My 2024 Polk SDA 2b Modification Progress Thread (Drop1)
drop1
Posts: 23
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). -
A not-so enjoyable start to this project - removing the factory glue from the cabinet seams. Probably not entirely necessary. Next I'll re-seal everything with Loctite Power Grab and possibly add a few wooden dowels for added bracing.
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In my experience the glue is usually very adhered to the cabinet and not needed to be removed. Haven't experienced any seal issues working around it with the power grab- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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Definitely not needed!!!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'm nearly done with it now. Agree. It's more work than it's worth.
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I like your efforts!
Live and learn then you will be able to help other people in the furture."Sometimes you have to look to the past to understand where you are going in the future"“Fa sol sol la la fa sol la ... " ~ a soul-stirring sound that is at once alluring and haunting surges through the room as their voices rise and merge. First they sing the notes, then the words from the Sacred Harp hymnal, which was first published in 1844. Sacred Harp a singing tradition that dates back nearly to the founding of the nation.
Harry / Marietta GA -
Much rather have someone over do a job than just enough.
Would always drive me nuts when our apprentices asked…. Is that good enough?
Carry on with your attention to detail in going above and beyond. -
For reference, here is about how much glue came out of one SDA 2b cabinet. The glue softens up with heat and I was able to scrape it out with small plastic scraper tool. I don't regret doing it as a matter of being thorough however I don't know that it was entirely necessary. Certain spots within the cabinet were overly difficult to reach.
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Waste of time and effort.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 -
Since you went to the effort you could use something stronger like JB Weld epoxy on all the seams and make the enclosure that much stronger than if you used construction adhesive.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 wrote: »Since you went to the effort you could use something stronger like JB Weld epoxy on all the seams and make the enclosure that much stronger than if you used construction adhesive.
Why not lay in some fiberglass matting? -
Gardenstater wrote: »Since you went to the effort you could use something stronger like JB Weld epoxy on all the seams and make the enclosure that much stronger than if you used construction adhesive.
Why not lay in some fiberglass matting?
I'm going to assume you mean after you embed some titanium rods into the JB Weld epoxy fillets.
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 -
*What makes titanium the choice material?Gardenstater wrote: »I'm going to assume you mean after you embed some titanium rods* into the JB Weld epoxy fillets.
To OP: consider Armacell in place of Dynamat - much lower $
Samsung 60" UN60ES6100 LED, 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 - 981, connected w/Monoprice Premiere ICs
Ctr Ch: Rotel RB981 -> Bi-amped CSi A6 Surrounds: Premiere ICs ->Rotel 981 -> AR 12 ga -> RTi A3. 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 -
Armacel is nothing like dynamat... You would be better off using flashing tape which is a bitumen type product like dynamat. I'm actually not fully convinced that dynamat is not just a large sheet of flashing tape to be honest haha- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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Armacel is nothing like dynamat... You would be better off using flashing tape which is a bitumen type product like dynamat. I'm actually not fully convinced that dynamat is not just a large sheet of flashing tape to be honest haha
If you ever bought a really old wedge pack of dynamat and saw really old flashing tape you would probably see they look eerily similar.
I bought a wedge pack of dynamat off of eBay. When it showed up I took it out of the package and unrolled the dynamat and let me tell you as I unrolled it it just crackled like glass. It had absolutely no sticky to it. I reached out to the seller and the seller told me I needed to use a propane torch to heat it up and it would be just fine. I laughed and told him NO, what you need to do is refund my money because this stuff is junk, no good, past its life!
They did and I bought more from another seller which was as pliable as clay, like it should be. -
Armacel is nothing like dynamat... You would be better off using flashing tape which is a bitumen type product like dynamat. I'm actually not fully convinced that dynamat is not just a large sheet of flashing tape to be honest haha
I believe it is, just has a thicker layer of bitumen in it. There is actually a product used for car soundproofing called modified bitumen, and it's very similar if not identical to the stuff used in roofing, it's a little different than dynamat though. -
Yep, back when we added on our house I used left over flashing tape to apply to the outside of our acrylic shower to dampen it, has worked great! Haha
I mean if you really need to dampen something and couldn't find dynamat I would have no problem slapping it on!- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit. -
”…nothing like Dynamat? I admit DM maybe more effective in some circumstancesArmacel is nothing like dynamat...
Samsung 60" UN60ES6100 LED, 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 - 981, connected w/Monoprice Premiere ICs
Ctr Ch: Rotel RB981 -> Bi-amped CSi A6 Surrounds: Premiere ICs ->Rotel 981 -> AR 12 ga -> RTi A3. 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 -
Armacel is nothing like dynamat... You would be better off using flashing tape which is a bitumen type product like dynamat. I'm actually not fully convinced that dynamat is not just a large sheet of flashing tape to be honest haha
I believe it is, just has a thicker layer of bitumen in it. There is actually a product used for car soundproofing called modified bitumen, and it's very similar if not identical to the stuff used in roofing, it's a little different than dynamat though.
Dynamat is actually butyl based. They say it is a proprietary formula (of course).
There is a souped up version of Dynamat Xtreme called Dynamat XPro which is 130 mills thick with a 5 mills aluminum layer. Looks like it may be about 36% more effective at 200Hz. Dynamat Xtreme is 4 mills aluminum and 67 mills total thickness.
https://dynamateurope.com/wp-content/uploads/2024/04/DynamatProX-Datasheet.pdf
https://www.dynamat.com/wp-content/uploads/2021/02/2010-Dynamat-Xtreme-Sell-Sheet_Web.pdfGeorge / 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 -
Yep nothing as in completely different in each and every way possible.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 -
So flashing tape comes in bitumen and butyl versions.
Dynamat is also privately owned so hard to find connections
Either way dynamat is a great product- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit. -
Another contender for the top spot is Resonix CLD. 132 mills total thickness, 12 mills aluminum.
When they give the data it is obvious that temperature has a significant impact, even around room temperature variations.
https://resonixsoundsolutions.com/product/resonix-mega-cld-squares-heavy-duty-sound-deadening-material/?srsltid=AfmBOoqTw3YDZQzFnApOAEOus_WT8rawqxj19mRs8G7w_Vn8OoLnT0KR
Dynamat ProX (meas. temp. not given
Dynamat Xtreme (almost as good as Resonix at room temp. at least)
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
