Post by: ratite on June 28, 2007, 01:07:46 PM
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?
Post by: J.J. Blair on June 28, 2007, 01:38:27 PM
Oliver is sending me a couple of these. I'll report back after I play with them.
Post by: ratite on June 28, 2007, 08:44:06 PM
Post by: J.J. Blair on June 28, 2007, 09:53:21 PM
Post by: J.J. Blair on June 29, 2007, 06:44:32 PM
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
Post by: Klaus Heyne on June 29, 2007, 06:50:57 PM
Post by: J.J. Blair on June 29, 2007, 07:32:39 PM
I hope that makes sense.
Post by: maxdimario on June 30, 2007, 05:33:10 AM
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.
Post by: J.J. Blair on June 30, 2007, 12:52:49 PM
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.
Post by: compasspnt on July 01, 2007, 08:14:58 PM
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/
Post by: J.J. Blair on July 11, 2007, 01:17:54 AM
: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.
Post by: compasspnt on July 11, 2007, 07:31:02 PM
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
Post by: compasspnt on July 11, 2007, 07:51:03 PM
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.
Post by: J.J. Blair on July 11, 2007, 08:58:21 PM
Post by: bushwick on July 13, 2007, 10:30:16 AM
Best,
joshua
Post by: Jim Williams on July 13, 2007, 11:15:56 AM
Post by: maxdimario on July 14, 2007, 07:05:57 AM
Yes,I heard a difference on JJ's sound files, especially the drums.
with the guitar, being an artificial and distorted sound to begin with, it's difficult to determine what is obviously 'cleaner' one way or another, but there is a noteable difference between the two...
What you need to listen to is the initial attack of the drums and the decay in the bottom end, as well as the general air around the sound.
the AMI transformer beat the shure..
regarding the older shure mic..as with all circuit improvements, there is MORE of a difference when the sound source is better to begin with (has more reality-information to it) so that would imply that the AMI transformer is letting the sound through, unless the old shure transformer is worse than the new..
Post by: J.J. Blair on July 14, 2007, 10:18:48 AM
Max, I think maybe I was looking for improvement in tone, and not just transient response. I think what sucks about 57s is their tone, and I guess my hope was that the T58 would do something about that.
Post by: maxdimario on July 15, 2007, 12:54:27 PM
transformer distortion can be described as fuzzy, tinny, lo-fi but unless it is a *total* piece of junk it will not significantly alter the sound of the mic.
Does the D12 have a transformer? I didn't know that.
Post by: Barry Hufker on July 15, 2007, 12:58:42 PM
Post by: J.J. Blair on July 15, 2007, 03:00:32 PM
Post by: Tomas Danko on July 15, 2007, 03:04:06 PM
| J.J. Blair wrote on Sun, 15 July 2007 20:00 |
Earlier D12s do. I just worked on a friend's plastic ringed D12, and there's a dummy plastic transformer for the capsule to attach to. |
Not to hi-jack this thread, but how can one spot the difference between those two D12's without pulling them apart?
Post by: Oh! My Sea Captain! on July 15, 2007, 04:54:39 PM
To those of you who have them, and minus whatever enjoyment you may have had while doing the conversion, is it worth it?
Post by: compasspnt on July 15, 2007, 05:22:19 PM
When the drive to improve *anything* stops, the betterment of humanity lessens.
Post by: maxdimario on July 15, 2007, 05:35:34 PM
otherwise change mic altogether.
it seems many people DO use 57's though... right?
Post by: Barry Hufker on July 15, 2007, 05:52:05 PM
Barry
Post by: Tomas Danko on July 15, 2007, 06:08:59 PM
Some people say they fail easily, but I have yet to see one that didn't survive a weekend in Mr. Wittman's carpenter shed after the completion of putting together a wooden stool.
It's still a useful tool (stool?) sometimes.
Post by: J.J. Blair on July 16, 2007, 03:43:59 AM
| Tomas Danko wrote on Sun, 15 July 2007 12:04 | ||
Not to hi-jack this thread, but how can one spot the difference between those two D12's without pulling them apart? |
The frame that the baskets attach to is either plastic or painted brass. I've only been inside one D12 with plastic a frame, and it was as I described. I do recommend that you try bypassing the transformer, if there is one in your D12. Just wire the capsule directly to the XLR output. In my case, the results were great.
Post by: panman on July 16, 2007, 05:23:27 AM
J.J.stated an improvement, when removing the x-former. I agree, but at the same time you may loose the ideal 200ohm. So a better x-former would be the solution.
