[Eric]

I was just fooling around with this same idea the other day...

I drew up a model of a trumpet and the beginnings of an idea for a filter.

In this model, there are 2 rings that sandwich a pre-formed filter foam. The sandwich rings are bolted together with M2 fine bolts. The assembly uses a double adhesive backed epdm rubber ring to bond to the top of the trumpet (not the best I know-still working on it)

There could also be a minimal wire dome form to keep the filter foam from sucking into the trumpet and tearing. There are some new very strong foam types available now from companies like ITG that resist tearing and flame very well.

I would probably redesign it to be a complete assembly where the trumpet itself forms the lower sandwich.

I am going to run it past Fran at RCR to see if he wants to take on building something along these lines.

Cheers
Eric