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#1
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Posted to rec.audio.tech
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I have some nice speakers made with remnants from Parts Express excess. 8
inch woofers have a rubbery type surround. Just in the last two years the surrounds started breaking what looks like tearing apart. I have redone the two sets with rubber replacements think they are working well. Just wondered if anyone knew what type of rubber they used. I guess they were made in late 80s by Onkyo, so that would be about 30 years old. The driver was on the front cover of a Speaker Builder Magazine with Keith Johnson. Greg |
#2
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Posted to rec.audio.tech
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I have some nice speakers made with remnants from Parts Express excess. 8
inch woofers have a rubbery type surround. Just in the last two years the surrounds started breaking what looks like tearing apart. I have redone the two sets with rubber replacements think they are working well. Just wondered if anyone knew what type of rubber they used. I guess they were made in late 80s by Onkyo, so that would be about 30 years old. The driver was on the front cover of a Speaker Builder Magazine with Keith Johnson. From what I've seen, speaker surrounds are most commonly made either of a closed-cell foam, or of butyl rubber. They are not necessarily interchangeable. Rubber surrounds are (I believe) both heavier and stiffer than foam surrounds of the same dimension. Their weight, and lower compliance can change the acoustic characteristics of the speaker - quite possibly enough to de-tune the speaker/enclosure relationship and throw off the speaker's frequency response. This would be more of an issue with vented/ported/ bass-reflex enclosures than with sealed (acoustic-suspension) systems. Rubber surrounds seem to have a longer lifespan than foam surrounds, but they can go bad over time. I had to replace the rubber surrounds on a pair of 4" drivers in some Optimus AV mini-monitors - I believe they'd been used outdoors, and sunlight and heat had caused the rubber surrounds to become stiff and brittle. |
#3
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Posted to rec.audio.tech
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Dave Platt wrote:
I have some nice speakers made with remnants from Parts Express excess. 8 inch woofers have a rubbery type surround. Just in the last two years the surrounds started breaking what looks like tearing apart. I have redone the two sets with rubber replacements think they are working well. Just wondered if anyone knew what type of rubber they used. I guess they were made in late 80s by Onkyo, so that would be about 30 years old. The driver was on the front cover of a Speaker Builder Magazine with Keith Johnson. From what I've seen, speaker surrounds are most commonly made either of a closed-cell foam, or of butyl rubber. They are not necessarily interchangeable. Rubber surrounds are (I believe) both heavier and stiffer than foam surrounds of the same dimension. Their weight, and lower compliance can change the acoustic characteristics of the speaker - quite possibly enough to de-tune the speaker/enclosure relationship and throw off the speaker's frequency response. This would be more of an issue with vented/ported/ bass-reflex enclosures than with sealed (acoustic-suspension) systems. Rubber surrounds seem to have a longer lifespan than foam surrounds, but they can go bad over time. I had to replace the rubber surrounds on a pair of 4" drivers in some Optimus AV mini-monitors - I believe they'd been used outdoors, and sunlight and heat had caused the rubber surrounds to become stiff and brittle. Someone on this group might have known about these drivers. I don't have many rubber surrounded speakers, but these were a first for me. All of hese drivers seem to have failed about the same time regardless of use, including being in original shipping container. Greg |
#4
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On 1/12/2020 1:28 pm, gregz wrote:
