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Author Topic: New AMI Transfomer For Shure SM57/58/AKG D12  (Read 53270 times)

panman

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #30 on: July 16, 2007, 01:32:01 PM »

Tomas Danko wrote on Mon, 16 July 2007 11:32

 Mine has the plastic frame, so I guess I don't need to bypass the transformer. Do you prefer the plastic framed one to the brass one, then?


Sorry Tomas! Not that simple. The frame weather brass or plastic only indicates roughly the age of the mic. The older ones had painted brass-frames, later ones plastic.

Roughly: If it says 60 ohm on the mic, it doesn`t have a transformer. If it says 200 ohm, it may or may not have it. If it is sold as Echolette, it usually is 200 ohm and does not have it. Nevertheless to be sure, you need to look inside.
                                                Esa

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J.J. Blair

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #31 on: July 16, 2007, 05:59:52 PM »

Oliver said his transformer should work on my D12.

Tomas, I can't say definitely that you don't have the xformer.  You might have to peak inside.  If there is a brass colored cylinder underneath, it's there, and you have to see if it's already been bypassed or not.  If it's a black cylinder, it's the plastic dummy.

As panman is saying, coils were wired at different ohms, just like the D19s, which came in 60, 200 and 1k.  I replaced all my D12 elements with the NOS capsules AKG made in the '90s, and I think those are 200.  I'm not sure, and I'm hardly an authority on this.  I'm just pointing out my findings from the five different D12s or D25s I've worked on.
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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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Tomas Danko

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #32 on: July 17, 2007, 07:46:26 AM »

J.J. Blair wrote on Mon, 16 July 2007 22:59

Oliver said his transformer should work on my D12.

Tomas, I can't say definitely that you don't have the xformer.  You might have to peak inside.  If there is a brass colored cylinder underneath, it's there, and you have to see if it's already been bypassed or not.  If it's a black cylinder, it's the plastic dummy.

As panman is saying, coils were wired at different ohms, just like the D19s, which came in 60, 200 and 1k.  I replaced all my D12 elements with the NOS capsules AKG made in the '90s, and I think those are 200.  I'm not sure, and I'm hardly an authority on this.  I'm just pointing out my findings from the five different D12s or D25s I've worked on.


Thanks for the input, Panman and JJ.

My D12 says 200 Ohm, snr: 68851 doesn't sound very early although I do know you can't really trace AKG's through the serial numbers. It sounds great, the best D12 I've heard in fact (not having heard that many, though).

My D19C says "Impedanz Var. 15 Hi" on the original cardboard box. Not that it matters in the end, but it'd be nice to know the impedance value on that mic as well. Any ideas?
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J.J. Blair

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #33 on: July 17, 2007, 11:04:03 AM »

Tomas, the collar for the low end attenuator should say either D19C/60 or D19C/200.  Whatever the last number is is your impedance.  The ones with the cable attached are D19BKs, which are 1K ohms.  
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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

Tomas Danko

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #34 on: July 17, 2007, 11:19:19 AM »

My collar (I take it you mean the ring below the bulb that you use to select S or M-mode which is the low end attenuation) only says:

AKG D19C   PATENTED   Nr: 19992   S   MADE IN AUSTRIA   M


Since it says Hi in several places on the box I guess it's not 20 Ohm. Smile

It says "D19C comb Hi" in big letters on top of the box.
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"T(Z)= (n1+n2*Z^-1+n2*Z^-2)/(1+d1*z^-1+d2*z^-2)" - Mr. Dan Lavry
"Shaw baa laa raaw, sidle' yaa doot in dee splaa" . Mr Shooby Taylor

panman

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #35 on: July 17, 2007, 11:27:26 AM »

Tomas Danko wrote on Tue, 17 July 2007 13:46


My D19C says "Impedanz Var. 15 Hi" on the original cardboard box. Not that it matters in the end, but it'd be nice to know the impedance value on that mic as well. Any ideas?


D19:s only have 60 or 200ohm coils. The "Hi"-impedance(50`000 ohm) is achieved with a transformer. These "Hi"-models usually have a cable instead of a connector on the end. There are also those with variable impedance and a five-pin XLR-connector(D19E)and then you can choose 60,200 or 50`000 ohm.

It is possible, that there are other variations, but these are what I know about.
            Esa
 
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J.J. Blair

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #36 on: July 17, 2007, 12:32:43 PM »

Yeah.  I have yet to see a "C" model with the 1k ohm output.  I've only seen those as Esa described.  Can you measure the ohm load with a multimeter?  I've never done that one a mic, so I don't know how.
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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

Barry Hufker

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #37 on: July 17, 2007, 01:38:05 PM »

It is my understanding one should not measure the resistance of a transformered mic with a volt-ohm meter...  Someone correct me.

