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Author Topic: The (Semi) Official Sony C37A Thread  (Read 43837 times)

J.J. Blair

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The (Semi) Official Sony C37A Thread
« on: December 01, 2007, 03:18:40 PM »

I wanted to talk about the Sony C37A.  

http://web.mac.com/jjblair/iWeb/Site/C37A_files/IMG_1249.jpg

I have a pair, and the bass response is totally different in one than the other, so I started taking them apart to check the component values, to make sure they are matched, and are as the schematic calls for.  What I realized is that it's a totally different implementation from most European mics of that vintage, and we never really discuss the mic.  I thought it would be interesting to get into.

First thing that sticks out to me is the edge terminated capsule.  It's different than the most well known Euro edge terminated capsule of the day, the CK12, in a few obvious ways.  First, notice this beveled edge on the membrane, and the space between the outer ring and the back plate.  

http://web.mac.com/jjblair/iWeb/Site/C37A_files/IMG_1251.jpg

The network of through holes on the backplate looks very different from typical Euro capsules, as well.  

http://web.mac.com/jjblair/iWeb/Site/C37A_files/IMG_1241.jpg

And then to really set itself apart, there is a screw that lets the user choose between cardioid and omni, or "unidirectional" and "nondirectional," as their manual puts it.  I can't see the mechanism employed.  I'm assuming it is physically manipulating something in the backplate, but I can't see what it's doing.  If anybody knows how it works, please do tell.

http://web.mac.com/jjblair/iWeb/Site/C37A_files/IMG_1244.jpg

It employs a 6AU6 tube.  Maybe Oliver can tell us if anybody was making these with specs that would have met Teutonic standards for microphones.  I just found 5  NOS JAN versions on eBay for $25.  Wish me luck!

http://web.mac.com/jjblair/iWeb/Site/C37A_files/IMG_1242.jpg
http://web.mac.com/jjblair/iWeb/Site/C37A_files/IMG_1243.jpg

The other departure from Euro mics is locating the transformer in the PSU.  I know Altec used this approach in some of their mics.  Does increasing the distance from the tube to the transformer increase the mic's noise?  Is there a reason they weren't doing this in Vienna or Berlin?  However, this also gives them the ability to use a HUGE transformer (with the sony label on top) and rather large capacitors.

http://web.mac.com/jjblair/iWeb/Site/C37A_files/IMG_1245.jpg

And then there is a switch attached to the coupling cap that adds either one or two more in series, to act as a hi pass filter.  You can see that switch here on the schematic.  Maybe one of you designers can talk about the pros and cons of this method.  (You can also see the the 6X4 recifier tube in the above pic, and below is the primary coupling cap in the .5
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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

MagnetoSound

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Re: the official Sony C37A thread
« Reply #1 on: December 01, 2007, 04:40:32 PM »

Hi JJ,

Firstly, I thought what a nice (simply, but well, made) looking mic!

The C60 is the only other mic that I know to have the transformer in the power supply, and tapped off the cathode as in this one.
There is also a bass roll-off on the PSU.

(I think there may be others that use this arrangement, though .... as you say, Altec)

Love that screw thing on the capsule for pattern selection, how quaint!

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Music can make me get right up out of my chair and start dancing or it can get me so pumped up I have to walk around the block.
It can also knock me back and make me sit there and cry like a little baby. This shit is as powerful as any drug!!!
- Larry DeVivo

Barry Hufker

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Re: the official Sony C37A thread
« Reply #2 on: December 01, 2007, 04:45:21 PM »

The Sony C57 has the transformer in the power supply.  They are great sounding,but very noisy, mics.  My friend has a pair.

Barry
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J.J. Blair

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Re: the official Sony C37A thread
« Reply #3 on: December 01, 2007, 04:49:32 PM »

Dan, my Altec 175 has that scenario, and, IIRC, that Altec coke bottle version that Sinatra used with Count Basie did it, too.  (Transformer in the PSU.)
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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

Chris Moore

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Re: the official Sony C37A thread
« Reply #4 on: December 01, 2007, 04:55:21 PM »

I have one of these from 1957. Interestingly, it has a different Sony logo (the same as on the schematic JJ posted) which is silkscreened (?) on the front of the body rather than being engraved on the silver band like JJ's (and all the others I've seen).
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Chris Moore

MagnetoSound

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Re: the official Sony C37A thread
« Reply #5 on: December 01, 2007, 05:07:38 PM »


JJ, I'm curious, how does this mic sound in terms of noise, and character? I know there is a general consensus that the C60/C61 mics sound kind of 'tubby' and 'closed' due to the cathode follower circuit.

Would you put this mic into that category?

(And how about the Altec?)

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Music can make me get right up out of my chair and start dancing or it can get me so pumped up I have to walk around the block.
It can also knock me back and make me sit there and cry like a little baby. This shit is as powerful as any drug!!!
- Larry DeVivo

J.J. Blair

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Re: the official Sony C37A thread
« Reply #6 on: December 01, 2007, 05:11:04 PM »

Back to my low end difference dilemma: My Wavetek multimeter meter doesn't have a capacitance meter, so I just ordered one.  But I am hazarding a guess that the instability of these paper filled coupling caps is what is causing my different bass response between the two mics.  I'll know when the meter shows up.  I can't recall what happens when I switched PSUs with the mics.  That should tell me right away.  But if they use the capacitance of the coupling transformer as the means of hi pass, that should indicate at least where to start looking at the source of the problem.