Dave Platt wrote: I have some nice speakers made with remnants from Parts Express excess. 8 inch woofers have a rubbery type surround. Just in the last two years the surrounds started breaking what looks like tearing apart. I have redone the two sets with rubber replacements think they are working well. Just wondered if anyone knew what type of rubber they used. I guess they were made in late 80s by Onkyo, so that would be about 30 years old. The driver was on the front cover of a Speaker Builder Magazine with Keith Johnson. From what I've seen, speaker surrounds are most commonly made either of a closed-cell foam, or of butyl rubber. They are not necessarily interchangeable. Rubber surrounds are (I believe) both heavier and stiffer than foam surrounds of the same dimension. Their weight, and lower compliance can change the acoustic characteristics of the speaker - quite possibly enough to de-tune the speaker/enclosure relationship and throw off the speaker's frequency response. This would be more of an issue with vented/ported/ bass-reflex enclosures than with sealed (acoustic-suspension) systems. Rubber surrounds seem to have a longer lifespan than foam surrounds, but they can go bad over time. I had to replace the rubber surrounds on a pair of 4" drivers in some Optimus AV mini-monitors - I believe they'd been used outdoors, and sunlight and heat had caused the rubber surrounds to become stiff and brittle. Someone on this group might have known about these drivers. I don't have many rubber surrounded speakers, but these were a first for me. All of hese drivers seem to have failed about the same time regardless of use, including being in original shipping container. Greg Oxygen alone will break the foam surrounds down so it doesn't matter if you use them or not, they last 20 - 30 years max depending on the thickness of the material. (Unless they're stored in an oxygen-free atmosphere.) Rubber surrounds can last 50 years. However if they're stored and not used for a decade or so they'll go hard and brittle. Also UV light and/or excess heat will cause similar degradation. -- Shaun. "Humans will have advanced a long, long way when religious belief has a cozy little classification in the DSM" David Melville This is not an email and hasn't been checked for viruses by any half-arsed self-promoting software. |
#5
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Posted to rec.audio.tech
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On 2/12/2020 5:39 pm, ~misfit~ wrote:
On 1/12/2020 1:28 pm, gregz wrote: Dave Platt wrote: I have some nice speakers made with remnants from Parts Express excess. 8 inch woofers have a rubbery type surround. Just in the last two years the surrounds started breaking what looks like tearing apart. I have redone the two sets with rubber replacements think they are working well. Just wondered if anyone knew what type of rubber they used. I guess they were made in late 80s by Onkyo, so that would be about 30 years old. The driver was on the front cover of a Speaker Builder Magazine with Keith Johnson. Â*From what I've seen, speaker surrounds are most commonly made either of a closed-cell foam, or of butyl rubber. They are not necessarily interchangeable.Â* Rubber surrounds are (I believe) both heavier and stiffer than foam surrounds of the same dimension.Â* Their weight, and lower compliance can change the acoustic characteristics of the speaker - quite possibly enough to de-tune the speaker/enclosure relationship and throw off the speaker's frequency response.Â* This would be more of an issue with vented/ported/ bass-reflex enclosures than with sealed (acoustic-suspension) systems. Rubber surrounds seem to have a longer lifespan than foam surrounds, but they can go bad over time.Â* I had to replace the rubber surrounds on a pair of 4" drivers in some Optimus AV mini-monitors - I believe they'd been used outdoors, and sunlight and heat had caused the rubber surrounds to become stiff and brittle. Someone on this group might have known about these drivers. I don't have many rubber surrounded speakers, but these were a first for me. All of hese drivers seem to have failed about the same time regardless of use, including being in original shipping container. Greg Oxygen alone will break the foam surrounds down so it doesn't matter if you use them or not, they last 20 - 30 years max depending on the thickness of the material. (Unless they're stored in an oxygen-free atmosphere.) I remember when I picked up my KEF R107s of TradeMe when opening and looking down with a torch, I could see right through the two bass driver surrounds to the bottom of the cabinet ! Rubber surrounds can last 50 years. However if they're stored and not used for a decade or so they'll go hard and brittle. Also UV light and/or excess heat will cause similar degradation. The butyl on my B110s on LS3-5As after 'just' 40 years-ish. geoff |
#6
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On 4/12/2020 7:08 am, geoff wrote:
On 2/12/2020 5:39 pm, ~misfit~ wrote: Rubber surrounds can last 50 years. However if they're stored and not used for a decade or so they'll go hard and brittle. Also UV light and/or excess heat will cause similar degradation. The butyl on my B110s on LS3-5As after 'just' 40 years-ish. My B139's and B110's are still fine after 45 years. Hope they last a bit longer. :-) |
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