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[Silvertone]

Somewhere I have pictures of Sinatra singing into the C37A. Hal Blaine showed me several different pictures of the "cokebottle" mic positions they would use for his drums. You can see Sinatra in the background (foreground really) singing into the C37A. I believe they were all taken at Capitol. I will have to look for them.

If they start to get a bit noisy (and they will over time), I've usually found it to be the tube. Sometimes just re-seating the tube solves this problem. Same with the "Cokebottle" mic's. I have one right now where the tube is going (or the tube isn't making perfect contact in the socket) and it's them most wonderful distorted sound I've ever gotten. Sounds like the source is exploding. I'll be bummed when she goes all the way.

Funny as we shot the C37A mic out against a U67 and a Sony 800 (not a 800G). It sounded exactly like the 800 but the 800 was about 6 db quieter and that was really the only difference. It was also very different sounding then the U67's we had but they had been modified by Klaus so they weren't stock.

I also use this mic where you would normally use ribbon. I love them on drum overheads as I find they work with cymbals in a very pleasing manor. It also just so happens to be the best sound mic for my voice. Not that I'm a singer but it flatters the negative aspects of my voice. It took me years to find this out and I went through many a Neumann trying to find the right vocal mic.

[Gustav]

It is a cathode follower type circuit thats why the microphone output transformer can be in the power supply.  Capsule voltage is derived by the voltage drop across the 100K and the tube bias by the voltage drop across the 3 K.  The 100meg "appears" to the capsule as a larger value because of the feedback.  Other microphones use a circuit like this some older AKGs etc.

Now the power supply is not regulated so the power supply is sensitive to wall line voltage.  It is a nice design it "floats" the heater above ground for better operation of the 6au6 and the cathode to heater voltage ratings

I find part of getting 6au6 circuit quiet is getting the heater voltage just right and finding a good 6au6 tube.

What I do is use a autotransformer(variac) to get the correct AC into the power supply. In this case I might adjust the autotransformer/variac to say 110VAC and then move it up to 117VAC(using the 117VAC setting).

 Why did I post some tech stuff? Because as Klaus often posts the power supply voltage can be important.  High line voltage will raise the heater voltage above the designed voltage and in this case raise the charge voltage higher on the capsule, you might not want that

Wall voltages can be > 120VAC sometimes depend were you live

I will use a autotransformer/variac and a power strip plugged into it to  power unregulated microphone power supplies that were set up for the same AC line voltage.

Also be careful if you change the heater bridge you will most likely need to add a power resistor to adjust the heater voltage.

Gustav

[Doug Walker]

J.J.

All unidirectional microphone transducers that I am familiar with derive their unidirectional properties by having sound act on both the front and the rear of the transducer membrane (or ribbon).  Non-directional transducers are constructed in such a way that sound acts only on the front of the membrane.  

The screw on the rear of the Sony C-37A capsule controls a circular shutter which opens or closes a sound entry port on the rear of the capsule.  The shutter is open for unidirectional operation allowing sound to reach the rear of the membrane.   When the screw is moved to the 'non-directional' setting, the shutter closes the rear-entry port preventing sound from reaching the rear of the membrane.  In this pattern setting, the capsule becomes a pressure transducer having (somewhat) omni-directional properties.

Regards,

Doug Walker

[jetbase]

Do any other mics use that method for adjusting the polar pattern? I distinctly remember adjusting a polar pattern that way with a screwdriver, but I can't for the life of me remember when, where, or what mic.

[Klaus Heyne]

The Schoeps 934 capsules widely used on M221 tube mics use a slider switch on the side of the capsule which basically does the same mechanical pattern switching with a baffle.

[Silvertone]

jetbase wrote on Sun, 02 December 2007 17:34

Do any other mics use that method for adjusting the polar pattern? I distinctly remember adjusting a polar pattern that way with a screwdriver, but I can't for the life of me remember when, where, or what mic.

RCA 77DX and Shure 330 ribbon mics...

[Mike Cleaver]

The RCA 77D and DX models used a similar system but I believe the Shure 330 is unidirectional.
It does have a screwdriver adjustment for impedance.

[Tim Campbell]

An early Groove Tube model condenser mic had a capsule with the same type of pattern adjustment. I was lead to believe it was a Josephson capsule patterned after the Sony.

