6500 anomaly

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xschop
xschop Posts: 4,784
edited March 2023 in Vintage Speakers
Got a set of these 6500s on the bench....
Never seen this before...
They both ohm out at 6.5 ohms...

1) No doping compound on cone so butyl surround is separating

bgb2xg21subi.jpg

2) Terminals affixed to outside of basket tab and no writing on label..

3w67160xerkg.jpg

3) Magnets same O.D. but the oddball one is 0.110" thinner

b9e9ek06iny6.jpg

4) Spider is shorter than normal on oddball one...

dwmz63trmyqq.jpg


Don't take experimental gene therapies from known eugenicists.
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Comments

  • bcwsrt
    bcwsrt Posts: 1,714
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    I don't see "polk" embossed in the surround of the bottom one in the first pic. Counterfeit?

    Brian

    One-owner Polk Audio RTA 15TL speakers refreshed w/ Sonicap, Vishay/Mills and Cardas components by "pitdogg2," "xschop" billet tweeter plates and BH5 | Stereo REL Acoustics T/5x subwoofers w/ Bassline Blue cables | Rogue Audio Cronus Magnum III integrated tube amp | Technics SL-1210G turntable w/ Ortofon 2M Black LVB 250 MM cart | Sony CDP-508ESD CD player (as a transport) | LampizatOr Baltic 4 tube DAC | Nordost & DH Labs cables/interconnects | APC H15 Power Conditioner | GIK Acoustics room treatments | Degritter RCM
  • xschop
    xschop Posts: 4,784
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    Good catch. I just measured it's dimensions and it matches factory however.

    The biggest/strangest problem is that magnet is not shifted. So if Polk sent this out, then surely it's TS parameters are way out of spec in regards to BL.
    Don't take experimental gene therapies from known eugenicists.
  • Gardenstater
    Gardenstater Posts: 4,232
    edited March 2023
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    Pretty weird stuff there! What hangover day was that drive made on.....St. Patrick's Day? :D

    In addition to the surround not having the "Polk" raised letters, the notch cutouts for screw locations still do look factory made but they are not rectangular, they are circular. Probably a different source mfg. for that surround.

    If you take them apart can't wait to find out how the 2 magnets compare in breakaway strength with your pail of water technique!

    PS: It looks like the pole piece back plate may have come from a different supplier as well because the circumference looks like it doesn't have the rounding that the more normal driver has. Pretty much a straight die punch operation without any rounding forging.

    PPS: What are this driver's pronouns lol?
    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
  • Gardenstater
    Gardenstater Posts: 4,232
    edited March 2023
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    I wonder if the height of the pole piece is also 0.110" less than typical. Maybe Polk was trying to reduce some of the excess cavity volume underneath the voice coil to change resonance/distortion characteristics? Also, maybe this driver's voice coil will have edge wound voice coil or maybe even double windings.

    I think you HAVE to dissect this one for science :D

    PS: If you remove the label is there an IEC mfg. code?
    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
  • MrGeology
    MrGeology Posts: 83
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    RE: 6500 anomaly

    The surround had been poorly and obviously replaced when I got that driver. Was wondering if it had been completely reworked by someone who did not know what they were doing. I understand if it is not salvageable. Thanks for doing whatever you can for it.
    "One great object of the Constitution was to restrain majorities from oppressing minoritites or encroaching upon their just rights."
    -James K. Polk, 11th President of the United States
  • F1nut
    F1nut Posts: 49,968
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    Even the gasket material is wrong. That is not a Polk driver.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."


    President of Club Polk

  • MrGeology
    MrGeology Posts: 83
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    F1nut wrote: »
    Even the gasket material is wrong. That is not a Polk driver.

    Th gasket was missing when I got it. That was just the best material I could find for a gasket.

    Have another 6500 on the way to replace the oddball, so xschop can have fun with the odball.
    "One great object of the Constitution was to restrain majorities from oppressing minoritites or encroaching upon their just rights."
    -James K. Polk, 11th President of the United States
  • xschop
    xschop Posts: 4,784
    edited March 2023
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    Will take a further inspection of it tomorrow.
    What's strange is the label looks authentic as in original crusty faded paper label.

