Important Advice for SDA's with bolted on end caps
F1nut
Posts: 50,551
While inside my 2.3TL's today I discovered that every end cap nut was loose, so loose I could turn them by hand. To ensure this would not happen again I added a lock washer. I encourage all owners of 2.3's, 1.2's, 2.3TL's and 1.2TL's to check your end cap nuts because if they are loose, your speakers are leaking air. Those are the models I know have bolt on end caps, but there may be others.
It seemed to me that even with the nuts tight those areas could still leak air, so I made a gasket to go under each flat washer. I used some adhesive backed thin foam gasket material similar to the original driver gasket material. Using the flat washer as a template I cut the material with surgical scissors. I then used an X-ACTO knife to cut out the center. Make the center cut slightly smaller than the hole in the washer, that way it'll make a nice seal around the bolt.
Speaking of the stock driver gaskets. I've been saying for years that unless they are damaged there's no reason to replace them, especially if you have Larry's rings installed. What I found today re-enforces that. I had to pry the first driver loose and then had to push the rest out from the rear. I shake my head when I think about all those that went through the trouble of replacing perfectly good gaskets with Armacell or Mortite.
It seemed to me that even with the nuts tight those areas could still leak air, so I made a gasket to go under each flat washer. I used some adhesive backed thin foam gasket material similar to the original driver gasket material. Using the flat washer as a template I cut the material with surgical scissors. I then used an X-ACTO knife to cut out the center. Make the center cut slightly smaller than the hole in the washer, that way it'll make a nice seal around the bolt.
Speaking of the stock driver gaskets. I've been saying for years that unless they are damaged there's no reason to replace them, especially if you have Larry's rings installed. What I found today re-enforces that. I had to pry the first driver loose and then had to push the rest out from the rear. I shake my head when I think about all those that went through the trouble of replacing perfectly good gaskets with Armacell or Mortite.
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
"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
Comments
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I used mortite for the 8 inch driver upgrade on my lsi 15's. It's was too tight to push out with my hand, I had to use a pry bar through the hole for the binding post plate to crack it loose. That shite holds strong.2 channel:
Bryston 4B3, Bryston BDA3, Cary SLP05, Shanling CDT1000SE with parts conneXion level 2 mods, Nottingham analogue ace space 294, soundsmith Carmen MKii, Zu DL103 MKii, Ortofon MC 20 MKii, Dynavector XX2 MKii, Rogue Audio Ares, Core power technologies balanced power conditioner, Akiko Corelli power conditioner with Akiko Audio HQ power cable, Nordost heimdall 2, Frey 2, interconnects, speaker and power cables, Focal Electra 1028 BE 2, Auralic Aries Femto, Black diamond racing cones, ingress audio level 1 roller blocks, JL Audio E110 with Auralic subdude, Primacoustics room treatments.
Theater:
Focal Aria 926,905,CC900, SVS PB ultra x2. Pioneer Elite SC85, Oppo BDP93, Panamax M5400PM, Minix neox6, Nordost Blue heaven LS power cables. -
Makes sense. A couple of decades of expanding and contracting due to temperature and humidity. Check your crossover mounts too. I've found many SDAs with loose cap screws.Home Theater/2 Channel:
Front: SDA-2ATL forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
Center: Custom Built forum.polkaudio.com/discussion/150760/my-center-channel-project/p1
Surrounds & Rears: Custom Built forum.polkaudio.com/discussion/151647/my-surround-project/p1
Sonicaps, Mills, RDO-194s-198s, Dynamat, Hurricane Nuts, Blackhole5
Pioneer Elite VSX-72TXV, Carver PM-600, SVS PB2-Plus Subwoofer
dhsspeakerservice.com/ -
While inside my 2.3TL's today I discovered that every end cap nut was loose, so loose I could turn them by hand. To ensure this would not happen again I added a lock washer. I encourage all owners of 2.3's, 1.2's, 2.3TL's and 1.2TL's to check your end cap nuts because if they are loose, your speakers are leaking air. Those are the models I know have bolt on end caps, but there may be others.
Thanks for the tip. I checked mine and they are still tight. When I replaced the end caps on my SRSs and 1.2TLs, the end cap nuts were still tight after 20+ years.
I can see where vibration, moving the speakers around, and expansion/contraction due to humidity changes might loosen the nuts over time.Speaking of the stock driver gaskets. I've been saying for years that unless they are damaged there's no reason to replace them, especially if you have Larry's rings installed. What I found today re-enforces that. I had to pry the first driver loose and then had to push the rest out from the rear. I shake my head when I think about all those that went through the trouble of replacing perfectly good gaskets with Armacell or Mortite.
