Magnet Brace - Touch or No Touch

[Warmon]

Hey guys,

I tried searching for the answer, but couldn't find exactly what I was looking for. When creating a brace parallel to the front baffle and inline with the subs magnets, is it okay for that hole to be tight to the magnet?..or should there be some clearance and if so, how much? I was looking at the CSS cabinet designs earlier and noticed those holes are 1/16" more than the magnet - thats 1/32" clearance all the way around.

[thxgoon]

I can't imagine it would matter either way just as long as you can get the woofer in the box when its all said and done. Maybe the transmission of vibration would change by touching at the back of the woofer as well???

[eyekode]

I think that if it were not supposed to touch then the hole would be cut much much larger. Maybe they have you cut it a little larger to ease assembly. And you end up filling the gap with... something? Liquid nails?

I think supporting the magnet would be a good thing. Especially if the basket is stamped steel.

[Mike P.]

Good question, Warmon. I asked Bob from Creative Sound to join in. We'll see what he says.

[Warmon]

You guys hit the nail on the head. Not tight enough and you might get vibration...maybe even some knocking. Too loose, then it doesn't do much good. Liquid nails is a good idea and yes, the drivers are stamp steel. I'll probably go with that - hoping I never have to take them back out...

[Mike P.]

But if you do have to remove the sub for some reason, how hard will it be if you have Liquid Nails between the magnet and the brace?

[Warmon]

Mike P. wrote:

But if you do have to remove the sub for some reason, how hard will it be if you have Liquid Nails between the magnet and the brace?

I think it would be near impossible without tearing something up in the process. I suppose if you knew the driver was bad, you could rip the cone out get a hold of it with something, but since these are the $20 NHT Sub 2's, it's not a huge concern.

Hey [lightbulb going off] this gives me another idea! What if I liquid nail a MDF doughnut onto the magnets and then tight fit that into the brace?

[ccdoggy]

you could use some anti-vibration goop. I have some sealing a few things in my box and it never dries but it holds its shape and provides a buffer. that way you could pull it out if you wanted to.

[Warmon]

ccdoggy wrote:

you could use some anti-vibration goop.

What kind of goop are you using?

[Creative Sound]

The main point of the brace is for support, ultra rigidity and bracing. Dave (aka Planet_10) who does the drawings is a firm believer in this and there are those who have patience and skill to do it.

Bob

[Warmon]

My kudos to Dave then on his designs. I want to use his brace ideas on my next sealed build - whole lot of rigidity with only two/three main braces. I won't have any problem making a tight fit and I like swiss cheese over window. What I was wondering is why the 1/32" of clearance.

[Creative Sound]

Not sure which drawing you are referring to but there is a difference in the width of the SD12 and SDX15 motors. Perhaps Dave missed that. Can you tel me which drawing you're looking at?

Bob

[Warmon]

Well now I feel stupid. This is on the SD12. I misread one dimension on the back brace. He didn't overlook anything - he just made the notch on the back brace slightly less...7" - yet the magnet diameter is 7-1/6" and that's the magnet brace diameter too. So yeah, I think this answers it - make it an exact fit!!..no slop, no glue.

[looneybomber]

I've been thinking of doing that same thing. A parallel brace to hold up the magnet and a perpendicular, vertical brace to couple the driver to the back wall. (The SDX-15 is pretty deep and heavy, so it puts a lot of leverage against the front panel without support) Tolorances need to be very tight and my tools aren't the best, so it'll require some skill and likely a lot of hand sanding to shave 'em down

I was also thinking of using gasketing tape between the motor and any wood, just in case.

[brucek]

Magnet Brace - Touch or No Touch ?

Way back in this post I asked the same question, and planet10 gave reasons over the next page or so......

brucek

[Warmon]

brucek wrote:

I asked the same question, and planet10 gave reasons over the next page or so.

Good read! thanks!

[SQCherokee]

again...from my car audio background... I helped a buddy build a wall for a couple of 18's. We made a brace from birch ply wood. We made it about 1" wider than the magnet structure and made it to the height of the center of the magnets. We then routered a curve that it would sit into. We used a strip of window foam seal to keep it from scratching if it did happen to move at all...and then braced the support to the enclosure.
I don't think you really need to worry about it vibrating...because all the rest of the enclosure vibrates inside there.

[mayhem13]

Hey Warmon, i'm using the NHT's and i'm about to install my baffle in the cabinet. My drivers are downfiring on a 1.5" baffle. With these relatively light drivers do you think i need a brace for the magnet or are you just overkillin it for fun?

[Warmon]

It may look like overkill, but it's actually quite simple. The main reason for my going with the magnet brace is because it looks to me like the best way to get the most rigid box possible with the least amount of bracing. Another reason for wanting to use the magnet brace is in how I intend to stuff the box. If you want to do it, then by all means, but I don't think its an absolute necessity.