SM57 Mod

bayoucables · Post by **bayoucables** » Tue Mar 21, 2006 11:03 pm

So I guess by now everyone has modded at least one SM57 by taking out the transformer? As soon as I read the article in this months TapeOp, I tried it. I'm sure the boiling water will work fine, but it takes about 10 seconds with a heat gun. It does just what the article says - increases low and high end and cuts output and some mids. I'm looking forward to trying it mic'ing a bass cab tomorrow.

RodC · Post by **RodC** » Wed Mar 22, 2006 5:33 am

I must have missed that one, was it in Issue #51 (January/February 2006)?

I have toyed with the idea of using a switch in the 545SD to bypass the transformer. I bypassed the tranny on a 544 one time it sounded OK but I guess I'm use to placing these mics with their normal sounds. I'll have to go back and revisit it.

ubertar · Post by **ubertar** » Wed Mar 22, 2006 7:15 am

or you could just get a DY45G. It's the same as a 545 (the predecessor the 57, and identical except it's black and silver instead of all black) except it is already transformerless.

ubertar · Post by **ubertar** » Wed Mar 22, 2006 7:19 am

I have a DY45G that I'm pretty sure has never been used (except to test). It came with an amp I got a while back. I'm happy with a plain ol' sm57, so if anyone's interested...
It has a three pin din socket, not xlr, but I have the cable for it, made by shure and also probably never used.

RodC · Post by **RodC** » Wed Mar 22, 2006 7:21 am

ubertar wrote:or you could just get a DY45G. It's the same as a 545 (the predecessor the 57, and identical except it's black and silver instead of all black) except it is already transformerless.

I guess, but I wouldn't get to destroy anthing in the process! and I would have to walk over to the mic drawer if I decided I wanted a tranny or not. Plus the DY45G is getting hard to find. Along with the 544, which is another nice one with a tranny that can be wired High or low impedance.....

bayoucables · Post by **bayoucables** » Wed Mar 22, 2006 7:39 am

The article is in issue #52, which just hit my mailbox yesterday. I'm going to take the transformer and wire it inline in a short mic cable and cover it with heatshrink. That way if I decide that I want the original sound back, I can just put the transformer back in line. I have four 57's. If the outboarding the transformer works out well, I may mod all of mine. The differnence in sound is really remarkable.

RodC · Post by **RodC** » Wed Mar 22, 2006 7:44 am

I bet a lot of it has to do with the input impedance of the preamp you are connecting to. Most newer stuff that is for low impedance is actually pretty high.

I wonder what the difference would be with an input impedance of say 500K vs 600 ohms.

Dave-H · Post by **Dave-H** » Wed Mar 22, 2006 8:35 am

I have a old 57 I got at a yard sale that is going to lose it's transformer. I have a 16" X 18" floor tom I bet it will sound great on.
Dave H.

floid · Post by **floid** » Wed Mar 22, 2006 8:47 am

cool. instant happy eq - any chance you could just wire in a bypas switch? haven't got the new issue yet (maybe i should check my mailbox?)

A-Barr · Post by **A-Barr** » Wed Mar 22, 2006 9:00 am

Hmmmmmmmm... I wonder if the PG57 and SM57 share the same capsule. The frequency responses look similar, could it be that the PG is the same mic witrh a cheaperr transformer? If so, I think I know what my next purchase will be...

bayoucables · Post by **bayoucables** » Wed Mar 22, 2006 9:34 am

You could wire in a DPDT bypass switch, but where would you put it? The shell of the SM57 is very heavy. The typical slide type switch would work, but how do you get a rectangular hole in a 1/8" thick metal cylinder? Outboarding the transformer will be very easy. I will post a pic after I do mine.

A-Barr · Post by **A-Barr** » Wed Mar 22, 2006 9:45 am

Wonder what it would sound like to plug an OTL mic like a Baby Bottle into that 57 transformer... Probably bad, but you might find some cool cobinations.

A-Barr · Post by **A-Barr** » Wed Mar 22, 2006 10:47 am

Found this on the Shure site:

"The SM58 and the SM57 elements are nearly the same; there are a few minor variations.

The Beta 57A is completely different."

Also checked the 57 schematic, and all it's got is a capsule and a transformer, so a modded 57 pretty much equals a modded 58 and vice versa. Still haven't found out about the PG's though...

A-Barr · Post by **A-Barr** » Wed Mar 22, 2006 11:07 am

OK well it looks like the PG57 uses a different capsule - RPM152 vs. R57. OPh well...

Cyan421 · Post by **Cyan421** » Wed Mar 22, 2006 12:32 pm

I was told that once you get the transformer out of the sm57 its pretty much a sennhiser 421..... But the 421 has a roll off swich. Voice to music......haha

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