    A legit 6500 with 0.54 thick magnet is a must. I could lightly coat with thin layer latex paint to solve that issue and try glue down surround better.
    Don't take experimental gene therapies from known eugenicists.
  • MrGeology
    MrGeology Posts: 83
    edited March 2023
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    xschop wrote: »
    Will take a further inspection of it tomorrow.
    What's strange is the label looks authentic as in original crusty faded paper label.

    That label was found under the stuffing in the cabinet the driver had been placed in. Assuming the driver was a 6500 I glued the label on it myself. Probably wont come off easily.
    "One great object of the Constitution was to restrain majorities from oppressing minoritites or encroaching upon their just rights."
    -James K. Polk, 11th President of the United States
  • audioluvr
    audioluvr Posts: 5,480
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    That's as weird as an inverted anticline! Welcome to Club Polk!
    Gustard X26 Pro DAC
    Belles 21A Pre modded with Mundorf Supreme caps
    B&K M200 Sonata monoblocks refreshed and upgraded
    Polk SDA 1C's modded / 1000Va Dreadnaught
    Wireworld Silver Eclipse IC's and speaker cables
    Harman Kardon T65C w/Grado Gold. (Don't laugh. It sounds great!)


    There is about a 5% genetic difference between apes and men …but that difference is the difference between throwing your own poo when you are annoyed …and Einstein, Shakespeare and Miss January. by Dr. Sardonicus
  • joebass3
    joebass3 Posts: 269
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    MrGeology wrote: »

    That label was found under the stuffing in the cabinet the driver had been placed in. Assuming the driver was a 6500 I glued the label on it myself. Probably wont come off easily.

    Mystery solved definitely not OE
  • Gardenstater
    Gardenstater Posts: 4,232
    edited March 2023
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    MrGeology wrote: »
    xschop wrote: »
    Will take a further inspection of it tomorrow.
    What's strange is the label looks authentic as in original crusty faded paper label.

    That label was found under the stuffing in the cabinet the driver had been placed in. Assuming the driver was a 6500 I glued the label on it myself. Probably wont come off easily.

    Did it have an EIA (I said IEC by mistake previously) manufacturers code? Was there a 557 which is Matrecs Industries?

    Like in this thread:

    https://forum.polkaudio.com/discussion/comment/2698515#Comment_2698515
    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
  • MrGeology
    MrGeology Posts: 83
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    Did it have an EIA (I said IEC by mistake previously) manufacturers code? Was there a 557 which is Matrecs Industries?

    Like in this thread:

    https://forum.polkaudio.com/discussion/comment/2698515#Comment_2698515

    Here are a couple pics from when I first pulled the oddball driver.
    https://forum.polkaudio.com/discussion/196707/is-this-driver-a-mw6503-if-not-what-is-it#latest
    "One great object of the Constitution was to restrain majorities from oppressing minoritites or encroaching upon their just rights."
    -James K. Polk, 11th President of the United States
  • Gardenstater
    Gardenstater Posts: 4,232
    edited March 2023
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    I forgot that interesting thread. Hopefully not pre altzheimers lol. Anyways that part#, Mfg. # do not coincide with what we have seen so far on known confirmed MW6500s. The "8634" would be 34th week in 1986, which was probably a couple years after Polk was selling any speakers out the door with 6500s but I would have to make certain of that. Could still have been a warranty replacement driver. I purchased a Made In Mexico NOS open box MW6500 that has a Polk stamped date of 1999 on it so they were having drivers made still then. Some day I'll have to take the paper label off and see if there are any EIA Source codes on it.

