Tumults for PA bass bin

Discussion in 'Home Theater Projects' started by Jordan_Brulotte, Oct 4, 2004.

  1. Jordan_Brulotte

    Jordan_Brulotte Stunt Coordinator

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    As I have never been able to hear the Adire Tumult in person I have no idea how they perform in the real world. I will soon be constructing a bass bin for my friends audio business, that will need to be able to play in large rooms. Most places, where this setup will play, will be ~1600 ft^2, but I would like to build it with the strength to handle 4000 ft^2 rooms if need be. As he will be playing a lot of Drum n'Bass type music, the setup will need to play with authority in large areas.

    Will 2-4 Tumults be able to handle this type of application in a vented enclosure? I have looked for tumult horn designs but have found nothing. Any suggestions at all, for creating an insane PA Subwoofer would be greatly appreciated. Thanks.
     
  2. Allen Ross

    Allen Ross Supporting Actor

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    GO PRO, With PA there's no real need to get low, and thats what the tumult does best, sensitivity is horrible on the tumult.

    Also look at sensitivity and price, you can score two amazing Selenium 18 subs with 97 SPL for the price of one Tumult.

    Toss them in one of their folded horn designs, mix in a nice crown Macro Tech. Sit back and feel the insanely low group delay and slap people around with bass.


    you won't find a horn enclosure for the the tumult cause the EPB is so low is makes for an enclosure that would be the size of the room.

    Dan mentioned a horn enclosure for the tempest that would actually be reasonably sized, he hasn't mentioned anything recently, but ask him.
     
  3. Jordan_Brulotte

    Jordan_Brulotte Stunt Coordinator

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    Those drivers do look great, however I will need the bins to be able to play as low as possible. The music that my friend will be playing often goes below 30hz.

    The sensitivity is much better with the selenium drivers as you mentioned, but would 2 18"s be able to fill a 4000 ft^2 room? It just doesn't seem as though they'd push nearly enough air.
     
  4. Kyle Richardson

    Kyle Richardson Screenwriter

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    Try the Adire Tempests in the folded horn design they just released recently. At $150ea 4 of them wouldnt break the bank and should be able to put out nice SPL in that room.
     
  5. Jordan_Brulotte

    Jordan_Brulotte Stunt Coordinator

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    Yeah the tempest horns look great too. Maybe my concerns are unjustified, but I'm still worried about room size. My DIY HT Tempest sub is awesome, but it also plays in a 364 ft^2 room.

    I may have to try the tempest horns and the selenium drivers and see what could work best. I wish there was somewhere nearby me where I could audition them.
     
  6. Wayne A. Pflughaupt

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    Jordon,

    Allen is right. Don’t mess with success and don’t try to reinvent the wheel. There’s a reason why pro subs are the way they are, all the way from cabinet designs and drivers used to output and response characteristics. There are plenty of highly experienced and highly successful companies that know what they’re doing in that realm. The best thing to do is either buy their products or DIY their designs. Anything else is in fact a R&D experiment, and you run the risk of wasting a lot of time and money.

    Regards,
    Wayne A. Pflughaupt
     
  7. Greg Monfort

    Greg Monfort Supporting Actor

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    Since 1600ft^2 is large enough to push useful room gain below the desired BW, it becomes a simple matter of determining the SPL required based on distance. Using the worst case scenario of a 6dB loss/doubling of distance to ensure meeting your goal regardless of the room's Vb:

    dBt = dB + (dB(loss) = 20 log (D2/D1 (usually 1M or ~3.28084ft))

    For example you want it to hit 100dB 40ft from the speaker:

    100 + (20*log(40/3.28084)) = ~121.72dB/m

    I assume you want reasonable quality/durability, so best to calculate the speaker requirements based on its half power rating at the lowest frequency of interest and use digital EQ to attenuate/shape the rest of the response rather than overdriving it with boost.

    That said, it's the midbass/lower mids that puts the 'kick' in kick drums and the 'thump' in the bass, so you want plenty of dynamic headroom (SPL capability) in the 60 - 300Hz BW.

