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Author Topic: New AMI Transfomer For Shure SM57/58/AKG D12  (Read 23986 times)

ratite

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New AMI Transfomer For Shure SM57/58/AKG D12
« on: June 28, 2007, 01:07:46 pm »

 In the recent AMI Tabfunken newsletter I found (a notice that Oliver Archut has developed a replacement transformer for the Shure SM58 stage mic.)

Has anyone used it or know any details as to installation, benefits, design philosophy et al?

Futhermore what is a "voicecoil to mic-pre" transformer?  
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Richard Horner
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J.J. Blair

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #1 on: June 28, 2007, 01:38:27 pm »

A voice coil to mic pre transformer converts the signal from the voice coil to a usable level.  Most dynamic mics have them.  In this case, you replace the existing SM57 transformer.  

Oliver is sending me a couple of these. I'll report back after I play with them.
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They say the heart of Rock & Roll is still beating, which is amazing if you consider all the blow it's done over the years.

"The Internet enables pompous blowhards to interact with other pompous blowhards in a big circle jerk of pomposity." - Bill Maher

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ratite

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #2 on: June 28, 2007, 08:44:06 pm »

So does this mean you need to boil out the glue that holds in the original xformer as detailed in Terry Mannings transformerless 57 thread?Does it also mean there are no components between the voice coil and transformer in a 57/58?I've never opened one.
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Richard Horner
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J.J. Blair

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #3 on: June 28, 2007, 09:53:21 pm »

Yes, I boiled out the transformer.  It is as you described.
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They say the heart of Rock & Roll is still beating, which is amazing if you consider all the blow it's done over the years.

"The Internet enables pompous blowhards to interact with other pompous blowhards in a big circle jerk of pomposity." - Bill Maher

"The negative aspects of this business, not only will continue to prevail, but will continue to accelerate in madness. Conditions aren't going to get better, because the economics of rock and roll are getting closer and closer to the economics of Big Business America." - Bill Graham

J.J. Blair

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #4 on: June 29, 2007, 06:44:32 pm »

Here's the deal:

I took two Shure SM-57s (about twelves years old, very low miles, made in Mexico).  I replaced the transformer in one of them, and  used the capsule portion of only one of the mics, to eliminate any differences.  Using alligator clips, I changed the lower half of the bodies with the different transformers, never moving the capsule portion on the source.  They went into the same cable, with the same API 512b with pad engaged (which I had to, considering the source).  That went directly into an Apogee AD16-X, with no soft limiting, at 88.2/24 bit.  The final file is a mono 44.1/16 bit aiff.

The sources are a black beauty snare, a keystone badge Ludwig tom, and a badly played Keith Richards riff, on a reverse Firebird through a Selmer.  The first go round of the figure is on transformer, and the second go round is the other.

I'll tell you all in a week or less which was which, as I want to keep it blind.  

I don't know if these are the best sources for these test, but these are the only things I would consider using SM57s on in the studio, and on toms, it would be my very last option.

Shure v. AMI.zip
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They say the heart of Rock & Roll is still beating, which is amazing if you consider all the blow it's done over the years.

"The Internet enables pompous blowhards to interact with other pompous blowhards in a big circle jerk of pomposity." - Bill Maher

"The negative aspects of this business, not only will continue to prevail, but will continue to accelerate in madness. Conditions aren't going to get better, because the economics of rock and roll are getting closer and closer to the economics of Big Business America." - Bill Graham

Klaus Heyne

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #5 on: June 29, 2007, 06:50:57 pm »

A hint on the file, where one mic/trafo ends and the other starts, would help me greatly!
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J.J. Blair

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #6 on: June 29, 2007, 07:32:39 pm »

Sorry.  The first snare is one xformer, the second is the other.  Same with the tom.  Each sample starts quiet, gets louder and then quiet again.  And with the guitar, the first four bars are one xformer, and the last four are the other.

I hope that makes sense.
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They say the heart of Rock & Roll is still beating, which is amazing if you consider all the blow it's done over the years.

