Billet Midwoofer Magnet Repair Kit

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xschop
xschop Posts: 4,694
edited September 2020 in For Sale (FS) Classifieds
Finishing up these sets this week on CNC.
I will only make 8 sets of these and no
more. All 6061-T6 alloy magnet jig and locating/removal tool with stainless set screws included.
$112 shipped USPS PRIORITY Insured.
US-48 Only
Just PM

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Don't take experimental gene therapies from known eugenicists.
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  • BlueBirdMusic
    BlueBirdMusic Posts: 2,076
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    It could serve as a piece of art too.
    "Sometimes you have to look to the past to understand where you are going in the future"


    Harry / Marietta GA
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  • xschop
    xschop Posts: 4,694
    edited October 2020
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    6 available.

    Thanks BlueBird, I'll take that as a compliment.

    Disclaimer...
    100% Made in America
    Don't take experimental gene therapies from known eugenicists.
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  • milesaway
    milesaway Posts: 14
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    They look pretty snazzy!! Any left??
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  • xschop
    xschop Posts: 4,694
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    I have 5 sets unspoken for.
    I'll be sending a set out to member lawdogg, as he helps out the "not so mechanically inclined" members here.
    Don't take experimental gene therapies from known eugenicists.
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  • milesaway
    milesaway Posts: 14
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    Xschop how do I order a set? Is there a website?
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  • pitdogg2
    pitdogg2 Posts: 24,574
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    milesaway wrote: »
    Xschop how do I order a set? Is there a website?

    Send him a PM
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  • milesaway
    milesaway Posts: 14
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    Got your point Pitdogg2 , had to laugh at the stupidity on my part for that post!! Wanted to get the process for ordering and payment to Xschop...
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  • xschop
    xschop Posts: 4,694
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    Just PM, I take paypal or USPS money order.

    These will be even snazzier (sic), as I have a knurling tool for the dowel handle area that I'm adding to the design....
    I'll ship first orders this Thurs or Friday...

    6waukurbnz0m.jpg


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  • xschop
    xschop Posts: 4,694
    edited October 2020
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  • milesaway
    milesaway Posts: 14
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    Nice!!, Knurl job really sets it off...
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  • verb
    verb Posts: 10,176
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    Nice machining! Ditto on the knurling! Quality stuff @xschop !

    I do have a question about the groove on the ID of the large ring. How did you do the (looks like a axial jog) in the otherwise radial groove? What cutter did you use? Setup?

    Thank you!
    Basement: Polk SDA SRS 1.2tl's, Cary SLP-05 Pre with ultimate upgrade,McIntosh MCD301 CD/SACD player, Northstar Designs Excelsio DAC, Cambridge 851N streamer, McIntosh MC300 Amp, Silnote Morpheus Ref2, Series2 Digital Cables, Silnote Morpheus Ref2 Series2 XLR's, Furman 15PFi Power Conditioner, Pangea Power Cables, MIT Shotgun S3 IC's, MIT Shotgun S1 Bi-Wire speaker cables
    Office: PC, EAR Acute CD Player, EAR 834L Pre, Northstar Designs Intenso DAC, Antique Sound Labs AV8 Monoblocks, Denon UDR-F10 Cassette, Acoustic Technologies Classic FR Speakers, SVS SB12 Plus sub, MIT AVt2 speaker cables, IFI Purifier2, AQ Cinnamon USB cable, Groneberg Quatro Reference IC's
    Spare Room: Dayens Ampino Integrated Amp, Tjoeb 99 tube CD player (modified Marantz CD-38), Analysis Plus Oval 9's, Zu Jumpers, AudioEngine B1 Streamer, Klipsch RB-61 v2, SVS PB1000 sub, Blue Jeans RCA IC's, Shunyata Hydra 8 Power Conditioner
    Living Room: Peachtree Nova Integrated, Cambridge CXN v2 Streamer, Rotel RCD-1072 CD player, Furman 15PFi Power Conditioner, Polk RT265 In Wall Speakers, Polk DSW Pro 660wi sub
    Garage #1: Cambridge Audio 640A Integrated Amp, Project Box-E BT Streamer, Polk Tsi200 Bookies, Douglas Speaker Cables, Shunyata Power Conditioner
    Garage #2: Cambridge Audio EVO150 Integrated Amplifier, Polk L200's, Analysis Plus Silver Oval 2 Speaker Cables, IC's TBD.
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  • xschop
    xschop Posts: 4,694
    edited October 2020
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    verb wrote: »
    Nice machining! Ditto on the knurling! Quality stuff @xschop !

