SM58 refurb

keith.rogers

Well-known member
Got a couple of old SM58s from a friend I was visiting so I could leave my newer mics at home when I host an open mic in a couple weeks. He has a bunch and said just grab what you want. The first two worked ("testing 1,2,3") when I plugged them in so I tossed them in the case. Wish I'd looked a little closer at the one, since the foam has completely disintegrated. I actually had ordered a replacement grill/foam aftermarket piece because they were both beat up enough I figured I'd probably need one. Good thing. Already trimmed a bit of some open-cell foam I had to cover the diaphragm (after carefully picking up loose stuff with masking tape). It will be interesting to see how they sound once I get them both done and side-by-side.

The older one (rusty grill, too) actually has 3 wires inside, green/yellow/black. Any ideas when they switched to just 2 wires?

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There's little more satisfying that giving old gear a new lease of life.
Keep us posted on how it goes. ;)

Also, thanks for the pics. I recently advised someone with a faulty mic that there shouldn't be any third wire, so I linked up your thread and corrected myself.
 
Don't know, just extrapolatin'... The black wire ties the otherwise floating capsule to ground I am assuming?
This makes sense for a mic intended for the broadcast industry where it might be immersed in some strong RF fields, I doubt the basket makes a good contact to the mic body and therefore could not be relied upon as an RF screen.

However, it is likely that as the mic found more favour out in the PA/recording world the extra cost of the wire was deemed unnecessary, certainly I have never heard of a 57/58 being vulnerable to RFI? The delectable SM7b is I know specially built to reject external fields.

Another observation, IIM? The soldering on some of those tags looks a bit suss'?

Dave.
 
Snooping around the old old (unidynes) Shures had three wires and the newer MIM had 2wire and more epoxy on the transformer per the internet so it must be true!
Ive never seen three wire before.
Green and Yellow always.

add> 2006 HR post mentions the black old wiring went to pin 1 on the XLR, the newer pin 1 is direct body ground.
 
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Got them back together. The cheapo aftermarket grill is a bit more oblong and appears to be the tiniest bit more open (wire spacing) than the spherical original, and the inner foam lets more light pass through, so not sure what that's going to do. I could swap the things around and see if it makes a difference but I did a quick and dirty test by pointing both at one of my monitors (5" driver Yamaha) and just recorded pink noise. Up to 5k they're about the same but there's a few small spots between 5-15k that show some differences that might bother me if these were for anything other than a noisy open mic. I may try a more controlled test someday, but think I'll let the actual usage decide for me if I have squandered $6 and a few hours of time :).

First graph is the SM58 that only got a grill washing, 2nd is with new grill and a bit of I-don't-know-what foam I could find to tack on over the diaphragm. (no idea what that little bump above 20k is - noise from somewhere, but I can't hear it!)

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I have been using aftermarket grills for many years, not noticed any difference. Maybe there is more then one brand of aftermarket grill some better then others, but I would not worry too much.

Alan.
 
you could swap grills and do the test again and see if the difference follows the grill.
but yeah...can anyone hear this? I dont know....depends how drunk the sound guy is and how loud hes cranked it up..lol
 
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