Mod/repair vintage Shure mic?

[Justin Thomas]

Hi all,

I've only got a Kindle so am technologically limited. Sorry for not being able to attach an image or anything.

A friend just bought an old 55sw. It's very tinny sounding, no bass at all, even w. bass cranked & treble cut on the PA. When he bought it, the output was very low, so we tried the 9V across the terminals to loosen it up (we read it on the internet...). That boosted the output dramatically, but very tinny sound. Looking at a user guide for this thing, it doesn't appear to have any user-moddable parts, and a new capsule is probably not happening. Anyone have any ideas to warm it up, or just save it for experimenting with? I did manage to get a standard XLR plug put on it.

User guide is here, scroll down to "55sw"
Again, apologize for lack of technological aptitude....

http://www.shure.com/americas/suppor...ts/microphones

[Enzo]

Probably is not an answer. CONTACT Shure and ask them if they still service the 55. (SW for switch)

I can't get your link to work, but on the Shure web site under support and repairs, they list flat rates for two versions of 55. They have been ther when I needed them in the past.

[Justin Thomas]

Hey Enzo,

Thanks for the reply.

My friend said he'll call/email, but their website basically said, "why would you want to use THAT old thing when we have new better stuff?" But I will pass on your experience, given your time in the business! The new 55's all have standard 58 insides, put into an old-style case. Or so it says on their website.

We're trying to do 20s-40s era retro swing, but doing it like we were in the 60s/70s. Hence the trying to fix this
one... one option is to transplant guts from sm58 into old case, same as Shure. My friend just informed me he's willing to sacrifice one of his 58's, so it sounds like brain surgery is in order! Our "PA" is my Spitfire (thanks to everyone here for that!) built in a 1962 Stromberg-Carlson PA head... if I had known it'd be put to this use I'da left it alone...

Thanks again,

Justin

[Jazz P Bass]

In looking at the frequency curve of the mic, the lower bass frequencies are not that defined..
It kinda comes on strong at 200 Hz.

[g1]

Sometimes if the mic gets dropped or a major pop/air pressure, the diaphragm may collapse or the magnet can shift and pinch the coil, same as with speakers. With something like a SM57, the diaphragm is plastic, and you can sometimes get lucky by applying vacuum to the diaphragm (sucking on it in other words ) which may pop a collapsed diaphragm back into shape.
However, the 55SW uses the R55 cartridge (which is extinct) with a metal diaphragm, so it would be very difficult to repair in this manner. There may be people who specialize in repair of these but I think it would be very expensive.

The newer units use the R115 cartridge, relatively inexpensive, not quite the same as the '58 cartridge

Your idea of refitting with the '58 guts is probably the easiest and most economical approach, doesn't sound like authenticity is a big deal here.

P.S. I hope it was sounding tinny before the 9V battery was applied. I don't know where you read that but I don't think you should ever do that to a mic. It is done with speakers to see if they are dead or alive but mics are too delicate and can not handle the power a 9volt can deliver. The pop alone from a 9volt would likely deform the diaphragm or pop it right out of the gap.

[Enzo]

Forget what the web site hinted at, CONTACT them and specifically ask what they can and cannot do. You would not be the first person - nor the last - to want a vintage mic working just for its own sake. I am sure Chevrolet would prefer you to buy a new one, but that doesn't mean you shouldn't fix up that 1957 model.


If all you want is the appearance, just find any retro looking mic. The audience won;t know if it is authentic or not.

[Justin Thomas]

Hi everyone,

Thanks for all the input; we'll contact Shure next week. If they don't have one we'll go ahead with transplant.

G-one, before the battery it didn't do anything. The suggestion was that sometimes the diaphragms would freeze, sometimes that would free them. It was recommended as a crap-shoot for a non-functioning-from-the-beginning mic. So, we're not out anything there. Live & learn, right?

I'll keep everyone posted, thanks again.

Justin

[km6xz]

What input are you using? It was multi-Z with most set for 25-50 or 150-250 ohms but you can also wire it for unbalanced Hi-Z. If you have a Hi-z input like a modern solid-state mixer be sure to use wiring for Hi-z but any cable runs more than 20 feet or so will be noise. Usually they were used with transformer inputs or a matching transformer in-line.
Assuming you are using the original cable and if you are using a tube mixer without input transformer or solid-state mixer, use the unbalanced Hi-Z option. Switch the switch on the back to hi-z and use the white wire for signal and the black and ground wire for ground return and shield. If your mixer is suitable for low Z, (mic low-z not balanced line 600 or 500 ohm z used to connect various line level signal devices together) then use the white and black wires for + and _ and the shield as shield.
The output, open circuit, is about 20 times higher in Hi-Z mode than low-z mode but with proper matching, there is only 3db or so difference. So I am suspecting you have it in Low-Z and feeding a Hi-z input. Try setting it for Hi-z and wiring it for unbalanced to see if it is working better. In Hi-z it is intended for 100k or higher and most solid state mixers are around 50k so there will be a little drop there, and the bass will be affected a bit but not the problem you are experiencing.
They were intended for PA application so never had much bottom end nor intended to. But as with all unidirectional mics, proximity effect boost bottom end a lot when lips are touching the grill. Since the element is set back further than most dynamics, the bass boost with close mic'ing is less dramatic than for most mics. That made it a good PA mic.
NEVER use DC across a mic unless you know it is configured for phantom power, then only apply it through 6.8k pull resistors to both sides of the balanced line. A 9 volt battery can't supply much current but more than enough to destroy a moving coil diaphragm or most mic transformers.

[Justin Thomas]

Hey km6xz,

Thanks for the info! I'm not using the original cable. But I'll check all the wiring. We compared it to an SM58 lying around the house, and the 58 works great. I don't quite get the Hi-z/Lo-z thing yet, but I kow we had the switch on "hi." Our "PA" is my Spitfire clone into a homemade 4x10" column, and using the 58, it sounds great for what we want - a warm yet detailed sound without the harsh high end. We just leave the tone knob @ 12 oclock. The other night some friends were over and didn't realize we were micing vocals. They just thought my friend was singing louder. But my friend does want me to make him a tube PA!

I haven't had a chance to contact Shure yet, but I'll look into all your suggestions. Thanks again!

Justin

P.S. thanks for the signature line - I agree wholeheartedly!

[Gary audio]

Looking for the little round bottom it fits on the bottom of chair Fatboy videos in the microphone stand

[Pixel]

The Shure site says they do not repair this microphone anymore. Just put 55SW in the search box on the Shure website to get a whole bunch of information about this microphone. One of the hits will give you the name of an antique microphone specialist to contact.

https://service.shure.com/s/article/...language=en_US

I found this guy who specializes in 55s too, http://www.mutantmics.com/

You should phone Shure though, you never know if the person you talk to is going to go the extra mile for you.

[xtian]

I modded a client's broken 55 by replacing the original capsule with one from an SM58.