Modify the Shure SM57 Microphone

[Walrus]

[quote author="rodabod"][quote author="Walrus"]
Sorry, but the 588 Unisphere B was not the same as the SM58.[/quote]

My apologies. I assumed they were the same.

However, I still stand by my argument that the cheaper Shures are pretty crap and that the Germans and Austrians do it better. :razz: But then you get what you pay for....

Walrus, any input on the SM7 and Unidyne 545 capsules?

Cheers,

Roddy[/quote]
No probs. :grin:

I agree, the cheap end Shures were just that! But they still stood up to some serious treatment before failing.

Sorry, can't really help re the SM7 other than what was pointed to already on the Shure website. It definitely uses the guts and grille of the 545 cartridege (an R45). Whether it was tweaked more re diaphragm stiffness or whatever I don't know. Certainly having a larger cavity to sit in will alter it's response.
Same goes for the 57, taking out the transformer will alter the airloading behind the diaphragm.

 

[Walrus]

[quote author="CJ"]Good stuff, Walrus!

Hey, how do I get that pop screen back on the 57?

:twisted:[/quote]
Send it over and I'll do it for you. :grin:

It's a tricky one, you have to put the bump of the circlip into one of the holes in the grille, but leave the two ends of the circlip sticking out. Then offer up the cartridge head to the grille with one of the flutes that the wires *don't8 run in to the hole side where the circlip is sitting. Then as you close the grille down onto the cartridge, you slide the circlip ends under the grilleuntil eventually you only have the two ends sticking out, and the grille is nearling down. You then use a jewellers screwdriver to flick the ends under the grille abd push the grille the final way down.
If you are lucky, they will just pop into the other hole and hold it all in place.
If you are unlucky, the diaphragm gets chewd to buggery.....

 

[khstudio]

I have an old Shure Model PE54D Unidyne III with the silver shell & it was always my favorite among the 57's I owned, especially on guitar cabs & snare but I was doing a sound job about 10 years ago & the drummer knocked the head off & now it doesn't want to work... can it be fixed? It looks like the plastic diafram is lifted up a little & deformed just a hair but I'm not sure if it's that or something else. If it's not fixable, maybe the tranny is better & can be transplanted?
All this 57 talk makes me want to fix it. I could take pictures if that would help.
Kevin

Walrus,
Thanks for your input here :thumb:

You did answer part of my question but I'd like to know if & how the PE54D's transformer is different that a regular 57:?:

Do you think transplanting it into a 57 would have any benifits :?:
... or even just a different "57 color" ?

Thanks,
Kevin

 

[Walrus]

[quote author="khstudio"]

Walrus,
Thanks for your input here :thumb:

You did answer part of my question but I'd like to know if & how the PE54D's transformer is different that a regular 57:?:

Do you think transplanting it into a 57 would have any benifits :?:
... or even just a different "57 color" ?

Thanks,
Kevin[/quote]
The transformer for the 545 has low and high impedance outputs i.e. desgned to work into either 1 to 1.5k Ohms or so for low, and into 50k Ohms or more for high.
Whereas the original 57 transformer was dual low impedance output designed for characteristic impedances of 50 or 150 Ohms.

I'm not sure if the primary of both transformers was identical or not. But you certainly won't cause any damage by putting the 57 cartridge onto the base of the 545. This would theoretically give you a high impedance 57!
As to sound, let me know. :grin:

 

[Rossi]

Thanks for the info, Walrus :thumb:

Another idea: how about using a ribbon transformer instead of the stock transformer. Primary DCR is very low on those. Even a poor ribbon tranny is usually no more than .4 DCR. Of course the output impedance would be very high. If the SM57 moving coil is about 12 ohms and the tranny has a ratio of about 1:30, you'd be at about 11 kOhms. So a phantom powered impedance converter stage would be needed. I suppose it would be impossible to fit this into the original housing, but you could either build a custom mic body - kinda like a SM7 style body - or make a little box to be used with your transformerless SM57 for low volume sources. The ribbon tranny + active impedance converter should give plenty of extra gain. Alternatively you could use the high impedance option on the dual impedance mics and use a phantom powered impedance converter stage. Actually, I might try this on the weekend with my 565SD...

Whaddeya guys think?

 

[CJ]

Way cool!

Walrus, do you know if the higher sec inpedane on the earlier 57's was just more wire on the sec, same core with a tap?
Thanks!

 

[khstudio]

KILLER :thumb:

Are you saying the actual impedence is 1-1.5k or is that what it would like to see?

Also, how close are the capsules of the 57 & 545 ?



Kevin

 

[Walrus]

[quote author="CJ"]Way cool!

Walrus, do you know if the higher sec inpedane on the earlier 57's was just more wire on the sec, same core with a tap?
Thanks![/quote]
Yes, I think it was just a tap, as there was only three wires coming out of the transformer. It's always possible that there was an internal connection from a second winding. But I think it's unlikely.
They were always supplied set for 150 Ohms.

