about 1/3rd up on the gain knob makes more noise from the sub than I know what to do with). It's crossed at 100hz on the amp as the receiver is crossing it's LFE output over at 80hz. It's more than ridiculosly loud enough, it's just passing over so much low frequency detail compared to the little sub.

    (Oops, also... the Tempest is downfiring, the 10 inch'er is front firing... would that make any difference? The Tempest is way too big to put on its side [​IMG])
     
  4. TimForman

    TimForman Supporting Actor

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    Hmmm..not sure. I should ask the obvious questions. How do you have the voice coils wired? Did you stuff the box? What size vent did you use?
     
  5. Michael R Price

    Michael R Price Screenwriter

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    Double-check that the voice coils are working in parallel. If one is left unconnected the sub is way underdamped, losing a lot of low frequency output and sounding generally boomy. This happened to my friend's sub which is exactly the same as yours. And believe me, once that was fixed, it is pretty detailed and not boomy (unless you want it to be). [​IMG]
     
  6. Patrick D

    Patrick D Stunt Coordinator

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    I pulled the driver to double check the connections. The VC's are both connected and connected in parallel. I suppose the only thing to try is to build a new, sealed box.

    I suppose what I'm still wondering is, would the bass be more accurate on a 12" driver like the Shiva than it would be on a 15" like the Tempest? Am I simply trying to compare two too different things in my quest for the bass accuracy of the smaller sub driver? I wouldn't expect a 6.5" mid-woofer to be as accurate as a 5" one, but I don't know how that translates to the sub-frequencies (
     
  7. Robert_Gaither

    Robert_Gaither Screenwriter

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    You never stated the positioning of the subs in the room and whether you adjust the variable phase on the amp, I'd recommend putting the Tempest where the main seating and crawl and find the best location to put it and recalibrate and try again. I'd also recommend turning the gain to max on the plate amp (maybe a cross-over interaction), spiking your sub, and go along all the internal creases of your sub with silicon just to make sure the there isn't an air leak. Trust me the tempest should easily be detailed in such an alignment.
     
  8. Patrick D

    Patrick D Stunt Coordinator

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    I've put the sub all around the room (it's small, 12x20) and played with the phase switch at all positions. No difference. The volume isn't the problem, there's more than enough of that to damage stuff in the room, it's just that the reproduction of that bass is very muddy and "un-detailed".

    I figure it could be room modes but it did sound a lot better (detailed) when I stuffed the ports, although not nearly up to the level of the small 10" sub.

    Since I don't like the box it's in anyway, I'm just going to build a smaller one that I can seal up nice and good from the start. I need to also check that plate amp with the smaller sub to make sure that's not at fault. I have the small guy going out of a spare channel on the receiver right now (140 watts).
     
  9. Dustin B

    Dustin B Producer

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    I'm not sure what's going on Patrick, but something definately has to be wrong. I have a Tempest in a 260L enclosure tuned to just over 16hz with a 6" port being powered by an AVA250. It produces noticably better quality bass than the Paradigm PDR-10 it replaces. And when I experimented with plugging the port the quality of the bass was ever so slightly improved (I'm not sure I could tell plugged and not plugged appart in a blind comparison). Also as good as the bass was, it got a lot better after I EQed the thing.

    Driver size has very little to do with the sound quality of the bass. 18" drivers can and do sound much better than subs with 8" drivers.

    http://www.adireaudio.com/tech_papers/woofer_speed.htm

    Be careful with this new box. If you build it too small you'll have a high Q Tempest and you definately won't like the sound of that.

    Are you confident there are no air leaks in your enclosure? Have you tried using the PE amp to power your 10" sub, maybe something is wrong with it. Get in touch with Adire and get them to help you trouble shoot. Something is not right, a 10" Kenwood can not compare to an Adire Alignment Tempest that is working properly.

    Can you do a 12th or 6th octave frequency response of both subs at your listening position?

    It's also possible you are not used to and/or don't like really deep bass. The Kenwood won't be doing much below 30hz while the Tempest will be doing it all.
     
  10. Allen Ross

    Allen Ross Supporting Actor

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  11. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    I've compared dual sealed PPI 10" car audio subs to my tempest adire alignment.

    The huge difference was the bass sound quality. I could hear a large amount of distortion come from the PPI subs that caused ear pain at loud volumes while the tempest created no fatigue. The tempest was also able to hit specific deep notes well and not sound as single tone as the car audio sub.

    I just fired up matrix chp32, and when the helecopter looms over Morpheus, the Adire alignment tempest (PE 250) clearly makes each woosh of the chopper blade. The hits are easily countable and felt in the chest at reference level. I also turned off the sub to find that the sub plays 90% of that sound. That sound is like 30-50hz+ so the ports may not be a big factor.

    Maybe the Kenwood has a 40hz spike in which case you're hearing more of that sound effect than with the tempest which could be more lineal.
     
  12. Patrick D

    Patrick D Stunt Coordinator

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    As to putting the Tempest on it's side, I meant the box... [​IMG]

    I pulled the amp out and used it to power the little sub. Previously I was using a spare channel from my AVR-8000. The plate amp definately does not seem as "detailed" but oh well. It's close. I think I may have to do with the gain control, because I notice there's a definate point on the dial where it sounds like it did before (on the AVR8k amp), and then loses all that detail with just a small movement.

    I think I'll go and build the new box, make sure it's airtight to the hilt, and try it again when the Tempest is front-firing and I can power it off the receiver. I do think it's more amp and box than speaker right now. Thanks for the help, guys! [​IMG]
     
  13. Scott Simonian

    Scott Simonian Screenwriter

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  14. Patrick D

    Patrick D Stunt Coordinator

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    It could be a bass hump on the little sub, possibly. The problem really is that on that matrix scene I'm using for testing (with just the sub playing) I can hear each 'whoosh' of the helicopter blade distinctly, as well as a rapid pulsing at 8 secs in, on the small sealed sub.

    On the Tempest, it's just a very bassy rumble for a lot of the scene, with no definition and nothing near defined blade 'whooshes'. I mean zero detail, just a rather bloaty rumbling, no matter how the gain on the amp is set (the gain just makes it a louder bloaty rumble, or a quieter bloaty rumble). I figured this is not how it should be, and now I know it is indeed not. The VC's are wired in parallel and I've verified this (as well as the polarity with a 9v battery). I haven't been really happy with this box (the actual physical box the driver is in -- getting that much panelage to make friends while the glue dries was no simple trick) since day 1, so I will re-evaluate how things work after I get a new, hopefully better braced and sealed box going.

    Right now I have the plate amp powering the small sub with no problems, except I do lose that definition if I turn the gain knob up too high (odd). I'll know better when the new box is built, since I'll just put some spare binding posts on it and leave the amp external, so I can try various amps and see how it goes.

    On the bright side, I did get the last speakers done for the 7.1 setup... that does work very well (yay). [​IMG]
     

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