We're sorry that we do not offer that service. We only modify brand new SM57s that we purchase from authorized dealers. We do offer a Do-It-Yourself kit that comes with the machined part, wires and heat-shrink tubing, thread sealer, and instructions that you or a qualified tech in your area can use to modify your existing mics.
Click here to check it out.
*You make want to ask yourself first whether your 57 still sounds as good as the day you got it out of the box or if the years of abuse have taken their toll on the diaphragm. If you would like a crisp, new SM57 professionally modified and gauranteed for two years, then you may want the complete G5790.
We're not affiliated, but we've become friends over the process of developing this mod. They seem glad that we've helped their ubiquitous mic become even more ubiquitous (is ubiquitouser a word ?). We are an independent company, so the G5790 is not a Shure product and is no longer covered by the SM57's original warranty. We offer our own two-year warranty.
It took a few prototypes to get it right, but we finally achieved the results we were looking for. We sent mics to be independantly tested by Arthur Sloatman of Midget Electronics in Nashville and by the lab at Shure. Arthur sent us specs that confirmed identical results on the same mic before and after modification, and Shure told us that the on axis frequency response was "a near perfect match."
We've also been asked if the body of the mic makes an impact either way since it's behind the capsule. You can see for yourself by unscrewing one of your stock SM57s and testing the tone with the back open or by stuffing the inside of the mic with some kind of absorptive material. You will notice a change because acoustical pathways coming from behind the capsule reach into the open space in the middle of the microphone. This space was engineered by the original mic's designers, and we had to engineer a new version of this internal cavity that would fit our modified shape yet produce the same results. Read more in our interview with Recordinghacks.com.