Must try MOD - Foam inside the stamped steel baskets - YES!

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  • xschop
    xschop Posts: 5,856
    edited March 2022
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    Vandersteen mod is done and glue drying...

    I would only do this to a burnt voice Midwoofer before replacing the coil itself. Good luck doing it any other way.
    The MW 6500s have VERY little VC-baseplate gap clearance than all other MWs I've measured (1.070 vs 1.085), so I opened this one up to match all other MWs to prevent VC rubbing.

    I added a little extra Power Grab to the central circumference to make sure the small voids around the protruding baseplate rivets filled in as I pressed it in. I simply scrolled it in and it went in without hassle and sits perfectly in the inner chamber on raised basket frame...

    I cut the 1/8" thick PVA 2.50" OD and 1.1" ID using the same cutter I used on the phase plug felts.
    The diagonal cut on the foam allows for final adjustment away from baseplate ID where Voice coil travels....

    i1c1id9a1bcc.jpg

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    oqhxwdvuduxq.jpg
    Don't take experimental gene therapies from known eugenicists.
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  • Gardenstater
    Gardenstater Posts: 4,948
    edited March 2022
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    The spiders are remarkably gauze-like and therefore somewhat transparent to sound. I held one of my dismembered....disassembled baskets up to the direct sunlight coming in through the kitchen window and I could see through the spider into the space beneath including all the features thereof and it is pretty *cavernous*. I was surprised at that for a driver with a max excursion rating of around 3mm.

    Can't wait to hear some listening impressions, however you may not have a XO that is compatible....?

    PS: I wouldn't be surprised if the sound is more.......emotionally engaging.....with a touch of nutmeg even.
    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: 5,856
    edited March 2022
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    I will wait til another burnt 6500 rears it's ugly voice coil lol

    I will hold off from phase-plugging it until I get another donor.
    Don't take experimental gene therapies from known eugenicists.
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  • xschop
    xschop Posts: 5,856
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    Gardenstater wrote: »
    The spiders are remarkably gauze-like and therefore somewhat transparent to sound. I held one of my dismembered....disassembled baskets up to the direct sunlight coming in through the kitchen window and I could see through the spider into the space beneath including all the features thereof and it is pretty *cavernous*. I was surprised at that for a driver with a max excursion rating of around 3mm.

    Can't wait to hear some listening impressions, however you may not have a XO that is compatible....?

    PS: I wouldn't be surprised if the sound is more.......emotionally engaging.....with a touch of nutmeg even.

    Now that Ive dissected this thing, the spider and surround look and feel exactly like the 6510, which happens to be about same ohm DCR.
    Don't take experimental gene therapies from known eugenicists.
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  • xschop
    xschop Posts: 5,856
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    6500 is done, vestigial tabs evicted too...

    4dqw6ms7pwya.jpg

    x2o1ry33yb4b.jpg

    Don't take experimental gene therapies from known eugenicists.
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  • mordar
    mordar Posts: 1
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    ... Regarding the basket acoustic treatment, I seem to recall some speaker baskets produced with a rough textured black undercoating type material on the outer basket...anyone? Also would like to see a before and after frequency response of just the basket treatment mod.
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  • F1nut
    F1nut Posts: 52,406
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    Also would like to see a before and after frequency response of just the basket treatment mod.
    Feel free.
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  • Gardenstater
    Gardenstater Posts: 4,948
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    mordar wrote: »
    ... Regarding the basket acoustic treatment, I seem to recall some speaker baskets produced with a rough textured black undercoating type material on the outer basket...anyone?

    Sounds like it is just a damping compound, trying to get a similar effect to what we're after with the Dynamat Xtreme or other similar product. I think Soundcoat is a material that comes in a can and can be rolled or brushed on. Could make a real mess if you weren't careful and it wouldn't be constrained layer damping because it wouldn't also have the aluminum layer on the outside.

    mordar wrote: »
    Also would like to see a before and after frequency response of just the basket treatment mod.

    I'm assuming you mean the inside the basket sound absorbing material. It'd be technically interesting and I think you would see a difference if you had the right equipment and method but I doubt that you'd be able to look at the two curves and go.......see there.......look at the greater transparency and detail and separation of vocals and instruments. You have to use your ears for that.

