I know this has been discussed before, but of course it never quite fits your own situation 😕
I recently scored a really nice pair of Videoton Minimax II's (for those who don't know them a budget Hungarian mini speaker with 5" bass unit and 4" cone tweeter that were hugely popular in the early/mid 70's) for some reason they were really quite magical, way greater then the sum of their parts.
This pair though the rubber surrounds on the bass units has rather dried and has some cracking, not bad, I've seen way worse but I'd like to stop or at least slow any further deterioration. Apparently the amount of degradation in these particular speakers was due to the exact amount of sulphur present in the rubber used in that batch..
I was thinking of maybe coating the surround with Copydex (a flexible water based latex rubber glue) I've heard of it used for rubber seals etc to 'repair' the cracking and/or maybe silicone grease, the type used by plumbers as a lubricant to rehydrate as members seem to rate silicone quite highly, maybe after a copydex application..
Any thoughts anyone? Has anyone tried anything similar?
I recently scored a really nice pair of Videoton Minimax II's (for those who don't know them a budget Hungarian mini speaker with 5" bass unit and 4" cone tweeter that were hugely popular in the early/mid 70's) for some reason they were really quite magical, way greater then the sum of their parts.
This pair though the rubber surrounds on the bass units has rather dried and has some cracking, not bad, I've seen way worse but I'd like to stop or at least slow any further deterioration. Apparently the amount of degradation in these particular speakers was due to the exact amount of sulphur present in the rubber used in that batch..
I was thinking of maybe coating the surround with Copydex (a flexible water based latex rubber glue) I've heard of it used for rubber seals etc to 'repair' the cracking and/or maybe silicone grease, the type used by plumbers as a lubricant to rehydrate as members seem to rate silicone quite highly, maybe after a copydex application..
Any thoughts anyone? Has anyone tried anything similar?
no grease.
it's a tough fix after it is cracked or hardened.
I do not know about this Copydex stuff... or what its properties are long or short term.
Whatever you add to the surround will add to the mass and increase stiffness, which will alter the speaker somewhat.
But given the condition there is not much to lose.
They make a "flowable" silicone rubber compound. It is sold in auto parts stores here in the USA for sealing windshield gaskets when there is a leak. It can be painted on with a brush, and is somewhat self leveling, but has a short work time, but not too short. It is ALSO available through industrial distributors, and is made here by places like DOW Chemical & GE Silicones... that may be worth looking for. Although the autoparts store stuff likely comes from the same places.
There are different grades, and depending on mfr it may dry to different characteristics... some may be too soft and easy to peel, dunno.
I would test on something random, like maybe some paper or an inner tube from a bicycle, and see how it ends up when fully cured... but assuming you found some that looked good, then I would do the following:
- clean the surrounds with alcohol & a cotton swab.
- tape the cracked areas with simple "scotch tape" (clear tape used for paper & books) to hold them together and prevent leak through.
- having removed the speaker (did I say that? ) apply a thin thin coat on the inside rear of the surround - an artists brush is good here...
- permit to dry overnight - high humidity conditions (non-desert) are best for curing silicone rubber
- inspect... remove outside tape (re-clean the taped area)
- apply a smooth thin coat to the outside of the surrounds; a turntable will help considerably although you can do it by hand too... be sure to cover the flat edges and the point where the half roll transitions
The silicone rubber stuff will flow and try to drip down if the speaker is face up, that is fine, just account for it.
Might make sense to practice on a dead or random driver if you have one on hand.
Otoh, this latex base might be fine. However latex has a very short life when exposed to air/ozone/UV light.
Worst case you buy some new 5" drivers... 😀
_-_-bear
it's a tough fix after it is cracked or hardened.
I do not know about this Copydex stuff... or what its properties are long or short term.
Whatever you add to the surround will add to the mass and increase stiffness, which will alter the speaker somewhat.
But given the condition there is not much to lose.