    I do have a question about the groove on the ID of the large ring. How did you do the (looks like a axial jog) in the otherwise radial groove? What cutter did you use? Setup?

    Thank you!

    That was the original prototype I sent out to a member who had multiple frozen magnets. I drilled three spots at 120 degrees to allow magnet to pole-piece gluing after setting magnet. After doing the reset a couple times myself, I found it wasn't necessary as the magnet holds the pole- piece together with plenty of force to allow set screw removal without re-shifting magnet.
    I don't believe I posted about it, but the inner lip utilizes the accuracy of the blanch-ground magnets for all centering, just make sure your magnet and pole-piece are clean before assembly.

    If you ordered a set in last couple weeks I am shipping this Wed. I only have 4 sets left and I assure you, I won't be making more. I busted my bandsaw on these large diameter billets and Amazon puts the blades as a non-essential item lol.

    Final lathe CNC peak....

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    Post edited by xschop on
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  • xschop
    xschop Posts: 4,694
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    I've discovered the Polk magnet shift mystery...

    https://youtu.be/UOJiEgxt7RY

    Don't take experimental gene therapies from known eugenicists.
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  • VSAT88
    VSAT88 Posts: 1,227
    edited October 2020
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    That 1st old geezer was me ... Like...WTF ???
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  • verb
    verb Posts: 10,176
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    That's awesome @xschop ! Thanks for the insight! I admire folks like you that actually build things! With great accuracy and quality too. Well done sir!
    Basement: Polk SDA SRS 1.2tl's, Cary SLP-05 Pre with ultimate upgrade,McIntosh MCD301 CD/SACD player, Northstar Designs Excelsio DAC, Cambridge 851N streamer, McIntosh MC300 Amp, Silnote Morpheus Ref2, Series2 Digital Cables, Silnote Morpheus Ref2 Series2 XLR's, Furman 15PFi Power Conditioner, Pangea Power Cables, MIT Shotgun S3 IC's, MIT Shotgun S1 Bi-Wire speaker cables
    Office: PC, EAR Acute CD Player, EAR 834L Pre, Northstar Designs Intenso DAC, Antique Sound Labs AV8 Monoblocks, Denon UDR-F10 Cassette, Acoustic Technologies Classic FR Speakers, SVS SB12 Plus sub, MIT AVt2 speaker cables, IFI Purifier2, AQ Cinnamon USB cable, Groneberg Quatro Reference IC's
    Spare Room: Dayens Ampino Integrated Amp, Tjoeb 99 tube CD player (modified Marantz CD-38), Analysis Plus Oval 9's, Zu Jumpers, AudioEngine B1 Streamer, Klipsch RB-61 v2, SVS PB1000 sub, Blue Jeans RCA IC's, Shunyata Hydra 8 Power Conditioner
    Living Room: Peachtree Nova Integrated, Cambridge CXN v2 Streamer, Rotel RCD-1072 CD player, Furman 15PFi Power Conditioner, Polk RT265 In Wall Speakers, Polk DSW Pro 660wi sub
    Garage #1: Cambridge Audio 640A Integrated Amp, Project Box-E BT Streamer, Polk Tsi200 Bookies, Douglas Speaker Cables, Shunyata Power Conditioner
    Garage #2: Cambridge Audio EVO150 Integrated Amplifier, Polk L200's, Analysis Plus Silver Oval 2 Speaker Cables, IC's TBD.
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  • xschop
    xschop Posts: 4,694
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    Thanks Verb, I needed this moons ago myself as I enjoy rebuilding the vintage Polks. I got alot of insight and feedback/measurements from knowledgable members here to help make it happen. I'll be completely dismantling and phase-plugging (with another mod in the works) another set of MWs soon and this will be an invaluable tool.
    Don't take experimental gene therapies from known eugenicists.
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  • halo71
    halo71 Posts: 4,572
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    How does this set up differ from the jig made from PVC that was posted on Audiokarma years ago? I built that PVC jig and have realigned a few Polk drivers over the years.
    --Gary--
    Onkyo Integra M504, Bottlehead Foreplay III, Denon SACD, Thiel CS2.3, NHT VT-2, VT-3 and Evolution T6, Infinity RSIIIa, SDA1C and a few dozen other speakers around the house I change in and out.
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  • xschop
    xschop Posts: 4,694
    edited October 2020
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    halo71 wrote: »
    How does this set up differ from the jig made from PVC that was posted on Audiokarma years ago? I built that PVC jig and have realigned a few Polk drivers over the years.

