Large Bookshelf or Tower -> Aperiodic In-wall ?

Discussion in 'Archived Threads 2001-2004' started by Chris Eriksen, Jun 24, 2001.

  1. Chris Eriksen

    Chris Eriksen Stunt Coordinator

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    Hi Everyone,
    I hope you can offer advice on my speaker dilemma. For spouse approval reasons, I am limited to in-wall speakers for my rear channels. My mains are a/d/s/ L1290/2's, which are large, floor-standing 3.5-way towers with soft dome mids and tweters. After a lot of listening, I am having a hard time finding anything that is a good sonic match. I have auditioned a ton of in-wall speakers, and the closest match so far is the NHT 6.3 Ci. The current in-walls from a/d/s/ were also similar, but not as close as I would like. (Possibly due to their poly woofers versus my paper cones?)
    Recently, I have found a good deal on a pair of a/d/s/ L520's, which are large, sealed-enclosure, two-way bookshelf speakers. Sonically, these are a good match to my mains. I also found a pair of a/d/s/ L1230's, which are large, sealed-enclosure, floor-standing, 3.5-way designs that are a perfect match for my mains. (identical drivers)
    I have been playing around with the idea of removing the drivers and mounting them as in-walls. Has anyone tried something similar to this? Since a large sealed enclosure behind the wall is not an option, would aperiodic loading be appropriate? I have built AP subs, but I am unsure of what effect the AP loading would have on the midrange response.
    The speakers will be driven off of the rear channels of my Onkyo 696, so they will see around 100 watts per channel. I am almost positive that I would set the L520's to 'small', and I am equally as confident that I would run the L1230's as 'large'. If I use the L520's and a 'small' setting for the rear channels, would it be possible to run them in an infinite baffle configuration? My receiver's high-pass filter is fixed at 80 Hz @ 12 dB/octave.
    Any advice that you can offer will be greatly appreciated.
    Thank you,
    Chris
     
  2. ThomasW

    ThomasW Cinematographer

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    The stock crossovers are probably designed with built in baffle step compensation for the drivers in the stock size box. Wall mounting would very likely change the amount of compensation needed. So it would probably be necessary to redesign the crossover to obtain optimium performance.
    quote: If I use the L520's and a 'small' setting for the rear channels, would it be possible to run them in an infinite baffle configuration?[/quote]
    This would be a 'crap-shoot'. Not all woofers/midwoofers work well open air. The midwoofer output would without doubt drop considerably, changing the balance between it and the tweeter
     
  3. Chris Eriksen

    Chris Eriksen Stunt Coordinator

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    Thank you for the helpful reply, ThomasW. I had not considered the effects of the change in cabinet face geometry.
    Does anyone have thoughts about aperiodically loading the woofers? I know that I could achieve good low-frequency response, but would this impact the sonic characteristics of the woofer in other ways? Would I be compromising the midrange response?
    Thanks in advance,
    -Chris
     
  4. Greg Monfort

    Greg Monfort Supporting Actor

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    Thank you for the helpful reply, ThomasW. I had not considered the effects of the change in cabinet face geometry.
    Does anyone have thoughts about aperiodically loading the woofers? I know that I could achieve good low-frequency response, but would this impact the sonic characteristics of the woofer in other ways? Would I be compromising the midrange response?
    Thanks in advance,
    -Chris
    =====
    I assume the mid driver is either a sealed unit, or has its own back chamber. Either way, Aperiodically loading the LF shouldn't affect the mids except possibly making them sound a bit 'thin' if you roll the LF off a bunch.
    Like TW said, this will be a crap shoot no matter what you do unless you invest in measurements and work out all the variables. About the best you can do otherwise is put matching components in the wall, baffled off at the ~same net volume, and insert a parametric EQ in the rear channels to adjust them to something 'in the ballpark' FR wise to the mains.
    BTW, is the woofer going to fit in such a shallow depth?
    GM
    ------------------
    Loud is beautiful, if it's clean
     

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