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More power needed for Tempests?

Discussion in 'Home Theater Projects' started by David Giesbrecht, Aug 18, 2003.

  1. David Giesbrecht

    David Giesbrecht Well-Known Member

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    As some of you know I have received an RMX1450 to power my two Tempest sealed subs (230L). I guess what I want to know is how much power is required for them to reach their potential? because 450 watts doesnt seem to cut it. I've tested them with some real bass heavy material (LOTR,JP3 etc.) and seem to be able to clip the amp quite easily with that material and the subs arn't even breaking a sweat! My first thought was that I had one of the low frequency filters on but i've doubled checked many times and all filters are off. I've been thinking about getting a second RMX1450 and bridging one amp into each sub. I know it sounds crazy but I think the subs could probably handle it, not continuesly of course but for short transients I think they could, and theirs nothing wrong with having a little extra headroom! I don't even want to venture a guess at how much power would be required to drive a Tumult full out!
     
  2. Pete Mazz

    Pete Mazz Well-Known Member

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    It should take ~170W to reach max excursion at 20Hz, according to WinISD.

    Pete
     
  3. TimForman

    TimForman Well-Known Member

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    Since the Tempest is rated at 750W max with both VCs wired I can see the amp giving out before the drivers. It takes a lot of power down low in a sealed enclosure to hit the levels you seem to be looking for. Another amp will get you closer. I've used a 1000W amp on my sealed Tempest and could only get the gain up about 3/4 on LOTR. (That was loud enough thank you).
     
  4. David Giesbrecht

    David Giesbrecht Well-Known Member

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  5. Jack Gilvey

    Jack Gilvey Well-Known Member

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  6. David Giesbrecht

    David Giesbrecht Well-Known Member

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  7. Brian Bunge

    Brian Bunge Well-Known Member

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    450W is more than enough power. You're getting caught up in analysis paralysis.
     
  8. Hank Frankenberg

    Hank Frankenberg Well-Known Member

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    Brian, "analysis paralysis" came up in Six Sigma statistical analysis training last week. It's a common pitfall. Good catch[​IMG]
     
  9. TimForman

    TimForman Well-Known Member

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    Now that I've educated myself on the model 1450 these guys are correct. 450W per sub should be plenty. Are you sure there isn't a problem with the room? Perhaps you're sitting at a null spot during the movies.
     
  10. David Giesbrecht

    David Giesbrecht Well-Known Member

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  11. Jack Gilvey

    Jack Gilvey Well-Known Member

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  12. David Giesbrecht

    David Giesbrecht Well-Known Member

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  13. Jack Gilvey

    Jack Gilvey Well-Known Member

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  14. David Giesbrecht

    David Giesbrecht Well-Known Member

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    Try running a pink noise test through your system, shut off your mains and try to bottom out your subs. I couldn't do it with 450 watts not even close the amp clipped long before the subs reached their xmax.

    The 450 watts I have is divided up between all the sine waves contained in the material.
     
  15. Chad Kuypers

    Chad Kuypers Well-Known Member

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    I can think of one thing that would definitely be the cause of your problems. I used to own a Crown CE-1000 that put out nearly the same amount of power that your QSC amplifier puts out. It put out 450 watts into each channel at 4 ohms.

    HOWEVER, this only seemed to work when I ran each channel seperately to each subwoofer. I can't explain why, but when I bridged the amplifier (yes the wiring was correct) it would run out of steam and clip very often. I could even get it to shut down if I pushed it really hard. When running each channel seperately, I never had this problem and never saw the clip lights. With each channel of the amplifier hooked independantly to each subwoofer driver, I could make mince-meat out of the subwoofer drivers and the amplifier wouldn't even blink.

    That being said, if I run 400+ watts to a Dayton DVC 15" etc. in a larger sealed enclosure, I can bottom it out pretty easily. I can't imagine that 475 watts x 2 would not be more than enough for your two sealed Tempests. If you have the amplifier bridged, try "seperating" the amplifier channels and running one each to a subwoofer. I hope that this helps.
     
  16. David Giesbrecht

    David Giesbrecht Well-Known Member

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    I currently have the amp connected in stereo and I have tried bridge and it didn't seem to make much difference, even if I did run it in bridged mode the amp is not recomended for 2 ohm operation in bridged mode.
     
  17. Jack Gilvey

    Jack Gilvey Well-Known Member

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  18. David Giesbrecht

    David Giesbrecht Well-Known Member

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    That of course depends on the material and how its recorded.
    LOTR must have a fairly complex mix of sounds because my amp clips quite easily during the moria battle scenes with the belrog and the subs arn't hitten their bottoms thats for sure.
     
  19. Brian Bunge

    Brian Bunge Well-Known Member

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    Chad,

    Is it possible that when running both channels at once your amp's current demands are greater than what it can actually supply?

    Jack,

    [​IMG]
     
  20. Pete Mazz

    Pete Mazz Well-Known Member

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    Do you have the Tempest wired in parallel (+ to +, - to -) for a 4 ohm load?

    Pete
     

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