The 1.2TL, Project Monolith

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  • xschop
    xschop Posts: 5,897
    edited September 29
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    Updated the design to omit one of the pointed detents. This will let the other end self-align perpendicular while pressure is increased. Will make install a breeze....

    vwt3q3im4g6e.png
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  • xschop
    xschop Posts: 5,897
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    Hey Sean, version 2 can be accomplished by machining the large bolt head flat. A 9/16-18 bolt head would have same contact area as 1" round dowel....


    v4jqh27t8ltn.png
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  • ptrooper
    ptrooper Posts: 800
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    Nice work Rob B) . I'll get that measurement soon ,What materials will you use and which glue do you recommend?
    VR3 SDA SRS 1.2TL Duelund Monoliths+VR31000va Dreadnaught +VR3 MM2 SDA cable, <3 ,Lumin u2x ,<-sfp fibre <-LHYas8 Pro+ Switch,Transparent Reference MM2 xlr,power and speaker cables.FTA Sinope SE usb.40 Amp power line for amp with earth stake&Faraday shield ,20 Amp power line for digital equipment ->shunyata 8 venom power board...Working on it!
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  • xschop
    xschop Posts: 5,897
    edited October 1
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    Plan on using 7075 alloy and Grade 8 zinc plated bolts and nyloc nuts with copper anti-sieze.
    you'll just need a 13/16" (21mm for you Blokes) wrench to install after a good dab of Loctite Powergrab or Liquid Nails.

    A spring-loaded punch will make for pinpoint placement accuracy as well.
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  • ptrooper
    ptrooper Posts: 800
    edited October 5
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    xschop wrote: »
    Im looking into using 1.25-1.5 Dia. Black Delrin too for damping and resonant characteristics vs. sand filled alloy.

    You given up on this idea Xschop?

    Sinope SE usb Hitting 200 hours, wowza ,I wouldn't recommend using bypass caps!......Upwards and onwards.
    VR3 SDA SRS 1.2TL Duelund Monoliths+VR31000va Dreadnaught +VR3 MM2 SDA cable, <3 ,Lumin u2x ,<-sfp fibre <-LHYas8 Pro+ Switch,Transparent Reference MM2 xlr,power and speaker cables.FTA Sinope SE usb.40 Amp power line for amp with earth stake&Faraday shield ,20 Amp power line for digital equipment ->shunyata 8 venom power board...Working on it!
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  • xschop
    xschop Posts: 5,897
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    The point would be pointless as it wouldn't penetrate the particle board under compression. Would be a smudgey affair I'm afraid.

    Think I'll go the extra trouble to butyl wrap the alloy rods just for good measure. B)
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  • ptrooper
    ptrooper Posts: 800
    edited October 8
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    @xscop Hey Rob. How much thread are you planning to be visualised when they’r locked in place ?

    Today the Monoliths play another Aussie Classic. the song that turned my hometown pub , The Morley Generator into a bar fight 875 people with a head full piss(alcohol). The memories. o:) The Angels !,,,,,,Take a long line. A story of individual defiance and alienation when faced with systematic oppression and abuse of power.
    https://www.youtube.com/watch?v=MoYWhzuyNPQ
    Pump it up
    VR3 SDA SRS 1.2TL Duelund Monoliths+VR31000va Dreadnaught +VR3 MM2 SDA cable, <3 ,Lumin u2x ,<-sfp fibre <-LHYas8 Pro+ Switch,Transparent Reference MM2 xlr,power and speaker cables.FTA Sinope SE usb.40 Amp power line for amp with earth stake&Faraday shield ,20 Amp power line for digital equipment ->shunyata 8 venom power board...Working on it!
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  • xschop
    xschop Posts: 5,897
    edited October 8
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    Rebellion to tyrants is obedience to God.
    From the bloke on my hunnerds.

    @ 1/2" or less when installed. Why I need a good measurement from you.

    Looking back, I remember an old thread/post that stated there was a thicker front baffle between later and earlier 1.2's.

