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Dude, where's my bass? Oh, lost to stiffened rubber surrounds...who knew?

Started a thread on "Cables" re: better cables to help restore bass to my B&W CM-4 speakers...so while preparing and listening to speakers for cable evaluation, our daughter - who has very acute hearing, unlike my senior ears! - noticed sort of a "crackling" sound in left speaker, and sure enough, removing cloth speaker covers, we notice a 6cm hairline fracture in the surround of the mid-range cone.  In fact, checking the rubber surrounds of bass and mid-range cones in both speakers, there were significant areas of stiffened and brittle rubber material, which - I would presume - drastically muted the speaker responses to incoming audio signal.  So, what to do?  Can the surrounds themselves be replaced w/o impairing cone native sonic qualities?  Totally new area here for me, having never dealt with material failure or deterioration in speaker components.  Suggestions most welcome!
compass_rose
trelja
3,223 posts
 
+3 on Millersound.

Bill listened to my speakers, and immediately felt the rubber surrounds hamstrung them.  After he worked his stuff on them, he had them soaring like eagles.  He's a master at getting a driver to work optimally and actually make music
crazyeddy's avatar
crazyeddy
381 posts
 

Jim at Fab Audio has done a number of repairs for me over the years, and does good work. If the Toronto area is not a logistical issue for you, perhaps you could give him a call


mr_m
1,900 posts
 
Does anyone think there would be a difference in repair procedure on rubber surrounds vs. foam???
wesheadley's avatar
wesheadley
146 posts
 
I have a set of Genesis III's and two of their Servo12's-- all of the woofers used foam surrounds and after about 12 years the foam began to fail on many of them-- used a local speaker restoration specialist and he recommended using a light rubber replacement surround instead of the foam-- I went with that and did them all-- that was more than ten years ago and they all sound great to this day. I never noticed any degradation in the sound quality-- and in the case of the subs I think it made a small improvement. Would do it again in a second if I had to. 
compass_rose OP
23 posts
 
Well, thanks to all the responses pointing me toward on-line sources for either speaker/driver repairs or replacement surrounds.  After considering shipping costs, repair and materials fees, etc, I opted for a first-pass DIY approach, as I am a bit of a hobbyist and have quite an array of tools, what-have-you to do the necessary remove/refit of new rubber surrounds.  Went on-line to SimplySpeakers.com, ordered two repair kits (four surrounds and adhesive) for 6.5in B&W cones.  Removed the perished original grey rubber surrounds, cleaned cones, then followed directions to correctly place and glue up new rubber.  Everything went smoothly, then connected up speakers to some old vintage gear (Carver) with existing Monster cables, just for initial evaluation...WHOA!  bass is back, with a vengeance!  Put on some bass-heavy tunes, can't believe the difference...complete restoration of dynamic, full-range response, w/o any optimisation.  Also nulled out tone controls, and ran speakers at moderate volume with a ton of Trentemoller to really work the woofers/mid-range drivers.  Seems as though sound improved after a couple of hours, then  leveled out.  Whatever, I'm so pleased that the CM-4s, as Lazarus, have arisen from the dead!  Will be relocating back to HT room, pairing with sub for some cracking LFE.
Now, about those cable evaluations...(?)
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