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Author Topic: Schoeps CMC4--D  (Read 7488 times)

oldsoulsound

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Schoeps CMC4--D
« on: April 29, 2012, 08:58:09 pm »

Can anyone tell what this mic is all about? I've a bit on the CMC4-U but not the D.
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David Satz

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Re: Schoeps CMC4--D
« Reply #1 on: April 30, 2012, 08:40:46 pm »

The CMC 4-- series is parallel powered rather than phantom powered. The "D" suffix means that it has a 3-pin Tuchel output connector rather than an XLR.
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klaus

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Re: Schoeps CMC4--D
« Reply #2 on: April 30, 2012, 08:45:12 pm »

... where the "D" probably stands for "DIN" as in "Deutsche Industrie Norm"
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Klaus Heyne
German Masterworks®
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oldsoulsound

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Re: Schoeps CMC4--D
« Reply #3 on: May 11, 2012, 07:00:37 pm »

Thanks. Any idea what part number this connector is or where to find one? I'm having a hard time tracking down a cable.
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klaus

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Re: Schoeps CMC4--D
« Reply #4 on: May 11, 2012, 08:32:18 pm »

Female three-pin Din connectors are readily available from Mouser, Digi-Key, etc.

You need to make up your own cable and add a 3-pin male XLR on the other end (try Gotham's GAC 3 cable material, one of the most resistant to RF, and, besides, a good sounding cable too.)

DIN Pin-out standard for Parallel/T Powering:
Pin 1 Audio (+)
Pin 2 Ground/Shield
Pin 3 Audio (-)
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Klaus Heyne
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David Satz

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Re: Schoeps CMC4--D
« Reply #5 on: May 18, 2012, 08:01:53 am »

Parallel-powered microphones can be a bit problematic to wire up because the system was made popular by Nagra and Sennheiser, but then the DIN standard that was eventually enacted specified the opposite signal polarity.

Schoeps was very loyal to the DIN standards, so their original parallel-powered models (in the late 60s/early 70s "CMT" series) often required reverse polarity adapters (between the power supply and the input of the mixer or recorder) if you wanted to mix their signals with those from, for example, Sennheiser microphones. Or the microphones themselves could be modified--although that could create real confusion, since then two microphones with identical markings might have opposite signal polarity.

Later on (in the Colette or "CMC" series, which is what you have), Schoeps offered special versions of their parallel-powered amplifiers with Nagra/Sennheiser polarity rather than DIN standard polarity. These were generally marked with a "k" (for "Kudelski"--inventor of the Nagra tape recorders), although here, too, people sometimes modified the microphones without marking them specially.

So be sure to test for signal polarity, and depending on the outcome, be prepared to use a so-called "phase inverter" adapter whenever you're using your CMC 4 along with other microphones. Or I suspect that the factory may still be willing to rewire the microphone for you and mark it so that it's clearly a "k" model.
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oldsoulsound

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Re: Schoeps CMC4--D
« Reply #6 on: July 28, 2012, 05:51:04 pm »

Ok I'm having trouble with the powering. I have a cable with  standard XLR wiring with Pin2+,Pin3-& Pin1 Ground this goes to the tuchel connector where I wired +to pin 3, - to pin1 & Ground to Pin 2. I purchased a PSC P48 to T12 adapter. When connected i get some noise but no mic signal. Any ideas?
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Kai

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Re: Schoeps CMC4--D
« Reply #7 on: July 29, 2012, 02:54:57 am »

There are even some Schoeps mic's out with reversed polarity as David described.
As long as you use a P48 to T-power adapter you can just try to reverse pins without fear to fry something, max. current is too low to harm anything.
The same can be the reason for the Schoeps not working.
The max. current P48 can supply is too low for a T-powered Schoeps (needs 9mA), a simple adapter won't do the job.
It might be possible to get some sound out, but never to run the mic at full specs.

I once modified some older CMT340p (p means reversed polarity) to regular P48.
With a CMC type a mod to P48 should be more easy then this one.
If it was my mic I would go that road.

I've attached this mod, it contains the small tuchel /XLR pinout.
Remember, it's for a CMT340p, not a CMC-type mic.

Regards
Kai
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oldsoulsound

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Re: Schoeps CMC4--D
« Reply #8 on: July 29, 2012, 07:40:56 am »

I tried a phase inverted cable reversing pins 2 & 3 and still nothing. I measured the DC voltage between the ground pin and pin 2 and was getting around 18v after the adapter.
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oldsoulsound

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Re: Schoeps CMC4--D
« Reply #9 on: July 29, 2012, 09:57:11 am »

I've read that the PSC type adapters are not ideal. Would something like  the Denecke PS-T power supply be better?
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Kai

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Re: Schoeps CMC4--D
« Reply #10 on: July 29, 2012, 02:25:11 pm »

...the DC voltage between the ground pin and pin 2....18v after the adapter.
You mean 1 and ground(?), pin 2 is ground with small tuchel connectors.
With mic connected? Would be far too much!
Should be 12V open loop and much less with the mic.
Otherwise it's a clear sign the mic doesn't draw any current, hence not working.

What is the voltage between Pin 3 and ground, or between pin 1 and 3, open loop and with mic?

BTW: the wikipedia schematic is not completely correct, the T-power supply should better be floating relative to ground.
This avoids some problems.
It can't of course, with the adapter, as P48 is referenced to ground.

Would something like  the Denecke PS-T power supply be better?
First make it work at all.

Regards
Kai
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Kai

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Re: Schoeps CMC4--D
« Reply #11 on: July 29, 2012, 02:30:41 pm »

(Sorry, corrected wrong audio polarity in earlier original post. Kai's is right. K.H.):

Pin 1 Audio (+) / Hot
Pin 2 Ground/Shield
Pin 3 Audio (-) / Cold

Regards
Kai
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oldsoulsound

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Re: Schoeps CMC4--D
« Reply #12 on: July 30, 2012, 07:01:42 am »

Thanks guys. I got it, I was putting the phase reverse cable on the wrong place. When I put it after the PSC adapter it worked perfectly. Man what a great mic this is. WOW! Thanks for the help.
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