    I'm going to build a set for my XS-8TLs too.
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  • xschop
    xschop Posts: 5,897
    edited October 9
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    Started prototypes. Still waiting on new tap and nylocs....

    cs6u6qddds18.jpg
    3ha65hany6oj.jpg

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    iqyhzl1cxq3b.jpg
    dc8dugba6q5y.jpg
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    1a56fgo6qxee.jpg



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  • xschop
    xschop Posts: 5,897
    edited October 9
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    Shop neighbors are the best...

    41z698d8c02q.jpg

    uhvtgd9wxaa9.jpg

    Now just waiting on some locknuts from Fastenal...

    ql23ew6z639y.jpg

    When all said and done, hex heads are still 0.950 apex to apex....

    ctrtg2q0qjva.jpg




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  • skipshot12
    skipshot12 Posts: 2,167
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    How will you be attaching it to the inside, pressure?
    Would putting some type of rubber damping material on the ends help with the cabinet resonance?
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  • xschop
    xschop Posts: 5,897
    edited October 9
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    Yes, pressure set by hand-twist of the dowel. These will attach with PowerGrab or Liquid Nails once set just like a wooden dowel, but be simple to install and remove. I plan on pinpointing this set right between top MW and tweeter on the 8TLs as it is the weak spot from factory.

    I just tested the dimple in a piece of plywood. Too easy and won't budge laterally without glue. The old particle board will provide a little more resistance before bottoming out at interface.
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  • ptrooper
    ptrooper Posts: 800
    edited October 10
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    Excellent 😎 this will lock that tweeter array in solid as a rock ,10 in each enclosure ?
    Neutral pressure will be my goal !
    4fytapsv9pgg.jpeg
    Tuned to 17 Hz
    VR3 SDA SRS 1.2TL Duelund Monoliths+VR31000va Dreadnaught +VR3 MM2 SDA cable, <3 ,Lumin u2x ,<-sfp fibre <-LHYas8 Pro+ Switch,Transparent Reference MM2 xlr,power and speaker cables.FTA Sinope SE usb.40 Amp power line for amp with earth stake&Faraday shield ,20 Amp power line for digital equipment ->shunyata 8 venom power board...Working on it!
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  • xschop
    xschop Posts: 5,897
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    That looks like all the weak points are addressed given the orientation of the semi-rings. B)
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  • ptrooper
    ptrooper Posts: 800
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    This was the local 💦 watering hole!
    AC⚡️DC.
    k6xvc4b8r2po.jpeg
    VR3 SDA SRS 1.2TL Duelund Monoliths+VR31000va Dreadnaught +VR3 MM2 SDA cable, <3 ,Lumin u2x ,<-sfp fibre <-LHYas8 Pro+ Switch,Transparent Reference MM2 xlr,power and speaker cables.FTA Sinope SE usb.40 Amp power line for amp with earth stake&Faraday shield ,20 Amp power line for digital equipment ->shunyata 8 venom power board...Working on it!
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  • ptrooper
    ptrooper Posts: 800
    edited October 12
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    xschop wrote: »
    Shop neighbors are the best...

    41z698d8c02q.jpg

    uhvtgd9wxaa9.jpg

    Now just waiting on some locknuts from Fastenal...

    ql23ew6z639y.jpg

    When all said and done, hex heads are still 0.950 apex to apex....

    ctrtg2q0qjva.jpg




    When I receive these ,I will wait for the xover plates and tweeter bezzle upgrades before I install them!

    This Sinope cable is in a completely different ball park at 275 hours ,Absolute mesmerising with the depth and detail,I can't wait to get the cabinet vibrations sorted.I listened to a full Sinope cable system ,total cost, 1.2 mill ,OMG ,Could be bye bye to transparent!

    Your 1 Semi ring ,I find do allot more than the other thinner full rings in my SDA SRS ! They actually rung until I glued them along the edges.
    In future ,do you think you could make at least 2 semi rings to interlock as installed per WM? The thicker material definitely shifts any vibrations to a much lower frequency!

