sub comparison please?

Discussion in 'Home Theater Projects' started by Wayne_D, Jul 14, 2003.

  1. Wayne_D

    Wayne_D Agent

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    Could any one give me a quick comparison of the tempest and the av15? telling the strengths of each sub, and the ideal enclosers for home theater?

    thank you
     
  2. Darren_T

    Darren_T Second Unit

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    I'll be able to comment in a month or so. I have an AV15 and 2 PR's sitting in my shop right now and am currently using my 214L Tempest.

    I can tell you some of the physical differences. The specs speak for themselves if you compare them. The Tempest is an excellent driver and gives great bang for the buck. The AV15 is a bit of a step up. It has better XMAX and is much more rigid. It has a rubber surround where the Tempest has a foam surround. The build materials are heavier and it is just an all around beefier driver.

    Sound? Can't comment yet as I haven't had a chance to build the AV15 enclosure. The Tempest is one heck of a performer though. Either sub will be leagues above many commercial offerings at a fraction of the price.

    What am I expecting the differences to be?
    Well, since the AV15 has 2 18" PR's I and higher excursion limits I expect better SPL, I also expect tighter bass as the AV15 will be in a PR'd enclosure and my Tempest is in a vented enclosure. I expect more articulate bass because of the AV15's design.

    We'll see [​IMG] I've been incredibly happy with the Tempest but I think the AV15 would compare more favorably with the Tumult under normal operating conditions. If you were to push each to their limits the Tumult promises to excel.

    Darren
     
  3. Wayne_D

    Wayne_D Agent

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    thanks alot Darren! how much power are u supplying your tempest...and how much will you be supplying your av15?
     
  4. Darren_T

    Darren_T Second Unit

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    I have the PE 250watt plate amp powering my Tempest. I can only turn up the gain about 1/3 of the way but properly calibrated is even lower than that. In the large ported enclosure it doesn't require much in the way of power. It hits very low and with great authority.

    I plan to use a pro amp that supplies about 1200 watts into 4 ohms for my AV15 but I won't be using the full 1200 watts which is major overkill. I just want an amp that I won't have to upgrade with changes. I've been told 500 watts to 800 watts is the sweet spot for the AV15. Anything over 500 watts is probably overkill for the PR'd design.

    Darren
     
  5. Wayne_D

    Wayne_D Agent

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    that would be cool...i have two 700watt rms amps sitting here colecting dust....i would like to run a av15 off of each amp....

    i just was looking for some input on if the tempest would compare....every one has told me i have way to much power any way for the tempest...and i sounds like the av15 can produce alot of bass for smaller box size.....i am looking at a vented encloser for the sub
     
  6. Wayne_D

    Wayne_D Agent

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    Can any one that is familiar with pro power amps, give me a couple brand names that are knowen to be very good? without braking the bank?
     
  7. Andrew Pratt

    Andrew Pratt Producer

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    Wayne out of curiosity where "middle of Canada"?

    As for amp names QSC is a popular budget choice.
     
  8. Wayne_D

    Wayne_D Agent

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    i am in regina sask andrew..... i have been looking at the QSC RMX 2450 looks like a powerfull amp and inexpensive!
     
  9. Andrew Pratt

    Andrew Pratt Producer

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    That's a nice amp! Do you ever get out to Winnipeg?
     
  10. Allen Ross

    Allen Ross Supporting Actor

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    If you aren't afraid of ebay, they have some nice Vintage Crown DC300As on there that will supply more then enough bang for the buck. The DC 300A II (the one i have) is rated at 610W into a 8 ohm load bridged so i am guessing thats something like 800W or so at 4 ohms. But i am not sure.

    I think something with such a great history as the DC300 is a marvel in itself. Seeing those two 33 joule caps, for the first time, made me cry in happiness [​IMG]
     
  11. Allen Ross

    Allen Ross Supporting Actor

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    If you aren't afraid of ebay, they have some nice Vintage Crown DC300As on there that will supply more then enough bang for the buck. The DC 300A II (the one i have) is rated at 610W into a 8 ohm load bridged so i am guessing thats something like 800W or so at 4 ohms. But i am not sure.

    I think something with such a great history as the DC300 is a marvel in itself. It is the first high power solid state amp ever designed, dating back to 1967. Seeing those two 33 joule caps, for the first time, made me cry in happiness [​IMG]

    Plus there's no loud fan to worry about dead silent
     
  12. Pete Mazz

    Pete Mazz Supporting Actor

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    I'm partial to the Carver PX-850 for sub duty. Built for 2 ohm operation and has some nice features for "bass heads" like us (in Bold by me). [​IMG]

    Parts Expresshas them.


