Shure model 55 (vintage) for repair

[xtian]

This mic puts out a very low, "boxy" signal. I opened it, and all connections look good. How can I figure out if the moving coil element or the transformer is at fault?

[xtian]

I'm thinking I can unsolder the capsule from the transformer, and connect my signal generator there, or even my iPhone with some music, and see how it sounds at the other end of the microphone cable. Any trouble with this test?

[pdf64]

Don’t see why not
Also, could test the capsule element by connecting it directly to a high gain, low impedance input, to check if that helps with the boxy tone.
Or patch in a transformer from another dynamic mic, eg wire up the capsule of this one to be in place of the one from that mic. Assuming you’ve got another high impedance mic handy

[xtian]

The model 55 has a three way impedance switch, M position is 150R, same as SM57/58. Thanks, Pete.

[xtian]

I tested the model 55's transformer by playing music thru it, and it sounded perfect--full bandwidth. So, I cannabalized an old SM58 for its capsule and installed it in the model 55. Works great! Sounds like a 58, no surprise. I made a web of zip ties to hold the new capsule in the spring-suspended cage. A real MacGyver bodge, but it will last another 60 years!

[Leo_Gnardo]

I tested the model 55's transformer by playing music thru it, and it sounded perfect--full bandwidth. So, I cannabalized an old SM58 for its capsule and installed it in the model 55. Works great! Sounds like a 58, no surprise. I made a web of zip ties to hold the new capsule in the spring-suspended cage. A real MacGyver bodge, but it will last another 60 years!

Nice work there, McGyver would be proud! Recently had a 55 in for a fix, but it was just a botched cable, thank hevvins. Rewired it for balanced, with a regular XLR plug. To me, the original working 55 sounds much like an SM58 anyway, with a slightly rounded off high end. Mellow, suitable for music of the time it was built. Shure had their house curve built in, all the way back then.

[The Dude]

Just an FYI: That "house curve" or presence peak was built in so that their mics would sound good with the Shure Vocal Master system which had no tweeters.

[bsco]

Funny you should mention that PA system....I have a Vocal Master here kicking around down in the basement somewhere.....been there for years...

[Leo_Gnardo]

Just an FYI: That "house curve" or presence peak was built in so that their mics would sound good with the Shure Vocal Master system which had no tweeters.

If that's the case, they "shure" hit a winner. The 55 and its relatives, later SM58 and all of its relatives, sound pretty darn good with any competent PA system.

Tweeters (horns) who knew... use Shure mics and you don't need em!

[nevetslab]

I tested the model 55's transformer by playing music thru it, and it sounded perfect--full bandwidth. So, I cannabalized an old SM58 for its capsule and installed it in the model 55. Works great! Sounds like a 58, no surprise. I made a web of zip ties to hold the new capsule in the spring-suspended cage. A real MacGyver bodge, but it will last another 60 years!

Excellent cobbling job there!! I've always liked those old 55's, so even if it's a different capsule in there, it's still a Shure Bros' mic! Rock on!

[DrGonz78]

When I was in my first band in middle school and high school years we had that Vocal Master as our PA system. We always used sm58 mics too and it sounded pretty good. I use to plug my guitar in and crank it till it created the nastiest fuzz sound. It was not a fuzz distortion that could be used for anything other than making an experimental type noise.