SM57 Mod

A-Barr · Post by **A-Barr** » Wed Mar 22, 2006 1:15 pm

I know I've posted the hell out of this thread but here goes..

I was told that once you get the transformer out of the sm57 its pretty much a sennhiser 421

I'd love to hear some opinions on the sonic differences between the two. This seems pretty crazy to me, if Shure could make an 80 dollar mic sound like a 350 dollar mic by actually using fewer parts, I'd think they would have figured that out. Although maybe that's what the SM7 is, that and the 57 and 58 are all based on the Unidyne III capsule, according to their site. Anyone have all 3 and feel like doing a comparison?

...Please??

A-Barr · Post by **A-Barr** » Wed Mar 22, 2006 1:19 pm

OK... one more!
The SM7B does is in fact transformerless! Though it does have a humbucking coil.

RodC · Post by **RodC** » Wed Mar 22, 2006 1:33 pm

I have always thought the difference we hear between the 57 and the 545 is the transformer. The 545 and most like it have a tranny with 2 taps, sooo... you know they have to sound different.

valverec · Post by **valverec** » Thu Mar 23, 2006 8:20 am

Okay, so it sounds different. Does it sound good though?

bayoucables · Post by **bayoucables** » Thu Mar 23, 2006 11:58 am

Yes, it sounds better. More lows, more highs, and less honk.

bayoucables · Post by **bayoucables** » Thu Mar 23, 2006 4:15 pm

I remoted the transformer so that it could be put back if needed. I have all this on the Altec info page linked in my sig as well.

Here it is:
After taking it apart and cutting the wires at the capsule and jack, heating the mic body with a heat gun will soften the hot glue and a tug on the wires will pull it out. The glue is easy to take off the transformer while it's still warm.

I wanted to remote the transformer in case I needed the mic to sound like it originally did or if I needed the extra gain back. I shielded it with some sticky back copper foil. I left the paper on so that it would act as an insulator and soldered the cable ground leads on the copper side. Be sure to note which of the leads is for + and - before cutting the leads. On all four of my mics, green was positive at the capsule and blue was hot at the jack. FYI pin two of XLR mic cable connectors is hot(+), pin 3 is cold(-), and pin 1 is ground.

jonmatifa · Post by **jonmatifa** » Sat Apr 08, 2006 8:25 am

Yeah, I like the idea of keeping the transformer, plus it also brings the interesting idea of using it on mics its not supposed to be used on. I think I want to take the transformer and put it into a box and put a Pot on it so I can dial in the amount of transformer and non-transformer signal, see if anything useful comes out of that.

weatherbox · Post by **weatherbox** » Sat Apr 08, 2006 10:32 am

jonmatifa wrote:Yeah, I like the idea of keeping the transformer, plus it also brings the interesting idea of using it on mics its not supposed to be used on. I think I want to take the transformer and put it into a box and put a Pot on it so I can dial in the amount of transformer and non-transformer signal, see if anything useful comes out of that.

cool idea. let us know what happens.

pedalboy · Post by **pedalboy** » Sat Apr 22, 2006 6:19 pm

hey i'm doing the mod RIGHT NOW... but either the directions for the grounding are unclear or i'm just not getting it... Do you just run the TWO wires from + and - on the capsule to pins two and three, and leave pin 1 alone? that APPEARS to be how it is on the original sm57 but it seems odd to me... help if you're out there.

pedalboy · Post by **pedalboy** » Sun Apr 23, 2006 12:46 pm

I just completed my 57 mod yesterday... Here's some feedback.

First off, the article says that there's supposed to be three wires going to the capsule. Mine only has two, positive and negative.... Anyone else run into this? It looks like from the picture in the article that the mic in the pic only has two as well...

I also decided to sand off all the grey paint on the foreward part of the mic instead of painting it... it looks sweeeeet but its a pain in the butt, and i think i'm getting black lung from doing it. all that really fine black powder in the air can't be good. not necessarily a recommended option, but your 57 sorta ends up looking like luke skywalker's lightsaber, so that's pretty cool, i guess.

And yeah, less honk. Did an A/B on voice with a regular 57, and the regular 57 sounded like it had a low-pass filter on by comparison. Here's a pic:

Yosh · Post by **Yosh** » Wed May 03, 2006 9:21 am

This mod looks really cool, but I don't think I'm ever going to get the current issue (#52). Somehow it must have been lost in the mail or something. I know this might be a lot to ask, but does anyone have access to a scanner so that they could post a url to a pdf of the article with the mod, so I could do it as well? Or maybe just the key instructions, and I can make sense of the rest myself. Thanks!

-Josh

bayoucables · Post by **bayoucables** » Wed May 03, 2006 9:53 am

This should be everything you need:

1. Unscrew the capsule and connector and cut the wires.
2. Heat the body of the mic with a heat gun, hair dryer, or boil in water.
3. Once the hot glue is loose, pull on the wires to remove the transformer.
4. Add two wires, one from + on the capsule to pin 2 on the connector, and one from - on the capsule to pin 3 on the connector.

Yosh · Post by **Yosh** » Wed May 03, 2006 12:09 pm

Wow, that easy. Thanks!

-Josh

gutsofgold · Post by **gutsofgold** » Tue May 16, 2006 8:02 am

I just did this to an sm58 and its decently quieter. I compensated by upping the trim on my pre's and it just seems to have a weaker pick up to it. After upping the input gain and normalising recording, it is a far broader sound with smoother lows and I guess you could say subtler mids.

mingus2112 · Post by **mingus2112** » Tue May 16, 2006 8:14 am

gutsofgold wrote:I just did this to an sm58 and its decently quieter. I compensated by upping the trim on my pre's and it just seems to have a weaker pick up to it. After upping the input gain and normalising recording, it is a far broader sound with smoother lows and I guess you could say subtler mids.

I was wondering when someone was going to try this! I've only got 2 SM57s so i don't want to trash one for the sake of science. I've got 5 SM58s though. . .so trash 'em!

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