Onkyo Precise Acoustics

[gregz]

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

[Dave Platt]

Post by gregz
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.

[gregz]

Post by Dave Platt

Post by gregz
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

[~misfit~]

Post by gregz

Post by Dave Platt

Post by gregz
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.

[geoff]

Post by ~misfit~

Post by gregz

Post by gregz
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.)

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 !

Post by ~misfit~
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

[Trevor]

Post by geoff

Post by ~misfit~
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. :-)

[~misfit~]

Post by geoff

Post by ~misfit~
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. :-)

The (butyl?) rubber surrounds on my Wharfedale Denton 2s 8" woofers are still supple. However the
(brown) glue has gone brittle and come away from the aluminium chassis. They never sounded great to
start with so I've not got around to fixing them but must do something with them soon, they're
taking up space and gathering dust.

I had some contemporary large 3-way floorstanding Wharfedales (the name of which escapes me right
now) with a 13" woofer. They'd been in storage for a decade when I bought them (deceased estate)
and the surrounds were rock hard. I tried everything I could think of to soften them again
including gentle heat, silicone oil and playing them at moderate volume for hours. None of that
helped so I started 'massaging' them and they started to slightly soften but ultimately shattered.

They were an on odd size so I couldn't get replacement surrounds. It was suggested by a
'professional' driver restorer that I get 15" surrounds and cut them down and join them but I
didn't fancy that.

Dovedale 3s! That's what they were called. I ended up selling the mid drivers and 'purple fried
egg' tweeters and got my money back but was disappointed that I never got to hear the speakers.

[geoff]

Post by Trevor

Post by geoff

Post by ~misfit~
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. :-)

Bailey TLs ?

geoff

[Trevor]

Post by geoff

Post by Trevor

Post by geoff

Post by ~misfit~
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. :-)

Bailey TLs ?

No, just a custom cabinet I designed and made for the SK3. Larger than
the Concerto's. Didn't think the Baileys were really worth the effort,
but I know a lot of people did.
Later replaced the tweeters with Dynaudio's and made new Xovers. Have
had lots of other speakers, but they still sound OK compared to many.

[~misfit~]

On 4/12/2020 8:45 pm, ~misfit~ wrote:

Odd. I don't see any text in this previous post I wrote about Wharfedales. Does anyone else?

Anyway it turns out I had Dovedale IIIs, apparently quite a bit different to the Dovedale 3s.

<https://audiokarma.org/forums/index.php?threads/impressive-wharfedale-dovedale-3-speakers.513613/>
post 19 explains the difference. The guy in post 41 had the same issue I did but better luck in
finding surrounds (and I emailed suppliers all over the world). Maybe replacements started being
manufactured since I was looking about 10 years ago?

[Trevor]

Post by ~misfit~
Odd. I don't see any text in this previous post I wrote about
Wharfedales. Does anyone else?
Anyway it turns out I had Dovedale IIIs, apparently quite a bit
different to the Dovedale 3s.
<https://audiokarma.org/forums/index.php?threads/impressive-wharfedale-dovedale-3-speakers.513613/>
post 19 explains the difference.

I was puzzled because my brother still has Dovedale 3's he bought new at
the time, and they are a 12" driver, not 13".

[~misfit~]

Post by ~misfit~
Odd. I don't see any text in this previous post I wrote about Wharfedales. Does anyone else?
Anyway it turns out I had Dovedale IIIs, apparently quite a bit different to the Dovedale 3s.
<https://audiokarma.org/forums/index.php?threads/impressive-wharfedale-dovedale-3-speakers.513613/>
post 19 explains the difference.

I was puzzled because my brother still has Dovedale 3's he bought new at the time, and they are a
12" driver, not 13".

I think that the drivers in the Dovedale IIIs were described as 12" but when compared with other
12" drivers they were very close to 1" bigger. When I couldn't find a Dovedale-specific surround I
looked at others and couldn't find a 12" surround that was suitable to use, they were all much too
small.