They make a "flowable" silicone rubber compound. It is sold in auto parts stores here in the USA for sealing windshield gaskets when there is a leak. It can be painted on with a brush, and is somewhat self leveling, but has a short work time, but not too short. It is ALSO available through industrial distributors, and is made here by places like DOW Chemical & GE Silicones... that may be worth looking for. Although the autoparts store stuff likely comes from the same places.
There are different grades, and depending on mfr it may dry to different characteristics... some may be too soft and easy to peel, dunno.
I would test on something random, like maybe some paper or an inner tube from a bicycle, and see how it ends up when fully cured... but assuming you found some that looked good, then I would do the following:
- clean the surrounds with alcohol & a cotton swab.
- tape the cracked areas with simple "scotch tape" (clear tape used for paper & books) to hold them together and prevent leak through.
- having removed the speaker (did I say that? ) apply a thin thin coat on the inside rear of the surround - an artists brush is good here...
- permit to dry overnight - high humidity conditions (non-desert) are best for curing silicone rubber
- inspect... remove outside tape (re-clean the taped area)
- apply a smooth thin coat to the outside of the surrounds; a turntable will help considerably although you can do it by hand too... be sure to cover the flat edges and the point where the half roll transitions
The silicone rubber stuff will flow and try to drip down if the speaker is face up, that is fine, just account for it.
Might make sense to practice on a dead or random driver if you have one on hand.
Otoh, this latex base might be fine. However latex has a very short life when exposed to air/ozone/UV light.
Worst case you buy some new 5" drivers... 😀
_-_-bear
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Hi bear,
He might have a hard time getting a silicone product to stick to a butyl rubber surround
vinyl dragon,
I'm going to suggest you use something called Liquid Tape.
https://www.google.ca/search?aq=f&sourceid=chrome&ie=UTF-8&q=liquid+tape
Good luck with it.
He might have a hard time getting a silicone product to stick to a butyl rubber surround
vinyl dragon,
I'm going to suggest you use something called Liquid Tape.
https://www.google.ca/search?aq=f&sourceid=chrome&ie=UTF-8&q=liquid+tape
Good luck with it.
Hi
Some time ago I repaired two cracks in an old Kef speaker by painting evo-stick rubber solution onto the cracks. It seems to have worked fine ( I think because evo-stick is very flexible when set ) Before applying the evo-stick I cleaned the rubber very quickly with cellulose thinners ( available from car accessory shops ) to ensure the evo-stick would bond properly. If you do clean the rubber with cellulose thinners wipe the area with cellulose thinners very quickly and then dry it to aviod the celulose thinners softening the rubber.
Don
Some time ago I repaired two cracks in an old Kef speaker by painting evo-stick rubber solution onto the cracks. It seems to have worked fine ( I think because evo-stick is very flexible when set ) Before applying the evo-stick I cleaned the rubber very quickly with cellulose thinners ( available from car accessory shops ) to ensure the evo-stick would bond properly. If you do clean the rubber with cellulose thinners wipe the area with cellulose thinners very quickly and then dry it to aviod the celulose thinners softening the rubber.
Don
I'm having major problems finding any of this stuff in the UK but I can see the way you guys are thinking, will have to spend some time in Halfords (automotive shop) and see what I can come up with in the same area..
Will report back of course but any further ideas are very welcome!
BTW Don, do you mean one of those Evo products sold as sealant in tubes that you use with a gun?
Will report back of course but any further ideas are very welcome!
BTW Don, do you mean one of those Evo products sold as sealant in tubes that you use with a gun?
I just had a brilliant Idea; mask off the rest of the driver and spray the surround with Plasti-Dip. It's flexible, durable, and removable (but sticks really well). Do one thick coat and quickly remove any tape used for masking. If you try to remove it after it dries it will pull the coating off.
After applying it treat it and the back side of the surround with some 303 Aerospace Protectant.
After applying it treat it and the back side of the surround with some 303 Aerospace Protectant.
Silicone grease is easy enough to find. Maplin have it. I just wanted to protect these 20-y-o speakers a bit. Looks nice. I put it on the cones too since it seemed harmless.
