How can rubber surrounds become hard and brittle on RTA-11T?
Mystery
Posts: 2,546
How can rubber surrounds become hard and brittle on RTA-11T?
No one can ever tell it was rubber at one time.
Pieces were on the floor but they felt like egg shell.
I pressed on the surrounds and I had to push hard and pieces broke apart like black plastic without any flexibility.
What the hell? :eek:
May be that PR was replaced.
I can't imagine original rubber being that stiff while all other drivers have good surrounds even though I think one mid may be not working right.
Heavy water rings on top.
Sad pair but I could not leave them behind.
I don't think the PR can be salvaged as it'll be hard to get that hard rubber off the cone.
:sad:
No one can ever tell it was rubber at one time.
Pieces were on the floor but they felt like egg shell.
I pressed on the surrounds and I had to push hard and pieces broke apart like black plastic without any flexibility.
What the hell? :eek:
May be that PR was replaced.
I can't imagine original rubber being that stiff while all other drivers have good surrounds even though I think one mid may be not working right.
Heavy water rings on top.
Sad pair but I could not leave them behind.
I don't think the PR can be salvaged as it'll be hard to get that hard rubber off the cone.
:sad:
Klipsch RB81, KG3.5, B&W DM602.5, Polk.
Subwoofers: Klipsch RW10, Triad ProSub Bronze.
Post edited by Mystery on
Comments
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Before I feel in love with Polks. My favorites were ADS. Did not know how hard the rubber surrounds were til I bumped some funk with a newly acquired NAD pre and they just came apart. Bought a surround kit from local speaker shop and back in business. Good luck. DMIT Magnum MH-750, Monster HTS 5100MKII, Sony 77" Class - A80CJ Series - 4K UHD OLED,PS4, Def Tech 15” sub,LSIM 706c, Sunfire Signature Grand 425 x 4,Parasound hca 120, LSiM 702 x 4, Oppo 103D, SDA SRS 1.2, Pioneer Elite SC63 , Pioneer Elite BDP-05 “Why did you get married if you wanted big speakers?”
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Hmm... older than 6 years tires not good huh? Time to change mine then.
Anywho, back to the RTA-11T. They need some TLC definitely.
I had RTA-8TL and didn't impress me much but these are massive compared to them so may sound better.
The base stands are damaged/loose and one round stabilizing thingy out of four is missing in each so they tilt at one corner but that's not a biggy.
One cabinet has almost all the grill pegs broken.
Except the hard/brittle plastic surround on one PR, other drivers look okay but I didn't hear much output from the top mid woofer of the damaged PR cabinet but the cone moves freely in/out.
Close up of the brittle/hard surround.
There is not even .0001% rubber like characteristics on them. It's like dry plastic cone.
It does look original so I have no idea what caused only this one to be like that.
What are my options? Can I remove it from the cone using some goo-gone and then re-foam or find another PR?
Horrible water rings on top of both.
I read hydrogen peroxide or some other chemical like Oxalic acid can remove the water rings.
Any idea?
BTW, also grabbed a pair of S4 today. They sound pretty decent for that size.
Klipsch RB81, KG3.5, B&W DM602.5, Polk.
Subwoofers: Klipsch RW10, Triad ProSub Bronze. -
There have been lower PR's for these on Ebay lately...Remember, when you're running from something, you're running to something...-me
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The base stands are damaged/loose and one round stabilizing thingy out of four is missing in each so they tilt at one corner but that's not a biggy.
The large white glides someone put on, the small brown one is an original. I'd remove the busted up bases, plug the screw holes and install tall spikes, say at least 2 inches.Horrible water rings on top of both.
I read hydrogen peroxide or some other chemical like Oxalic acid can remove the water rings.
Any idea?
Those are pretty bad, but I've seen worse. Oxalic acid is your friend, but it would tough to do without the slurry getting on the baffle and you really should do all the veneer to equal out. I'd suggest reveenering them.There is not even .0001% rubber like characteristics on them. It's like dry plastic cone.
It does look original so I have no idea what caused only this one to be like that.
I've never seen a Polk PR or driver with that issue. nbrowser listed likely causes. Acidic liquids such as dog piss could also cause 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 -
I see they have two, one for low resonance and another for high resonance.There have been lower PR's for these on Ebay lately...
Lower is SW81 and SW80 is the upper???
I'll try some chemicals and stain. Reveneering is out of scope due to my lack of skill/time.I'd suggest reveenering them.
I've never seen a Polk PR or driver with that issue. nbrowser listed likely causes. Acidic liquids such as dog piss could also cause that.
Weird thing is it only happened to that PR and it's not at one spot but all around the PR as if it's made with entirely different material. Even the PR above has good surrounds. :rolleyes:
Klipsch RB81, KG3.5, B&W DM602.5, Polk.