So my question to Oliver Archut: Have you made or do you plan to make a transformer for D12? I understand, that the difference cannot be big, but anything audible makes sense already.
Esa
Post by: Tomas Danko on July 16, 2007, 05:32:56 AM
| J.J. Blair wrote on Mon, 16 July 2007 08:43 | ||||
The frame that the baskets attach to is either plastic or painted brass. I've only been inside one D12 with plastic a frame, and it was as I described. I do recommend that you try bypassing the transformer, if there is one in your D12. Just wire the capsule directly to the XLR output. In my case, the results were great. |
Thanks JJ. 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?
Post by: panman 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
Post by: J.J. Blair on July 16, 2007, 05:59:52 PM
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.
Post by: Tomas Danko 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?
Post by: J.J. Blair on July 17, 2007, 11:04:03 AM
Post by: Tomas Danko on July 17, 2007, 11:19:19 AM
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.
It says "D19C comb Hi" in big letters on top of the box.
Post by: panman 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
Post by: J.J. Blair on July 17, 2007, 12:32:43 PM
Post by: Barry Hufker on July 17, 2007, 01:38:05 PM
Barry
Post by: panman 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
Post by: maxdimario on July 20, 2007, 06:25:08 PM
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...
Post by: J.J. Blair on July 20, 2007, 07:49:19 PM
I found the Fuji cannisters to retain better transients than the Kodak cannisters, FYI. (Sorry, Klaus!)
Post by: maxdimario on July 21, 2007, 05:24:17 AM
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?
Post by: J.J. Blair on July 21, 2007, 02:15:18 PM
Post by: J.J. Blair on July 21, 2007, 04:50:02 PM
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.
Post by: Tomas Danko on July 22, 2007, 02:14:17 PM
Post by: rodabod on July 30, 2007, 12:34:12 PM
With the AKG D12, adding the transformer in the standard step-up configuration will result in an output impedance which is too high and this will result in low-end losses when paired with a standard mic preamp.
I think even with the lower output impedance of the AKG 60 Ohm models you might be pushing it. As far as theory goes, I don't really see the need in using a transformer in these mics unless it offers some sonic benefit (as it did for JJ in reverse with his D12).
I'm interested in the results with the D12 paired with the transformer in reverse. Could it be that the lower impedance presented by the combination worked better with JJ's preamp? Who knows.
As far as the D19 is concerned, there would only be a transformer use inside if it were a multiple output impedance model as far as I know.
Roddy
Post by: maxdimario on July 30, 2007, 03:37:40 PM
Oliver's transformer was designed for the voice coil of the sm 57 which I am GUESSING (so please someone correct me) is very low, like less than 10-20 ohms.
placing a d12 with a source of 200 ohms will reduce high end and possibly cut off bottom.
by turning the transformer around you are actually raising the impedance that the d12 sees and lowering the impedance to the mic pre, which results in more extreme bottom and top.. depending on overload. In this case the transformer acts as a step-down.
Post by: jrmintz on April 24, 2009, 08:43:29 PM
| panman wrote on Tue, 17 July 2007 11:27 | ||
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. Esa |
I resurrected this thread because I have a Norelco D12 HI with attached cable. The sound of it has never killed me, but I'm just realizing that I've been using a high-impedance microphone into a low impedance preamp input. Can I just bypass the transformer to get a 200 Ohm output? Would it be better to use a line transformer, or even a direct box?
Thanks,
Seth
Post by: panman on April 25, 2009, 06:19:03 AM
| jrmintz wrote on Sat, 25 April 2009 02:43 |
I resurrected this thread because I have a Norelco D12 HI with attached cable. The sound of it has never killed me, but I'm just realizing that I've been using a high-impedance microphone into a low impedance preamp input. Can I just bypass the transformer to get a 200 Ohm output? |
Hi Seth, first to answer your question: bypassing the transformer will get you 60ohms output and a decent sound if the capsule(60ohms) itself is ok. This unfortunately is usually not the case. I`ve seen only one of these Norelco D12Hi:s and it had the same transformer as the slightly different looking Philips D12:s sold in Europe, just wired differently. They have 50/500/50000ohms (unbalanced)depending on how the special connector is twisted around. This trafo is filling up all the space inside the bass-chamber and has to be removed to get full bass-responce. For 200ohms a proper transformer would be needed to step up 60 to 200ohms.
Regards,
Esa
Post by: jrmintz on April 25, 2009, 11:50:49 AM
Thanks for your help. I don't see a switch anywhere, but I do see the transformer potted in some sort of hard resin in the bass chamber. Is it possible to remove the trafo without destroying the mic?
