floorstanding with built in subs + a seperate subwoofer

Discussion in 'Speakers' started by GregBe, Jun 8, 2004.

  1. GregBe

    GregBe Second Unit

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    I certainly understand that it is better to have a separate sub so you can place it optimally, and almost all good subs will blow away a floorstanding with built in subs. My question is to supplement my sub with towers with built ins.

    I currently have a Cambridge Soundworks P1000 sub which I love. I also have CSW's largest satellite which has two 4" midrange drivers + one 1" tweeter. They blend nicely. I have the opportunity to purchase CSW's T300 Tower for only $600 which is normally a $1600 speaker. The T300 has the same two 4" midrange + one 1" tweeter MTM arrangement, but adds one passive and one active 10" subs to each tower.

    I would obviously keep the P1000 sub. Do you think I would see huge gains from this new setup in midrange. I don't feel I need anything in the bass region and I would think the highs would be very similar with the same MTM arrangement. If the gains would be minimal, I would just keep my current setup; save $600 and have much smaller main speakers.

    Greg
     
  2. Brian L

    Brian L Cinematographer

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    You would then run the new towers full range, right?

    One of the theoretical advantages of a sat/sub system is that the midrange is said to be cleaner if the same cabinet is not also tasked with delivering low frequencies.

    I can't say I have observed that myself, but have read it in a few places (Richard Hardesty's writings for WSR comes to mind). As such, you may actually loose something in terms of midrange performance.

    And if you would cross them over, there's really no point right?

    Methinks the $600 would be happier in your pocket[​IMG]

    BGL
     
  3. SethH

    SethH Cinematographer

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    This is certainly possible to do with good results, but be ready to do lots of tweaking, moving, and equalizing. The problem with multiple subs is phase and cancelation issues. These can be very difficult to work around, but if you're willing to put the work in you could probably make it sound pretty good.
     
  4. Edward J M

    Edward J M Cinematographer

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    I've read about problems from powered tower owners who (unsuccessfully) tried to integrate several sources of low bass in one room. It usually ends up being trouble with peaks and nulls.

    Most (but not all) powered towers are nothing more than a 10" (or smaller) woofer in a small enclosure driven by a 50-100 watt amp. No true deep extension, no real SPL capability, and high THD are the norm rather than the exception.

    I can't see how the addition of a 10" passive and a 10" powered woofer will increase the mids over what you already have (since both speaks in question have the same dual 4" midrange drivers and tweeter).

    Follow the ACI philosophy on HT speakers and buy the best midrange and highs you can afford and cross them over at 80 Hz to the best subwoofer you can afford. Even the TOTL ACI powered center channel is limited to 80 Hz by design.
     
  5. GregBe

    GregBe Second Unit

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    Thanks for saving me $600. I need to learn to be happy with what I have.

    Greg
     
  6. Wayne A. Pflughaupt

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    Greg,

    You could always get the speakers and set them to small, just like the ones you have now. There are at least a few good reasons to do it this way.

    For one, 4-inch woofers, while they sound great for midrange, are a little small for bass. You might well find that with the bigger speakers your upper bass would sound fuller, the point between where the 4’s start to naturally roll off and the sub kicks in. This improvement would be especially noticeable with music.

    Second, if you have been setting the sub at a high crossover frequency to fill in the upper bass for the 4’s, you would now be able to set your crossover lower, like at 80Hz or so. This would help make the sub less able to be localized.

    Third, if you listen at high levels, the bigger speakers will take the strain off the little 4’s, so midrange clarity should improve.

    Perhaps the selling party will let you "try before you buy," or bring the speakers to your place for a demo. Can't hurt to ask.

    Regards,
    Wayne A. Pflughaupt
     
  7. dave alan

    dave alan Second Unit

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    I agree with Wayne on this one.

    The mains should be flat to 40-60 Hz in order to complete a 4th order crossover @ 80 Hz with the sub, otherwise, holes in the crossover region.

    Not only will the sub be more easily localized at higher LP, most subs just sound poorly or lose steam above 120 Hz., and IMD comes into play.

    An audition would be the way to go to see if they work in your setup.
     
  8. Jacinto

    Jacinto Second Unit

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    If fine tuned properly, the floorstandings plus a sub can sound great. I've got two 10" drivers in the fronts and the surrounds, along with an 18" sub for the really low stuff. I've got everything except the center set to "large" on the processor. The fact that my brother is an ISF and HAA certified home theater consultant certainly helped in the fine-tuning of the setup, but when it's called for, I can produce some ridiculous bass.
     
  9. Edward J M

    Edward J M Cinematographer

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    There's the rub. Most digital BM HPFs are 2nd order.

    Speakers flat to 50 Hz will typically produce an emphasis in the 50-90 Hz region when set to small @ 80 Hz and blended with a subwoofer.

    Irregularities in the FR at/near the xo are all too common, primarily due to the fact that the slopes of the digital high/low pass filters are different, and the natural roll-off of the surrounds is not always 2nd order, and roll-off doesn't always start to occur at the chosen xo frequency. A vented surround for example has a 4th order roll-off below its tune point.

    In the day, THX recommended an 80 Hz xo and the 2nd order high pass and 4th order low pass filter rates because THX certified surround speakers were sealed units with a natural 2nd order roll-off and an F3 of about 75 Hz.

    The combined effect of a 2nd order high pass filter at 80 Hz, and a 2nd order natural speaker roll-off at 80 Hz, resulted in a 4th order roll-off - not coincidentally the same as the low pass filter rate imposed on the subwoofer. The final result: a 4th order high pass and 4th order low pass filter rate at the selected xo of 80 Hz and a nice neat crossover.

    Unfortunately, nearly all surround speakers these days are vented, and imposing a 2nd order filter above the tune point will result in a 2nd order roll-off. Below the tune point, the combined roll-off suddenly steepens to 6th order.

    With an 80 Hz xo, the use of vented surround speakers with an F3 of 50 Hz will likely result in an emphasis in the 90-50 Hz region because the vented speaker has not yet begun to naturally roll-off, and is only being artificially filtered at a 2nd order rate.
     

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