Subwoofers: Klipsch RW10, Triad ProSub Bronze. -
Those water stains are harsh looking! I have had great results with water stain removal by taking a clothes iron to it. Take a white old t-shirt and set on top so it is two layers thick. Then iron on high without steam on . Work at it until you see the results you are happy with. It might do the trick or at least lessen the damaged look. I have not heard those speakers. But Some people swear by the sound stage. Good luck. DMIT Magnum MH-750, Monster HTS 5100MKII, Sony 77" Class - A80CJ Series - 4K UHD OLED,PS4, Def Tech 15” sub,LSIM 706c, Sunfire Signature Grand 425 x 4,Parasound hca 120, LSiM 702 x 4, Oppo 103D, SDA SRS 1.2, Pioneer Elite SC63 , Pioneer Elite BDP-05 “Why did you get married if you wanted big speakers?”
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is that real wood veneer on those? I was not aware Polk used this on the 11T. I suppose the water stains would be too deep for light sanding if it is, in fact, wood?Polk Lsi9
N.E.W. A-20 class A 20W
NAD 1020 completely refurbished
Keces DA-131 mk.II
Analysis Plus Copper Oval, Douglass, Morrow SUB3, Huffman Digital
Paradigm DSP-3100 v.2 -
gonna try the t-shirt and iron trick later today on these.
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Rubber surrounds can be replaced, more of a PITA than foam though. You're better off picking up one off eBay.How can rubber surrounds become hard and brittle on RTA-11T?
No one can ever tell it was rubber at one time.
Pieces were on the floor but they felt like egg shell.
I pressed on the surrounds and I had to push hard and pieces broke apart like black plastic without any flexibility.
What the hell? :eek:
May be that PR was replaced.
I can't imagine original rubber being that stiff while all other drivers have good surrounds even though I think one mid may be not working right.
Heavy water rings on top.
Sad pair but I could not leave them behind.
I don't think the PR can be salvaged as it'll be hard to get that hard rubber off the cone.
:sad: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/ -
is that real wood veneer on those? I was not aware Polk used this on the 11T. I suppose the water stains would be too deep for light sanding if it is, in fact, wood?
Yes, real wood. A light sanding should be done before applying Oxalic acid, but a light sanding is not going to remove the stains on those speakers.I have had great results with water stain removal by taking a clothes iron to it.
The heat from an iron can remove cloudy marks, which are from moisture being trapped beneath a clear coat finish. However, this is NOT the case here.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 -
Ironing didn't do anything.
On the right speaker, water marks are so bad that I see fine wood splits in few places, not deep, only on surface.
Not really big but can see them when looking at the water damage closely. Looks like water stayed on the top for a while to soak in.
I took the PR out and it is indeed original SW81 dated 10-21-87.
Whatever made them brittle must have been equally applied to the whole PR or the material is made such that if one spot is brittle, it makes the whole thing brittle. Not sure what's the case.
I'll see if I can remove the surrounds as I have bunch of 8" stiff foam surrounds lying around.
Not rubber but they are pretty stiff so may work out fine.
eBay doesn't have a single one.
There are few upper PR's (SW80) for $15 but I need SW81.
Klipsch RB81, KG3.5, B&W DM602.5, Polk.
Subwoofers: Klipsch RW10, Triad ProSub Bronze. -
I wouldn't advise foam surrounds in place of the rubber. The T/S parameters will change quite a bitHome 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/ -
There are some in the For Sale section.
http://www.polkaudio.com/forums/showthread.php?138066-Passives-SW81-SW83-NOS-for-RTA11T-TL-sStan
Main 2ch:
Polk LSi15 (DB840 upgrade), Parasound: P/LD-1100, HCA-1000A; Denon: DVD-2910, DRM-800A; Benchmark DAC1, Monster HTS3600-MKII, Grado SR-225i; Technics SL-J2, Parasound PPH-100.
HT:
Marantz SR7010, Polk: RTA11TL (RDO198-1, XO and Damping Upgrades), S4, CS250, PSW110 , Marantz UD5005, Pioneer PL-530, Panasonic TC-P42S60
Other stuff:
Denon: DRA-835R, AVR-888, DCD-660, DRM-700A, DRR-780; Polk: S8, Monitor 5A, 5B, TSi100, RM7, PSW10 (DXi104 upgrade); Pioneer: CT-6R; Onkyo CP-1046F; Ortofon OM5E, Marantz: PM5004, CD5004, CDR-615; Parasound C/PT-600, HCA-800ii, Sony CDP-650ESD, Technics SA 5070, B&W DM601 -
Yes already in touch with him.There are some in the For Sale section.
http://www.polkaudio.com/forums/showthread.php?138066-Passives-SW81-SW83-NOS-for-RTA11T-TL-s
Klipsch RB81, KG3.5, B&W DM602.5, Polk.