    Here's 1 pic ,<3

    Big thanks again to Xschop and Vr3 ,I highly recommend their upgrades!
    fjni7gfvgzjy.png
    VR3 SDA SRS 1.2TL Duelund Monoliths+VR31000va Dreadnaught +VR3 MM2 SDA cable, <3 ,Lumin u2x ,<-sfp fibre <-LHYas8 Pro+ Switch,Transparent Reference MM2 xlr,power and speaker cables.FTA Sinope SE usb.40 Amp power line for amp with earth stake&Faraday shield ,20 Amp power line for digital equipment ->shunyata 8 venom power board...Working on it!
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  • xschop
    xschop Posts: 5,897
    edited October 13
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    Final testing. Temp. Installed one in the 8TL right between top MW and tweeter. Point facing forward, adjustable bolt in rear, it self aligns perpendicular EASILY with a simple twist of the rod holding the hex steady. Main design goal achieved. I Rasped on it before and after. Even with only a 9" wide baffle, it stiffened right up and sounds much more inert.

    I still haven't received the locknuts, but once location is decided, all would be needed is Blue Loctite and the PowerGrab/Liq. Nails...


    They are almost dead silent without butyl wrap. Even when I hit them with a metal punch, they have a short clink, but no ringing.

    With butyl wrap....Dead silent....

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  • ptrooper
    ptrooper Posts: 800
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    I will probable wrap these in dynomat etc when they arrive down under, that will save some coinage/postage weight etc.
    one layer on the top dowel and add more to the braces the closer they get to the PR thus making sure not all dowels resonate to the same frequencies.OVERKILL or not?Exciting stuff <3
    VR3 SDA SRS 1.2TL Duelund Monoliths+VR31000va Dreadnaught +VR3 MM2 SDA cable, <3 ,Lumin u2x ,<-sfp fibre <-LHYas8 Pro+ Switch,Transparent Reference MM2 xlr,power and speaker cables.FTA Sinope SE usb.40 Amp power line for amp with earth stake&Faraday shield ,20 Amp power line for digital equipment ->shunyata 8 venom power board...Working on it!
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  • xschop
    xschop Posts: 5,897
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    Not so sure that'd be necessary. Even with ear up to them, they are silent when rung.

    When you get me that final dimension, I'm curious what the front baffle thickness is also on the Monoliths, 3/4" or 1" ?
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  • ptrooper
    ptrooper Posts: 800
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    Malang to bandung ,I'll be infront of those puppies again soon!

    I don't want these braces all marching to the same tune! Extra dynamat is simple .Adding this progressive mass loading should transform how the cabinet handles energy.

    a rough estimate has me thinking ~560 Hz. is where these rods might tend to get excited.

    By scattering the resonant frequencies across a broad spectrum instead of letting them pile up at 560 Hz, you gain two massive sonic advantages

    • Eliminates Midrange Smearing: The 500 Hz to 600 Hz range is where human hearing is most sensitive to vocals and acoustic details. Stripping out the synchronized rod vibrations ensures that the cabinet stays dead silent, preventing
    forwardness in your midrange.

    • Tighter, Cleaner Infrasonic Bass: With the cabinet completely locked down against baffle-flex , the air pressure generated by 12–15 Hz notes is focused entirely on driving the active mid-bass array and the 15-inch passive radiator rather than shaking the cabinet walls. The bass becomes faster, harder hitting, and completely effortless.

    I'll break up the harmonic chain by altering the weight of the rods from top to bottom. This splits a single 560 Hz resonant spike into a broad, harmless 61 Hz wide spectrum (503 Hz to 564 Hz).

    I was thinking.

    • Top Zone (Dowel 1 at top; Dowels 2 & 3 at top sides of tweeter array) Leave Dowel 1 bare aluminium with a 50mm center collar. Apply 1 single layer of Dynamat to Dowels 2 and 3.

