Billet Midwoofer Magnet Repair Kit

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  • xschop
    xschop Posts: 4,684
    edited July 2022
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    Nice score on those 7B's and good job aligning that 6500. It's the toughest one to get centered from my experience, and you even did it without seeing through the dust cap. These old monitors can be modded to sound just as good as new high $ stuff.
    Don't take experimental gene therapies from known eugenicists.
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  • bbabb
    bbabb Posts: 12
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    @Gardenstater yes, the voice coils were nicely centered thankfully.

    @xschop, yeah it took a little time to get things aligned where I was happy with it. Not difficult, just took patience. I found on both of them what I can only describe as a “sweet spot” where I could just tell they were aligned perfectly. I got really close multiple times where there was no scraping if I pushed gently on the dust cap or very evenly with multiple fingers spread out around the cone but if I pushed more on one side than another I could hear it just barely rubbing. I almost left it like that but decided to mess with it some more and I’m glad I did. It took rotating the magnet a little bit and trying a few more times but I finally found that sweet spot where it just feels right and even pressing down on any one side of the cone doesn’t cause any rubbing. And on one of them I would get it all aligned and then as soon as I loosened the set screws on the jig the magnet would shift. Once again just took rotating the magnet a bit and trying again.

    And yeah I’m looking forward to recapping them. Anything else that I should do that makes a difference?

    Thanks again, both of you, for the help!
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  • xschop
    xschop Posts: 4,684
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    Do @Gardenstater inner frame foam mod. Well worth the time.
    Don't take experimental gene therapies from known eugenicists.
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  • bbabb
    bbabb Posts: 12
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    Is that putting a small piece of acoustic foam behind the woofer that I’ve seen mentioned?
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  • Gardenstater
    Gardenstater Posts: 4,182
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    Never mind the naysayers and controversy. :s Just do it as they say lol. You won't regret it, after listening awhile first to get a baseline.

    https://forum.polkaudio.com/discussion/195562/must-try-mod-foam-inside-the-stamped-steel-baskets-yes/p1
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Crown D150 amp
    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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  • bbabb
    bbabb Posts: 12
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    I think I found what you were talking about. Lining the inside of the speaker frame arms with some foam. I hadn’t seen that one yet. Do you guys do that in conjunction with the sonic barrier foam on the back wall?
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  • Gardenstater
    Gardenstater Posts: 4,182
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    I did the Blackhole5 mod of 6" x 6" piece behind each MW some months before doing the Armacell inside the basket mod. I like doing things one at a time to appreciate the individual effects.
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Crown D150 amp
    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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  • bbabb
    bbabb Posts: 12
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    iny616142rq4.jpeg

    This is what the polyfil stuff looks like in mine. I assume it’s the factory stuff and in the correct location. Does it appear that way to you?

    It’s pretty thick and fills the cabinet front to back above the PR. I’m obviously no audio engineer but with all of that material directly behind the woofer what is the purpose of that extra bit of BH5? Does it really make an audible difference? Sorry if that’s a dumb question.
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  • bbabb
    bbabb Posts: 12
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    And sorry, I know I’m wandering a little off topic for this thread. :#
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  • pitdogg2
    pitdogg2 Posts: 24,556
    edited July 2022
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    The polyfil acts as a weak BH5 or sonic barrier. Adding the BH5/SB with the polyfil really cleans up everything real well. It's as if you just made you box twice as large.
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  • xschop
    xschop Posts: 4,684
    edited October 2022
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    This is the LAST one, never used. I just clearanced brand new phosphate-coated set screws to clearance Polk Tweeters also. Will come preassembled with moly lube for buttery-smooth operation.

    Shipped anywhere US-48 ONLY
    $115

    67u36vwmqkjz.jpg
    Don't take experimental gene therapies from known eugenicists.
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  • xschop
    xschop Posts: 4,684
    edited March 2023
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    Still available and still the LAST one for sale. Will also include an MW6500 brass seat ring/insert.

    Just PM
    Post edited by xschop on
    Don't take experimental gene therapies from known eugenicists.
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  • xschop
    xschop Posts: 4,684
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    These are sold.
    Don't take experimental gene therapies from known eugenicists.
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