Lahive & Cockfield
Transducer assembly
 A housing and diaphragm assembly for use in an acoustic transducer comprises a performed face plate having a ring shaped ridge for mounting the diaphragm. The housing includes a tubular sleeve having one end received over the ridge and secured to the face plate. Additional elements comprising an electret transducer are mounted with the diaphragm on the ridge internally of the housing. 
Tibbetts Industries, Inc.
H H
H04R H04R
inventional additional
Peter L. James S.
Madaffari Collins