Seth
Post by: jrmintz on April 25, 2009, 11:52:15 AM
Post by: panman on April 25, 2009, 05:34:51 PM
Is it possible to remove the trafo without destroying the mic?
Sure it is, but I suggest you just bypass the trafo first and see how it sounds. Just disconnect the four wires(yellow, brown, blue and green)going to the trafo and tape the ends to prevent them causing a short. Then you have to connect the blue wire coming from the capsule with the brown wire of the mic-cable and the green with the white one. On the other end you should have a normal balanced wired XLR. Now the mic unplugged, if you measure between blue and green wire with an ohmic-meter, it should read about 50 ohms. That normally means, the capsule is 60 ohms. However, if it reads about 230-240 ohms, the capsule is then the so called 200 ohms one. This may be possible, because your second pic shows the humbucking coil, which suspiciously looks like of a 200 ohms capsule. The measuring or a sidewiew-pic of the capsule would clear that out.
To remove the trafo you need to unscrew the four retaining screws that hold the bass-chamber and then you can carefully tap the rear-cap loose and remove it. If you don`t want to use the trafo, you can just pull it off and the wires will be destroyed. then replace the cap tapping it back carefully and sealing it with glue. Now just attach the chamber on the capsule. That`s it.
If you want to save the trafo for some other purpose, you need to carefully solder the wiring loose before pulling the trafo out. That is very tricky, but can be done, if you know exactly what to do. I`d say, better leave it for someone more experienced to do.
Regards,
Esa
Post by: jrmintz on April 27, 2009, 02:11:43 PM
Seth
Post by: J.J. Blair on April 27, 2009, 03:17:12 PM
Post by: compasspnt on April 27, 2009, 05:21:22 PM
Post by: jrmintz on April 27, 2009, 05:23:11 PM
| J.J. Blair wrote on Mon, 27 April 2009 15:17 |
but is there really any benefit to removing the transformer? |
I'll let you know next time I cut drums. Unfortunately, I didn't think to do a reference recording before I took the trafo out.
Post by: jrmintz on April 28, 2009, 10:03:14 AM
Seth
http://files.me.com/jrmintz/dig1iu.wav Modified_D12-test
Post by: J.J. Blair on April 28, 2009, 01:12:41 PM
| compasspnt wrote on Mon, 27 April 2009 14:21 |
So JJ, are you running it straight in with no xfrmr, or going through an AMI (or other) with those D12's? |
Terry, it depends. When recording kick, into my 1073, I have been liking it through the TAB, but reversed.
But in general, if I'm going to use it for something, I don't use the transformer or my little film cannister thing.
Post by: panman on April 28, 2009, 02:58:25 PM
| J.J. Blair wrote on Mon, 27 April 2009 21:17 |
Even in the D12E, they use a plastic dummy, to keeps that space filled, even though there is no transformer. What's the acoustic difference with that space there? |
J.J., that „dummy“ is just the the same size and form inside as the older metal chambers. Even sonically it is replaceable with the older one.
As for your question, I`ve been experimenting a lot with the older type bass-chambers limiting its volume and found out, that the more volume, the more bass and of course reducing the space you get bass-rolloff. In fact I have been using D12:s with acoustical bass-rolloffs like that for close micing purposes. Also the form is important. You can take exactly the same volume, but different form like Echolette Top 12 using the same capsule. The chamber is right there in the rear of the capsule and is very short giving a strong bass-boost, but not extending as low as with the"normal" long chamber. Then there are the D30/D36/D45 just both capsules sharing the chamber. It is a fact that transformers in D12:s were somewhat different in size in different badges and times, but I also noticed that the vents sometimes were filled with some filtering stuff, but mostly not. So, it is again not that simple. It is all about manipulating the rear wave, that the mic will give that bass-boost. The idea is to get the sound reflecting back in the right phase. This can also be achieved by putting obstacles on the way. If the transformer is filling exactly the right space, it can really be ideal for bass-boosting. As it happens, I have a D20/60ohms, that I converted to 200ohms by swapping the bass-chamber with one, that has the transformer inside. Well, that is the one with the most bass and extending lowest of all the D12-type mics that I posses and I do have quite a few, plus the sound is more pleasant in general. Maybe a coincidence? One of these days perhaps I will open up the chamber to find out the secret, but not until I find one that is as good, because this mic is my favorite for too many things.
Regards,
Esa
Post by: muddy on June 04, 2009, 06:26:30 PM
http://soundclick.com/share?songid=7618823
ml