SM57 Mod in the new TapeOP

[AdamLazlo]

I had a bunch of 57's laying around so I didn't mind doing the mod to at least one of them.

There was the obvious drop in dB but by a/b'ing a stock 57 at unity and a mod'd 57 at a compensating test level, I prefer the mod.

I find the mod'd (transformerless) 57 to be less "dumpy" and have less "honk" than a stock 57. The mod'd 57, to me, is rounder and more even.

I did a session where I had a mod'd 57 for the top snare and a stock 57 on the bottom and I loved it. I loved the top mod 57 cuz it had the beef while the bottom stock 57 had the nuts.

BUT, playing devil's advocate, my friend that owns a studio checked out my mod'd 57 and he swore he couldn't tell the difference; therefor, negating the advantage of the mod. He acknowledged the dB drop but not the characteristic difference. He said, to him, it still sounded like an SM57.

Regardless, I went ahead and mod'd another one of my SM57's, so now I have two mod'd 57's and 3 stock.... which do I grab first? The mod'd 57's. To me, yes, it's a huge difference. Am I listening for other things that my friend isn't?

I don't know. Never-the-less, I prefer the mod... and to each their own.

-- Adam Lazlo

[hugo_zair]

Originally Posted by Jim Williams

Don't apply 48 volts to these. Any mismatch of the phantom distibution resistors will cause one end of the capsule's coil to be a higher voltage potential than the other, possibly frying the coil wire. Most phantom resistors are 6.81 k 1%. This could let around .25 volts difference from one end to another. If one matches these resistors to .1% that would keep the potential down to 25 mv or less.
The other effect would be to push/pull the capsule out of it's idle position, sort of like when dc offsets push/pull a speaker in a power amp.

Best to be attentive and keep that phantom switch off at all times.

Protect the Unidyne III's!

Jim Williams
Audio Upgrades

Many many apologies for resurrecting an old thread. Wouldn't have done it except I got pointed to Jim's reply from another site here: Shure SM57 (RecordingHacks.com) where this post is linked to to expand on the statement there that phantom power may damage a tranformerless SM57.

As a newbie to this forum I ask this question with some trepidation..but ask it I must. Where, in an electrically isolated capsule, as is the case in a balanced microphone circuit, can current flow? With no current flow, irrespective of the source resitance of each leg, the voltage (to ground) is 48v. Both sides of the capsule surely are at 48v and hence no current can flow through it, and no damage can be done.

If current flow could occur (due to mismatched resistors or whatever) then the situation with a dynamic mic WITH a transformer might also be a problem. These tiny transformers might be fully or partially saturated by the DC current flow Tim refers to above. This surely would have a substantial effect on the audio quality of the mic's output.

Quote from the Shure website "A balanced dynamic microphone is not affected by phantom power. However, an unbalanced dynamic microphone will be affected. Although the microphone will probably not be damaged, it will not work properly."


(source Shure - Phantom Power and Bias Voltage: Is There A Difference?)


If the microphone was wired for unbalanced use, ie fitted with a 1/4 mono jack, phantom power might be an issue - assuming of course it was somehow possible to plug it in to the phantom powered source. Not something that's likey to be done.

Anyone got any thoughts?

[Michael_Joly]

Originally Posted by hugo_zair

...Where, in an electrically isolated capsule, as is the case in a balanced microphone circuit, can current flow? With no current flow, irrespective of the source resitance of each leg, the voltage (to ground) is 48v. Both sides of the capsule surely are at 48v and hence no current can flow through it, and no damage can be done.

Right. You describe a theoretically ideal situation where phantom power resitors are closely matched and the entire phantom power circuit from preamp to microphone XLR is in good working order (no cable breaks, cable pair resistance imbalance or intermittant connections).

But the caveat against phantom power in ribbon and dynamic microphones is a real world warning - phantom resistors may not be perfectly matched, cable leads may go intermittant, connections may corrode and lead to higher resistance, patch bay connections may introduce conductor pair resistance imbalance etc. So the popular admonition to avoid phantom power with ribbon and moving coil dynamic mics is good advice.

But back to SM-57 mods...

...I'm working on free mods for the ES-57 and ES-58 copies of the SM-57 and SM-58 mics. The before / after difference in tonal quality is much more pronounced that the popular transformer swap or cut-out mod. And, in the case of the ES-58 the mod is reversable. The mods provide a timbre-balance more closely related to the SM7 sound than the 57 / 58 sound. I'll publish these soon as a holiday gift.

