Tonight I got around to the destructive part of this mod.  I pulled the SM57 apart, which is pretty straightforward.  A small screwdriver to loosen the XLR connection, and then you can just unscrew the mic capsule from the body.  Cut the wires, and you’re ready to attack the transformer.

I put the body of the mic in a pot with a small amount of water - the water just covered the body while it was on its side.  I heated the water, and as it approached a boil, I picked up the mic body with needle nose pliers and an oven mitt.  Then I used the needle nose pliers to grab the transformer, and it slid right out of the mic.  Check the gallery to the right.

I cleaned up the glue from the transformer, in case I need or want to use it again.  If I don’t like the way this mod sounds, I could hot glue the mic back together (for better or worse).

The only comment I have on this step is the effect of the hot water on the exterior of the microphone - it seems to have really affected the finish.  It’s much rougher on this section of the microphone now than it is on the capsule end.

The only remaining step is to connect the mic capsule directly to the XLR jack and screw the body back together.  Pin 1 will still go to the body of the mic, and the blue and red wires will go to pins 2 and 3.  I’ll just have to try one arrangement, look at the polarity, and flip as needed.  I’ll post again once I’ve finished!

Back in the March/April 2006 edition of Tape Op, I saw an article about modding an SM57.  The premise is that the transformer adds a lot of unpleasantness to the sound.  The solution?  Remove the transformer!

Of course, the transformer is in there for a reason.  The two biggest reasons are to balance the output, and provide better voltage/impedance matching.  Removing the transformer will then unbalance the output (which could cause noise issues if you’re dealing with a significant cable run), and knock down the voltage output (by 10-20dB, reportedly).

With a small stack of 57s, it seems worth a try.  I’ll report back on my progress.

 

 

Links:

Tape Op - Best recording magazine available.

Gearslutz Forum #1 - Discussion of the mod outcome, plus pics.

Gearslutz Forum #2 - More discussion.