[jetbase]

Aah yes, it was an early Groove Tubes mic, in my own studio (though not my own mic), & no wonder I chose to forget. Thanks Tim.

[Gone]

Djembe wrote on Sat, 01 December 2007 19:49

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?

Regarding his Capitol career; the majority of photos and descriptions suggest Sinatra used a U47 for his Capitol recordings - the only exception I know of is "Sinatra's Swingin' Session!!!" which he used a Telefunken ELA M251.

The book "Sessions with Sinatra" shows session photos from "Close To You"(1957), "Where Are You?" (1957), "In The Wee Small Hours" (1955) and several shots from 1953 and 1954, all using a U47. There is no mention of the Sony C37 in the book (which covers his entire recording career). Of course, they don't mention every mic for every album - but only the RCA 44 and U47 are highlighted.

During his Reprise years, he seemed to use a wide variety of mics, including an M49 (Great Songs From Great Britain), Sennheiser 405 (Strangers In The Night), a U67 (or 87?) (Ol Blue Eyes Is Back). He used several small diaphragm mics in those years, which, in my opinion, don't do his voice justice.

The cover photo of Sinatra & Strings (engineered by Bill Putnam in 1961) shows a Sony C37, but it's impossible to tell where the photo is from. It looks like it might be a stage shot.

As a curiosity, he used an AKG "The Tube" on 1984's "LA is my Lady" produced by Quincy Jones.

[J.J. Blair]

Doug Walker wrote on Sun, 02 December 2007 09:43

J.J. All unidirectional microphone transducers that I am familiar with derive their unidirectional properties by having sound act on both the front and the rear of the transducer membrane (or ribbon).  Non-directional transducers are constructed in such a way that sound acts only on the front of the membrane.   The screw on the rear of the Sony C-37A capsule controls a circular shutter which opens or closes a sound entry port on the rear of the capsule.  The shutter is open for unidirectional operation allowing sound to reach the rear of the membrane.   When the screw is moved to the 'non-directional' setting, the shutter closes the rear-entry port preventing sound from reaching the rear of the membrane.  In this pattern setting, the capsule becomes a pressure transducer having (somewhat) omni-directional properties.

Doug, thanks for that.  This is what I suspected, but I could not see any light being occluded through the membrane, etc., to confirm my suspicion.  

It actually made me think of the RCA 77DX.

[Oliver Archut]

The cathode follower is very sensitive to weak filter caps, most of the noise comes from the low grade Japanese components and with a lot of TLC, a few new components a good Philips (Mullard) or Telefunken EF94 aka 6AU6 the mic can be very low noise.  The EF94 was introduced as an audio pentode with technical specs similar to an EF86/804 but with a 7 pin socket. It was used by several microphone manufactures, Schoeps used it as well as other small german mic companies at the time.
Aside exchanging the low grade tube socket, cleaning of the connectors as well as a new mic cable will help in a big way.

Most of the C37 mics that I saw, the coupling cap were bleeding, and pre-biasing the output x-former and cutting off the low end. The spread of the capsule in the different mics is quite wide too, so an additional source of low end difference..

I do not know if they recorded with the mic, but most of the "Traveling Wilburys" music videos show they guys singing in front of a C37a mic.

Best regards,

[MagnetoSound]

Oliver, The Wilburys' vocal sessions were tracked with ELA M251, as can be seen in the 'True History of The Traveling Wilburys' DVD.  


Dan

[Silvertone]

Mike Cleaver wrote on Sun, 02 December 2007 21:09

The RCA 77D and DX models used a similar system but I believe the Shure 330 is unidirectional. It does have a screwdriver adjustment for impedance.

Yep, you are right on the 330. To quote Kelly Bundy "the mind, it wobbles"...

[Silvertone]

Thanks for all the info Oliver. James Gangwer reworked my mic some 5 or 6 years ago and the one thing I remembered when I got it back was that the low end was so much better than I remembered. Mine must have developed the problem with the coupling cap.

Since then I've had to replace the tube and we did notice a very big difference in noise depending on which tube we put in there. Tried about 5 different ones. Can't remember which NOS tube we ended up with but she's been running like a champ the last few years.