Subwoofers: Klipsch RW10, Triad ProSub Bronze. -
Ironing didn't do anything.
Told ya. I do this stuff for a living, I'm damn good at it and I know all the tricks.On the right speaker, water marks are so bad that I see fine wood splits in few places, not deep, only on surface.
Not really big but can see them when looking at the water damage closely. Looks like water stayed on the top for a while to soak in.
It's fairly thin veneer, I'd say it's worse than you think. I mean, I can tell from your pic that the right speaker top is basically F'd. The only way you'll get the black marks out is with Oxalic acid, but like I said it would be almost impossible to do without getting it all over the baffle and back. Time for new veneer.
The oak has turned black because the moisture has caused a reaction with the tannin in the oak. As you suspect, it took a bit of time for that to happen, but perhaps only a few weeks if the moisture was present all the time.westmassguy wrote:I wouldn't advise foam surrounds in place of the rubber. The T/S parameters will change quite a bit
I agree 100%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 -
If I go oxalic acid method, I'll put it in a plastic tub and flip the speaker upside down so it only touches the top end.
BTW, my suspicion of the top mid woofer MW6501 not working on the cab with bad PR is correct.
It measures 7.7 ohms and cone freely moves in/out so it must be okay.
May be a loose connection in the crossover.
Klipsch RB81, KG3.5, B&W DM602.5, Polk.
Subwoofers: Klipsch RW10, Triad ProSub Bronze. -
If I go oxalic acid method, I'll put it in a plastic tub and flip the speaker upside down so it only touches the top end.
Keep in mind that the Oxalic acid/water mix has to evaporate and return to a crystal form in order for the process to work, so the surface needs contact with the air.
BTW, do NOT breath the crystals or you will have a sneezing fit like no other.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 -
Mystery thats a nice project ya got here. One would think if done right those could be a nice set of speakers saved from burn pit LOL you always stumble on boat loads of items. Good luck n look forward to seing them when you get finished..
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Thanks for comments.
It actually is good to put things upon.
I have a laptop on one and CD's on the other to cover the top.
Got a PR from Larry so all I have to check is that one mid woofer that doesn't make any sound, at least for functionality.
No drooling but look at all those drivers!
Yes, all are hooked up to a Phoenix Gold 6-speaker selector powered by Rotel RB-990BX.
I was thinking I am thinning the herd but looks like I am just replacing the herd. :rolleyes:
They are crowded but two pairs are up for sale so hopefully it'll thin out soon.
Klipsch RB81, KG3.5, B&W DM602.5, Polk.
Subwoofers: Klipsch RW10, Triad ProSub Bronze. -
I thought it read 7.7 ohms before but I took it out and it's open.
The cone moves freely without any noise of rub.
The mid woofer is 6510, not 6501.
It has MW6510 SDA CRS written on the label as well as M 11t (may be for monitor 11?). Date is Nov 12 1987.
Looks like VC is gone kaput.
Anyway to fix it?
I had a Polk driver lying around without any sticker so used it for now.
It measures 7.7 ohms in my cheapo DMM while the working mid driver from other RTA-11T cabinet measures 8.0 ohms.
I'm not sure if they are same drivers since there is .3 ohms difference.
They sound the same so it may work out.
What say you?
Klipsch RB81, KG3.5, B&W DM602.5, Polk.
Subwoofers: Klipsch RW10, Triad ProSub Bronze. -
westmassguy wrote: »I wouldn't advise foam surrounds in place of the rubber. The T/S parameters will change quite a bit
I have seen replacement rubber surround kits available. http://www.simplyspeakers.com/Rubber-Edge-Kits_c_254-1-3.html
It may still change the characteristics some but it would be a better match than going with foam.Stan
Main 2ch:
Polk LSi15 (DB840 upgrade), Parasound: P/LD-1100, HCA-1000A; Denon: DVD-2910, DRM-800A; Benchmark DAC1, Monster HTS3600-MKII, Grado SR-225i; Technics SL-J2, Parasound PPH-100.
HT:
Marantz SR7010, Polk: RTA11TL (RDO198-1, XO and Damping Upgrades), S4, CS250, PSW110 , Marantz UD5005, Pioneer PL-530, Panasonic TC-P42S60
Other stuff:
Denon: DRA-835R, AVR-888, DCD-660, DRM-700A, DRR-780; Polk: S8, Monitor 5A, 5B, TSi100, RM7, PSW10 (DXi104 upgrade); Pioneer: CT-6R; Onkyo CP-1046F; Ortofon OM5E, Marantz: PM5004, CD5004, CDR-615; Parasound C/PT-600, HCA-800ii, Sony CDP-650ESD, Technics SA 5070, B&W DM601 -
Oxalic acid does work but it is a pita to work w/ and is very labor intensive and time consuming. If you do not have a garage or dedicated work space dried crystals can fly all over. I did get good results but would try to shy away from this procedure if you can. Photo of finished top was before 4 coats of poly sealer.