I may still have an old transformer laying around, I could possibly post it to you if you're interested.

 

[Walrus]

[quote author="khstudio"]KILLER :thumb:

Are you saying the actual impedence is 1-1.5k or is that what it would like to see?

Also, how close are the capsules of the 57 & 545 ?



Kevin[/quote]
The 1-1.5k is the actual input load impedance the mic needs to see.

Basically the 57 is an improved and tweaked version of the 545. Same as the 58 and 565.

 

[bitman]

I just took out the tranny of one of my sm57s.

Woo-Hoo!

Not one of the 3 I use, are going to be stock anymore. It really smooths out the sound and I can get the sound without EQing that I had to EQ the snot out of the tracks before.

Do it now!

:Ron
:thumb:

 

[khstudio]

[quote author="bitman"]I just took out the tranny of one of my sm57s.

Woo-Hoo!

Not one of the 3 I use, are going to be stock anymore. It really smooths out the sound and I can get the sound without EQing that I had to EQ the snot out of the tracks before.

Do it now!

:Ron
:thumb:[/quote]
VERY COOL.

What did you try it on & how much volume drop did you notice?

I think for a snare & a MARSHALL it would be nice... I STILL haven't tried it yet... & I started this damn thread

 

[bitman]

Gee , I thought I replied to this but I don't see my post so I'll try again.

I recorded the stock 57 in front of a jcm800 1/2 stack. Then carefully removed the mic from the clip so as to not move the mic position. Then I did the mod per the tape op post, boiling out the tranny and hooking it up as follows:

Capsule End --- XLR

A -----------------> 2
Center post -----> 1
unmarked -------> 3

Then I slid it back into the clip and recorded the same riff. The marshall had heated up and sounded different as I played. (doh!) And the resulting wave form was visibly larger by about 3db than the stock one! - Hmm.

Audibly there was no difference in volume as the stock version is screechy
and the tranny removed one is smooth.

My amp must have been putting out more after it warmed up. She is an old coot of a 50w after all.

:Ron

 

[bitman]

Well, tonight the other 2 57s I have got a nice warm bath too.
Mmmmm...hard-boiled trannys......

Anyway, Mama. Mama their all modded now!
And working as dandy as the first one.

:grin:

:Ron

 

[lofi]

i hate this place!! every time i come on here some fool convinces me that way b is better than way a and i get nothing done whilst modifieing everything!!!

but as i dont shout the mods out, ppl use my studio cos it 'sounds better' than some of the others locally, but i only use cheap stuff :wink:

Iain

 

[ubertar]

How about this sm57 mod? Take out the transformer, then make up for the lost output by replacing the voice coil with one that has more windings but is the same weight by using aluminum wire. Then you've got the shure sm77.

 

[Kit]

Isnt the SM7 the same bird (as the 57´) just locked in a different cage?

It certainly looks like the same cartridge.

Hmmmmmmm..............DIY SM7? :twisted:

 

[lofi]

did the mod, but wired it up backwards no prob and easily fixed, but i recorded my mate wacking fu*k out of a snare drum with a stock 57 right next to it, and the drumers verdict ...

loads more balls and not as harsh to the ears. got to admit i agree, and this was through some bear ringer ada8000 pres.

now to change the other 4 i have .....

 

[rascalseven]

Easy there, lofi!

:shock:

I'm not sure you need to make the change to all 5 of your 57's. If you read earlier in the thread, I too have done this mod to a 57 and a 58, both of which are great, but the 'harsh to the ears' thing is exactly what can HELP the snare cut through a dense mix in a pleasant way (compared to stacks of guitar amps). You may find, in some situations (which you will be able to forcast as you get more comfortable with the modded 57) that the fullness and smoother quality of the modified 57 would now require extreme amounts of eq to sit properly in the mix, while in other mixes it'll be perfect with almost no tweaking whatsoever.

I dig the sound of the modified mic, but I don't think it blanketly makes all 57's 'better.' You might be better off keeping at least one or two stock.

Just a thought.

JC

 

[CJ]

especially if you use the 57 on stage, which is where it is used every nite.
you need the xfmr to keep the stage lights from using your mic cord as an open invitation.

hey jc, what up.
i think i figured out the carnhill thing, we were only supposed to reverse wind one of the bobbins, but it tests the same, which is why i did not take aoart the new blue one.

just a hunch, but i would have to open up a blue one and dismantle.
so no change in sound, maybe a little less hum rejection, which is the main reason for thew reverse wind.

 

[lofi]

[quote author="rascalseven"]Easy there, lofi!

:shock:

I dig the sound of the modified mic, but I don't think it blanketly makes all 57's 'better.' You might be better off keeping at least one or two stock.

Just a thought.

JC[/quote]

quite right too, i will leave one alone, but i only use them in the studio, and i record bands as seperates (small live room) so i would only need 1 for guitars.

was very impressed with the difference though.

Iain