Shure Unidune III, vintage SM57 with Pleiades (R,L) filters

As a guide only:


(89ω,14mH)    2 in
(76ω,30mH)     6in
(176ω,30mH) 12in
(315ω,40mH) Sowter 9127g  12in, best?
(221ω,40mH)