"The Internet enables pompous blowhards to interact with other pompous blowhards in a big circle jerk of pomposity." - Bill Maher

"The negative aspects of this business, not only will continue to prevail, but will continue to accelerate in madness. Conditions aren't going to get better, because the economics of rock and roll are getting closer and closer to the economics of Big Business America." - Bill Graham

maxdimario

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #7 on: June 30, 2007, 05:33:10 am »

another idea would be to have an external transformer, this way you could make it bigger, and you could also switch it in and out in case you were recording loud sources and you didn't need the step-up transformer.

JJ, I would have liked to have heard a drum kit overhead as I think it's a good way to judge any mic. can you record one?

anyway it seems the second of each take saturates less and has a better bottom and top as well as integrity of the transients.
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J.J. Blair

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #8 on: June 30, 2007, 12:52:49 pm »

Max, I'll give that a try today.  

BTW, it's worth noting that Oliver says that having the rear section of the 57 removed changes the pickup pattern and possibly the frequency response, as the mic uses that cavity for its acoustic network.  Having to change the body though would have required soldering and unsoldering each time, as well as moving the capsule, which would have created another variable.  So just keep in mind that the final results may sound different with the rear half of the mic attached.
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studio info

They say the heart of Rock & Roll is still beating, which is amazing if you consider all the blow it's done over the years.

"The Internet enables pompous blowhards to interact with other pompous blowhards in a big circle jerk of pomposity." - Bill Maher

"The negative aspects of this business, not only will continue to prevail, but will continue to accelerate in madness. Conditions aren't going to get better, because the economics of rock and roll are getting closer and closer to the economics of Big Business America." - Bill Graham

compasspnt

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #9 on: July 01, 2007, 08:14:58 pm »

I actually have high hopes for these, as the tranformerless ones I modded had better highs and lows than with the Shure trans.  But the level was about 12 dB lower.

BTW, the procedure I posted a while back for removing the stock trans from both a 57 and a 545S was in this thread:

  http://recforums.prosoundweb.com/index.php/mv/msg/8394/0/0/6 490/
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J.J. Blair

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #10 on: July 11, 2007, 01:17:54 am »

Here's the answer to what's what.  Honestly, I had a hard time hearing a difference.  That may be more the shortcoming of the moving coil element.  You can only make that thing sound so good, you know?

:00 - :16 is the SM57 xformer
:16 - :36 is the T58
:36 - :52 is the SM57
:52 - 1:00 is the T58
1:06 - 1:3 is the T58
1:13 - end is the SM57

I gain adjusted the guitar tracks so that I could bounce the file and have a fairly consistent RMS level between the drums and the guitar.  

I put up the soundfiles in case you guys here something that I don't.   Max seemed to hear a difference.  I can generally tell the difference between capsules.  All my D19s are marked with their qualities on them (clear, dark, boomy, bright, etc.).  Perhaps the spectrum of the SM57 is too narrow for me to discern the type of differences that my ears are trained for.  I dunno.  As I said, please listen to the aiff files and draw your own conclusion.
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They say the heart of Rock & Roll is still beating, which is amazing if you consider all the blow it's done over the years.

"The Internet enables pompous blowhards to interact with other pompous blowhards in a big circle jerk of pomposity." - Bill Maher

"The negative aspects of this business, not only will continue to prevail, but will continue to accelerate in madness. Conditions aren't going to get better, because the economics of rock and roll are getting closer and closer to the economics of Big Business America." - Bill Graham

compasspnt

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #11 on: July 11, 2007, 07:31:02 pm »

Osie today mounted each of the two transformers into a small Bud Box, with XLR panel mount jacks on either end for I/O.

My plan had been for the end of a 57/58/what-have-you to just plug straight into the box itself, but I forgot that the microphone body was too big in diameter for that to happen.  So we just got the very shortest mic cable we could find, barely longer than the two connectors themselves.

I haven't yet had time to do a proper test with instruments and voices, but I couldn't stand waiting to hear this, so I just perfrormed a very simple, non-scientific, uncontrolled "Voice In The Control Room" test.

