Phase Plug design for MW65xx

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  • gp4jesus
    gp4jesus Posts: 2,021
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    W/all the skill of a brain surgeon… you’re the man Rob😊
    Samsung 60" QN65Q7FAMFXZA QLED, Outlaw Audio 976 Pre/Pro, Samsung BDP, Amazon Firestick, Phillips CD Changer

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  • xschop
    xschop Posts: 5,838
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    Cant remember the thread but someone just recently asked how to accomplish this exact problem.

    This particular driver was not mag- shifted but was too far out of concentricty for my taste. So set up on mag jig and punched pole-piece out and magnet stayed attached to base plate.
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  • skipshot12
    skipshot12 Posts: 2,156
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    Ever since I jb welded the magnets on my SDA’s there’s something that has bothered my ocd grey matter…….

    I keep pondering whether I should have centered the magnets, of my MW’s, then do the jb weld gig!
    Would there be a noticeable difference in performance?
    Is there a negative to jb welding the magnets in place if they’ve shifted a tad but haven’t gotten to the point of the voice coil scraping.

    May be over thinking things but this is the stupid things a very anal/perfectionist deals with!
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  • bcwsrt
    bcwsrt Posts: 2,691
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    What I've gathered on here is if you do the "push test" and things check out, you are good-to-go. Mine all checked out, so they are now set for eternity where they were at the time I J-B Weld-ed them (hopefully).

    Brian

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  • xschop
    xschop Posts: 5,838
    edited March 2023
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    Until your coils start rubbing on the baseplates due to the off-kilter pull of the mag flux gap. Your 6510's
    and 6511's are critical.

    See the 0.020" plastic shim wedged between the coil spud/jig and baseplate above? I have not found an out-of-concentric driver yet where the coil was not also relaxed/set too close to the base-plate, sometimes lightly rubbing. I use a hot air gun or blow dryer to heat and relax the coil away from the base plate ID to fix.
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  • skipshot12
    skipshot12 Posts: 2,156
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    Aaaah, I see.
    Will sleep better tonight that I did good.
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  • xschop
    xschop Posts: 5,838
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    7075 material finally showed up for the next phase of the phase-plug journey... Focus rings... 1.375 OD x 1.125 ID

    tigm128l18r3.jpg
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  • xschop
    xschop Posts: 5,838
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    MW-6516 focus rings...

    hsyq3mfovewc.jpg


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  • Gardenstater
    Gardenstater Posts: 4,945
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    I was reading this yesterday and found it interesting:

    https://speakerwizard.co.uk/driver-ts-parameters-xmax/

    pxua5siztyph.jpg


    George / NJ

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  • xschop
    xschop Posts: 5,838
    edited April 2023
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    Very interesting phenomenon I observed. When I dropped the ring down into the VC gap, it went at about 1/3 speed of gravity.

    k67jlc0rv42a.jpg

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  • Gardenstater
    Gardenstater Posts: 4,945
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    Very cool. The same thing happens if you drop a magnet down a copper pipe (or aluminum).
    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
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  • Gardenstater
    Gardenstater Posts: 4,945
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    It is discussed in this quora chat:

    https://www.quora.com/Are-copper-and-aluminum-though-not-magnetic-affected-by-magnetic-fields
    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
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  • xschop
    xschop Posts: 5,838
    edited April 2023
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    After lower area of Red Loc-Tite dries, I'll seep more Loc-Tite into the top between interstitial area of alloy ring and magnet,. I left @ .007 clearance for glue.

    cytv24dnnmyz.jpg

    BTW I confirmed on this extra set of 6516's that their magnets are different from all other MWs....
    1.30" ID
    3.425"OD
    0.540" thick

    xa4vctsopvwt.jpg
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  • xschop
    xschop Posts: 5,838
    edited April 2023
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    Today I've been listening to a set of bone-stock 6516's in the right channel and this set with focus-rings only before I cut the caps off and phase plug.
    So far by ear I can say that the rings improve bass and mid-base speed/transition.

    s0zd6dk65d60.jpg

    updlu2zczn2c.jpg

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  • xschop
    xschop Posts: 5,838
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    I've been moving the balance knob from left to right and they certainly are cleaner sounding all around.
    I switched speakers L-R and listened carefully to same tracks.
    I also did a blind test and wife picked out the ringed set as "better sounding voices"

    I don't hear any diminished output on the ringed set either compared to the un-ringed set.
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  • xschop
    xschop Posts: 5,838
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    Now to phase-plug the ringed set...

    nociuzbeipag.jpg


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  • xschop
    xschop Posts: 5,838
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    Ready for some fresh gaskets...

    c4my5i8e69me.jpg
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  • xschop
    xschop Posts: 5,838
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    Already have some bass-heavy tracks that cannot bottom out or distort these at even the highest volumes.
    The bone-stock drivers are bottoming out and distorting voices at accompanying bass notes.