    You said in the other thread that you someone put a felt dust cap on top of the dust cap that was there? Not a good idea by the way, because it will throw the weight off and also the venting of the pole although the felt dust caps on my MW6500s are not very porous looking and probably do not pass much air at all. If the original cap underneath that one wasn't black felt, then that is more evidence that it is not a Polk MW6500, even one that was made with a different sized magnet.

    e6h550b2mjgh.png
    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
  • Gardenstater
    Gardenstater Posts: 4,232
    Options
    1056 (?) is GEFCO Mfg. Co., Grayslake, IL.. All I can find out is a phone no. and they are involved in Household Audio and Video Equipment.

    https://www.ecianow.org/assets/docs/EIAStandards/1.7.6_EIA Source Codes_1981.pdf
    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: 4,784
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    If it says Poke Audio, you know it's MIC.
    Don't take experimental gene therapies from known eugenicists.
  • Gardenstater
    Gardenstater Posts: 4,232
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    X5095 Dual voice coil Gefco midwoofers FS on eBay. Not the same but shows the company was making similar drivers fo sho:

    https://www.ebay.com/itm/134494355360

    ocrl1cc1cxew.jpg

    0n5erj51wlcv.jpg

    lg681xbfbmzg.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: 4,784
    Options
    Intetesting. Looks like 2ea. of the same thin-size magnets on those.
    Don't take experimental gene therapies from known eugenicists.
  • xschop
    xschop Posts: 4,784
    edited March 2023
    Options
    Mystery solved... Pole piece is 0.110" shorter than all others Ive measured. So it sets in plane with the 0.25" thick base plate, as 0.25" protrudes past magnet.

    Base plate ID doesn't have to be clearanced at 1.080", however the coil is cocked in the ID causing rub.
    The different spider does not allow as much cone excursion, @30% less than a normal 6500...


    4iad8hxtijwz.jpg

    I used the same black latex based paint to reseal surround and dope the cone...

    a7mfwxd3eccd.jpg



    Post edited by xschop on
    Don't take experimental gene therapies from known eugenicists.
  • skrol
    skrol Posts: 3,345
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    Could it be one of the Mobile Monitor speakers? They were MM65xx. I have a few around that I can take some measurements.
    Stan

    Main 2ch:
    Polk LSi15 (DB840 upgrade), Parasound: P/LD-1100, HCA-1000A; Denon: DVD-2910, DRM-800A; Benchmark DAC1, Monster HTS3600-MKII, Grado SR-225i; Technics SL-J2, Parasound PPH-100.

    HT:
    Marantz SR7010, Polk: RTA11TL (RDO198-1, XO and Damping Upgrades), S4, CS250, PSW110 , Marantz UD5005, Pioneer PL-530, Panasonic TC-P42S60

    Other stuff:
    Denon: DRA-835R, AVR-888, DCD-660, DRM-700A, DRR-780; Polk: S8, Monitor 5A, 5B, TSi100, RM7, PSW10 (DXi104 upgrade); Pioneer: CT-6R; Onkyo CP-1046F; Ortofon OM5E, Marantz: PM5004, CD5004, CDR-615; Parasound C/PT-600, HCA-800ii, Sony CDP-650ESD, Technics SA 5070, B&W DM601
  • audioluvr
    audioluvr Posts: 5,480
    Options
    You ain't cool unless someone's copying ya.
    Gustard X26 Pro DAC
    Belles 21A Pre modded with Mundorf Supreme caps
    B&K M200 Sonata monoblocks refreshed and upgraded
    Polk SDA 1C's modded / 1000Va Dreadnaught
    Wireworld Silver Eclipse IC's and speaker cables
    Harman Kardon T65C w/Grado Gold. (Don't laugh. It sounds great!)


    There is about a 5% genetic difference between apes and men …but that difference is the difference between throwing your own poo when you are annoyed …and Einstein, Shakespeare and Miss January. by Dr. Sardonicus
  • Gardenstater
    Gardenstater Posts: 4,232
    Options
    skrol wrote: »
    Could it be one of the Mobile Monitor speakers? They were MM65xx. I have a few around that I can take some measurements.