Multi Purpose Silicone Grease : Lubricants & Butane Gas : Maplin Electronics
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Multi Purpose Silicone Grease : Lubricants & Butane Gas : Maplin Electronics
Hello,
the Videoton loudspeaker factory does exist currently in Hungary, and I work for them. We produce foam membrane edges to this old 130mm midbass driver (HA13/13K). In my opinion, the simpliest and safest way to replace the old damaged latex foam, and generally this is how we repair the HA13 loudspeakers.
That hadn't turned up in any of my searches, I'd not realised Videoton still existed, that's great news!
How would I get a pair of the surrounds? Though the original surrounds on the Minimax are rubber aren't they, would that matter?
Graham
silicone grease???
what for?
will mostly attract dust... might provide some antioxidant coating for rubber surrounds, but I think I'd prefer to use something else... certainly will not repair holes...
rubber has somewhat different characteristics, but one can put damping stuff on the foam and get pretty close I would expect...
_-_-bear
what for?
will mostly attract dust... might provide some antioxidant coating for rubber surrounds, but I think I'd prefer to use something else... certainly will not repair holes...
rubber has somewhat different characteristics, but one can put damping stuff on the foam and get pretty close I would expect...
_-_-bear
Hi Bear
A lot of people on other threads had recommended silicone grease to 'rehydrate' dried out rubber is all, it could easy be that ive read so much ive ended up confusing myself..
I was thinking of trying out various different things on some dried out rubber I have before putting anything near my speaker surrounds!
I know many would not be impressed by a pair of 30 year old budget speakers anyway, but I like them and sure don't want to ruin them - well if possible 🙄
A lot of people on other threads had recommended silicone grease to 'rehydrate' dried out rubber is all, it could easy be that ive read so much ive ended up confusing myself..
I was thinking of trying out various different things on some dried out rubber I have before putting anything near my speaker surrounds!
I know many would not be impressed by a pair of 30 year old budget speakers anyway, but I like them and sure don't want to ruin them - well if possible 🙄
For softening and protecting the rubber, try some of the 303 Aerospace protectant I mentioned earlier. It's also good for putting on foam surrounds.
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Definitely! Have to admit I'd not thought of silicone leaving the drivers sticky, I have a pair of 70's B&W's where the tweeter has some sort of really sticky coating and it's a right pain! The 303 sounds a lot better idea
The rubber is not "drying out". UV and other environmental factors cause the long chain molecules in the rubber to break. This is not reversible.
That's understood, but can it be mitigated? Maybe with treatments products mentioned here. The makers of Rubber Cleaner mentioned by theanonymous1 certainly seem to suggest just that..
I'd thought it looked really good, though might not be able to get it here in the UK (as usual .. :-( )
The Videoton was sold off, but the loudspeaker factory works now with new name, Hangszoro 2000.
The original surround of the HA13 was made from foam, rubber foam, like SEAS Exotic speakers now, and had a special coating on the rear side.
The new foam edges are made from an impregnated synthetic soft foam, and have better properties compared to the old one. Lower Cms, less egde-resonance, etc.
If you need, I'll gladly send to you a pair from this foam edge.
It's a blanket term that equates to the same. We know you can't just 'rejoin' the cracks but I think Liquid Tape is the answer. I wish I had some old rubber surrounds to do a demo.
Hi -
Some synthetic rubbers actually use oils similar to mineral oil as 'plasticizers', which might help shrink cracks and soften the rubber, and then when the oil is well cleaned off the surface a rubber adhesive might seal the cracks. But, overall, it might be less trouble and more effective to replace the surrounds because of likely UV or ozone damage.
Some synthetic rubbers actually use oils similar to mineral oil as 'plasticizers', which might help shrink cracks and soften the rubber, and then when the oil is well cleaned off the surface a rubber adhesive might seal the cracks. But, overall, it might be less trouble and more effective to replace the surrounds because of likely UV or ozone damage.