I took two SM-57's, versions purchased at the same exact time (about 1984).  One of these was totally stock.  The other one is the one from which I had previously removed the Shure transformer.  So ideally, as many variables as possible for such a quick test were eliminated.

I spoke a simple "test" phrase into each microphone, run through the same cable into the same API 512c, direct into Protools through Apogee AD-16x.  I recorded the phrase twice, once with each microphone, with my lips just almost touching the capsule end.  This of course put me into proximity effect, but if one were speaking or singing through such a microphone, that's what one usually would do.

Here are the results:

The new AMI seemed to have a slight bit more volume overall, but of course, that could possibly be attributed to my speaking voice variance between the two recordings.  But I did make every effort to minimise this.

The stock Shure transformer version was more strident in the upper midrange and "sibilance" areas, and not in a pleasant way.  This is one of the things that I often dislike in a 57, that almost artificial "twang" that often seems to happen.  

The AMI transformer did not exhibit this effect nearly so much.  The AMI in fact had a noticeably smoother, rounder quality.  The lows were also more pronounced, so that may have actually been covering up any upper mid stridency a bit as well.  But the "extra lows" were not too much so, just fuller and more pleasing to the ear.

The AMI had a much more pleasing sound on "s's" and uncomfortable sibilance was reduced from what the stock trans exhibited.

Overall I would give the new trans a quick thumbs up.

But there is obviously a lot more testing to do, and I intend to get to that in the next few days.

For now, that's the quick and dirty 25
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compasspnt

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #12 on: July 11, 2007, 07:51:03 pm »

Addendum to the above test:

Because I also had some other elements at hand, I decided to quickly add to the test.

I also have a much older 545S with Unidyne capsule from which I had previously removed the transformer, so I did the same exact test with that microphone.  The results were very similar, but the older capsule *seemed* to have an even more pleasing sound to it (compared to the "newer" '84 version).  The lows were again rounder and more pleasing than the stock 57, but the high end was even smoother than with the AMI-modded 57.

As another comparison, I also did the test using yet a different 545S from which I had removed the transformer, but had replaced it with a Rode PowerPlug.  This device requires phantom power, so that had to be added.

The output was considerably higher, seemingly by about 5-6 dB, and there was a corresponding increase in self noise (hiss).  But the hiss seemed to be louder relative to the signal that it would have been had the overall volumes been consistent.  But the sound quality was more reminiscent of a powered (usually meaning condenser) microphone...the character had definitely changed.  This would be desireable for some things, and not so for others, depending upon your taste.

Non-Science concluded for the day.
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J.J. Blair

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #13 on: July 11, 2007, 08:58:21 pm »

Thanks, Terry.  Perhaps the '84 coil is better than the Mexican coil.  I also want to point out that the things I was recording have a limited range, so knock yourself out with trying other things.  I only included things that I might ever think of using a stock 57 on, which may have made my test faulty to begin with.  I dunno.
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They say the heart of Rock & Roll is still beating, which is amazing if you consider all the blow it's done over the years.

"The Internet enables pompous blowhards to interact with other pompous blowhards in a big circle jerk of pomposity." - Bill Maher

"The negative aspects of this business, not only will continue to prevail, but will continue to accelerate in madness. Conditions aren't going to get better, because the economics of rock and roll are getting closer and closer to the economics of Big Business America." - Bill Graham

bushwick

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #14 on: July 13, 2007, 10:30:16 am »

I tried a 58 that was already modded with one of these against a new one that I bought at the store. I tested the mics on voice and guitar. My assistant and I found the transformer gave the mic more reach on the top end than the mic has stock. It is interesting that the stock transformer is rolling off as much as it is. The difference was pretty clear to both of us, even as informal as our tests were. JJ, I am betting that having the mics opened on the back is the reason for you not hearing more of a difference. The only other possibility is that the 58 that was sent to me modded was just different than a newly made one. I have not heard a 57 or 58 with the transformer taken out like Terry has done, but I would suspect that Oli's transformer is much closer to that since it removes the limited frequency response of the mic in stock form. The coils inside the mic can definitely pick up more info than the stock transformer lets through.

Best,
joshua
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Joshua Kessler
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