    GM
     
  8. Rory Buszka

    Rory Buszka Supporting Actor

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    The Tempest horn sub enclosure doesn't seem to be that great for pro sound. First off, the sensitivity is very low for a pro sub like this. 97dB. Just playing around one weekend, I got an Eminence HL-10 driver (high excursion for horn loading) driver to hit 108dB sensitivity. What you want is to look at the Live Audio Board (LAB) subwoofer project at ProSoundWeb. Designed by Tom Danley of Servodrive, the LAB Horn subwoofer is a little complicated to build, but from two 12" drivers it gets enough output for six to eight 18" direct-radiating woofers. Four per side (their intended application) have been described as devastating capability, with plenty of headroom for even the most demanding outdoor gigs with 4-6 mid-hi packs. I'm currently in the process of developing a much smaller horn for the Eminence HL-10. The finished product will be less than 3 feet tall compared to the LAB's 4' height (or thereabouts). Maybe a couple years down the road I will be able to have a PA system and do weeked-warrior sound reinforcement services with this horn sub I'm designing, as it should be very cost-effective. The LAB Subwoofer is in use by several large local sound companies, all of which report very good results, but you need to be careful in the construction and wiring to follow the directions closely. The LAB Horn Subwoofer uses a custom driver, built by Eminence to Tom Danley's specifications. It is avialable from Parts Express. Look for the LAB12 GenII. For your friend's sound business, the LAB Horn Subwoofer looks like your best bet. Use at least 1 per side, but the more you use, the better. They were designed to reach into the upper 20s when used 4 to a side.

    ProSoundWeb's LAB Subwoofer Project forum

    Best of luck on your quest for bass.

    [​IMG]
    The Eminence LAB12 GenII subwoofer driver features an improved cone-surround glue joint. There were some failures with older drivers at very high sound levels.
     
  9. michael.e

    michael.e Extra

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    Hi all first of all,the Tempest horn is not 97db efficient.
    1- its measured at 2metres distance instead of 1metre
    2- its one box in 2pi space-youl find the labhorn response much like this in 2pi space.

    So really its not as bad as what it looks
    3-The only concern for the tempest is its power compression

    Also the labhorn uses 2 12"s-it couldve been one 15"(IMHO) but easier to fit smaller drivers i guess.

    You could always re design the horn to be how you want it ie lower frequency loading and even larger!
    Hearing Clean 50hz in a large venue is something unusual!

    The labhorn is ~97db efficient too in 2pi
    Check out the documentation page on the prosoundweb forum

    Cheers!
    Mike.e
     
  10. Rory Buszka

    Rory Buszka Supporting Actor

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    Aren't all horn-loaded pro sound boxes measured in 2pi space (ground plane)? I guess I still have some things to learn. The two 12" woofers will cost more than the Tempest but there will be more power compression with the tempest than if the power is divided up between the two drivers. Many say that the sound of the LAB subwoofer is like that of high-end theater subs from EAW, Meyer Sound, et cetera, more than one would think is necessary for pro sound but the fidelity certainly doesn't hurt anything. It is kind of big at 220lbs with all the touring hardware on it, but so are most other large horn subwoofers. It's basically a smaller version of the ServoDrive BassTech 7 with dynamic drivers instead of a servomotor and two diaphragms.
     
  11. Jordan_Brulotte

    Jordan_Brulotte Stunt Coordinator

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    Those LAB horns look great. They'll definately put my woodworking skills to the test.
     
  12. michael.e

    michael.e Extra

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    They do have tricky mitre joins!

    You can actually remove those hard mitre joins by using an expansion in 1 dimension only if you really want.

    Note that theres the HL10 which is a single ten,used 1 per horn of smaller size,3'x3' x 2' i think.

    -you have to measure at a distance (~4m) and then calculate the 1watt/1metre sensitivity due to the mouth acoustically extending further than the physical horn mouth.

