expired "yesterday" ?

[freddi]

5-28-19 does "application status" expired mean the patent is too ?

 

[tonskulus]

Looks like 8th order bandpass.

I think such a design is only good for very narrow band..

 

[freddi]

Its the BOSE patent

https://patentimages.storage.googleapis.com/23/23/ba/d5fc6cfbf3ea72/US5092424.pdf

 

[Circlomanen]

I think such a design is only good for very narrow band

An adventure with 8th order BP

It is not easy to get good punch and attack from a normal Helmholtz based 8th order BP, but they can be quite wide band and have a great efficiency.

I prefer the sound quality of a quarter wave based 8th order BP over the port-infected Helmholtz version.