A Real SL 2000 Hack. Replace stock (burnt voice coils) with "silk diaphragm dome ".

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  • Gardenstater
    Gardenstater Posts: 4,190
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    Yes we talked about it a lot in other threads so I wouldn't want to derail this one but @VR3 helped me by doing the intitial cutting on his laser and then I did refinements to get them the way I wanted, mainly beveling the inside edges with a scissors which is not that hard but definitely not *elegant* :# My opinion is its all about the sound but I have no WAF to deal with and I can ignore negative comments from girlfriends 👌. I love the soundstage and imaging I am getting and less distorted sound as well.

    https://forum.polkaudio.com/discussion/comment/2639729#Comment_2639729

    https://forum.polkaudio.com/discussion/128585/anti-diffraction-pads-on-sdas
    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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  • VSAT88
    VSAT88 Posts: 1,227
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    Cool deal. I have a wife but no approval factor. She soon give a rats cahoonas what I do as far as stereo stuff. She is on board. Personally, could not have it any other way. She is the Ace Of Spades ! Numero Uno !!
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  • Gardenstater
    Gardenstater Posts: 4,190
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    Ha ha nice! I have my limits......let's see......if it turned out that mounting a rack from a 12pt buck on the top of your speakers made an improvement, I *might* not do that 🤣
    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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  • F1nut
    F1nut Posts: 49,808
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    I tried anti-diffraction pads on SDA's years ago. Can't say they did a thing.
    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

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  • RandyCroissant
    RandyCroissant Posts: 475
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    I had a local shop do the anodizing here in the Chicago land area, cheap as in well worth it. Fifty for six I believe was the price and another 45 for the lettering. Hey it’s a hobby and no hobby is cheap I love the results and the sound is awesome. I won’t do the diffraction at this point. Thanks for the nice comments fellas.
    Yamaha RXA1030, Yamaha CD-S2100, Yamaha AS-2200, Bluesound node 2i
    Polk SDA2btl highly modded
    Polk SDA 1C modded
    Polk CS350 LS x2
    Kimber 8TC
    Sony 55" Bravia
    Wish list SVS sub

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  • xschop
    xschop Posts: 4,707
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    RandyCroissant wrote: »
    78r9cvb98gia.jpeg
    The tweeter plates Rob sent to me are awesome here is a little drool worthy pic for you gents

    Yeah you should probably keep a box of napkins near those droolees for the droolers.
    Very nice looking setup.
    Don't take experimental gene therapies from known eugenicists.
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  • VSAT88
    VSAT88 Posts: 1,227
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    BTW I do have a good size back up box of tweeter diaphragms @xschop
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  • VSAT88
    VSAT88 Posts: 1,227
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    Randy I meant to say the same. That is a very nice looking setup.
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  • plastic_avatar
    plastic_avatar Posts: 690
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    I'm going to have to re-read all 19 pages to digest half the stuff in this thread.

    Damn you glorious big-brained enthusiasts!
    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 * Ye Olde college stereo in the garage
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  • VSAT88
    VSAT88 Posts: 1,227
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    More like I have nothing to do and I am just cheap. Lol, @xschop did the heavy lifting.
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  • xschop
    xschop Posts: 4,707
    edited February 2022
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    Everyone contributed to the hacking. VSAT instigated the whole operation. If Polk and affiliates stop producing RDO's, this thread will become a staple.
    Don't take experimental gene therapies from known eugenicists.
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  • Tony M
    Tony M Posts: 11,017
    edited February 2022
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    The Wuhan domes are 6.5 +/- .1or .2 ohms. I tested 4 of them.

    bmndxgeczasn.jpg

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    8ne288fwf4f4.jpg

    fa79503hgm2w.jpg

    nq1vn3xudslb.jpg





    Most people just listen to music and watch movies. I EXPERIENCE them.
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  • VSAT88
    VSAT88 Posts: 1,227
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    Should show 6.5 or so DCR for an 8 ohm right ?
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  • Tony M
    Tony M Posts: 11,017
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    I have no idea about that stuff. :#
    Most people just listen to music and watch movies. I EXPERIENCE them.
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  • VSAT88
    VSAT88 Posts: 1,227
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    Yep, DCR=DC resistance so 6.3 6.5 are fine readings for an 8 ohm coil. As the VC moves up and down impedence changes as the AC runs through the coil and it moves back and forth in opposition to the spider/magnet on and on. I can't explain it as well as this.
    http://www.audioheritage.org/vbulletin/showthread.php?12681-DCR-AND-OHM-IMPEDANCE-CONNECTION
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  • Gardenstater
    Gardenstater Posts: 4,190
    edited February 2022
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    8 ohm nominal doesn't really have too much meaning. It's like "about 8 ohms". I once read that the nominal rating is supposed to be the minimum impedance at the frequency above the resonance point of maximum impedance but it doesn't really seem like they are very strict at all about this. Kind of a joke really.

