My 2024 Polk SDA 2b Modification Progress Thread (Drop1)
drop1
Posts: 16
Hey Folks. I'm going to use this thread to document my progress restoring/modifying my 1989 Polk SDA 2b's.
I made a short intro in another thread about a week ago but here's the backstory. A couple years ago I found a pair of 1982 Monitor 4's at the Thrift Store for $12. What a deal! I was aware of the make/model but didn't entirely realize how much love people still have for some of these old Polk Audio speakers. My next step was to replace the internals. This is when I found the Polk Audio Forum. I perused the threads and gave the M4's a much needed refresh. One thing led to another and I later found myself with a pair of SDA 2b's. At the time, I had some plans to perform similar mods but didn't entirely realize what I was getting myself into. I've now owned these for about a year and have entirely enjoyed them unmolested. But I think it's time to see what this whole SDA modification stuff is all about.
It's amazing the backlog of discussion, trial/error, testing, et cetera that is documented in this forum. And even more awesome is the transparency of Polk Audio Engineers about their manufacturing limitations and sanctioning of various modifications. I've been casually reading/note taking over the last couple of months and I think I'm finally ready to get started. So here's my list of everything that I plan to do. I definitely did not plan for this list to be so long initially, but again, one thing led to another and here I am. I figure I might as well go all the way. So here's the list of my plans:
I have assembled most of the materials already (as shown). Just a few more items are yet to be ordered.
I'll post my progress each step of the way. Partially for my own documentation purposes and partially as my own contribution to the forum. I'll try to be as detailed as possible. Between everything else that I have going on, I hope to have these done by the end of this Winter.
I made a short intro in another thread about a week ago but here's the backstory. A couple years ago I found a pair of 1982 Monitor 4's at the Thrift Store for $12. What a deal! I was aware of the make/model but didn't entirely realize how much love people still have for some of these old Polk Audio speakers. My next step was to replace the internals. This is when I found the Polk Audio Forum. I perused the threads and gave the M4's a much needed refresh. One thing led to another and I later found myself with a pair of SDA 2b's. At the time, I had some plans to perform similar mods but didn't entirely realize what I was getting myself into. I've now owned these for about a year and have entirely enjoyed them unmolested. But I think it's time to see what this whole SDA modification stuff is all about.
It's amazing the backlog of discussion, trial/error, testing, et cetera that is documented in this forum. And even more awesome is the transparency of Polk Audio Engineers about their manufacturing limitations and sanctioning of various modifications. I've been casually reading/note taking over the last couple of months and I think I'm finally ready to get started. So here's my list of everything that I plan to do. I definitely did not plan for this list to be so long initially, but again, one thing led to another and here I am. I figure I might as well go all the way. So here's the list of my plans:
- Re-seal cabinets
- Glue driver magnets
- Dynamat baskets
- Hurricane nuts
- Replace gaskets
- Black hole 5
- Outriggers
- Crossover mods
- Caps and resistors
- TL Mod + new tweeters
- Polyswitch Jump
- SDA Circuit Inductor
- Internal wiring
- Binding posts
- New Interconnect cable/sockets
- Billet Tweeter Bezel (Thanks @xschop)
I have assembled most of the materials already (as shown). Just a few more items are yet to be ordered.
I'll post my progress each step of the way. Partially for my own documentation purposes and partially as my own contribution to the forum. I'll try to be as detailed as possible. Between everything else that I have going on, I hope to have these done by the end of this Winter.
Comments
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I suggest replacing the poly with a 0.5 ohm resistor instead of jumping it. That half ohm difference is very audible.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 -
I have a pair of passives if you need them.Main system: Lyngdorf TDAI 2170 w/ Pioneer 42" plazma-> Polk LSiM 703 w/Tivo, Marantz tuner, BRPTT: Nothingham Spacedeck-> Pioneer PL L1000 linear arm-> Soundsmith DL 103R-> SUT->Bottlehead ErosDigital: I3 PC w/ Jriver playing flac -> Sonore Ultrarendu -> Twisted Pair Audio ESS 9028 w/ Mercury IVY Vinyl rips: ESI Juli@24/192-> i3 PC server
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I suggest replacing the poly with a 0.5 ohm resistor instead of jumping it. That half ohm difference is very audible.
Yep, I've already got the 0.5ohm resistor in possession. I've ready so many past threads that I like to think I've got it all covered. But I will gladly accept (and would request) any suggestions as I make more posts. Thank you -
To anyone who's re-veneered their Polk speakers - does anyone know how this trim piece on the front of my 2b is secured?
I'm considering veneering my Polks. For the sake of time, I also might not. Or I'll have someone do it for me. But if I were to do it myself, this front piece of trim might be a tad difficult for a beginner. I wonder if I can apply some heat and loosen the glue to remove it? (assuming that's how it's attached)
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I remember someone posting some time ago that they wanted to remove this piece and they were going to do it with a jig they would make and a router. So, when you look inside and underneath you don't see any screws?
Maybe a fine music wire held taut in a hacksaw frame could slice through the adhesive and take it off.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 -
I redid a pair of 1B’s a while back. I couldn’t get that panel off either. So I veneered them in place. Worked out fine.
Current Collection: Monitor 4a (Peerless), Monitor 5B (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), SDA CRS+ (194’s), SDA SRS 2.3TL, R100's, R200’s, R300 🤩 -
I couldn’t get that panel off either. So I veneered them in place. Worked out fine.
Just the response I needed. And those look fantastic. I might just have to go for it after seeing yours. I really enjoy the light color of the wood veneer you used. Well done. -
Those panels are glued on.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 -
Thanks @F1nut
I might apply continuous heat at a low output and see if it wiggles loose. If not, I'll veneer them as @JayMX did. Or I'll not veneer them at all.
Can't decide right now. I've been a bit too busy to even think much about it. One one hand I want them done ASAP. On another hand, I want them done right (entirely - the first time).
