B&O CX100 crossover enigma

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2

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  • xschop
    xschop Posts: 4,847
    edited July 2023
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    0.40 x 0.70" squares are glued and drying. A couple holes around perimeter were stamped out with more narrow frame between....

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    2nd Midrange done...

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    Woofer cones are doped, didn't do dust caps for no extra weight and contrast. I can black them out later with ink if I want them all black...

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    Post edited by xschop on
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  • xschop
    xschop Posts: 4,847
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  • xschop
    xschop Posts: 4,847
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    Ordered 304 stainless allen dome heads for the bezels and the MW drivers. All M3 x 0.5
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  • mhardy6647
    mhardy6647 Posts: 33,367
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    xschop wrote: »
    While waiting on the new Wu-rubbers, I've started dissecting the midrange for uber mods...
    Will have to shorten a set of MW65xx plugs, but they drop right in with B&O pole-piece ODs being 0.997, same as Polk🙂

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    Fiber backed neoprene rubber to ensure a good seal around the thin metal baffles and extra damping to boot with the Polyurethane coating on the frames. They'll get a layer of black latex after full cure....

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    Here we lost a lot of weight from a very thick and coated paper dust cap. I gave them one light coat of latex doping compound...

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    B&O upped their game along time ago...

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    Y'all probably know (but in case you don't) that this is a Philips polycarbonate dome tweeter. They sold zillions of those, both OEM and to the DIY market. A modest driver. :|

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  • xschop
    xschop Posts: 4,847
    edited August 2023
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    Bet they sound like SL2000's....asstastic

    These B&O's are not MIC, but Denmark treated silk domes with a dedicated back-chamber FYI.
    Post edited by xschop on
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  • xschop
    xschop Posts: 4,847
    edited August 2023
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    Butyl surrounds arrived. The inner cone edges that get the glue look like they are inverted. May be just from being fresh off the dies.
    Think it would affect midrange or bass by gluing them upside-down?
    They would virtually self-align this way if I were to proceed. Thoughts?

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    I machined a weighted centering spud to ensure the perimeter is glued concentric to cone at first, drying, then outer flange attached to basket....

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    Post edited by xschop on
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  • Gardenstater
    Gardenstater Posts: 4,288
    edited August 2023
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    I vote for non inverted. Nice solution with the gluing aid.

    Edit - I think that in a small cone, 1/2 the surround is effective towards Sd and you will be losing a little as it is with the phase plug. Inverted may not be as effective towards Sd?
    Post edited by Gardenstater on
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Onkyo A-8017 integrated
    Logitech Squeezebox Touch Streamer w/EDO applet
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    Custom Steve Wilson 1m UPOCC Interconnect
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
  • xschop
    xschop Posts: 4,847
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    After further inspection, I would have had to cut @ 1/8" off the top of the foam inserts to clear the surround if inverted.

    Found an electricial tape roll the right diameter and pre-heated the surrounds. Looks like it did the trick to relax the edges where they contour correctly....
    Just having to babysit the edges while the glue dries and tamp down every 5 minutes or so....

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  • xschop
    xschop Posts: 4,847
    edited August 2023
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    Midrange is alot easier with a missing dust cap...



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    Woofer #2

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    Post edited by xschop on
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  • xschop
    xschop Posts: 4,847
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    So far looks like a success. They are almost completely dry and clearance all way around when just pushing on one side of the cones. I think this method works well not allowing excess glue on the backside of the drivers...

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  • xschop
    xschop Posts: 4,847
    edited August 2023
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    Hammer time....

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  • xschop
    xschop Posts: 4,847
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    Will be making the billet bezels for these this weekend.
    Probably will go ahead and do the radius throat profile like the Dayton plates and get a wider off-axis listening sweet-spot.

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  • xschop
    xschop Posts: 4,847
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  • xschop
    xschop Posts: 4,847
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    I discovered a way to modify the factory plastic bezels in order to keep the back side as dome lead insulation and get the throat profile radius with billet rings.

    Saved alot of machine work too🙂

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  • xschop
    xschop Posts: 4,847
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    Cut some grooves for black O-rings on Neg- posts..

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  • xschop
    xschop Posts: 4,847
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    For @mhardy6647 ...

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  • ChrisD06
    ChrisD06 Posts: 915
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    Are they finished? They look to be...
  • Gardenstater
    Gardenstater Posts: 4,288
    edited August 2023
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    Could you add another layer of tweeter felt so that it helps protect that baffle edge from creating time delayed reflections? May or may not be a big factor with the waveguide limiting dispersion but couldn't hurt.
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Onkyo A-8017 integrated
    Logitech Squeezebox Touch Streamer w/EDO applet
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    Custom Steve Wilson 1m UPOCC Interconnect
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
  • xschop
    xschop Posts: 4,847
    edited August 2023
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    One down, one to go tomorrow. Then it's listening time. I did add some 1/8" foam to bases with tacky glue so I don't scratch them or my desk.
    I'll get a final weight when I'm done too. They are really weighty and inert from all the damping.
    Don't take experimental gene therapies from known eugenicists.
  • xschop
    xschop Posts: 4,847
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    Put them in the garage system for some cap burn-in. Was doing some low freq. sweeps and found they can go low 40's with good impact. Then I took out 1/3 of the factory filler and tested again with them just a few inches from wall. Hard to believe these can be so impactful in upper 30's.