    My early Peerless tweeters have DCR of 7.7 Ohms, 8 ohms "nominal" impedance. Of course, the inductance figures into the Impedance vs. Freq. curve but nobody seems to measure that or give that critical value. It probably changes quite a bit with frequency. DarqueKnight gave impedances at 10 kHz in the tweeters he tested, along with Impedance curves vs. Freq.
    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: 4,707
    edited February 2022
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    I'm postulating that these domes would be the ticket to SDA-1C TLs adding them to the lower tweeter spot.

    Thanks for posting Tony
    Don't take experimental gene therapies from known eugenicists.
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  • xschop
    xschop Posts: 4,707
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    s877kbrbj5nn.jpg
    Don't take experimental gene therapies from known eugenicists.
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  • xschop
    xschop Posts: 4,707
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    Fluke has them at 6.4 ohm

    ci1ysh8d6sln.jpg
    Don't take experimental gene therapies from known eugenicists.
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  • VSAT88
    VSAT88 Posts: 1,227
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    One is
    xschop wrote: »
    s877kbrbj5nn.jpg

    Did you "Discharge capacitor before measuring " ? Lol
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  • Gardenstater
    Gardenstater Posts: 4,190
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    I don't think I can hear above 600 kHz. :)
    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
  • xschop
    xschop Posts: 4,707
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    Oops, did I measure using the wrong leads? I'll have to find the instructions to the LCR.
    Don't take experimental gene therapies from known eugenicists.
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  • Gardenstater
    Gardenstater Posts: 4,190
    edited February 2022
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    I don't think you did. Manual says 1 to 3 like you have it. Doesn't give much info about Inductance measurements really.

    https://docplayer.net/41343837-Mk-328-tr-lcr-esr-transistor-lcr-esr-tester-user-guide-ezm-electronics-studio.html

    In amazon review one guy says not accurate below 5 mH
    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
    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
  • xschop
    xschop Posts: 4,707
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    VSAT88 wrote: »
    One is
    xschop wrote: »
    s877kbrbj5nn.jpg

    Did you "Discharge capacitor before measuring " ? Lol

    I had a spicy chicken sandwich today, so let's refrain from talking @ discharges ok.
    Don't take experimental gene therapies from known eugenicists.
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  • Notenoughtaco
    Notenoughtaco Posts: 43
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    Hello, I have learned a lot from this thread, so I will share my experience with some SL2500's that blew.
    The 2500's are on a set of Monitor 2 M5JR speakers that have had a rough life. I pulled them out of storage and gave them some new bass radiators, plugged them in and no sound from the tweeters. I found that it was probably the VC that was shot, and it turned out to be true. I ordered the silk dome ones from China, and waited and waited.
    One thing that I didn't know is that these have ferrofluid in them, so I still need to replace that. The coils came in finally, and I put them in, and voila, a working tweeter again. They will have to come apart again to replace the fluid, but I am very pleased. 1qum3v3s0zgr.jpg
    ltmd9uamhcmc.jpg
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    wcnr2ljf7g9p.jpg
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  • VSAT88
    VSAT88 Posts: 1,227
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    It seems you have found another diaphragm available here. I have not seen one with a square housing. Would you please post a link to them ?
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  • Notenoughtaco
    Notenoughtaco Posts: 43
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    https://www.ebay.com/itm/2pcs-AFT-1-Tweeter-Diaphragm-for-Polk-Audio-RD0198-1-SL2500-for-Monitor-Series-/154882982392?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=711-127632-2357-0

    They are just the domes, I had to glue them onto the plate, carefully. The backing plate with the terminals, that is.
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  • VSAT88
    VSAT88 Posts: 1,227
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    OK, I see now you used the round ones. The sl 2500 tweeter I am not familiar with. I can see now that the plastic square plate was re used. Excellent! Another tweet repair.
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  • xschop
    xschop Posts: 4,707
    edited March 2022
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    I believe the large diameter circular diaphragms would drop right in after removing the factory square one.
    You'd have to drill the 4 locating holes into the new frames, no biggie.

    And looks like the SL2500 has a factory copper ring on the pole-piece....
    Don't take experimental gene therapies from known eugenicists.
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  • Gardenstater
    Gardenstater Posts: 4,190
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    Notenoughtaco wrote: »
    https://www.ebay.com/itm/2pcs-AFT-1-Tweeter-Diaphragm-for-Polk-Audio-RD0198-1-SL2500-for-Monitor-Series-/154882982392?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=711-127632-2357-0

    They are just the domes, I had to glue them onto the plate, carefully. The backing plate with the terminals, that is.

    Couple questions. Do you have a meter so you could check the resistance and maybe even the inductance of the new coils?

    What is the voice coil former made out of in the Polk ones?.....Aluminum? Some plastic material (probably Kapton)?
    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