resin loudspeaker cabinets

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usekgb

usekgb

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Joined 2003
Has anyone checked out how JBL built the baffles in their LSR32, LSR12P, and LSR28P monitor speakers? The entire front baffle is made from a carbon fiber and kevlar woven material that is encased in resin. The baffles are around 1" thick and are very heavy and inert. Unfortunately, they stoped producing them this way because they cost too much to manufacture. I hope their re-designed LSR's are as good as the original ones.

Cheers,
Zach
 
Thunau

Thunau

Member
Joined 2001
thuneau.com
usekgb said:
Has anyone checked out how JBL built the baffles in their LSR32, LSR12P, and LSR28P monitor speakers? The entire front baffle is made from a carbon fiber and kevlar woven material that is encased in resin. The baffles are around 1" thick and are very heavy and inert. Unfortunately, they stoped producing them this way because they cost too much to manufacture. I hope their re-designed LSR's are as good as the original ones.

Cheers,
Zach
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I own both the JBL LSR12P sub and a set of LSR25P monitors. Yes the sub has a 1" thick composite resin cast baffle. It's a stiff and dead as anything I've seen. I love the LSR 25P boxes. Cast aluminum with rounded edges and tweeter horn loading incorporated right into the baffle. Something that DIY guys would love to be able to do. What is truly amazing is that JBL can sell a cast aluminum enclosure loudspeaker with 2 power amps and an active crossover built in for less than $200.00/piece. We could not buy the components alone for that price. I measured them in my house and they have as flat a FR as in the spec sheet. With the sub it's a great little studio monitoring system.
The sub is priced a bit high, but the 12" driver is very high tech. Comparable to Scan Speak with it's advanced motor and copper Faraday rings. I looked into doing a group buy of this 12" driver, but it's a 2 Ohm job designed to work with JBL's own plate amp. I don't think I could get too many participants.

LSR12P

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LSR25P

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usekgb

usekgb

Member
Joined 2003
Just to let you know, I can get these drivers at dealer cost. I can also get the plate amps at dealer cost. (It's good to be a JBL warranty tech :D ). Anyway, I've got the full schematics for the amp PCB's for these things too. Let me know if you would like me to send any out.

Cheers,
Zach
 
A

antiresonant

Member
Joined 2003
cowanrg said:
i was in my car today and an idea popped into my head... wouldnt it be cool to mount a midrange driver inside a bored out bowling ball? i figure, cant get much more dense that that, and there would be almost NO resonance.

then i thought, wait, isnt a bowling ball just pure resin? why not make an entire cabinet out of it.

if you made a typical loudspeaker (floorstander) cabinet from resin, it would be MUCH denser and heavier than wood or MDF, it would have a lot less resonance, be fairly easy to make into different shapes, and very flexible in design.

is there downsides to this? cost really isnt a factor. it would almost be cheaper than MDF if you could just plan out the molds right. foam is cheap, and so is resin. finishing it would be a dream. you could just sand and polish it, and basically paint it. or, just dye it before it hits the molds.

seems to me that a very complex structure with vented ports, chambers, etc, could be made without too much effort with resin.

anyone else have any comments on this?
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A sphere is the perfect shape for optimizing standing waves, thus terrible shape in use together with hi-fi components.
A better shape is a asymmetrical pyramidal shape with triangles in all sides.

Br.
 
D

Dave Jones

Member
Joined 2003
Re: Future speaker prediction

Circlotron said:
From the standpoint of today, this sounds pretty off the wall, but I wonder (seriously) if the time will come when we will have self-assembling carbon nanotube boxes. Draw up the box on your "computer"(?) and download the data into a 20kg wad of general purpose molecules you got from the hardware store this morning. :cool:
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When I was 12 or 13, soon after the structure of DNA was discovered, I speculated that one day you would be able to grow a bicycle in your garden. I figured the first person to invent a wheel seed would become very wealthy. Progress has been a little slower than I anticipated.
 
Mark Techer

Mark Techer

Member
Joined 2005
cavx.blogspot.com/
Re: DIY Nautilus

kristijan-k said:


Hello,

It is not so easy, but with some effort it is possible to build this
speaker from wood. :)
Here below are some pictures how it would go:

Best regards,
Kristijan Kljucaric
http://web.vip.hr/pcb-design.vip
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Refer back to pages 2 and 3 of this thread for the images...

Now that we are past half way of 2006 (this part of the thread was in '02), how did these beauties turn out? I was curious about the real Natilus, and found that it is a 4 way design, not three, but none the less, the work shown in this thread is some of the best DIY I've seen...

Mark
 
Cody Dowling

Cody Dowling

Member
Joined 2004
upstreamaudio.com
Know this is old... but.... :)

cowanrg said:
sure, ill call my friend and ask him for a phone number or website of the place... supposedly its pretty lightweight yet very strong. might be something good for you. plus, keep in mind since its resin, you can make molds of any shape you want. so you can pretty much make it stronger by using interesting shapes and internal bracing. a 1/4" wall should be as non-resonant as MDF i would think... that could keep weight way down.
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Hey Guys, I know that this thread is over a decade old, but I'm actually looking at Resin enclosures as well. Did anyone ever post where to find this resin, or have suggestions for alternatives? Thanks!
Cody
 
T

TMM

Member
Joined 2007
Cody Dowling said:
Hey Guys, I know that this thread is over a decade old, but I'm actually looking at Resin enclosures as well. Did anyone ever post where to find this resin, or have suggestions for alternatives? Thanks!
Cody
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I'd recommend a fiberglass layup over just straight resin. Will be much stronger than straight resin and avoids the need for a 2-part mold.

You can use either polyester resin or epoxy resin. Polyester is cheaper but epoxy is stronger. Polyester with glass mat is still pretty damn strong.

If you are just making a simple geometric shape with flat segments (i.e. a box) then don't bother with resin, just make it out of 3/4" MDF.
 
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