    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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  • lms
    lms Posts: 54
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    Two weeks ago, I did this to one of my CRS speakers, both drivers. I don't have the ability to speak the way others do in regard to statements like, more air, etc. All I can say is this... After two weeks it's apparent that the speaker I didn't do this to has more "shout" to it. LOL, it sounds louder and mids are tad more in your face. The one that I did do this to is mellower sounding, which I like. And that's all I have to say.
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  • Gardenstater
    Gardenstater Posts: 4,948
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    If your experience parallels mine, you will have the magic come in when you do the other speaker as well. Things need to be balanced. Let us know how it works out :)
    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
    · Share on Facebook
  • JayMX
    JayMX Posts: 464
    edited March 2022
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    I put my Monitor 4’s under the knife the other day. Figured since I was doing the whole Monte I’d give the inner foam thing a shot, just to see if it made any difference. Now, I did re-cap and damp the baskets with Noico all at the same time. Overall, I am just blown away how much better the speakers sound. Warm, but clear, tons of detail. Female vocals are lush. Norah Jones, more please. I’ll do my 7B’s when I do my rework of them and report back. Fun experiment. I think it has some merit! 🤘🏻
    o6kljq0d22lc.jpeg
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    It’s in there, Armacell, kinda tricky to fish it in there but not too tough to do.
    k1qm6fuwqmk9.jpeg
    Current Collection: Monitor 4a (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), Full mod SDA CRS 4.1TL (198’s), SDA SRS 2.3TL (198’s), R100's, R200’s, R300 🤩
    Pairs that have passed through: Monitor 4b (Peerless), Monitor 5a (Peerless), Monitor 5B (Peerless), Monitor 5b (SL1000), Monitor 5b (SL2000) (4x pair), Monitor 7b (Peerless), Modified Monitor 7c’s (194’s), Monitor 10a (Peerless), Monitor 10b (5x pair), RTA8, RTA8TL, RTA 11T, RTA12c (194's), SDA1(mod to “a” & SL1000 Wuhan mod), SDA CRS, SDA 2 (2x pair), SDA 2a, SDA 2b, SDA 1b, SDA 1c, SDA SRS 2 (2x pair), SDA SRS 3.1TL (198’s) (2x pair)...and more to come, it’s a sickness.
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  • gp4jesus
    gp4jesus Posts: 2,021
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    mordar wrote: »
    Also would like to see a before and after frequency response of just the basket treatment mod.
    Pre & post mod measurements may parallel those of IC, speaker cables, and/or power cable upgrades/swaps
    Samsung 60" QN65Q7FAMFXZA QLED, Outlaw Audio 976 Pre/Pro, Samsung BDP, Amazon Firestick, Phillips CD Changer

    Canare 14 ga - LCR tweeters inside*; Ctr Ch outside
    BJC 10 ga - LCR mids “Foamed” & “Plugged**”, inside* & out
    8 ga Powerline: LR woofers, inside* & out
    *soldered **Rob the Man (Xschop)

    LR: Tri-amped RTi A7 w/Rotels*. Woofers - 980BX; Tweets & Mids - RB981*
    Ctr Ch: Rotel RB981* -> Bi-amped CSi A6
    Surrounds: Rotel 981* -> AR 12 ga -> RTi A3
    *all connected w/Premiere ICs
    5 Subs: Sunfire True SW Signature -> LFE & Ctr Ch; 4 Audio Pro Evidence @ the “Corners”

    Power Conditioning & Distribution:
    4 dedicated 20A feeds; APC H15; 5 Furman Miniport 20s
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  • Gardenstater
    Gardenstater Posts: 4,948
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    gp4jesus wrote: »
    mordar wrote: »
    Also would like to see a before and after frequency response of just the basket treatment mod.
    Pre & post mod measurements may parallel those of IC, speaker cables, and/or power cable upgrades/swaps

    I think THD measurements similar to what @DarqueKnight did with the tweeters in his epic thread "A Tale of 5 Tweeters" would probably show something beneficial.

    @JayMX way to step up to the plate and those are great little bookies! Did you also do the section between the spokes/uprights, by the spider? I really think that's not to be neglected and is not an insignificant amount of surface area for reflection back at the cone.
    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
    · Share on Facebook
  • gp4jesus
    gp4jesus Posts: 2,021
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    Gardenstater wrote: »
    @JayMX way to step up to the plate and those are great little bookies! Did you also do the section between the spokes/uprights, by the spider? I really think that's not to be neglected and is not an insignificant amount of surface area for reflection back at the cone.
    Look carefully at JayMX’s last pic - he did the spokes. He’ll hafta say how close he got to the spider.