[xhavepatiencex]

Originally Posted by Michael_Joly

...I'm working on free mods for the ES-57 and ES-58 copies of the SM-57 and SM-58 mics. The before / after difference in tonal quality is much more pronounced that the popular transformer swap or cut-out mod. And, in the case of the ES-58 the mod is reversable. The mods provide a timbre-balance more closely related to the SM7 sound than the 57 / 58 sound. I'll publish these soon as a holiday gift.

this sounds awesome, i have a few of these mics laying around from years ago. I can't wait!

[big country]

easyer than boiling the mic , just take the cap off that covers the diaphram or with the 57s use a dremil
and grind it off , gives ton low end

takes the ch out of it

for vocals I think leave it alone but but drums it would be cool

[big country]

I m thinking boiling a transformer wouldn't be a good idea

if you cook the lacker off of the wire the transformer wouldnt work but
finally a lesson I did not learn on my own ( yeah!)

could be a good way to clean the wire
before soldering mag wire ?

[big country]

how do guys clean mag wire ?

I have found the best is drimil with a sander .
I used a belt sander, cooked it off with a lighter ( not so good )
( a good way to weld small wire together is with a lighter)

pickups and voice coil wire it works .

[Michael_Joly]

Originally Posted by xhavepatiencex

this sounds awesome, i have a few of these mics laying around from years ago. I can't wait!

Ok, here's the tutorial for a Free Do-it-Yourself modification for the popular SM-58 copy - the ES 58.

This mod allows you to tune or eliminate the stock presence boost built into this mic. Enjoy! Best, Michael

[big country]

Originally Posted by Michael_Joly

Ok, here's the tutorial for a Free Do-it-Yourself modification for the popular SM-58 copy - the ES 58.

This mod allows you to tune or eliminate the stock presence boost built into this mic. Enjoy! Best, Michael

do you prefer this to no cap over the diaphram?

[Michael_Joly]

Similar to choosing any mic, this mod is application dependent. There is less smearing of "S"s, transient response is improved and a certain mid-to-high frequency range presence is reduced. This all may be a good thing if that is what the situation calls for, or a bad thing if more hyped and lo-fi sound is called for.

[hobson]

review old threads on this subject - one included a shootout among the popular (3) variations - Mercenary TabFunk57 / stock 57 / xformless 57.

at the studio we have (1) Mercenary TabFunk57 - very nice! we took (3) of our original (6) SM57's and removed the tranformers - results were quite nice too - though initially the boiling of the first test 57 went a little longer than expected (note: do not leave boiling unattended - despite the old saying).

we also discovered that if boiled too long the barrel paint will chip and become cracked - so we removed the paint and brushed the metal - damn! if they don't look like older two-tone unidyne's now... cosmetic'ly speaking.

but sonically - we liked the results - more apparent lowend response and a smoother (somewhat) extended topend... volume loss was negligible.

just my .02

[hugo_zair]

Originally Posted by Michael_Joly

Right. You describe a theoretically ideal situation where phantom power resitors are closely matched and the entire phantom power circuit from preamp to microphone XLR is in good working order (no cable breaks, cable pair resistance imbalance or intermittant connections).

But the caveat against phantom power in ribbon and dynamic microphones is a real world warning - phantom resistors may not be perfectly matched, cable leads may go intermittant, connections may corrode and lead to higher resistance, patch bay connections may introduce conductor pair resistance imbalance etc. So the popular admonition to avoid phantom power with ribbon and moving coil dynamic mics is good advice.

But back to SM-57 mods...

...I'm working on free mods for the ES-57 and ES-58 copies of the SM-57 and SM-58 mics. The before / after difference in tonal quality is much more pronounced that the popular transformer swap or cut-out mod. And, in the case of the ES-58 the mod is reversable. The mods provide a timbre-balance more closely related to the SM7 sound than the 57 / 58 sound. I'll publish these soon as a holiday gift.

The easy one first...I can'y find that ES-58 advertised anywhere except in the US. I'm UK and am wondering if you've ever opened an easily available Behringer XM8500 and can say whether the construction is similar....

Now I'm going to stick my head over the parapet on the capsule damage isssue. Mike.. you've reitereated the same argument given by Jim - that phase line resistance imbalance can cause a voltage difference across the capsule. The extra resistances you mention - cables, patchbay jacks or XLR's are all normally very low R and insignificant compared to the 6.8k source resistances. If they go high, they can only reduce dc current flow thru a (faulty) dynamic mic circuit. If a phase leg goes OC that would stop any current flow completely.
Basically these variations or mismatches in all of the resistances mentioned only affect the CMRR.