    When i look at the thd and impulse responses i like what i see with the labhorn-not that im super experienced with these-surely some one else can comment-but the labhorns have a nicely damped impulse response!No boomyness here!

    Cheers !
    Mike.e
     
  13. Rory Buszka

    Rory Buszka Supporting Actor

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    That was the idea of the LAB Subwoofer Project: to put a high-quality, low-priced horn-loaded subwoofer at the fingertips of people who couldn't afford things like EAW bent-horn subs. I am actually in the process of designing a horn that is less than 3'x3' on each side (33") and less than 1.5' wide (16"). A horn with a mouth of 3'x2' would certainly allow a nice low cutoff in 2 pi space. I'm aiming for a bass cutoff right around 45 Hz. Also, the other ting about the Lab sub is that I think its power handling is very conservatively rated, because people use 2400w amps on each box on a regular basis without failures. Of course, there is also a plan which puts an aluminum plate on the woofer access hole because the small compression chamber doesn't let the baskets of the woofers face out into the horn, so the drivers cause a sort of "hot oven" effect at high power over long periods, where the air in the rear chamber heats up furiously. In my own design, for the HL-10, the woofer is actually facing into the rear chamber and the basket sticks out into the compression chamber, which allows the thermal mass of air in the compression chamber to couple with that of the horn and transmit heat out that way, preventing the hot oven effect and extending the service life of the driver.
     
  14. Jordan_Brulotte

    Jordan_Brulotte Stunt Coordinator

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    Yeah I noticed that the design calls for an aluminum plate behind he driver, on the access panel. Is this strictly for cooling purposes?
     
  15. Allen Ross

    Allen Ross Supporting Actor

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    why couldn't you just turn the driver around like you mentioned?
     
  16. Rory Buszka

    Rory Buszka Supporting Actor

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    There is not enough clearance in the compression chamber of the Lab subwoofer to turn the drivers around. However, people only run into problems with that when they're putting more than 2000 watts per box for those crazy dynamic peaks. (The Lab Subwoofer has an RMS power handling of 800 watts.) What main speakers will these subwoofers be used with, and how many per side? Perhaps with that information I can make a better recommendation of how many sub boxes to be built.
     
  17. michael.e

    michael.e Extra

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    Although ideally having the driver magnet structure in the horn 'should' cause some cooling effect,youd have to ask a thermodynamics fluid specialist!

    I wouldnt be risking driver problems by using so much power!

    People have destroyed drivers by LF over excursion,and thermally as far as i know.

    It seems silly to input that last 1kw which results in driver failures-when it provides less than 3db more output due to power compression.

    Cheers!
     
  18. Greg Monfort

    Greg Monfort Supporting Actor

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    Hmm, the throat has a ~uniform particle density so is heating up on its own, and since it's volume is considerably < the rear chamber's, I'm skeptical. I do know that my front vented AlNiCo drivers thermally compress at lower power in a compression horn than they do in a BR and I see no reason why it would be any different with a driver's motor in the throat.

    GM
     
  19. DanWiggins

    DanWiggins Second Unit

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    Excellent point. I'd just add that the thermal transfer from a driver to air is painfully low - steel and ceramic radiate heat to air extremely poorly. You need large temperature differentials to get any significant cooling of the motor. And just because the outside of the motor is cool does not mean the voice coil is cool. I've seen cooked voice coils from PA stacks that were used in sub-freezing venues...

    I'd actually expect worse cooling with this approach because of the small volume in the throat as compared to the typical sealed chamber. Things should be worse, not better.

    Dan Wiggins
    Adire Audio
     
  20. Rory Buszka

    Rory Buszka Supporting Actor

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    I simply made the design decision to invert the HL-10 in my horn design in order to allow the motor's own forced-air cooling to be able to tap into a larger thermal mass. Though the horn throat may be smaller than the cross-section of the compression chamber, the two thermal masses should couple well enough, rather than one thermal mass building up all this heat in a small space.
     

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