Compensating Recess For Foam Tape

[jimofoakcreek]

If one is using foam speaker tape that is 1/2"X1/8" thick then the recess for the speaker flange must be routed 1/8" deeper than the the flange.

Is that correct?

Or is there a different approach?...Thanks

[djarchow]

The gasket take will compress as you tighten the driver down. So it will be less than 1/8"

Regards,

Dennis

[ocool_15]

You have to compress it and measure, The nice stuff I use that is low density compresses to ~.51mm if I remember correctly. You basically have to measure whatever product your using.

[bmaupin]

I usually squeeze the foam with calipers (on the blade area with some cross section) to figure out what the thickness will be when compressed.

[billfitzmaurice]

If one is using foam speaker tape that is 1/2"X1/8" thick then the recess for the speaker flange must be routed 1/8" deeper than the the flange.

Is that correct?

Or is there a different approach?...Thanks

The tape compression can be assumed as complete, so no additional recess beyond the actual frame thickness is required. Where recessing frames is concerned keep in mind that anything less than 1/4 wavelength within the driver pass band is essentially acoustically invisible.

[the kid]

The tape compression can be assumed as complete, so no additional recess beyond the actual frame thickness is required. Where recessing frames is concerned keep in mind that anything less than 1/4 wavelength within the driver pass band is essentially acoustically invisible.

Geez Bill, you had me understanding you until you threw in the 1/4 wavelength thingy! Please explain this to me - the lesser undrstanding.

[billfitzmaurice]

Geez Bill, you had me understanding you until you threw in the 1/4 wavelength thingy! Please explain this to me - the lesser undrstanding.

The primary acoustic reason for recessing is so that the wave won't wrap around the driver frame, reflect off the baffle and then merge again with the original wave far enough out of phase to cause a response bump or dip. If the distance the wave has to travel around the frame to the baffle is less than a quarter wavelength the phase differential usually isn't problematic. It gets even more complicated, for if the radiating plane is more than a wavelength in dimension the wave won't wrap around the frame anyway, its dispersion angle will be too narrow. What it boils down to in practice is that few woofers will benefit from recessing, some mids might, as will most small tweeters. But from a visual standpoint the larger frames of woofers means they're more likely to be recessed.

[the kid]

Thanks for the reply Bill. I was at least thinking a little something like that for the woofer.

[PunkSweeper]

Is off-setting the tweeter in the baffle an alternative to recessing?

[johnastockman]

Is off-setting the tweeter in the baffle an alternative to recessing?

Short answer: no.

For jimofoakcreek, most of the foam gasket tape I use (like the stuff PE carries) will compress down to about 1/32". Some of the hardware store stuff might be different according to the density, but I try to find closed-cell foam of a medium-to-firm density. I add 1/32" to the depth of the recess for all my mortises and it's worked very well. Maybe 1/64" could work, but it really depends on the gasket material. Smash some down and see how far it'll compress. If you add 1/8" to your mortise depth, it will be too much.

John A.

[rogoll]

Short answer: no.

For jimofoakcreek, most of the foam gasket tape I use (like the stuff PE carries) will compress down to about 1/32". Some of the hardware store stuff might be different according to the density, but I try to find closed-cell foam of a medium-to-firm density. I add 1/32" to the depth of the recess for all my mortises and it's worked very well. Maybe 1/64" could work, but it really depends on the gasket material. Smash some down and see how far it'll compress. If you add 1/8" to your mortise depth, it will be too much.

John A.

FWIW, the closed-cell foam that John is referring to can be found at Lowes. They carry both types, closed and open-cell, so you'll be able to compare and see the differences. I too prefer the closed-cell. It's just a gut feeling thing, but I think it will last longer before deteriating and perform better than the open-celled.