    • Resonance: 531 Hz – 564 Hz
    • Mid Zone (Dowels 4 & 5 at mid-sides; Dowels 6 & 7 at lower-sides of array) Apply 1 full layer plus a 50mm centre collar to 4 and 5. Apply a 1.5-layer spiral wrap to 6 and 7.

    • Resonance: ~516 Hz
    • Bottom Zone (Dowel 8 below tweeter array; Dowels 9 & 10 above passive radiator) Apply 2 full layers to Dowel 8. Apply 2 full layers plus a thick 75mm center collar to 9 and 10.

    Let me know if I'm overthinking it?

    Right now ,I believe Monday to be the measuring day.



    VR3 SDA SRS 1.2TL Duelund Monoliths+VR31000va Dreadnaught +VR3 MM2 SDA cable, <3 ,Lumin u2x ,<-sfp fibre <-LHYas8 Pro+ Switch,Transparent Reference MM2 xlr,power and speaker cables.FTA Sinope SE usb.40 Amp power line for amp with earth stake&Faraday shield ,20 Amp power line for digital equipment ->shunyata 8 venom power board...Working on it!
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  • xschop
    xschop Posts: 5,897
    edited October 16
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    Sounds like a plan. I remembered GM added a bell weight to the C5 Vette torque tube to stop it from ringing but it is hollow and 6 Ft long. Dropped right in the 928 with a carriage and custom axles.
    FYI... C=πD but I had to add extra quarter inch length to the butyl mat when I rolled it on due to the dual layers. Easy Peasy.

    Have a good trip and let us known how the local beer is. B)
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  • Sideous
    Sideous Posts: 2
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    What an impressive build!

    I cannot help but ask mate, as these speakers are 40 bloody years old. Why spend so much quid on these
    when you could have had a bloody set of Magico and still had money left over?
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  • ptrooper
    ptrooper Posts: 800
    edited October 16
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    Sideous wrote: »
    What an impressive build!

    I cannot help but ask mate, as these speakers are 40 bloody years old. Why spend so much quid on these
    when you could have had a bloody set of Magico and still had money left over?

    Thank @VR3 Why not ?
    Most companies work to a price limit. Me? I work to the absolute limit. If you're not redlining it, you're not trying. Plus, you need a hobby that keeps life interesting.

    Mathew Polks SDA SRS 1.2tl's <3

    If your out there Mr Polk, Thank you for all the joy you have brought me in my life , listening to music through you'r amazing speakers.
    Magico are ok , These upgrades are much cheeper and give a side of the performance that Magico just can't reproduce!
    VR3 SDA SRS 1.2TL Duelund Monoliths+VR31000va Dreadnaught +VR3 MM2 SDA cable, <3 ,Lumin u2x ,<-sfp fibre <-LHYas8 Pro+ Switch,Transparent Reference MM2 xlr,power and speaker cables.FTA Sinope SE usb.40 Amp power line for amp with earth stake&Faraday shield ,20 Amp power line for digital equipment ->shunyata 8 venom power board...Working on it!
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  • xschop
    xschop Posts: 5,897
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    Do the Magicos produce a massive enveloping SDA soundstage?
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  • ptrooper
    ptrooper Posts: 800
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    xschop wrote: »
    Do the Magicos produce a massive enveloping SDA soundstage?

    They'r still trying :D
    VR3 SDA SRS 1.2TL Duelund Monoliths+VR31000va Dreadnaught +VR3 MM2 SDA cable, <3 ,Lumin u2x ,<-sfp fibre <-LHYas8 Pro+ Switch,Transparent Reference MM2 xlr,power and speaker cables.FTA Sinope SE usb.40 Amp power line for amp with earth stake&Faraday shield ,20 Amp power line for digital equipment ->shunyata 8 venom power board...Working on it!
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  • billbillw
    billbillw Posts: 8,346
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    xschop wrote: »
    Do the Magicos produce a massive enveloping SDA soundstage?