    Ironic that E-40's track Sideways, makes the stock MWs oscillate off axis at high SPL. The ringed, now ring/plugged drivers stay straight as an arrow on axis and the voices don't distort at all.

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  • Jazzhead
    Jazzhead Posts: 526
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    xschop wrote: »
    I've been moving the balance knob from left to right and they certainly are cleaner sounding all around.
    I switched speakers L-R and listened carefully to same tracks.
    I also did a blind test and wife picked out the ringed set as "better sounding voices"

    I don't hear any diminished output on the ringed set either compared to the un-ringed set.

    Interesting how women can hear changes in the rig (supposedly women have greater hearing sensitivity, particularly high frequency). I was trying out a silver interconnect once, and had not mentioned it to my wife. She casually passed through the room, made a face and said "what did you do to it"?
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  • xschop
    xschop Posts: 5,838
    edited April 2023
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    But she doesn't understand why I'm always listening to the same tracks/songs when tinkering with them.🤔
    She's just happy I don't build 500hp deathtraps anymore.
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  • Jazzhead
    Jazzhead Posts: 526
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    hohd0o3j56ti.png
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  • plastic_avatar
    plastic_avatar Posts: 747
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    I knew heavy steering when I got to drive a 79 whale tail and a fully-manual, base model beater Chevy S-10.

    Not much difference in ride nor feel on either below 25mph =P
    The Thrifty Setups in Mah House Big thrifty stereo in the basement w/ my custom SDA-1C (built with help from kind forum members) * Beautiful 1966 MCM GE console upgraded w/ Bluetooth, Dual turntable, and Paradigm speakers in family room * Swanky 1980 Realistic system and great TEAC eq with dancing colored lights in the living room * custom 5B on a system for my Dad * Ye Olde college stereo in the garage
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  • xschop
    xschop Posts: 5,838
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    xschop wrote: »
    ;)
    ufnimmxlqcvt.png

    I made the ID's of the rings 1.16" final.
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  • xschop
    xschop Posts: 5,838
    edited April 2023
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    Getting a jump on the right channel conversion.
    Found a very fast a thorough way of butyl mating the drivers whilst the magnets are off for realignment and ring insertion...
    More factory offset magnets I wouldn't trust anyway...


    gzkt87xu4wnd.jpg

    rks49a5ulvou.jpg

    as5czcm6ydfr.jpg

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  • plastic_avatar
    plastic_avatar Posts: 747
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    Ohhhhhhh. Nice.
    The Thrifty Setups in Mah House Big thrifty stereo in the basement w/ my custom SDA-1C (built with help from kind forum members) * Beautiful 1966 MCM GE console upgraded w/ Bluetooth, Dual turntable, and Paradigm speakers in family room * Swanky 1980 Realistic system and great TEAC eq with dancing colored lights in the living room * custom 5B on a system for my Dad * Ye Olde college stereo in the garage
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  • xschop
    xschop Posts: 5,838
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    jbo6h9a2itf0.jpg
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  • xschop
    xschop Posts: 5,838
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    Bump for the nearfield question...

    h6tlcts6ytzi.jpg
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  • xschop
    xschop Posts: 5,838
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    Getting around to building an adjustable jig so I can quickly clean up the shoddy factory pole-piece OD finish that I have been encountering....


    b24fzoa3indf.jpg

    4zvkzn1n4ty8.jpg

    d2fkl3zyzmku.jpg
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  • xschop
    xschop Posts: 5,838
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    hd445qglcs3r.jpg

    c0d02playo16.jpg
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  • xschop
    xschop Posts: 5,838
    edited July 2023
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    True up the T-Yoke OD
    Dial indicate in jig, then make the Pole Piece OD concentric...
    This was one of the way out-of-round ones by 0.006...


    48sdy5dyx4z4.jpg

    4gtp3zthuvhq.jpg

    Happy Birthday America.
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