driver gasket

[intojazz]

The Fostex mid driver on my speakers uses a foam seal ring/gasket. I believe there is some validity to how the drivers are mounted in an open baffle as it relates to potential vibration isolation. So the foam ring seems woefully incapable of isolating anything. Any suggestions on a material to use as a gasket?
Thanks,
John

 

[Tickwomp]

You can try Blu-Tac...  Break off a piece and roll it between your hands to make it thin and string like.  Nice and solid if you don't overdo it. 

Tick

 

[Grainger49]

RTV, AKA Silicone Seal is a glue like substance that will give you a rubbery seal when hardened.  It is my thought that Blue Tak would flatten out extremely.

 

[glynnw]

Hi John - We are still traveling similar paths.  Since building the BassZillas I have spent hours just thinking about driver isolation (even made a mock-up of one), with no current cost-effective solution in the real world with my poor carpentry skills.  However, I have just taken a step in the opposite direction.  I remade my new open-baffles, going from 3/4" MDF to 1 1/2" plywood (two 3/4" pieces joined) and attached the drivers tightly to this baffle with no isolation.  After just a couple of days listening, the highs from the Fostex drivers are noticeably cleaner and more well defined.  The bass from the Tone Tubby woofer is also tighter and better defined.  So increased rigidity (as well as a change in baffle material) really worked well in this case.

 

[Grainger49]

I have it!  My VIP belt becomes loose after a while; a year or two.  It has a circular cross sectional area.  Cut it once and lay it in to form a properly sized O-Ring.

I need a new one now.

 

[intojazz]

Grainger, I have to admit I really like the o-ring idea. Back in the day I used to assembly ion implanters where repairs to o-rings were done with an exacto and super glue. We could cut and glue until the perfect size was achieved. Of course that was all R&D. I'll just experiment with a few different gasket materials to see if these old ears can detect any real difference. Thanks!

Glynn,
Thanks for the update. Those baffles look great.
It's funny how this whole scenario has evolved. The whole idea of eliminating resonance through rigidity has motivated me to rebuild the bass bins. Your comments could not have been more timely. It's a basic principle that so many high end speakers employ that I'm embarrassed to admit I haven't given it enough consideration. Here's a couple pic's......

 

[Paul Birkeland]

Hello John,

I actually addressed this same issue for the speaker that Doc and I use.

What I did was to use Urethane rubber and a mold to create two identical gaskets that completely enveloped the basket flange.  One of these gaskets went against the cabinet, then the driver, then the second gasket.  We then clamped all of this together with a rigid ABS baffle. 

To make the mold for the gasket, I went to a local plastic supply shop and ordered an acrylic circle at the same diameter as my speaker cutout, then another circle with the basket diameter.  I glued these together and then glued them down into a square mold dish and cast my own gaskets.

-PB

 

[Grainger49]

John,

You have a PM.  Will delete this when read.

 

[2wo]

Hi John,

There is a kind of plastic foam. I see most often used as a packing materiel, usually white. I don't know what it is called, or where to get it but it seems ideal. I am sure you have come across it unpacking a monitor or DVD player. I have seen it in sheets from 3/16 to 1/2". here is a hunk I just pulled out of a cell phone holster I just got...John

 

 

[Laudanum]

Maybe rope caulk.  I used to use it to get an airtight seal for subwoofer/speaker to baffle.  It obviously does compress but I would think it would still provide some damping.  Im sure there are better materials though, some already mentioned here.  But in terms of readily available and cheap, maybe worth experimenting with.  On potential problem ...  It peels right off  the speaker frame and the baffle but could possibly leave a stain behind on a wood finish.  It does leave some discoloration on bare wood.  Probably an oil in the rope caulk. 

 

[intojazz]

John, that pic looks almost exactly like the gasket that came with the drivers. I can see this is going to be a trial and error process.
Here is what I plan on trying:
1) no gasket
2) the foam gasket that came with the driver
3) an o-ring
4) rope caulk
5) sheet rubber cut as gasket
and then??????