I have poted three circuit diagrams here: PHANTOM CCTS

The top circuit (A) is not a theorectical ideal but a real life circuit of a working mic connected to a phantom powered circuit. It's my contention that no current can flow through the capsule regardless of the values of any of the resistances in the circuit (Rcable, Resistance at connectors or even errors in the values of the 6.8K's) It's a bit like a bird sat on a powerline not being fried.

The next two circuits illustrate faults that might cause current flow through the capsule. Circuit (B) has a broken wire that has ALSO connected to ground. Perhaps inside an XLR. Circuit (C) illustates the situation where a duff cable is wired wrongly with ground and a phase wire crossed. Assuming that either of these faults could exist in your studio without being detected immediately (CT100 !), in either of these two circumstances approxiamately 7ma would flow throught the capsule.

This is a worse case cenario. It assumes a phantom supply that can source 14ma and I read that many older mixers etc may source less - from 2ma upwards. With the capsule resistance I've represented (200 ohms) the disapation (heating effect that could cause "frying") is 9.3 milliwatts. With a sm57 capsule which I understand has a 50 ohm capsule the disapation would be 2.35 milliwatts. My feeling is the capsule would not be bothered by such a small current flow. (I don't know about ribbon mics.)

So, I'm saying that in normal circumstances, with a working mic and properly wired cable no damage can occur to a dynamic mic plugged into a phantom powered socket - or even that any current can flow through it at all.

A small current may flow if the mic already has a broken wire internally that is ALSO shorted to case..or it is connected up with a faulty cable as shown incircuits B & C.

It would however be zapped if one of the 6.8k's had gone very low resistance AND a cable fault existed. but so would condensor electronics in any circumstances.

I agree that's there no harm in "the popular admonition to avoid phantom power with ribbon and moving coil dynamic mics" but with many interfaces available now with no individual switches to control phantom power, many of us have no choice.

Ok now shoot me down...

[Colorblind]

Originally Posted by hugo_zair

The easy one first...I can'y find that ES-58 advertised anywhere except in the US. I'm UK and am wondering if you've ever opened an easily available Behringer XM8500 and can say whether the construction is similar....

I'm wondering the same thing...

[big country]

Originally Posted by Colorblind

I'm wondering the same thing...

Official Speaker Repair Site - Orange County Speaker Repair and Sales - SpeakerRepair.com

I think its OC speaker repairs design

its design is nothing like a 57

it looks like they just put new magnets in it ?

according to Michael Joly's pictures

[Marogru]

Ok, guys, I have a very important question...

Do boiling the SM57 downpart can detroy the pot?
Will the silicone (or whatever is in there) boil out and glue the pot or it will shrink?

I wanna use my cooking pot and I don't want to shit silicone after, even if it can come out smooth.

[Teddy Ray]

Originally Posted by Marogru

Ok, guys, I have a very important question...

Do boiling the SM57 downpart can detroy the pot?
Will the silicone (or whatever is in there) boil out and glue the pot or it will shrink?

I wanna use my cooking pot and I don't want to shit silicone after, even if it can come out smooth.

I cooked grits in my 57 pot this morning. didnt taste silicon.
it will be fine.

[PMoshay]

I have lots of 57's old and semi-new and they can vary a bit with age / abuse i have found.

I have a bunch of old "May" mics from the 80's that were in my drum kit, they obviously did not put transformers in them, and even when i was a kid starting out i knew they did not sound like a regular 57 on my kit. Back then a engineer friend of mine back then mentioned that they sounded "fatter" than a 57......... little did i know back then why.

I did a comparison in the Gear Shootout forum of a normal 57, Transformerless 57 & modded 57..... you can listen and see what they sound like on different instruments.
We did this for our own purposes......... Just because we love hearing things for ourselves.
SM57's Modified & Stock Tests

[John Eppstein]

This mod first surfaced in the SF Bay Area in the late '70s-early '80s when we used to use it to convert the old Hi z Unidyne IIIs to low Z. It works.

[John Eppstein]

Originally Posted by hugo_zair

Many many apologies for resurrecting an old thread. Wouldn't have done it except I got pointed to Jim's reply from another site here: Shure SM57 (RecordingHacks.com) where this post is linked to to expand on the statement there that phantom power may damage a tranformerless SM57.

As a newbie to this forum I ask this question with some trepidation..but ask it I must. Where, in an electrically isolated capsule, as is the case in a balanced microphone circuit, can current flow? With no current flow, irrespective of the source resitance of each leg, the voltage (to ground) is 48v. Both sides of the capsule surely are at 48v and hence no current can flow through it, and no damage can be done.

