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Re: [regsaudioforum] Measurements of the B&W 801 vs the CBT array

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  • Tom Mallin
    I used these same B&W 801 Matrix Series II speakers in my listening room for a few years in the early 1990s. I lived in a condo then and my listening room was
    Message 1 of 3 , May 1, 2013
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      I used these same B&W 801 Matrix Series II speakers in my listening room for a few years in the early 1990s.  I lived in a condo then and my listening room was a converted bedroom 15' x 11' x 8'.  I used the Van Alstine modded crossover which dispensed with the need for the external bass EQ box.

      I have to wonder what the "shading" of the drivers which are higher up on the array does to the perceived image height.  This shading means that the SPL of the drivers higher up on the array is significantly less than those lower down.  Since the article stresses that that the illumination of the ceiling is less with the CBT array than with the B&W, I wonder whether the perceived image height is rather low.  With an ordinary vertical array with all those drivers, the perceived image would be straight ahead for any listening height reasonably below the top of the array.

      If you have to reflect sound off the room surfaces, the reflections should be of similar response to those produced on axis.  Many speakers fail in this respect because the mid and high frequency response changes a lot  at significantly off-axis angles.  The CBT seems to have extraordinarily uniform response at various off-axis angles.  

      The JBL LSR6332 is another speaker which seems to have relatively smooth response (but in this case a bit down sloping) off axis up to the high treble where it rolls off harder as I think it should.  See:  http://www.jblpro.com/BackOffice/ProductAttachments/JBL.LSR6332.pdf  I think that this shape of room response is really what you want, not a more or less totally flat response at all angles up through the high treble as exhibited by the CBT.

      Note in the CBT system description on page 7 of the link that for response below 60 Hz, you need powered subwoofers and that the array itself must be bi-amped and EQed to reach even 60 Hz--that's because the "woofers" are only 3.5" each.  The $8,500 cost of the array is thus a bit misleading.  The price apparently does not include the extra amps or the EQ.
    • Robert
      As we have discussed before, what TM says here is true: flat power in the top is not a good idea. Keele knows that. He offers EQ to roll the top down.
      Message 2 of 3 , May 1, 2013
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        As we have discussed before, what TM says here
        is true: flat power in the top is not a good idea.
        Keele knows that. He offers EQ to roll the top down.
        Otherwise the sound is tolerable only in a very dead room--
        VERY dead.

        REG

        --- In regsaudioforum@yahoogroups.com, Tom Mallin <tmallin4@...> wrote:
        >
        > I used these same B&W 801 Matrix Series II speakers in my listening room
        > for a few years in the early 1990s. I lived in a condo then and my
        > listening room was a converted bedroom 15' x 11' x 8'. I used the Van
        > Alstine modded crossover which dispensed with the need for the external
        > bass EQ box.
        >
        > I have to wonder what the "shading" of the drivers which are higher up on
        > the array does to the perceived image height. This shading means that the
        > SPL of the drivers higher up on the array is significantly less than those
        > lower down. Since the article stresses that that the illumination of the
        > ceiling is less with the CBT array than with the B&W, I wonder whether the
        > perceived image height is rather low. With an ordinary vertical array with
        > all those drivers, the perceived image would be straight ahead for any
        > listening height reasonably below the top of the array.
        >
        > If you have to reflect sound off the room surfaces, the reflections should
        > be of similar response to those produced on axis. Many speakers fail in
        > this respect because the mid and high frequency response changes a lot at
        > significantly off-axis angles. The CBT seems to have extraordinarily
        > uniform response at various off-axis angles.
        >
        > The JBL LSR6332 is another speaker which seems to have relatively smooth
        > response (but in this case a bit down sloping) off axis up to the high
        > treble where it rolls off harder as I think it should. See:
        > http://www.jblpro.com/BackOffice/ProductAttachments/JBL.LSR6332.pdf I
        > think that this shape of room response is really what you want, not a more
        > or less totally flat response at all angles up through the high treble as
        > exhibited by the CBT.
        >
        > Note in the CBT system description on page 7 of the link that for response
        > below 60 Hz, you need powered subwoofers and that the array itself must be
        > bi-amped and EQed to reach even 60 Hz--that's because the "woofers" are
        > only 3.5" each. The $8,500 cost of the array is thus a bit misleading.
        > The price apparently does not include the extra amps or the EQ.
        >
        >
        > On Wed, May 1, 2013 at 1:08 AM, YMM <yipmangmeng@...> wrote:
        >
        > > **
        > >
        > >
        > >
        > > http://www.audioartistry.com/brochures/B&W%20801%20vs.%20CBT36%20Ground-Plane%20Measurements%20v8.1.pdf
        > >
        > > Comment?
        > >
        > > Yip
        > >
        > >
        > >
        >
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