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Bass Management 101 ??

Discussion in 'Archived Threads 2001-2004' started by Jeff Keene, Oct 17, 2001.

  1. Jeff Keene

    Jeff Keene Supporting Actor

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    I've had this question for a long time, and I've never been able to get a good answer.
    Is there bass management hardware and / or are there AV Controllers out there that allow you to set subwoofer crossovers where you want them for EACH SPEAKER?
    In other words, say I've got a nice pair of mains that can truly perform down to 40 hz or so. Then say my center needs help below 100 hz. My rears? Somewhere between 60-80 hz, they lose it.
    Does anyone else think that setting my speakers to "Large" or "Small" is not enough?
    Why should I send all 80hz and below to the sub when I've got truly "Large" speakers? But on the other hand, why should I live without that last octave just because I want almost all of my stereo music to come from my mains?
    Although my center is set to "Small", it is still dealing with a small amount of 80-100 hz material that it isn't best at.
    I think I've said enough? What do I need (a life?) ?
     
  2. Rich G

    Rich G Stunt Coordinator

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    There are some receivers and pre/pro's out there that will let you do what you desire. Outlaw's new pre does this to a great extent. B&K 30 does it as well as there 307 receiver. I believe some of the upper Sony's and Pioneer's do as well on there receivers. They don't have a variable crossover like a sub but a selectable crossover some starting at 40Hz. The outlaw ICBM may work but I don't know how many of inputs it has.
    Do you use a receiver or a pre/pro with external amps?
     
  3. Howard Christian

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    I think the Outlaw ICBM does that
    Check out the latest Sound&Vision if i remember correctly
    There's a review on it
     
  4. Howard Christian

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    I took this of AR
    read the thread, it's pretty good for your questions
    "From what I've read...."
    it pays to invest in a quality sub.
    Check out this lengthy thread for good reasons why.
    http://www.avsforum.com/ubb/Forum3/HTML/003524.html
    Scroll down to where Brian Florian jumps in if you don't want to read the whole thing.
     
  5. John Kotches

    John Kotches Cinematographer

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    The B&K has a flexible crossover, but it is presently global, so the same value applies for all speakers.
    Flexible and relatively modest cost?
    Definitely the Outlaw ICBM, if you have the proper setup it's pretty much the ticket.
    Some receivers might have a problem with taking the preamps out to the 5.1 inputs ;-)
    How's this for flexibility:
    Speakers grouped as Fronts, Center, Surrounds, Rear Surround
    Crossover adjustable for each group at 40, 60, 80, 100 and 120 Hz.
    Crossover slope 12dB or 36dB / octave your choice.
    Bass fill option, intriguingly named "L/R recombine" which I will explain in my review, I promise [​IMG]
    In short, a good product, and more flexible than many receivers and preamp/processors, which makes it a great value.
    Regards,
    ------------------
    John Kotches
    Contributing Writer
    Secrets of Home Theater and High Fidelity
     
  6. Nick G

    Nick G Stunt Coordinator

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    I second reading the link that Howard posted. Good information there. You may reconsider your plan after reading it.
    Nick
     
  7. Howard Christian

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    Hey you should listen to John
    He's the man!
     
  8. Drew Eckhardt

    Drew Eckhardt Stunt Coordinator

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    In theory you could get a Lexicon processor - the DC-1/DC-2/MC-1 support 40/80/120Hz cross overs selected individually for each set of speakers (IOW, left+right, center, left+right side, left+right rear, subwoofer).
    In practice, as the owner of a DC-1 and main speakers which are flat in-room into the 30s I think the lower cross-over points are unecessary in nearly all configurations.
    1. I think there are two ways to get seamless sub/main integration:
    - Where the main speakers extend at least a full octave bellow the cross-over point (IOW, 40Hz for an 80Hz cross-over).
    - Where the main speakers are sealed, the acoustic+electrical poles line up, and electrical low pass sums flat with this combination.
    In the first case, a speaker flat to 40Hz is still only good for an 80Hz cross-over. In the second, you're probably running a THX setup which only works with a second order high-pass at 80Hz and fourth order low-pass at 80Hz.
    2. Although the small bass or mid-bass drivers in your mains may play relatively low, a sub-woofer is capable of much lower distortion and higher excursion in the same area therefore yielding both better and more bass.
    3. In the typical two-way speaker (reasonable three-ways weren't in my price range the last time I bought speakers so I haven't played with this in that setup), getting the low frequencies out yields a cleaner midrange.
    4. If your main speakers (small) + a sub woofer don't sound better than the main speakers (large) alone, the problem is with the subwoofer and/or positioning and not that you're "wasting" response with a higher cross-over.
    (I was grumpy about trading off clarity in vocals for bass-slam using a 40Hz cross-over instead of 80 until I moved my sub and switched to an 80Hz cross-over).
     
  9. Charles J P

    Charles J P Cinematographer

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    I couldnt agree more with Drew. Especially about the mains going one octave lower than the crossover point rule.
    Want to know why so few manufacturers give you a flexable non 80Hz x-over. The few are giving you what you want, the rest are saving you money or giving you more features elsewhere, but giving you what you need. Its all about the sub and placement.
    ------------------
    My Website: http://www.hometheaterfanatic.com
    e-mail me: [email protected]
    My DVD Profiler
    Paradigm Lover
     
  10. Jeff Keene

    Jeff Keene Supporting Actor

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    Thanks for the responses and especially for the link.
    From what Brian says, setting all speakers (even the fronts) to small and using the sub for
     

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