On the other hand, while the paper caps have probably dried and have changed values, the resistor values in the mics are totally matched between the two mics, and fall within 10% of their marked values, which should indicate that it's not within the mic.  The strange thing is, the measured values are less than marked.  I would have thought that over age, from the heat of the tube, they would have increased resistance.  No?
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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: the official Sony C37A thread
« Reply #7 on: December 01, 2007, 05:21:47 PM »

MagnetoSound wrote on Sat, 01 December 2007 14:07


JJ, I'm curious, how does this mic sound in terms of noise, and character? I know there is a general consensus that the C60/C61 mics sound kind of 'tubby' and 'closed' due to the cathode follower circuit.

Would you put this mic into that category?

(And how about the Altec?)




These are a very nice sounding mic.  I'm not sure I recall them being tubby, they are one of the best tom mics ever, which maybe from tubbiness?  I never had a noticeable noise problem, but I wasn't measuring.

The Altec is VERY noisy.  I wish I could find a schematic for it.  It's an unusual mic.  It uses a 5840 subminiature tube, and then a M29B OEM capsule made by AKG.  I have not been able to find out if it's related to the CK28 or not, and can't tell by looking.  I'm reticent to disassemble the capsule.

The tubes are readily available and cheap.  I should order a couple and see if that helps the noise.  

(Edit: I just found the schematic.  http://www.purpleaudio.com/pdflib/AltecM30.pdf)
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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

MagnetoSound

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Re: the official Sony C37A thread
« Reply #8 on: December 01, 2007, 05:32:44 PM »

Looks to me like the low end problem would be either the cap right before the transformer (the 0.5 on the right in the diagram), or the capsule itself. (It's pretty much the exact same circuit as the AKG mics btw, apart from the tube, obviously).

Did you try swapping tubes?

J.J. Blair wrote on Sat, 01 December 2007 22:11

On the other hand, while the paper caps have probably dried and have changed values, the resistor values in the mics are totally matched between the two mics, and fall within 10% of their marked values, which should indicate that it's not within the mic.  The strange thing is, the measured values are less than marked.  I would have thought that over age, from the heat of the tube, they would have increased resistance.  No?


How hot is the tube, really, enough to put the resistors out? It's hard to tell (how close they are) from the picture, but I wouldn't have thought that would be a problem.

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Music can make me get right up out of my chair and start dancing or it can get me so pumped up I have to walk around the block.
It can also knock me back and make me sit there and cry like a little baby. This shit is as powerful as any drug!!!
- Larry DeVivo

Mike Cleaver

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Re: the official Sony C37A thread
« Reply #9 on: December 01, 2007, 06:48:20 PM »

We had a bunch of these in the late '60's early '70's at a radio station where I worked.
We used them in the control rooms and the studios.
They sounded better than anything we'd used up until that time and were the first "high end" mic's we'd had, since retiring the ribbons in the very early '60's.
Looking at that power supply, I'd get in there and swap out that selenium rectifier (red thing)  with a new bridge rectifier.
When those selenium's go, and they will, they can blow up but they always release a noxious odour.
If you want the supply to remain looking stock, leave the selenium there but disconnected and hide the new rectifier somewhere under the chassis.
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J.J. Blair

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Re: the official Sony C37A thread
« Reply #10 on: December 01, 2007, 06:49:20 PM »

Honestly, I hadn't messed with it for a while, so I can't remember which trouble shooting I did.  I just woke up at 4AM, and for some reason was obsessed with poking around the thing.
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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

djembe

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Re: the official Sony C37A thread
« Reply #11 on: December 01, 2007, 08:49:45 PM »

I'm interested in vocal recordings with the C-37A.
I've searched quite a bit and seen that link on the Sony site.

http://www.sony.net/Fun/SH/1-7/h1.html

But is that PR spin or did Frank Sinatra really use it?
All the photos I've seen show him using a U47. Am I to assume that most vocals recorded at Capitol in the late 50's/early 60's used a C-37A?

I'm aware that Daniel Lanois has used it quite a bit for Dylan and Emmylou Harris as well as himself, but what other well known artists have used it. Can you point me to some recordings?

Thanks

Blair
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Blair Greenberg

Dominick

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Re: the official Sony C37A thread
« Reply #12 on: December 02, 2007, 01:55:06 AM »

I can only speak of my experience with my C37A's on vocals.
They tend to scoop out upper mids, leaving you with prominent lower mids and top sparkle.
They are great for smoothing out nasal vocals.
Not what I would use with a strong baritone, unless the track has LOTS of open space.
I use them on the same sources I would use a ribbon mic.
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Dominick Costanzo

J.J. Blair

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Re: the official Sony C37A thread
« Reply #13 on: December 02, 2007, 02:02:21 AM »

Djembe wrote on Sat, 01 December 2007 17:49

Am I to assume that most vocals recorded at Capitol in the late 50's/early 60's used a C-37A?


When you are in the hallway at capitol, all the pictures of that era show people singing in U47s and 251s.
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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

Arf! Mastering

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Re: the official Sony C37A thread
« Reply #14 on: December 02, 2007, 04:47:45 AM »

On ebay recently there was a picture of Sinatra with a C37A but it was a live performance, on stage, in front of an audience.
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