I'll have to respectfully disagree here. I noted audible and measurable differences among original foam seals, Mortite, and Armacell. Mortite was recommended by Matthew Polk as a higher performance alternative to foam seals.
My comparisons of original seals, Mortite, and Armacell are here:
http://forum.polkaudio.com/discussion/123136/sda-driver-seals-original-foam-vs-mortite-vs-armaflex-foam/p1Proud and loyal citizen of the Digital Domain and Solid State Country! -
SRS 2's also have bolted on end caps.2-channelBelles 22A Pre, Emotiva XPA-2 Gen 2, Marantz SA8005, Pro-Ject RPM-10 Turntable, Pro-Ject Phono Box DS3B, Polk Audio Legend L800's, AudioQuest Cable throughout.
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Good info, TKS
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I will check mine when I get home tonight thanksPOLK SDA 2.3 TLS BOUGHT NEW IN 1990, Gimpod/Sonic Caps/Mills RDO-198
POLK CSI-A6 POLK MONITOR 70'S ONKYO TX NR-808 SONY CDP-333ES
PIONEER PL-510A SONY BDP S5100
POLK SDA 1C BOUGHT USED 2011,Gimpod/Sonic Caps/Mills RDO-194
ONKYO HT RC-360 SONY BDP S590 TECHNICS SL BD-1 -
First Guess: The nuts are not "backing off" except perhaps AFTER they become loose due to the changing thickness of the wood cabinet materials due to humidity variation or other causes.Personally, a very little dab of Blue (Loctite 242 medium strength) threadlocker on the threads of the studs the nuts thread on to might stop them from backing off...but just a small little dab, and no....don't use the red version....seriously...don't use the red stuff...trust me...red stuff will cause the studs themselves to unscrew frothe end caps.
Gluing the nuts in place won't help if dimensional changes cause the fastener preload to "go away". Gluing the nuts will keep the nuts secure, but doesn't assure fastener preload when the wood changes thickness.
Great...something else to deal with on my SRS 2 p/b speakers. I swear that someday I'll get back to working on them. -
The end caps in question are wood veneer over MDF, they are not subject to dimensional changes. If your end caps are the all wood version found on the SDA SRS model they may be subject.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 -
The end caps in question are wood veneer over MDF, they are not subject to dimensional changes. If your end caps are the all wood version found on the SDA SRS model they may be subject.
That is interesting. Are there any other vintage Polk models other than the SDA SDS, I'm assuming you're referring to the very first SDA SRS models, that used all wood instead of veneer? -
+1. Found the same tonight when I started the surgery on my 2.3TL's. Half of the end cap nuts were able to be loosened by hand. Was just going to use lockwashers but your +gasket idea makes sense, need to see what I can find.
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aprazer402 wrote: »That is interesting. Are there any other vintage Polk models other than the SDA SDS, I'm assuming you're referring to the very first SDA SRS models, that used all wood instead of veneer?
That is correct.
I'm not 100% sure, but I think the SDA SRS 2 end caps are all wood. Hopefully, Schurkey can verify that.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 -
My '86 SRS2's were jointed wood caps.aprazer402 wrote: »That is interesting. Are there any other vintage Polk models other than the SDA SDS, I'm assuming you're referring to the very first SDA SRS models, that used all wood instead of veneer?
That is correct.
I'm not 100% sure, but I think the SDA SRS 2 end caps are all wood. Hopefully, Schurkey can verify that.
b]Beach Audio[/b]: Rega RP6 (mods) - AT33PTG/II - Parks Budgie SUT - PSAudio NPC * Eversolo DMP-A6 * Topping D90iii * Joule-Electra LA-100 mkIII * Pass Aleph 30 * MIT S3 * Polk SRS 2.3tl (mods) * PSAudio PPP3
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My SRS 2 p/b have laminated wood top caps. I assume the bottoms are also laminated. Mine show minor splitting at the "seams".
My '86 SRS2's were jointed wood caps.aprazer402 wrote: »That is interesting. Are there any other vintage Polk models other than the SDA SDS, I'm assuming you're referring to the very first SDA SRS models, that used all wood instead of veneer?
That is correct.
I'm not 100% sure, but I think the SDA SRS 2 end caps are all wood. Hopefully, Schurkey can verify that.
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good heads up here, Jesse. I'm curious to check mine out, since I've had that mystery issue with absolutely zero bass. granted the crossovers need work, but wouldn't think to the point that the speakers would be completely empty.I disabled signatures.
