Sealer for woofer surrounds

[day67]

Some time back a post mentioned "liquid Tape" -- a vinyl or rubber brush on product used to apply insulation over a splice -- as a way of coating surrounds. Diluted with hexane (found in art supply stores

to remove/thin rubber cement -"Bestine" I think it is), the stuff sounded promising! Question: What if instead of the liquid tape another type of sealant like, "Aquaseal" was used. They use it on wet suits to seal neoprene, stays flexible, repairs waders that are cloth fabric with the rubber over it. Says it is "made of urethane rubber."

I'm wondering if diluting it with the hexane would also have the same sealing but flexible effect when applied to the cloth surrounds. I also dont know anything about "urethane" rubber as far as its use on surrounds verses latex based sealers. Any thoughts, warnings, or advice before I experiment??

[soundminded]

Warning! Warning! Danger Will Robinson!

Don't know, can't say. These sealers are useful for cloth surrounds on woofers like KLH6 or AR3 but are not useful for foam surrounds like late AR3a. The surround MUST remain as compliant as possible. The principle of acoustic suspension woofers is that air trapped inside the enclosure and not the mechanical stiffness of the surround supplies the restoring force to the woofer cone when it is displaced. When the sealant deteriorates, the inherent porousity of the cloth allows air to escape through it instead of pulling or pushing back on the woofer. If the surround is sealed with a material which increases the stiffness of the surround, it will decrease its compliance and bass response will be reduced. Some people have tried diluted rubber cement and I think someone tried something from an automotive store. Personally I would not take a chance with it considering that the XL-49 product which Orange County Speaker offered specifically for this use is so inexpensive. You could try some other speaker repair facilities to get their expert advice. If you know a chemist, you might also ask.

[dynaco_dan]

>Warning! Warning! Danger Will Robinson!

>

>Don't know, can't say. These sealers are useful for cloth

>surrounds on woofers like KLH6 or AR3 but are not useful for

>foam surrounds like late AR3a. The surround MUST remain as

>compliant as possible.

When the sealant deteriorates, the inherent porousity of the cloth

>allows air to escape through it instead of pulling or pushing

>back on the woofer. If the surround is sealed with a material

>which increases the stiffness of the surround, it will

>decrease its compliance and bass response will be reduced.

>Some people have tried diluted rubber cement and I think

>someone tried something from an automotive store. Personally

>I would not take a chance with it considering that the XL-49

>product which Orange County Speaker offered specifically for

>this use is so inexpensive. You could try some other speaker

>repair facilities to get their expert advice. If you know a

>chemist, you might also ask.

Hi there;

Just to add to this topic.

I believe that Armorall is the other liquid coating used for the cloth surrounds only, 2 separate coats.

It certainly would be nice if someone did come up with a brush-on coating to preserve without altering foam surrounds.

Better yet a new material for the surrounds that does not rot.

I can just see a rush out there now to invent a new non-rotting surround material and kill a multi-million dollar repeat business.

Was it forward progress when we went from cloth to foam surrounds, yes.

For the parts sales yes, not for the end user who may want to keep them more than 10 years or so.

It may have been less costly to produce and install on the cones but it has been very painful for the past and present and future owners.

Repeat sales will win this race, sadly, that is the reality.

If someone comes up with a good idea, the idea will be bought up and suppressed, history repeating itself.

Earlier AR, KLH, Dynaco, early EPI are just a few names that come to mind that used either cloth or rubber based surrounds successfully, I repeat, successfully, in their early efforts.

This does not include the European speakers which I seem to remember that they would not accept our cheap foam surrounds.

They also did not consider the un-clean front driver wiring to be of their choice either.

I did something really stupid years ago, not my only time mind you, I tried transferring a bit a car gas from one container to another outdoors.

I had used a sterifoam coffee cup.

It did work for about 1.5 micro-seconds maybe.

Take my word for it, don't try it.

Touching any material to the surround foam, even cooking oils may just disolve the foam surround material.

I just had another thought, our body perspiration may also work on them.

[day67]

I had to laugh, I've done the same thing with gas or other thinners in a plastic or foam cup! .. And other crazy stuff. Appreciate the advice. What I might do is try it on a junk speaker surround. Or, cloth first. I'd never experiment on foam, but my application is toward cloth surrounds, KLH style. I'll let you know how it turns out, better than Lost In Space, I hope!

[dynaco_dan]

Hi Dan;

I believe that is was a write-up from Tom Tyson that I saw Armorall and 2 coats, a day apart, for only the AR or KLH cloth surrounds.

I have never sat on the end of a tree branch that I was cutting off, but I am certain someone has, only once though, I would think. lol.

[Guest gregounours]

I just got a pair of 17 in bad cosmetic shape but with drivers intact ($15 of craiglsist). They surely sound good for 40 years old speakers. I was wondering if there was a way of testing their airtighness and if they happen to need some resealing (most likely) if it is better to seal them on high pressure or low pressure day.

I would say that having a slightly higer pressure in would allow the cone to bounce back better but would it make that mush of a difference?

Also do you know of any other maintenance that could/should be permormed?

Greg

[Andy]

Remember, the enclosure is not supposed to be air tight, if it were the cone would have difficulty in it's excursion. I have yet to see a pair of KLH's in which the suround was dried out and too porious....maybe if they spent years exposed to sunlight. If anything , just try a little Armorall as mentioned. I don't know what the factory specs were for surrounds, Tom Tyson may know in regards to his knowledge of AR loudspeakers ?

Andy

[day67]

That's a good question. How un-airtight should the enclosure be? --

The model 5 woofers I have have great surrounds as far as the cloth being in tact, but they are so porous air passes almost without resistance. If you think about it most cabinets are easily airtight -

most likely the speakers themselves (mainly the surrounds) are the only surfaces that would provide a pressure regulating effect. I guess the question is how porous is too porous....just thinking aloud and trying to strike the right balance --excuse the puns.

[dynaco_dan]

Hi Dan;

If one was to coat the AR or KLH cloth surrounds with 2 coats of Armorall, one each day and use new putty for sealing the drivers into the cabinets, I believe your system will be as close to new as is possible, with minimal outlay, financial and labour.

KLH never used putty but did use foam gaskets for a period of time to seal the driver to cabinet gap.

AR used putty and much later converted to time and money saving foam gaskets.

Dynaco used blue sticky goop.

[Guest gregounours]

Thanks for all the good advice.

I will be working on them over the week-end I think. I have read in another thread on the 20 that when you remove the drivers the inside is nasty because of the fiberglass padding material. Is it flaking because of age or was the material like this to start with? Would it be worth it

soundwise to put some newer fiberglass?

Also,I believe that the tweeters have been remove and remounted because you can see some cheap foam coming out on the side. I mean cheap foam like the one they are using these day to pack things. What kind of putty would you use?

Thanks in advance

PS: There is a pair on ebay but the grill have obviously been changed. The orginal is kind of cream color.

[dynaco_dan]

Hi Greg;

No need to replace the fiberglass, there is no advantage.

The white foam gasket material was common to a lot of brands, and it can be left alone if you want.

If you have the time, money and inclination go ahead, remove the foam gaskets and putty seal the drivers in.

A non-hardening putty, for one example, electrical departments in most stores have a putty seal, brick size, for a few dollars only.