    What was their EIA Source Code? I couldn't find anything about "Mobile Monitor". Gefco was definitely 1056 for many years (1958 to 2001) according to this google doc study someone posted on the internet. I couldn't find Mobile Monitor in this:

    https://docs.google.com/spreadsheets/d/1P1jeVIQ9UdwlhXTDLQEDxYuShjFQZO_4tUchw5_8N9o/edit#gid=174447209

    vyp559596psk.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
  • MrGeology
    MrGeology Posts: 83
    Options
    You said in the other thread that you someone put a felt dust cap on top of the dust cap that was there?

    I should have been more clear in that post (got lazy?), I had assumed they had done this as I was convinced it was a 6500. Also it looked like it may have been the case.
    I told Xschop to dissect the driver and discard it or experiment with it, whatever he wants, I won't use it either way as have another actual 6500 on the way.
    Seeing that it is not a 6500, he will probably find my assumption that there a second dust cover to be invalid.
    In the future I will be more diligent in not posting assumptions.
    "One great object of the Constitution was to restrain majorities from oppressing minoritites or encroaching upon their just rights."
    -James K. Polk, 11th President of the United States
  • F1nut
    F1nut Posts: 49,968
    Options
    I knew that wasn't a Polk driver just by looking at it and said so earlier.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."


    President of Club Polk

  • xschop
    xschop Posts: 4,784
    edited April 2023
    Options
    Factory Polk looking felt dust cap (no-light transmission). I pulled it straight off the cone so I can test the rubber latex paint in that area of bare paper to see what it looks like when phase-plugging. The glue that attaches the dust covers to paper cones is very strong and some dust caps are applied after full cone doping or after, I have discovered...

    7doxp282lpga.jpg

    The base-plate rivets are clocked different than factory drivers and the stamped steel basket is not quite as thick, along with it being a light/cheap coat of spray paint. All other authentic Polk drivers are powder-coated...

    po9zlpeulfto.jpg

    Not bad...

    5pdtwaisrqjc.jpg

    Don't take experimental gene therapies from known eugenicists.
  • xschop
    xschop Posts: 4,784
    edited April 2023
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    F1nut wrote: »
    I knew that wasn't a Polk driver just by looking at it and said so earlier.

    It's a Poke driver. Perfect for some destructive and repair testing.

    Authentic 6500 with a burnt voice coil...
    Perfect for a 6.5 ohm 25.9mm Wuhan coil...

    b0m09lv1yhfj.jpg

    e4cx5hbaff78.jpg

    Don't take experimental gene therapies from known eugenicists.
  • Gardenstater
    Gardenstater Posts: 4,232
    edited April 2023
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    Did you have trouble separating the spider and the surround from the basket? Drilled out the "rivets" from the front plate side?

    Curious because I very well may try this on one of my silver basket OEM 6500s that has the stubborn to align voice coil (badly cocked). May have to separate voice coil from cone and reglue as well, in my case that is.
    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: 4,784
    edited April 2023
    Options
    It takes a .25" HSS bit to clear the rivet. You have to have the frame locked down to a press table and a controlled depth plunge/stop.

    Once its off, you can chuck it up and clearance the ID very quickly with a boring bar. And add basket foam at leisure.😉

    Will be testing a high strength glue out next...

    q2ksa3ckbeo0.jpg
    Don't take experimental gene therapies from known eugenicists.
  • MrGeology
    MrGeology Posts: 83
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    F1nut wrote: »
    I knew that wasn't a Polk driver just by looking at it and said so earlier.

    This is true. But when someone tells me the sky isn't blue I need an explanation rather than a statement.
    "One great object of the Constitution was to restrain majorities from oppressing minoritites or encroaching upon their just rights."
    -James K. Polk, 11th President of the United States
  • F1nut
    F1nut Posts: 49,968
    Options
    MrGeology wrote: »
    F1nut wrote: »
    I knew that wasn't a Polk driver just by looking at it and said so earlier.

    This is true. But when someone tells me the sky isn't blue I need an explanation rather than a statement.

    Ummm...look up...lol
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."


    President of Club Polk