    @JayMX: you did use plain foam inside the frame. At least it looks that way from the pic.

    Regardless ENJOY! Tony
    Samsung 60" QN65Q7FAMFXZA QLED, Outlaw Audio 976 Pre/Pro, Samsung BDP, Amazon Firestick, Phillips CD Changer

    Canare 14 ga - LCR tweeters inside*; Ctr Ch outside
    BJC 10 ga - LCR mids “Foamed” & “Plugged**”, inside* & out
    8 ga Powerline: LR woofers, inside* & out
    *soldered **Rob the Man (Xschop)

    LR: Tri-amped RTi A7 w/Rotels*. Woofers - 980BX; Tweets & Mids - RB981*
    Ctr Ch: Rotel RB981* -> Bi-amped CSi A6
    Surrounds: Rotel 981* -> AR 12 ga -> RTi A3
    *all connected w/Premiere ICs
    5 Subs: Sunfire True SW Signature -> LFE & Ctr Ch; 4 Audio Pro Evidence @ the “Corners”

    Power Conditioning & Distribution:
    4 dedicated 20A feeds; APC H15; 5 Furman Miniport 20s
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  • Gardenstater
    Gardenstater Posts: 4,948
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    I'm talking about this area, in addition to the spokes:

    olbudro7cbwy.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
    · Share on Facebook
  • JayMX
    JayMX Posts: 464
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    Correct. I did not cover the rear perimeter/lip of the basket adjacent to the spider. I’ll do that on my 7B’s when the time comes.
    Current Collection: Monitor 4a (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), Full mod SDA CRS 4.1TL (198’s), SDA SRS 2.3TL (198’s), R100's, R200’s, R300 🤩
    Pairs that have passed through: Monitor 4b (Peerless), Monitor 5a (Peerless), Monitor 5B (Peerless), Monitor 5b (SL1000), Monitor 5b (SL2000) (4x pair), Monitor 7b (Peerless), Modified Monitor 7c’s (194’s), Monitor 10a (Peerless), Monitor 10b (5x pair), RTA8, RTA8TL, RTA 11T, RTA12c (194's), SDA1(mod to “a” & SL1000 Wuhan mod), SDA CRS, SDA 2 (2x pair), SDA 2a, SDA 2b, SDA 1b, SDA 1c, SDA SRS 2 (2x pair), SDA SRS 3.1TL (198’s) (2x pair)...and more to come, it’s a sickness.
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  • gp4jesus
    gp4jesus Posts: 2,021
    edited August 2022
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    fcnlpcc1gpb6.jpeg

    oa4hstej1jbe.jpeg

    9r9clxmoarn5.jpeg
    Some “foaming” on the inside of an RTi A7 mid that Rob (xschop) just finished “pluggin’” recently. Look for it mounted on my Tri-amp ‘7 thread
    Samsung 60" QN65Q7FAMFXZA QLED, Outlaw Audio 976 Pre/Pro, Samsung BDP, Amazon Firestick, Phillips CD Changer

    Canare 14 ga - LCR tweeters inside*; Ctr Ch outside
    BJC 10 ga - LCR mids “Foamed” & “Plugged**”, inside* & out
    8 ga Powerline: LR woofers, inside* & out
    *soldered **Rob the Man (Xschop)

    LR: Tri-amped RTi A7 w/Rotels*. Woofers - 980BX; Tweets & Mids - RB981*
    Ctr Ch: Rotel RB981* -> Bi-amped CSi A6
    Surrounds: Rotel 981* -> AR 12 ga -> RTi A3
    *all connected w/Premiere ICs
    5 Subs: Sunfire True SW Signature -> LFE & Ctr Ch; 4 Audio Pro Evidence @ the “Corners”

    Power Conditioning & Distribution:
    4 dedicated 20A feeds; APC H15; 5 Furman Miniport 20s
    · Share on Facebook
  • plastic_avatar
    plastic_avatar Posts: 747
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    Here's a question:

    Would foam be detrimental to a passive, because its sound generation is from the air behind the membrane- since it's not generated by the cone itself?

    I'm 'matting the exterior of the baskets of mine (man, they're flimsy). I don't plan to foam them, but might 'matt the interior of the arms, just to add mass to dampen basket vibration even more.

    Anyone played with this?

