[jeffh]

I'm doing some repair to a pair of Dahlquist DQ-10 and I need to replace the gaskets on the woofers.  The original is hard and brittle.  Is there anything at the big box stores or hardware store that would work well? 

[S Clark]

Lot of these are available.  You need to know the dimensions.  Parts Express and others have them for sale.  You may have more success calling them "surrounds". 
It occurs to me that you may actually mean the gasket between the woofer and the cabinet.  If so, use pretty much anything that will seal.  You can use foam stripping for window and doors, or even silicon caulking ( but this is not easily removable). 

[S Clark]

Even Amazon has them...
https://www.amazon.com/Dahlquist-Speaker-Repair-DQ-10-FSK-10F/dp/B009DNM66G

[FullRangeMan]

If possible try rubber gaskets avoid foam.

[jeffh]

Yes, I am talking about the gasket between the woofer and the cabinet.  I know I can order online. Was hoping for an alternative I could go pick up tonight so I could finish. Thanks for the suggestions.

[S Clark]

Yes, I am talking about the gasket between the woofer and the cabinet.  I know I can order online. Was hoping for an alternative I could go pick up tonight so I could finish. Thanks for the suggestions.

A quick option that you probably have around the house that can later be upgraded... cut out a gasket out of cardboard.  I should work fine until you can find a better option.  I've used windshield putty on lots of speakers... works great, doesn't get hard, will last for decades. 

[BobRex]

Go to an art store and pick up a sheet of cork.  Cut to fit your need.

[richidoo]

I use this stuff:

https://www.amazon.com/Frost-King-V25WA-Extreme-Weather-Strip/dp/B000B4N3OA

It is excellent. It is a molded foam "rubber" but it's not latex, so won't harden. It is very flexible, can make a 3" diameter circle without wrinkling. Adhesive is strong. Two adjacent strips are molded side by side, with peel off pressure sensitive adhesive. It can be squashed down to about 0.020" thickness so you don't have to make the rabbet deeper. After a year of squashed it bounces back fully, so I know it won't lose sealing ability. I've bought 4-5 packs of this over the years.  Comes in brown color, or white. They sell it at big orange.

Good luck with your project!
Rich

Edit: Be sure to locate the gasket so it passes to the *inside* of the mounting holes so air doesn't leak out through the mounting holes. I see a lot of pictures of gasket outside the holes, even on famous DIY speaker designers' projects.     

[FullRangeMan]

Yes, I am talking about the gasket between the woofer and the cabinet.  I know I can order online. Was hoping for an alternative I could go pick up tonight so I could finish. Thanks for the suggestions.

In this hi pressure use even rubber will have a short life, I used 5mm felt(last a life) a few years ago, but it was a hand cut job.

[jeffh]

Thanks everybody for the excellent suggestions.  I picked up some of the Frost King weatherstripping that richidoo suggested.