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
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
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.
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.
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.
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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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
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/C71 RUBBER-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
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
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
Attachments
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
http://www.spaenaur.com/pdf/sectionC/C147.pdf
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.
This assumes that you can access the back side while mounting the drivers though.
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Yep ... if a guy thought about it he could also insert a teenut in the hose too.
Thanks for all the great replies!
I have been thinking about this and I wonder if the following would be good enough to give a benefit without risking too much meat getting taken out of the mdf in the form of larger holes for the well nut.
All the drivers will be installed with a rubber gasket which if not over tightened should help. Then if I put a rubber washer under the head of the screw, between it and the frame I will isolate the screw from the driver and the gasket will isolate the driver from the baffle and by default the driver will be isolated....
Does this make sense and would it work?
Thanks
I have been thinking about this and I wonder if the following would be good enough to give a benefit without risking too much meat getting taken out of the mdf in the form of larger holes for the well nut.
All the drivers will be installed with a rubber gasket which if not over tightened should help. Then if I put a rubber washer under the head of the screw, between it and the frame I will isolate the screw from the driver and the gasket will isolate the driver from the baffle and by default the driver will be isolated....
Does this make sense and would it work?
Thanks
Should work in theory. The key is to have no metal to metal contact and sufficient compliance with your chosen rubber bits. The challenge, in practice, is that the unit tends to sag and reduce compliance. You want compliance in line with the axis of the speaker but good location at right angles to it.
David
David
With regards to the thick panels, there are plenty of wel nuts made to accommodate thicker materials. The "clamping range" is stated on the box. Primary use of these fasteners is in mounting solid objects in composite boat hulls and the like. I've used them in a number of loudspeaker enclosures and had no leakage issues or otherwise. Just drill a 3/8 diameter hole (for the #10 size), and plunk them in. The rubber flange is thin enough that the sealing tape can be run right over the top of them with no worries of causing leaks.
This reminds me of something I went over in my head recently. I've acquired some old rubber mat material that I believe was used at one point for flooring in a computer lab. It's about 5mm thick and fairly rigid. I thought about cutting a donut shaped piece out of it so that a driver could be mounted in the center using a rear ring and then the outer edge used to mount to the enclosure, much like a secondary "rubber surround" but just much more rigid.
It seems the rigidity of it could be manipulated by changing the outside diameter and gap between basket and cabinet.
Never tried it to see how it would affect measurements, but maybe I will now.
It seems the rigidity of it could be manipulated by changing the outside diameter and gap between basket and cabinet.
Never tried it to see how it would affect measurements, but maybe I will now.
I like to use well nuts and gasket tape covering the whole recess, then cut holes in the tape above each nut for the screws. A medium OD washer in back prevents pull-through. That washer may need to be cut with a cut-off wheel on one edge to prevent contact with the driver, then glued to prevent rotation. It amounts to a constrained layer between the driver and the enclosure. After break-in, I have had to go back and tighten the mounting screws 1/8 turn, then appy a half drop of clear nail polish to the screw to lock it.
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