Barry
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panman

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #38 on: July 17, 2007, 06:16:47 PM »

Barry Hufker wrote on Tue, 17 July 2007 19:38

It is my understanding one should not measure the resistance of a transformered mic with a volt-ohm meter...


I agree,that it can be dangerous to do so. However, there is a method to measure the impedance of a mic with a volt-ohm meter, where you do not measure the resistance, so there`s no danger:

Measuring  the output impedance of a microphone can be done by  driving the mic with a 1 kHz constant signal, ideally sine wave, in order to produce an unloaded reference output level, and then measuring the voltage level. A known load resistance is connected across the output and the voltage drop will be measured. The output voltage of the mic will drop exactly in half (–6.02 dB), when a load equal to the output impedance is connected across the mic output. This method is more estimating, if the the drop in voltage is not exactly half of the reference voltage.
                                     
                                     Esa
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maxdimario

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Re: New AMI Transfomer For Shure SM57/58: Anyone Know About It?
« Reply #39 on: July 20, 2007, 06:25:08 PM »

I was just thinking of a possible 'duh' version of the D12

that would be the D12 with the 50K step-up transformer with a canon plug soldered onto the wire and plugged into a 1K mic input..

now that would make for a 'vintage' sound...
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J.J. Blair

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Re: New AMI Transfomer For Shure SM57/58: Anyone Know About It?
« Reply #40 on: July 20, 2007, 07:49:19 PM »

Back on topic, I just built this little cannister last night, so that I can use the T58 with some of my transformerless dynamic mics, to see if there's a difference.

I found the Fuji cannisters to retain better transients than the Kodak cannisters, FYI.  (Sorry, Klaus!)

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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: New AMI Transfomer For Shure SM57/58: Anyone Know About It?
« Reply #41 on: July 21, 2007, 05:24:17 AM »

excellent.

the transformer will only work properly with a mic which has had the input transformer removed.

for instance the d19 which is transformerless has an impedance which is too high to drive that transformer.. If I am correct.. Oliver?


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J.J. Blair

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Re: New AMI Transfomer For Shure SM57/58: Anyone Know About It?
« Reply #42 on: July 21, 2007, 02:15:18 PM »

Unless it is a D19C/60.  IIRC, Oliver told me taht it should work with 200ohm mics, though.  I can't see the harm in trying them, anyway.  I really just want to try it with my D12, though.
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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: New AMI Transfomer For Shure SM57/58: Anyone Know About It?
« Reply #43 on: July 21, 2007, 04:50:02 PM »

OK, I just tested the T58 with a D12 retrofitted with a '90s AKG D12 capsule on a bass drum.  There were some interesting results, to say the least.  

First, I ran it into the Vac Rac pre.  I had wired the transformer in the same in/out direction as the SM57.  (At least I think I did.)  What I initially got was a serious reduction in the lower mids, with pretty much the same over all gain.  I changed the direction of the transformer, and the improvement was huge, but I lost -12dB of RMS gain.  I got all those mid lows back, plus the low end was more defined.  More important, there was a better transient attack, and the transient had more full range to it, where as without the T58, the transient was missing the lows and mids.

I then ran it into my usual 1073 that I use for kick, with my usual EQ: 12kHz shelf at 9:00, 360Hz at 3:00, and 110Hz at 8:00.  This time, the T58 only was losing -3dB, but the sound improvement was huge over the non-transformer recording, to my ears.  With the highs boosted, you could hear what that difference in the transient was with the Vac Rac.  Without the transformer, there is a boosted high frequency, but I don't know if it's something I like, at least on bass drum.  The T58 seemed to attenuate the frequency response in the 15kHz range, and put the power back into the low end, where it belongs.  This is for sure my new Ludwig bass drum configuration, from now on.  

My high end attenuation theory was confirmed when I tried the transformer with a Heil Pr30, which is a very, very bright mic.  I don't know if this is a qualitative situation, with the high end response.  It just might make it better suited for some capsules, the way that the T14/1 was better suited to the low end of the CK12, than the original T14 was.  But for my ears, the T58 is better suited to the D12, and particularly more so than the original transformer, which I quickly recognized as disliking more so than bypassing it.
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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

Tomas Danko

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Re: AMI transfomer for sm57/58 anyone know anything about it?
« Reply #44 on: July 22, 2007, 02:14:17 PM »

My D19C has a connector, but the included original cable has a grey lump inline some distance from the contact. Maybe that's the transformer?
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"T(Z)= (n1+n2*Z^-1+n2*Z^-2)/(1+d1*z^-1+d2*z^-2)" - Mr. Dan Lavry
"Shaw baa laa raaw, sidle' yaa doot in dee splaa" . Mr Shooby Taylor
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