Anyone using well-nuts to mount their drivers? - diyAudio
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Old 2nd December 2012, 01:55 AM   #1
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Default Anyone using well-nuts to mount their drivers?

Reading through the loudspeaker cookbook I came across a note regarding the mounting of the drivers in an isolated way using well nuts.

Has anyone here tried this and is there an audible difference? Also, where is a good source for these well nuts?
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Old 2nd December 2012, 12:37 PM   #2
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These should work as compliant mounts. At KEF we used a more sophisticated motor mount for 12" woofers and small rubber grommets for 8" woofers. Either approach greatly reduced the energy applied to the box and certainly reduced the audibility of box resonances.

You must put compliant foam tape around the perimeter of the woofer so that there is no metal to wood contact, as this would nulify the effect. If done correctly you should be able to press on the woofer chassis and see some deflection (say a millimeter for a hard press).

Regards,
David
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Old 2nd December 2012, 01:34 PM   #3
AndrewT is online now AndrewT  Scotland
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Hi Speaker,
I remember the KEF compliant info, both in datasheets and in press reports on the product.
I still have the datasheets detailing the compliant mount.
No where does it mention that the driver chassis must be air tight sealed to the mounting panel.

Because of this omission of a critical detail I never tried to implement the compliant mounting.

Maybe I am just too thick to realise that some info was missing that would allow the driver to operate correctly.
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Old 2nd December 2012, 01:40 PM   #4
sreten is offline sreten  United Kingdom
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Hi,

FWIW when compliant speaker mounting went out of fashion,
due to reviews slagging off any speaker featuring it, KEF got
round the problem for a while by decoupling the driver magnet.

It is still an approach that is effectively commercial suicide.
(Except for top end B&W mids and tweeters, not bass.)

rgds, sreten.

A current approach would be drilling out the driver to use rubber
grommets and using circuit board stand offs with the driver bolts.
Decent sized washers on the front are a very good idea.
You need a foam seal around it of course, though a caulk that
remains very flexible when cured might also work quite well.
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Last edited by sreten; 2nd December 2012 at 01:54 PM.
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Old 2nd December 2012, 02:03 PM   #5
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Quote:
Originally Posted by AndrewT View Post
Hi Speaker,
I remember the KEF compliant info, both in datasheets and in press reports on the product.
I still have the datasheets detailing the compliant mount.
No where does it mention that the driver chassis must be air tight sealed to the mounting panel.

Because of this omission of a critical detail I never tried to implement the compliant mounting.

Maybe I am just too thick to realise that some info was missing that would allow the driver to operate correctly.
Maybe....

I don't remember the particular data sheets but at KEF we would have assumed that sealing to the box was understood.

As to the press and their understanding of compliant mounting, yes some of them were offended on principle, as misguided by Linn (HORRORS, LOSS OF INFORMATION!!!)

Others got it.

David
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Old 2nd December 2012, 02:16 PM   #6
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Quote:
Originally Posted by speaker dave View Post
These should work as compliant mounts. At KEF we used a more sophisticated motor mount for 12" woofers and small rubber grommets for 8" woofers. Either approach greatly reduced the energy applied to the box and certainly reduced the audibility of box resonances.

You must put compliant foam tape around the perimeter of the woofer so that there is no metal to wood contact, as this would nulify the effect. If done correctly you should be able to press on the woofer chassis and see some deflection (say a millimeter for a hard press).

Regards,
David
I spent some time looking online for well nuts and what I find seems to really only apply to something being mounted in sheet metal or other thin material to get the correct hold.

http://www.hansonrivet.com/pdf2008/C...UBBER-NUTS.pdf

Check out the image in the link and you will see what I mean...so how do I get these to work in an mdf baffle?

Thx
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Old 2nd December 2012, 02:48 PM   #7
pos is offline pos  Europe
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What about attaching the driver to the baffle using only silicone caulk (or similar high damping caulk)?
Would that provide enough "glue" to secure a heavy driver over time?
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Old 2nd December 2012, 03:01 PM   #8
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It would be tricky but with some effort they might work.

As shown in metal the through hole needs to be snug on the well nut diameter. In MDF I would drill a clearance hole just equal to the diameter and then open up the back side of it for clearance, leaving just about an 1/8" of meat at the front of the baffle.

You want to retain maximum compliance so the key will not be tightening down any more than requires to compress the foam gasket you place behind the woofer.

You should glue the well nut to the cabinet surface rather than relying on expansion. This will allow you to use it a bit slacker.

See sketch.

David
Attached Images
File Type: jpg sketch001.jpg (88.5 KB, 225 views)
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Old 2nd December 2012, 03:10 PM   #9
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Speaker Dave, you are correct with your idea and sketch. See the following site from a supplier (found with quick google search):
http://www.spaenaur.com/pdf/sectionC/C147.pdf
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Old 2nd December 2012, 03:49 PM   #10
puppet is offline puppet  United States
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I'd think a guy could assemble a similar fastener solution using a rubber tubing such as vacuum line hose (automotive). A length sufficiently long enough to allow full pass through of the mdf panel and enough after that to allow a small nut/washer to compress the back side that contacts the drivers chassis. A bit like a rubber toggle bolt. A truss head machine screw would be ideal with a rubber washer under the head.

This assumes that you can access the back side while mounting the drivers though.

Last edited by puppet; 2nd December 2012 at 03:52 PM.
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