    Nothing much I have heard does. We like it, but some say it's not natural. Let them spend more for less enjoyment. SDAs always put a smile on my face when good recording hits the preamp.
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  • Gardenstater
    Gardenstater Posts: 4,983
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    ptrooper wrote: »
    Excellent 😎 this will lock that tweeter array in solid as a rock ,10 in each enclosure ?
    Neutral pressure will be my goal !
    4fytapsv9pgg.jpeg
    Tuned to 17 Hz

    I'm thinking little corner braces between both the front baffle and the back of the enclosure and the enclosure sides. Let us know what thicknesses Polk used if you can and whether they are MDF (I think people have reported MDF but there are different densities) or particle board. These 1 in. dia. braces will help to increase baffle stiffness, obviously, by coupling front baffle to the stiffer rear of the enclosure, but there is still some flex there. The little corner braces wouldn't decrease enclosure volume by much but would be big bang for the buck in stiffness.

    Also we can't forget the poor coupling of the midwoofers to the baffle with only 4 tiny head mounting screws on a fairly flimsy basket, although later models of midwoofers that Polk built had thinner still gauge of steel. That's why I use #10 1/8 in. thick steel square nuts under the heads of my mounting screws. You can really feel them tighten up and they stay tighter over time as well. Going to 8 holes in the basket is a no brainer if you are wanting to really couple well. Yeah 6 holes is probably a huge improvement but there is no way geometrically possible to just drill 2 more holes and have them be uniformly space so why not go 8.
    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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  • Gardenstater
    Gardenstater Posts: 4,983
    edited October 17
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    Do these speakers already have effective and sufficient corner bracing? Been a while since I saw a photo of the interior. But what I was thinking was just some 1 x 1 with a 1/4 roundover hardwood pieces cut on a 45 at each end and glued in wherever there seems to be a need, if anywhere.

    I see a brace in this pic (looks like particle board?) that accomplishes what I am referring to and presumably there are more than this one.......just above the tiny capacitors

    pu36ymqz1kdl.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
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  • ptrooper
    ptrooper Posts: 800
    edited October 17
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    @Gardenstater .I'll get the details soon regarding thickness etc .I'm on a mission at the moment with Pops!
    Totally agree with you on everything,the one person at the moment that knows these SDA SRS's the best is the Man that built them @VR3 .
    It would be nice to open them just once for the final treatment!
    Equilibrium/positioning regarding everything and drilling the extra WM screws holes x 6 maybe as @xschop semi braces are in place, You got me thinking, its a plan <3
    VR3 SDA SRS 1.2TL Duelund Monoliths+VR31000va Dreadnaught +VR3 MM2 SDA cable, <3 ,Lumin u2x ,<-sfp fibre <-LHYas8 Pro+ Switch,Transparent Reference MM2 xlr,power and speaker cables.FTA Sinope SE usb.40 Amp power line for amp with earth stake&Faraday shield ,20 Amp power line for digital equipment ->shunyata 8 venom power board...Working on it!
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  • Gardenstater
    Gardenstater Posts: 4,983
    edited October 18
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    Yeah the 1/4 in. thick (brilliantly designed) braces do complicate things when doing the 8 hole mod. Why I haven't gotten around to doing my 7Bs yet. Just a little more involved since they have to be drilled and tapped in place. I think one of those portable mini drill press accessories would help a lot with the process. For drilling the driver you just have to make sure no metal chips enter the basket windows by taping them off and I'd tape the magnets too so no ferromagnetic dust attaches there as well that can't be vacuumed off easily. If you (I mean others) have done the phase plug mod you also have to make sure nothing enters between the cone and the plug. I still swear by these #10 steel square nuts used as a pressure plate between the screw head and the basket. It basically triples the contact area especially with the oversized holes in the basket. Hasn't caught on and as far as I know nobody has tried it. The only PIA aspect is I had to mill down one side for clearance at the surround side rather than cut the rubber out.

    PS: OMG the flash photography makes the Polk trilayer pixie dust really stand out. Prior to cleaning.

    97pvblw29b5u.jpg

    kmmxihvz15k7.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
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