    Accuracy.
    Longevity.
    Quality.

    I have not posted about it, but I designed them to use longer head-clearanced setscrews to re-set all Polk tweeter top plate and magnets as well (given the magnets are no more that 0.60" thick as every one Ive measured are)

    uv6ispuopql6.jpg

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  • xschop
    xschop Posts: 4,694
    edited October 2020
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    I purposefully broke the top plate of this SL2000 magnet to test set screw thread clearancing and plate re-setting...


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  • xschop
    xschop Posts: 4,694
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    Took less than 2 minutes and better circumferal accuracy than when it left the factory. A true 0.0275" gap all around....

    rvtjbd0dq1b6.jpg
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  • Gardenstater
    Gardenstater Posts: 4,183
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    What was the annular gap error or concentricity error from the factory? How hard was it to break the glue and how did you do it? What do you think they use for adhesive.....Loctite or the like? Enquiring minds want to know! Great stuff you're doing for extending the lifespan of the vintage equipment out there!
    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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  • xschop
    xschop Posts: 4,694
    edited October 2020
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    Before I broke the top plate, measuring by feeler gauge it was off 0.006" either side.
    Simply screw down factory screws going clockwise and the plate will pop right off.
    I think these are held by old Loctite.
    I won't need to break top plate for the vented pole-piece mod, but will need to when I do some Eddy mods.
    Post edited by xschop on
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  • milesaway
    milesaway Posts: 14
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    Xschop,
    Got home today, jig was in my drop box...Nice lathe job on it!!...Going to start working on fixing a pair this week...Can’t thank you enough!!!
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  • xschop
    xschop Posts: 4,694
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    I have another spare tool kit for sale which now includes the MW6500 pole-piece removal seat/insert made from solid brass.

    $120 shipped Priority US-48. Just PM

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  • xschop
    xschop Posts: 4,694
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    Sold
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  • xschop
    xschop Posts: 4,694
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    Repost for Babb...

    Step 1.
    Set the woofer cone down on a smooth, perfectly flat surface and take a picture of it directly above.

    Step 2.
    If the pole-piece plate perimeter and magnet perimeter look evenly concentric to each other, then you are in luck as the culprit is the magnet-to-baseplate has shifted and you don't have to pull the magnet/pole-piece apart from baseplate nor use the dowel to recenter them.

    Step 3.
    Make sure magnet perimeter is perfectly clean near pole-piece perimeter. This is where the inner jig step/lip rests and automatically aligns all set screws.

    Step 4.
    Retract all Set screws until the ID of the jig has none protruding on the inside.

    Step 5
    Set the inner step/lip on the magnet top perimeter, then evenly lock the baseplate down with the baseplate set screws. Tighten only hand tight .

    Step 6

    Position pole-piece set screws on the pole-piece perimeter loosely.

