The Venerable Shure sm57 everyone has used it from garage bands to the President of the United States! This mic has been studio and live sound workhorse for decades. A desert island mic if there ever was one. But, can it be improved?

The Right Tool for the Job

The sm57 isn’t always the perfect mic for the job, but it seems to work on almost anything. It’s got a mid-forward sound and good noise rejection. The distance the mic is to the sound source also plays a big role with the sm57. If you are able to use the proximity effect to your advantage this will reduce the mid-range bump by adding some low end to the mic.

About the Modification

Removing the transformer is a very simple mod that smooths out the top end, beefs up low end, and makes the mic’s transients snappier all while retaining the “character” of the sm57. Seriously, I really enjoy what this mod does. I especially like a modded sm57 on the top head of a snare drum. The fast transient response and more open sound work extremely well on snare.

There are however a couple things to note if you are recording with a transformerless sm57. First off, the output will be a little lower than a “stock” sm57. It’s actually about 10dB quieter. This usually isn’t an issue. Grabbing a sm57 really isn’t anybody’s first choice when recording a delicate quiet source. The other thing to note is that phantom power can potentially damage a modded sm57. This main issue is if you are hot patching the mic through your patchbay. What I mean by hot patching is that the preamp has 48V’s engaged and you patch the mic via the TT or 1/4″ patch cable. This becomes an issue do the fact that the ground isn’t connected first when patching and the ground isn’t the last to be disconnected when unpatching. This causes a mismatch of the phantom power going to the microphone and results in the capsule being push/pulled out of it’s idle position. Now, In reality, I don’t know how sensitive the transformerless mic becomes to 48V, but why tempt fate. Just don’t send the mic phantom power and you’ll be fine.

Tools Needed

• Heat Gun
• Soldering Iron
• Solder
• Wire Stripper
• (2x) 3 inch 22 awg stranded copper wire (mic cable)
• Small Flat Head Screwdriver
• Solder Sucker (optional)
• Small Bench Vise Grip (optional)

Steps to Modify a 57

• Unscrew the XLR connector from the microphone
• Unsolder both of the output transformer leads at the connector. This will be a red wire and a blue wire
• Unscrew the microphone. There is a seam that goes all the way around the middle of the mic. This is where you’ll unscrew the mic in to two halves
• Unsolder both of the output transformer leads that where exposed by unscrewing the microphone. This will be a yellow and a green wire
• Clean off the solder lugs, the metal loops, with a solder sucker
• Heat up the glue around the now detached transformer. BE CAREFUL! Obviously, you can burn yourself very easily. It’s best to clamp the base of the mic in your bench vise while heating up the metal casing.
• Grab the yellow and green wires and gently pull and wiggle until you have removed the transformer. DON’T BE AN IDIOT! LET THE METAL CASING COOL BEFORE TO TOUCH IT!
• Strip and tin the ends of the two 3 inch bits of wire
• Solder one wire to pin 3 of the XLR connector & solder the second wire to pin 2. Keep track of which wire is which. Pin 2 is positive & pin 3 is negative.
• Slide the wires and connector back into the empty casing. Tighten the XLR connector back in place
• Solder the wires poking out of the casing to the solder lugs on the other section of the mic. The wire used for pin 2 (positive) will connect the the solder lug with a + sign next to it.
• Screw the two parts of the microphone back together
• Mark the modded mic in some way so that you know it has been altered and you are donezo my friend!

Conclusion

This mod opens up a new sound palette for the sm57. A smoother more open sounding top end, much more low end, and best of all, a faster transient response. It’s handy to keep a couple transformerless versions of the mic around to mix in with your standard ones. Personally, my preference leans toward grabbing the transformerless sm57 first. It’s like a sm57 on steroids! Let me know what your experience is like using your modded sm57. I’d like to know if you are hearing the same results I am.

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