KLH 17 Surround Material
- Thread starter awat
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- klh 17 surrounds woofer
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RTally
Speaker addict
What is supposed to be on the surrounds is butyl. It is applied at the factory in liquid form (toluene is the carrier). It needs to be rejuvenated every 20 to 40 years. 
The butyl seals the pores in the cloth surrounds to maintain the acoustic suspension properties of the speaker. A properly sealed surround is necessary for good bass.
Unfortunately, before RoyC performed testing on what to use to rejuvenate the surrounds, people used a wide variety of things to seal the surrounds. People used Permatex, latex, white glue, and other material. If that material cannot be removed and replaced with the proper butyl, then the drivers will not perform as they should. See this thread: https://audiokarma.org/forums/index.php?threads/virgin-cloth-surrounds.637112/page-2 RoyC found that the using anything other than butyl resulted in stiffening of the surround over time.
I imagine you could use toluene directly to see if the surrounds are doped with butyl. The toluene will soften whatever butyl is on the surrounds and the surround will become more pliable and sticky. Hopefully, the surrounds have not been touched and only need more butyl applied.
The proper doping material can be obtained directly from RoyC (an AK member) or from vintage-ar on the bay.
The butyl seals the pores in the cloth surrounds to maintain the acoustic suspension properties of the speaker. A properly sealed surround is necessary for good bass.Unfortunately, before RoyC performed testing on what to use to rejuvenate the surrounds, people used a wide variety of things to seal the surrounds. People used Permatex, latex, white glue, and other material. If that material cannot be removed and replaced with the proper butyl, then the drivers will not perform as they should. See this thread: https://audiokarma.org/forums/index.php?threads/virgin-cloth-surrounds.637112/page-2 RoyC found that the using anything other than butyl resulted in stiffening of the surround over time.
I imagine you could use toluene directly to see if the surrounds are doped with butyl. The toluene will soften whatever butyl is on the surrounds and the surround will become more pliable and sticky. Hopefully, the surrounds have not been touched and only need more butyl applied.
The proper doping material can be obtained directly from RoyC (an AK member) or from vintage-ar on the bay.
What is supposed to be on the surrounds is butyl. It is applied at the factory in liquid form (toluene is the carrier). It needs to be rejuvenated every 20 to 40 years.
Unfortunately, before RoyC performed testing on what to use to rejuvenate the surrounds, people used a wide variety of things to seal the surrounds. People used Permatex, latex, white glue, and other material. If that material cannot be removed and replaced with the proper butyl, then the drivers will not perform as they should. See this thread: https://audiokarma.org/forums/index.php?threads/virgin-cloth-surrounds.637112/page-2 RoyC found that the using anything other than butyl resulted in stiffening of the surround over time.
I imagine you could use toluene directly to see if the surrounds are doped with butyl. The toluene will soften whatever butyl is on the surrounds and the surround will become more pliable and sticky. Hopefully, the surrounds have not been touched and only need more butyl applied.
The proper doping material can be obtained directly from RoyC (an AK member) or from vintage-ar on the bay.
Thank you for the detailed reply. I recently picked up the butyl and I was planning to dope the surrounds but I thought I’d check in with you all to see what you recommend. The material is pretty sticky and the woofers are relatively tight. I’ll see if I can get that stuff off, but my feeling is that I’m going to be getting a new woofer. If you have any other advice for me, I’ll gladly take it.
thanks again for your help.
RTally
Speaker addict
What makes you think you need another woofer? I don't see anything unusual about your surround in the pic above. It is good that the surround is sticky. Butyl stays sticky for a long time. Many of the other things people used dried out and hardened within months.
To test air-tightness of your cabinet, press in the woofer cone evenly and hold in the depressed position for at least 10 seconds (longer is better). Quickly release the cone and time how long it takes to return to the normal resting position. Less than 1/2 second means you have a leak that needs to be fixed. The leak can be either through the surrounds or elsewhere in the cabinet. Find it and seal it. More than about 1 second to return to normal means you have a relatively good seal.
When applying the doping compound, remember, less is better. Use only enough to get a good seal. Apply it to both the dust cap and the surround.
To test air-tightness of your cabinet, press in the woofer cone evenly and hold in the depressed position for at least 10 seconds (longer is better). Quickly release the cone and time how long it takes to return to the normal resting position. Less than 1/2 second means you have a leak that needs to be fixed. The leak can be either through the surrounds or elsewhere in the cabinet. Find it and seal it. More than about 1 second to return to normal means you have a relatively good seal.
When applying the doping compound, remember, less is better. Use only enough to get a good seal. Apply it to both the dust cap and the surround.
Since the surrounds appear to have already been re-coated, if they aren't stiff and they pass the leak test that RTally suggested then I would leave them alone. If they're a bit stiff you could try wiping them down with a solvent to thin the coating. Just be careful, the glue that holds the surrounds to the basket and the cone is much more solvent resistant than the sealant but if you go overboard you can still dissolve it.
Thank you, RTally & RossW. You were really helpful.
RTally,
I thought that orange surround material, since it seems pretty heavily caked on, that the sheer weight of it would influence the speaker's sound or would restrict the woofer to a degree that affects the sound. Glad I can keep the woofer as is - upon pushing it in, the woofer return is pretty slow - unlike my other speakers which bounce right back - so I think that one is good to go!
Thanks again,
Adam
RTally,
I thought that orange surround material, since it seems pretty heavily caked on, that the sheer weight of it would influence the speaker's sound or would restrict the woofer to a degree that affects the sound. Glad I can keep the woofer as is - upon pushing it in, the woofer return is pretty slow - unlike my other speakers which bounce right back - so I think that one is good to go!
Thanks again,
Adam