http://s823.photobucket.com/user/leftwinger3/media/adctops007_zps808929ec.jpg.html
2chl- Adcom GFA- 555-Onkyo P-3150v pre/amp- JVC-QL-A200 tt- Denon 1940 ci cdp- Adcom GFS-6 -Modded '87 SDA 2Bs - Dynamat Ext.- BH-5- X-Overs VR-3, RDO-194 tweeters, Larry's Rings, Speakon/Neutrik I/C- Cherry stain tops Advent Maestros,Ohm model E
H/T- Toshiba au40" flat- Yamaha RX- V665 avr- YSD-11 Dock- I-Pod- Klipsch #400HD Speaker set-
Bdrm- Nikko 6065 receiver- JBL -G-200s--Pioneer 305 headphones--Sony CE375-5 disc -
I have a garage I can use.leftwinger57 wrote: »Oxalic acid does work but it is a pita to work w/ and is very labor intensive and time consuming. If you do not have a garage or dedicated work space dried crystals can fly all over. I did get good results but would try to shy away from this procedure if you can. Photo of finished top was before 4 coats of poly sealer.
http://s823.photobucket.com/user/leftwinger3/media/adctops007_zps808929ec.jpg.html
Did you stain them and apply poly seal afterwards?
Could you post product links for them please?
Klipsch RB81, KG3.5, B&W DM602.5, Polk.
Subwoofers: Klipsch RW10, Triad ProSub Bronze. -
Yes, all after direction and help from F-1. The oxaolic acid cost me $4 for a box and then I got medium walnut stain and then fast drying clear satin poly both small cans, I used foam brushes and avoided bubbles. Here's a before shot to see what I was dealing with. One other thing, directions on box was for a deck application, you need to make a tooth paste kind of mixture and not to wet or it can warp and or bubble the wood and you'll be in for a boatload more work. Sanding and buffing or roughing up w/ steel wool was also done. All relatively cheap products.
http://s823.photobucket.com/user/leftwinger3/media/adctops007_zps808929ec.jpg.html2chl- Adcom GFA- 555-Onkyo P-3150v pre/amp- JVC-QL-A200 tt- Denon 1940 ci cdp- Adcom GFS-6 -Modded '87 SDA 2Bs - Dynamat Ext.- BH-5- X-Overs VR-3, RDO-194 tweeters, Larry's Rings, Speakon/Neutrik I/C- Cherry stain tops Advent Maestros,Ohm model E
H/T- Toshiba au40" flat- Yamaha RX- V665 avr- YSD-11 Dock- I-Pod- Klipsch #400HD Speaker set-
Bdrm- Nikko 6065 receiver- JBL -G-200s--Pioneer 305 headphones--Sony CE375-5 disc -
Sorry for not posting links. The ONLY place in Jersey near me for the acid was Sipperstein Paints. HD,Lowes and other hardware ware chains did not have the acid. All other stuff was bought at Home Depot. 150 grit sand paper, 0001gu steel wool ?, 3/4'' foam brushes, masks,gloves,Minwax medium walnut stain and Minwax clear poly. Good luck.
http://s823.photobucket.com/user/leftwinger3/media/DSCN04031_zps62d964ec.jpg.html2chl- Adcom GFA- 555-Onkyo P-3150v pre/amp- JVC-QL-A200 tt- Denon 1940 ci cdp- Adcom GFS-6 -Modded '87 SDA 2Bs - Dynamat Ext.- BH-5- X-Overs VR-3, RDO-194 tweeters, Larry's Rings, Speakon/Neutrik I/C- Cherry stain tops Advent Maestros,Ohm model E
H/T- Toshiba au40" flat- Yamaha RX- V665 avr- YSD-11 Dock- I-Pod- Klipsch #400HD Speaker set-
Bdrm- Nikko 6065 receiver- JBL -G-200s--Pioneer 305 headphones--Sony CE375-5 disc -
After you're finished with the oxalic acid, you can neutralize it with baking soda mixed with water. The oxalic acid never goes away, it re-crystalizes in the wood fibersHome 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/ -
With all the time and work and dedicated space needed to do the oxalic acid procedure, wouldnt make more sense to learn how to veneer? It really isnt that hard and you will end up with a better finished result. Plus you will have a new skill.
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Yes but no interest to learning veneer for now.With all the time and work and dedicated space needed to do the oxalic acid procedure, wouldnt make more sense to learn how to veneer? It really isnt that hard and you will end up with a better finished result. Plus you will have a new skill.
I may buy veneer just for the top and glue it there or just paint something over the rings with darker stain instead of trying to remove the rings.
Klipsch RB81, KG3.5, B&W DM602.5, Polk.
Subwoofers: Klipsch RW10, Triad ProSub Bronze.
