SM-58 is De-volving!!

[stetto]

I've got an old 58 I bought new back when Ramblers were considered a pretty sharp family car...OK, not that long ago, but feels like it...Anyway, I've had the mic put up for a bit (8 years) and took 'er out of the box yesterday...Only to discover that the foam inner lining of the ball had disintegrated almost to a powder...After carefully removing the ball and cleaning it up, I see that the diaphragm looks to be either made of or coated with the same type of foam, and though it looks intact (no, didn't touch it, that would breach my time-honored fear of beration by People Who Know Better), I fully expected it to destabilize and crumble ala that old Star Trek episode where the bad aliens were turning the crew into dry bullion cubes...I plugged 'er in and it seems to work just fine, though I have no clue as to how long it will last...Thank god it's just a 58...

...So my concern? Well...I have a couple newer 58s that I'd rather this not happen to (not to mention my "better" mics), so do any of the rocket scientists here have an idea what exactly happened to my old 58? It was stored in a foam-lined box with silica gel sacks, pretty much like all my mics are, though over eight years I never swapped out the silica...Too wet? Too dry? Communist infiltration? Inquiring minds are desperate for your input!!

Thanks
Eric

 

[thajeremy]

I have a early 70's Shure PE585 and the EXACT same thing happened. The case it was in was also lined with the same green material...This mic was also put up for 8 to 10 years...if not longer.

things that make you go...HHHMMMMMMMMMMMMMMMMMM

 

[Harvey Gerst]

The diaphragm is made of clear mylar, so the foam particles are just stuck to it. Get a soft makeup brush and brush the foam off the diaphragm - GENTLY !!!

 

[Jack A.]

What's a good replacement for the disintegrated foam, other than just sticking on a replaceable external foamie? How about just some "silk" (i.e. pantyhose material)?

 

[gemsbok]

i would gently clean the foam off and get shure to give yoiu a replacement. maybe they use newer type foam. on my 58 i just orderd a new ball because mine was dented and gross from years of live use. a new ball is like 10-15$ they even make a gold one. this may change its tone a bit from the original ball though. maybe even better

 

[EdWonbass]

The same thing happened to my 58. I just bought a replacement ball for it. The old one was all dented up so it was time to replace it anyway. The replacement balls are under $20.

 

[stetto]

The diaphragm is made of clear mylar, so the foam particles are just stuck to it. Get a soft makeup brush and brush the foam off the diaphragm - GENTLY !!!

Aw jeez, I was afraid of this...never saw a diaphragm made of foam before, and I'd seen 58 capsules many times...I was just hoping that it was some "special issue"...Denial is a bitch....

So this;

is a NOT good thing then....

Eric

 

[Harvey Gerst]

Whoa, it looks like they've integrated a foam pop screen onto the diaphragm. Leave it alone!!!

 

[stetto]

Commencin' to leave it alone, Cap'n...Hey Harvey, this mic is 20 years old or more, is this the first you've seen of a 58 diaphragm like this? It sounds fine through the headphones, so even if it isn't supposed to be like this, maybe I shouldn't fix what ain't broke...

Thanks for all the help guys!

Eric

 

[Harvey Gerst]

The capsule is fine. The internal windscreen (in the ball end) has disintegrated and you can use any thin open-cell foam (or loose weave material) to cut down on pops. You can tell if it's open-cell foam by holding it up to a light. If you can actually see the light clearly thru the foam, it's open-cell.