    FEATURES
    • 300W per channel into 8 ohms*
    475W per channel into 4 ohms*
    760W per channel into 2 ohms*
    980W bridged mono into 8 ohms*
    1520W bridged mono into 4 ohms*
    • Three connector versions available:
    Standard - Neutrik™ combi inputs with Binding Post outputs
    BR Version - Barrier Strip inputs and outputs
    SP Version - Neutrik™ combi inputs with Neutrik™
    Speakons™ and Binding Post outputs
    • Independent 41 detent Level Controls for CH1 and CH2
    • Externally configurable for Parallel Mono mode to operate both
    channels with a mono signal
    • Externally configurable for Bridged Mono mode to combine the
    power of both channels into a higher powered mono channel
    • Externally configurable input sensitivity @ 0.775V or 1.5V fixed
    +28dB gain
    • Protection circuitry includes DC Fault, Thermal and Short Circuit
    • Power Ready, Signal Present, Clip, Protect, Thermal and Standby indicators for each channel
    • Variable Speed Fan
    • Front or Rear Gain Controls (field configurable)
    Signal Smart Standby Circuitry. Power saving feature which automatically turns off or on the amplifier based on the presence of a signal and the position of the threshold adjustment
    • RAMP optional computer monitoring port
    • CSA& NRTL/C approvals pending
    • CE 1997 approved
    * 1kHz @ 1% THD

    Pete
     
  13. Allen Ross

    Allen Ross Supporting Actor

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  14. Wayne_D

    Wayne_D Agent

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    and how much do they sell for pete?
     
  15. John E Janowitz

    John E Janowitz Second Unit

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    Allen,

    Don't pay too much attention to the THD ratings. They are pretty much meaningless. 10% distortion is the bare minimum level that becomes audible to human ears, and that is only to a very small percentage of people, and even less for subwoofer duty.

    When i was at michigan tech, Tom Nousaine spoke for an AES meeting about distortion. He had recordings of Uncle Tom's Diner, each with varried levels of distortion. He played them with increased distortion and asked us to tell him when distortion was audible. Up to 25% distortion nobody was able to hear anything different than the original. Some may be able to, but about 30 people there couldn't.

    The majority of distortion actually comes from the two energy transfer points where acoustic energy is converted to electrical, and the other way around. This is at the recording into the microphone, and the playback from the speaker into the air. Any small amounts of distortion put into the path between there are pretty much negligible.

    The point is, don't pay much attention to 1% distortion levels in an amplifier.

    John
     
  16. Wayne_D

    Wayne_D Agent

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    thanks john!
     
  17. Wayne_D

    Wayne_D Agent

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    ok here are some more questions for the pro's in here...

    two av15s in a 10cubic foot vented box (minus driver volume and vent) with 600 watts each.....

    what would you tune the box to? 20, 15, 10???

    and how do you figure the vent size...i am not looking for tube ports...but rectangle vent?


    i know thats alot of work for any one to figure...but i appreciate all the help i can get!
     
  18. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    I would tune a 10CF box with dual AV15s to at 21hz (or perhaps higher), and the vent size would depend on the box dimensions. I would choose a vent that has a very large opening, which would mean it will be relatively long.

    If you used three 4" diameter flared ports they would have to be 21" long.

    A 2"x18" slot that is 14.25" long is another option

    I'd honestly would consider buying 15" or 18" passive radiators though.
     
  19. Wayne_D

    Wayne_D Agent

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    Chris, if you dont mind me asking, why would you turn it higher?
     
  20. John E Janowitz

    John E Janowitz Second Unit

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    For a 10cf box using 2 AV15's you get the same alignment as a single AV15 in 5 cf. I would say tuning to 21hz would be just about right. You can get a little more low end response and slope off the bottom end a little more to work with room gain better, by tuning to about 18hz. The only problem is trying to fit the port in the box then.

    I like to stay away from rectangular ports myself. A circular port will have the lower amount of internal surface area for the same cross section than a rectangular port. That means the circular has less internal friction, lower losses, less prone to noise, etc. Also in a rectangular port, air has much more friction in the corners and moves much slower there. This also leads to compression sooner.

    I'd recommend a pair of 6" diameter vents for this application. They do get pretty long though, about 30" each to get the 21Hz tuning. The only reason I could see for tuning higher than 21Hz is just to get the port to fit in the box easier. Shortening the ports to about 24" each raises tuning to 23Hz, but this shorter length may be a lot easier to fit in.

    John
     

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