Sony PMW-EX1 with Schoeps CMIT5U
 

I am considering the Schoeps CMIT-5U with the PMW-EX1 but i read that the CMIT5U requires at least 5mA to run properly and while i just tested the mA out from the ends of a Mogami XLR cable to be +6.10mA from the Sony PMW-EX1, that does not ensure that the Sony will provide +5mA to the Schoeps CMIT-5U when connected as the impedence may reduce that mA to below 5mA.

now, i was told that if you don't get 5mA, the Schoeps will not reached it's full dynamics and worse, even distorts. the former may not be easily heard and the latter is obvious.

have anyone who owns and used the two together shed some light on this?

thanks!

paul

How did you measure the milliamps out of the EX1? Are you sure that's an accurate measure?

i used a keithley digital mutlimeter and as such, the amps measured may not be what a mike will "see" as the impedence is different.

still, my measurements were consistent over several xlr cables and directly from the leads off the pmw-ex1. all around 6.10mA to 6.13mA

paul

Did you measure the voltage at the mic as well, that'd give you a better picture.
From a test I did with another mic I'm not certain that the EX1 can deliver 5mA at 48V.
At the same time though does your mic need 5mA at 48V?

see bob,

that's the unknown.
i connected some mogami xlr cables to the ex1 and measured the end of the mogami's. there is where i got the 47.4v and 6.13mA. same for ch1 and ch2 from the mogami cables.
cables used were 50 feet length.

i don't have the schoeps yet and the supplier says the shotgun needs 5mA for full dynamics.

there are actually mikes that need up to 9mA out there and the specs for phantom power is supposed to be 2mA to 10mA, so the sony pmw-ex1 falls between those extremes.

this is from the schoeps specs:

Technical Specifications:
Directional pattern: . . . . . . . . . . . .supercardioid/ lobe-shaped
Frequency range: . . . . . . . . . . . . . .40 Hz – 20 kHz
Switchable filters: . . . . . . . . . . . . . .80 Hz with 18 dB/oct,
300 Hz with 6 dB/oct,
5 dB lift at 10 kHz (shelving)
Sensitivity: . . . . . . . . . . . . . . . . . . .17 mV/Pa
Equivalent noise level (filters off): .14 dB-A*, 24 dB CCIR**
Maximum sound pressure level: . . .132 dB SPL at 0.5% THD
Powering: . . . . . . . . . . . . . . . . . . .48 V phantom
Current consumption: . . . . . . . . . .4.4 mA
Maximum output voltage: . . . . . . .1.3 V (1 kHz, 1 kOhm)
Output impedance: . . . . . . . . . . . .50 Ohms
Recommended load impedance: . .600 Ohms or greater
Length: . . . . . . . . . . . . . . . . . . . . .251 mm (9.88")
Diameter: . . . . . . . . . . . . . . . . . . .21 mm (0.827")
Weight: . . . . . . . . . . . . . . . . . . . .89 grams (only 3-1/8 ounces!)


this is from the sony pmw-ex1

"nothing"....


paul

You can't really measure current that way. You should attach a load to the output and measure the voltage drop (if any) as Bob suggested.

Really, the best way to go is attach your Schoeps (borrow or rent) and measure the voltage across the XLR terminals while the mic is connected (and powered on). Also measure it with nothing connected. If it's 48v with the mic connected you are probably fine. If the voltage drops significantly when you connect the mic, you know that you are overloading the EX1.

(I doubt you will overload the EX1 at 5mA)

not sure how you can measure the voltage or amperage even if i have a mike in hand as the connector has ground on the entire outer shell with those 3 leads inside the positives.

paul

As far as I know the outer shell shouldn't be grounded in any Sony camera XLR, and if it is in the cable you use you should cut that connection. Grounded shells can cause hum in many situations and should be avoided.

To measure the voltage drop you should pull back the shell and (very carefully) measure pins 1-2 and 1-3 (it should be the same) with a DMM with the mic plugged and unplugged.

Correct.

You can withdraw or remove the shell without affecting any grounding on a female XLR connector.

As Carlos said, just pull the shell back and measure the voltage on the pins inside. No measurements should be needed from the shell itself.

carlos and eric
 

you're right, the outer shell isn't ground.
i had leads into 2 of the 3 holes for a voltage and amperage reading, not the shell.

the shell is just there, that's what i was trying to question.

the housing on the wiring is very tight, don't see how to pull the outer shell out or back.

paul

If it's a Neutrik connector, unscrew the plastic strain relief - this loosens the housing and it can be slipped back.

If it's a Switchcraft, with set scews, loosen the screws near the strain relief. You may also have to loosen the screw near the connector. It's often a reverse thread and when you loosen it (ccw) it will recede into the body of the connector as if you were tightening it.

Some xlr's have a phillips screw near the connector part which needs to be removed before the housing will separate from the connector.

yes, the mogami has the neutrik housing.
so, i untwist this and connect to a mike, then measure the amps as it's active?

how would this help determine if the schoeps would work?

the mikes i am testing with has different impedance.

paul

You would need to test it with the Schoeps (rent or borrow) or a mic with similar characteristics.

And you would want to measure the voltage across the pins, not the amperage. See if there is a voltage drop when the mic is connected versus no mike connected.

If there's a voltage drop, then you know the power supply is being overloaded.

I tried to test this for you, Paul, with my Schoeps MK4 mic on a CMC6u mic body which is very close to the voltage load you are testing (4mA at 48v). However, I discovered that my DMM is dead! I recorded some audio through the mic and some Canare cable and it sounded fine as long as I kept my breath sounds out of it. I tried to overload it and even hitting the red markers, it still sounded okay. Sorry I can't give you a definitive voltage reading under load. Off to Radio Shack, I guess.

As far as I know unless you're lucky enough to be using audio kit with transformer mic inputs there'll always be some sag in the phantom voltage under load. Some of the high end studio mics might have a problem with this at high SPLs, some even need 110V phantom power. I'd expect anyone designing a mic to go on a camera would factor this into their design. Typical mic specs I've seen around are phantom power from 18V to 54V.
Also probably worth factoring in that the whole audio section of cameras are, well, adequate.