Quote Originally Posted by subwoof View Post
OK guys - here is the accumulated info...A few caveats1) measurements were made in a dusty woodshop with an old set of ( now magnetized ) calipers(2) Some variations of magnet structures ( bolt thru vs plate screws ) *might* be found.(3) MOST magnets have a casting number that may or may not match others?? I'd bet JBL would know...(4) JBL has a "goes into" checklist that applies to 10% of their items so use with a grain of salt...(5) Some magnet structures use a thicker ring of ferrite - these WILL allow longer excursion ( wow - a whole 1/16 in.... )(6) The earlier Alnico magnetic gap depths are the same as the ferrite if the model number is the same.(7) Some variations of magnetic intensity are found in the published JBL literature - no attempt was made to confirm.(8) The vented gap types are in a different league - NOT interchangeable.(9) There are TOO MANY variations of magnets + cones on the smaller / consumer sizes so little info was compiled(10) The 18 ferrite magnet structures are larger in diameter than the others(110 Yeah I probably missed a bunch but I needs da sleep...MODEL NUMBER GAP DEPTH FERRITE THICKNESSE120 / 130 / 140 9 / 32 7 / 8E145 19 / 32 7 / 8E155 / 2240 / 2245 11 / 32 7 / 8 2220 11 / 32 3 / 42205 / 2230 / 22312135 / 2202 / 21302203 / 2204 / 22342235 / LE14H / etc 9 / 32 3 / 4( most common type by far )sub
I know this is an old thread, but still relevant.What about inner and outer pole piece diameters? Are there also some rules?are all the inner dias the same? if the gaps are different it means something has to be different?