If current flow could occur (due to mismatched resistors or whatever) then the situation with a dynamic mic WITH a transformer might also be a problem. These tiny transformers might be fully or partially saturated by the DC current flow Tim refers to above. This surely would have a substantial effect on the audio quality of the mic's output.

Quote from the Shure website "A balanced dynamic microphone is not affected by phantom power. However, an unbalanced dynamic microphone will be affected. Although the microphone will probably not be damaged, it will not work properly."


(source Shure - Phantom Power and Bias Voltage: Is There A Difference?)


If the microphone was wired for unbalanced use, ie fitted with a 1/4 mono jack, phantom power might be an issue - assuming of course it was somehow possible to plug it in to the phantom powered source. Not something that's likey to be done.

Anyone got any thoughts?

If capsule damage was a real possibility, Shure would never have produced their own transformerless version of the 57, the SM77... (I'm pretty sure that was the number, they only made it for a few years....)

[Beyersound]

Originally Posted by Sven

Why not just get Audix i-5?

I was thinking the same thing!

[Fletcher]

My word there is no shortage of really shitty information in this thread!!

First off, if you have a newer 57 you'll want to heat the handle [which you can do in boiling water or a toaster oven] to "melt" the adhesive they use to hold in the transformer... but if it's an older mic you need a chemical solution like acetone in order to break down the adhesive.

Second, taking the grill off is about the best way I know to give the mic a death sentence. Yeah... you'll get through the session... but subsequent handling will eventually lead to a rip in the diaphragm material.

Third... removing the transformer entirely is a viable trick... but you're going to not only end up with a lower output but also a serious impedance mismatch with most mic pre's... it also puts the mic at serious risk of getting trashed by phantom power. If you're very careful 100% of the time that won't be a problem... but if you're like me and thinking about 100 different things at any given second and sometimes mis mundane details like that [and work with people who tend to drink a bit]... perhaps it's best to keep your tools in a situation where they're not immediately exposed to imminent danger.

Good luck... some of you are gonna need it.

Peace.

[Les]

Second, taking the grill off is about the best way I know to give the mic a death sentence. Yeah... you'll get through the session... but subsequent handling will eventually lead to a rip in the diaphragm material.

Third... removing the transformer entirely is a viable trick... but you're going to not only end up with a lower output but also a serious impedance mismatch with most mic pre's

Hi Fletcher

I should mention that there is a small plastic resonator disc in the grill assembly that is removable. The grill can then be replaced. This will change the upper mid peak.

As far as the impedance mismatch... I think some of the response changes are from having the capsule much more electrically unloaded.
A 2K mic pre input is practically an open circuit to 12 ohms. 57s are a little load sensitive as far as frequency response, as are most cardioid dynamics and ribbons. I haven't measured, but I would expect a bit of a peak at diaphragm resonance... about 100 hz IIRC. Putting about 100 ohms across the capsule might change this.

Les
L M Watts Technology

[RTR]

I just operated on mine, I boiled it after removing the top part (cuting the wires) and the male xlr...I used a screwdriver to pull out the glue..no problem...now I am just woundering what wires go where..the capsual has a yellow and green wire and the xlr has a blue and red..what one go's to what?

[Les]

the capsual has a yellow and green wire and the xlr has a blue and red..what one go's to what?

Assuming the transformer secondary is unhooked, capsule green to xlr blue (pin 2) and capsule yellow to xlr red (pin 3).

Les
L M Watts Technology

[mdoelger]

Hi there did it!

And, I like the results. However, I didn't care to boil it. I just used one of those very hot "hairdryer"-things (edit: searched it: hot-air gun). I don't know whats it called in english. But if you have one of those around, use it. It took about half a minute, and you can heat it just as much up so that you can pull out the tranny.

I believe if you boil too long all the adhesive will melt and u end up with a mess.

Just a hint.

BTW...I think it sounds pretty good. I did an sm58 and it will do a good job on vocals I believe. Have to test it out tomorrow.

The whole mod took about 20 minutes. and if you are careful and don't **** with the tranny () you can even reassemble it. However, I won't.

Cheers!

[pittsburgh]

I'm looking for a part the housing, or cage, for the 57 or a part that will work in place of it made by another company. Does anyone know about the behringer XM8500? Does it screw apart like a 57? If so, does it fit a R57 replacement 57 capsule. Thanks for any help.

-p