#sm 57

12:01 AM EDT May 30, 2026:

Pussy Galore - "Sm 57" From the album Dial 'M' for Motherfucker (April 1989)

Last song scrobbled from iTunes at Last.fm

8:17 AM EDT April 5, 2025:

Pussy Galore - “Sm 57” From the album Dial ’M’ for Motherfucker (April 1989)

Last song scrobbled from iTunes at Last.fm

File under: Four Guitars And A Drummer

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11:46 PM EDT April 9, 2022:

Pussy Galore - "Sm 57" From the album Dial 'M' for Motherfucker (April 1989)

Last song scrobbled from iTunes at Last.fm

11:32 PM EST November 30, 2021:

Pussy Galore - "Sm 57" From the album Dial 'M' for Motherfucker (April 1989)

Last song scrobbled from iTunes at Last.fm

A little while back I listened to a Home Recording Show episode all about impedance matching (check that episode out here http://www.homerecordingshow.com/2011/08/show-130-microphone-impedance-adjustment-and-more/). Basically the gist is that some dynamic microphones (like the SM 57) have a much lower impedance than most modern preamps or interfaces. The theory is that this mismatch of resistances between the preamp and mic cause a loss of performance in the mic itself. The SM 57 seems to be the victim of choice because it's so universal; everyone has one pretty much and knows that while it's a great sounding mic in just about every single situation, most wish that it could do a bit better. This "mod" basically helps match the impedance a little closer and allows the mic to shine through in it's full glory. At least that's the theory. There are much more complex and expensive mods out there, like replacing or removing the transformer (ie http://www.diyrecordingequipment.com/4001/shure-sm57-sm58-mods/) but this one will only cost about 15$ in total. All it takes is either a short length of dedicated XLR cable or one of the female to male XLR adaptors as well as a resistor of a value which you can determine for yourself. By wrapping the resistor around pins 2 and 3 of the XLR cable/adaptor this changes the impedance value going through the chain.

This article: http://www.recordingmag.com/resources/resourceDetail/330.html goes into much greater detail about the modification and shows you the formula to determine what value of resistor you will need. Anyways, all of this is good and well in theory, how does it actually sound? In the HRS episode they do a quick shoot out, it uses a "Vari-ohm" which is a device that lets you pick your impedance using a potentiometer which is a lot quicker than swapping resistors in and out the end of an XLR cable, but hey, use whatcha got. For my test, which isn't all that scientific by any means, I set up my two SM 57s on my old fender 15 watt bass combo, one going straight into my interface, the other going through an adaptor with 1 of 3 different resistors I tried.  I did one take for each resistor value, giving me one clean, unmodded take and one modded take that would be exactly the same. I dont have a reamp box, so I couldn't just pump the exact same take out each time. That would have been the ideal way to go about it, but again, use whatcha got.

I got my resistor values by using the formula provided at the end of the the article I posted above. I started by going for about 600 ohms of overall impedance, which gave me a resistor value of 638 ohms (the closest I had was 680 ohms) to go against the 10k ohms of my interface.

The second value was achieved by going for an overall impedance of 310 ohms, the listed impedance of an SM 57 on their website, which gave me a value of 320 ohms. The third value was 25 ohms which matched the value I got by checking my SM 57s with my multimeter. I'm not entirely sure why my 57s seem to have such a low impedance, but I figured I would just give it a shot and see what would happen.

I knew SOMETHING was happening right away because the 25ohm test required a lot of extra gain, nearly 25% more, the 320 ohm test required a little extra (maybe 10% at most) and the 600 ohm test was just about even for both.

I wont say what I thought of each result, I'd like you (if there's anyone reading this) to make up your mind for yourself. I'll just say that during a blind test, I didn't always pick correctly.

Here's a link to all the audio files, complete with screencaps of each EQ curve (you can see slight differences between the takes in each test, but I dont think that they should be the basis of your decision.