    On the desk top, the sweeps were sloughing off in the 50's.

    Gorgeous sounding tweeters and I wont be padding them down. Those Germans did blend them so well with their crossover capers.

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  • ChrisD06
    ChrisD06 Posts: 915
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    Those look very elegant. Can't believe they get down to the 30s...

    Here's a suggestion, if you have a Dayton iMM6 or similar, why not measure it's response and then DSP it 🤔

    For fun, of course.
  • xschop
    xschop Posts: 4,847
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    Down to 38 Hz, and it disappears. Pretty amazing. They are outdoing my TSi nearfield dynamically. Ill try get a vid up soon on the desk top. Want to burn caps in a little longer.

    With a sub, these could easily be formidable in a larger listening space.
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  • Gardenstater
    Gardenstater Posts: 4,288
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    Disappears is in contrast with what they found with one of it's smaller siblings; the C40. They also mentioned a midrange colouration with vocals. I wonder if your phase plugs and the tweeter mod took care of both of those in your case. We know the phase plugs help with both and cutting away the piece in front of the dome may have helped too.

    It would be nice to hear yours even with the limitations of youtube.

    asba56n4jx9t.jpg
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Onkyo A-8017 integrated
    Logitech Squeezebox Touch Streamer w/EDO applet
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    Custom Steve Wilson 1m UPOCC Interconnect
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
  • xschop
    xschop Posts: 4,847
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    The coloration would be coming from the frame reflections directed back at the rear cone. These drivers have @ 50% blockage by the frame uprights.
    Don't take experimental gene therapies from known eugenicists.
  • xschop
    xschop Posts: 4,847
    edited August 2023
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    Lol. I tried weighing on the same scale and it errored out at over 12 lbs.
    Tried uploading video, but think my phone mic is lacking. Turning volume down and trying again. I'm not a videographer by no means either.

    https://www.youtube.com/watch?v=ZilZhMtHfYE
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  • Gardenstater
    Gardenstater Posts: 4,288
    edited August 2023
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    The vocals seem very clear. It would be interesting to see how they sound on some stands that put them at ear level, not on a reflective desk, and pulled out into a room away from surrounding walls. I know bass would suffer and you'd need a sub. For the desk, it would be interesting to hear how putting some foam on the desk in front of them to absorb the reflection might help.

    It would also be interesting to try 3 of the seismic isolators under each speaker although I know yours are stuck on with pressure sensitive pads, on the RTA 8TLs.
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Onkyo A-8017 integrated
    Logitech Squeezebox Touch Streamer w/EDO applet
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    Custom Steve Wilson 1m UPOCC Interconnect
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
  • xschop
    xschop Posts: 4,847
    Options
    Disappears is in contrast with what they found with one of it's smaller siblings; the C40. They also mentioned a midrange colouration with vocals. I wonder if your phase plugs and the tweeter mod took care of both of those in your case. We know the phase plugs help with both and cutting away the piece in front of the dome may have helped too.

    It would be nice to hear yours even with the limitations of youtube.

    asba56n4jx9t.jpg

    I will restore a set of C30's next. Looking forward to it. I like the fact that they are alloy enclosures and built to last eons.
    No dry-rotting mold species infused particle board to contend with.
    Don't take experimental gene therapies from known eugenicists.
  • ChrisD06
    ChrisD06 Posts: 915
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    xschop wrote: »
    Disappears is in contrast with what they found with one of it's smaller siblings; the C40. They also mentioned a midrange colouration with vocals. I wonder if your phase plugs and the tweeter mod took care of both of those in your case. We know the phase plugs help with both and cutting away the piece in front of the dome may have helped too.

    It would be nice to hear yours even with the limitations of youtube.

    asba56n4jx9t.jpg

    I will restore a set of C30's next. Looking forward to it. I like the fact that they are alloy enclosures and built to last eons.
    No dry-rotting mold species infused particle board to contend with.

    You know what I was to see get the XS treatment?

    Cerwin-Vegas. They're definitely not what is consider high fidelity but they are awesome sounding and I wish I owned a pair (almost had AT-15s for $250). They get super loud, handle a lot of power, and are what I'd definitely want to throw in a garage if I had one for parties and such.

    Make some Cerwin-Vega XS-12s or something then we can talk... phase plug mid, new ferrofluid, the whole BH5, armacell, dynamat treatment, crossover rebuild... man it'd be glorious.
  • xschop
    xschop Posts: 4,847
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    :D
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  • ChrisD06
    ChrisD06 Posts: 915
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    xschop wrote: »
    :D

    Seriously, man! I'm convinced that you could actually do some serious mods to them and it'd be super cool to see.