SM58 Mod for a SM57

Hello Harp Techs,

My second “harmonica” microphone, after the Astatic JT30-c that I bought from Quement Electronics in 1973 was (still is,‘cause I still have them both;o), a Shure PE54 with switch. Essentially the same as the Shure 545, except my PE54 was set up for Hi-Z. Over the years I migrated to the Shure 57, then to Greg’s Ultra57.

Recently, my obsolete (change in available frequency mumbo jumbo) Sansome wireless microphone gear, became a major liability with band members and sound guys--clipping and making loud monster noises were to blame. I migrated to the SLX Wireless Guitar System H5. With a Low Z to High Z adapter and couplings, I was able to plug the Shure body pack ¼’ mono to my Ultra57. It was a short honeymoon however, because unexplainable “searching for antennas” issues kept popping up--Ugh!

The singers in the band all use wireless SM58 microphones, and never have I heard any complaints, so I decided to try Shure SLX/SM58 wireless microphone. Of course, I would have prefered SM57, but Shure does not manufacture a wireless version of this microphone (p.s. the Beta87 is not the same, in case you’re wondering). I’ve had numerous successful gigs with the SLX/SM58--zero defects.

My only issue is that it’s not the SM57 (545) sound. A sound we harmonica players create by getting as close to the microphone cartridge as possible. I implemented a work around that works well:

Shure SLX2/SM58

Untwist the SM58 grill counter clockwise and place it squarely between the jaws of a machinist vise (note the magnetic soft jaw on the grill side)

Slowly turn the crank clockwise and watch the grill begin to collapse onto itself (stop and measure to verify)

The top of the SM58 grill will transform into a vortex shape

Lay the grill side flat onto a non-scratch surface (self healing PVC works great) and insert either a wooden dowel or urethane hammer (shown) and begin tapping to “flatten” the inside cone.

Lookin’ good in the neighborhood! The grill now has a perfect square like flatness to it.

Modified grill on the left, stock SM58 grill on the right. Notice the height reduction.

As you can see, the modified grill will be a safe distance from hitting the fragile microphone cartridge.

Now go and check out how much fatter your harmonica sounds!

Your Harpsmith, Kinya