    [in progress]
    gmj1tyf26bl0.jpeg


    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: 5,856
    edited October 2022
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    Dyna-Mat/butyl matting the inner frame spokes would be ok.
    My 5B PR baskets are inner-frame butyl matted. Foaming would be unnecessary as there are no midrange reflections to deal with from the passive. The passive is pneumatically decoupled from any midrange frequencies as well.

    P.S. Post edited and spell-checked for F1's peace of mind.
    Don't take experimental gene therapies from known eugenicists.
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  • F1nut
    F1nut Posts: 52,406
    edited October 2022
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    A little Dynamat or the like goes a long way, there's absolutely no reason to cover every square inch and none should go inside the spokes.
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  • plastic_avatar
    plastic_avatar Posts: 747
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    Luckily, my square cuts mean I miss spaces, so I canna cover it all, reasonably ;)

    Inside unnecessary, but doesn't hurt? I didn't put anything inside, yet. Just a fan of over engineering, ya'know. But you guys got me to peel off some extraneous material. Thank you =)

    Ever since I understood a line from my Superman vs. Captain Marvel XL comic from the 70's, it's kind of a motto.

    'In for a penny, in for a pound.'

    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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  • skipshot12
    skipshot12 Posts: 2,159
    edited October 2022
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    I agree…
    The anal side of me isn’t happy till it’s happy.
    Like Sinatra said… I did it my way.
    I also agree it’s not needed to cover every square inch but, I can’t help myself.

    t5dajnnapcy2.jpeg

    My passive is also as completely covered as I could get it.
    Allows me to sleep at night 🤣
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  • skipshot12
    skipshot12 Posts: 2,159
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    That obsessive side of me also wants to cut off those 4 tabs with the holes in them, mid-woofers, with my dremel tool.
    Why…. I haven’t a clue but, I still want to remove all my mid woofers and do it!
    Would it make a difference, beats the f outta me 🤣
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  • skipshot12
    skipshot12 Posts: 2,159
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    pitdogg2 wrote: »
    One must keep in mind these drivers are getting harder and harder to aquire. 10yrs ago most were plentiful on the used market, today MW6503,MW6511, MW6600 and MW6501 are MUCH harder to aquire in good condition. They may even be in good condition before shipped, but after shipping monkey's throw them around you could be SOL. I can remember in years past there could be several pages of 12" passive's on ebay. These days not so much. The MW6503 and MW6511 are almost impossible to find. TREAD CAREFULLY.

    Absolutely right on point.

    This is THE very reason I’m not experimenting with lining the inside of the spokes of my MW’s as they are all I have for my sda’s.
    The what if has me a tad too cautious should it be something I wanted to reverse.

    Having said that…
    If I had a complete set of additional mw drivers, I would sure as hell give it a go with the full Monty.


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  • Gardenstater
    Gardenstater Posts: 4,948
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    Wait until more and more have done it and weigh in, if you're nervous. Only positive glowing reports so far. Trust is always an issue I understand that. I trust the opinions of those who have tried something above those who have not. Why amazon only accepts reviews from actual customers B)
    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
    · Share on Facebook
  • xschop
    xschop Posts: 5,856
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    The fact of the matter is all of the original drivers are old/worn and out of factory TS specs. The DCRs are sometimes not what they are supposed to be either I've found.


    Don't take experimental gene therapies from known eugenicists.
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  • plastic_avatar
    plastic_avatar Posts: 747
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    Speaking of hard to find... if anyone comes across a 5B midwoofer cheap...

    @skipshot12 Your cuts looks great. I'm envious. Mine look like the Lego version and yours look fancy. 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
    · Share on Facebook
  • Gardenstater
    Gardenstater Posts: 4,948
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    This one looks pretty minty. 6502 right?

    https://www.ebay.com/itm/284983786288?hash=item425a5b7b30:g:PPAAAOSwx89jNPQE&amdata=enc:AQAHAAAAoMXVX054M0gKA5RgnkDM3TUDIAsHCjjyHsGVx+S8SMonHuVsnPFwK5BGausrEdqEqrZLYmP4xpt10ls/UMb3OglXr8ZkP7ZhhzhY/g7oOLsK/R20zPn7pXDfXHBP3oNVh0TTtNg6rohlXEOD8drAqGDYR6jYKDq+lrIMLngczNy8yCc6yEwR5E7+w7/xRVcoMolGIPLpAh2dKIABDCiyZWA=|tkp:Bk9SR_avj_71YA
    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
    · Share on Facebook