    Step 7

    Flip the jig and woofer over. Adjust pole-piece perimeter set screws, using a pen-light to see into dust cap, viewing the pole piece/voice coil ID gap. Then adjust incrementally 1/8 -1/4 turns until the woofer if free by lightly pushing on the cone. You can also play audio through woofer AT LOW VOLUME until you hear it free up.

    Step 8

    Once reset, gently unscrew all base plate setcrews fully, without any showing in the jig ID. Then carefully, ONLY loosen the pole-piece set screws and carefully lift the woofer out of jig. Flip it back over and start your glue process on the magnet perimeters.

    Note*

    I've had very good results with Superglue Gel as it is quick and easy and holds mega strong. You only need a thin line of it and it wicks into crevices.
    Don't take experimental gene therapies from known eugenicists.
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  • bbabb
    bbabb Posts: 12
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    To make a short story long, I'm super new to the world of vintage audio equipment and recently bought my very first pair of Polk speakers - some Monitor 7Bs. I had been looking for some decent speakers for a long time and wasn't having a ton of luck and things like older JBLs were just a little too pricey for me. Then I saw this pair of 7s on FB. I didn't know anything about them so I did a little online research and started to see that people really thought favorably of these speakers. During that research I found quite a few mentions of this forum and what a great community people thought it was. So I started poking around here and found tons of great information and it really did seem like a cool community. Then I started finding info on "upgrading" these particular speakers and as a habitual tinkerer I knew they were the ones I needed in my life.

    They worked and sounded great (at least to my untrained ears) and I used them for a bit. I saw lots of references to the shifted magnets so I figured I had better get them glued up before something bad happened. I took them apart and could see that the magnets were definitely not perfectly centered but the cone still moved freely so I asked for advice here. I was told to just glue them if they were working but @Gardenstater warned me that he had a similar pair that would only gave him trouble when some really deep tones were played through them. I decided to glue them in a few spots "temporarily" so I could get them back apart if necessary and do some more listening to them for a bit. Sure enough I found some music that started to make them rub when turned up a little bit. @Gardenstater you were right.

    So then I went about researching how to realign everything and eventually discovered the jigs that @xschop machined up and decided to order one for myself. I'm sure I could have figured it out and done it with the whole PVC pipe thing but I'm a sucker for nicely machined things and good tools. :p

    I was a little nervous about taking this on as I didn't want to screw up the speakers I just bought but this jig worked slick and made the job pretty damned easy. And @xschop was super responsive and helpful when I had questions about using it.

    I didn't figure I needed to do a full step by step write up because I feel like it's covered pretty well here but just included a few pictures I took during the process. While I had the driver out I also took the time to add some Dynamat type stuff to the frame that I had left over from my Bronco project.

    See I told you it would be long. Anyway mostly just wanted to say thank you to everyone that helped me out!! This really has been a great community so far.

    Cheers!cn6lbgaf4nfk.jpg
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  • Gardenstater
    Gardenstater Posts: 4,183
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    Nicely done! Your speakers are about 14 mos. younger than mine. Did you happen to check the clearance of the O.D. of the voice coil to the framepiece? My 1979's eventually rubbed there and I haven't been able to align them yet. Will probably have to disassemble further but it will be a fun experiment. We think that the early MW6500s had issues with the clearances being too tight there and it will be interesting to find out if they made adjustments to give it more clearance at any time.

    Enjoy the mod train you are just beginning the ride on!
    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 did not measure exactly what that clearance is but it's definitely tight. How do you date them? Is that like 11/2(?)/80?
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  • Gardenstater
    Gardenstater Posts: 4,183
    edited July 2022
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    It's never easy but you get better at reading their stampings with time. I think this guy was on some powerful jitter juice with the double strikes. :D Looks like 11/25/80 yes.

    Were your voice coils nicely centered in the framepiece? I think my spiders got damaged by my overzealous playing when I was young or they didn't center them up and align them right. The voice coils are a bit cocked. Been replaced with some 1982 black basket 6500s so all is well.
    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
    · Share on FacebookShare on Twitter