Repurposing SDI Cable as XLR?

lscherrer

Member
I have an odd question: the venue I work for has a large amount of 26-pin CCZ camera control cable (Sony) that we don't need anymore. We were trying to think of ways to reuse it and someone suggested splitting it and turning it into an XLR audio snake. I don't have the CCZ/SDI knowledge to know if this would work or not. Has anyone used SDI cable as XLR before?
 

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It really depends on how its shielded. I don't think there are that many individually shielded runs in that cable. What is the number on the cable itself?
 

RonHebbard

Well-Known Member
Premium Member
It really depends on how its shielded. I don't think there are that many individually shielded runs in that cable. What is the number on the cable itself?
How far are you hoping to run?
There are rules, irrefutable rules, rules that can be violated most of the time, and rules that can be broken some of the time.
In all cases; try it. Try one pair, if it works, try two pairs. Try only twisted pairs. Pre digital and wireless, analogue telephone companies successfully ran miles and MILES and MILES on unshielded, individually twisted pairs.
Toodleoo!
Ron Hebbard
 

FMEng

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Fight Leukemia
The critical detail of cable that makes balanced audio work is tightly twisted pairs. The pairs being twisted together insures that induced noise is equal in amplitude and phase in both wires, which allows it to be cancelled by the input stage. If the snake channels are not twisted in pairs, you will have lots of noise and crosstalk.

Running line level audio on unshielded, twisted pairs usually works great, as long the output and input stages are both truly balanced. I would be leery about running mic level without individual shields. I can't say that I've ever tried it in a serious way.

Given the amount of time and materials it would take to terminate the cable, I would spend the extra money to use proper cable instead of the camera stuff.
 

lscherrer

Member
It really depends on how its shielded. I don't think there are that many individually shielded runs in that cable. What is the number on the cable itself?
The only markings on the cable say "AWM E35664 STYLE 20002 VW-1 80C" (not sure how much of that is relevant) It would be a 50' run.

Thank you for your responses. I think we'll test it with one line first and see how it goes-- if nothing else it'll be good soldering practice haha. Completely agree that just getting an XLR snake would make more practical sense, this is more of an experiment than anything else.
 

DrewE

Well-Known Member
Microphones that use phantom power (basically, most condenser microphones) won't work at all without the shield, or at least a separate wire connecting the shield pins at each end. The phantom power voltage is applied between the shield and both of the balanced audio connections (through current limiting resistors).

Microphone signals over unshielded twisted pair apparently can work reasonably well. A fair number of the boxes that have three or four channel audio snakes over Ethernet cable are simply wiring the connectors together without any other components. Some do have balancing and/or impedance matching transformers or other stuff going on.
 

RonHebbard

Well-Known Member
Premium Member
Microphones that use phantom power (basically, most condenser microphones) won't work at all without the shield, or at least a separate wire connecting the shield pins at each end. The phantom power voltage is applied between the shield and both of the balanced audio connections (through current limiting resistors).

Microphone signals over unshielded twisted pair apparently can work reasonably well. A fair number of the boxes that have three or four channel audio snakes over Ethernet cable are simply wiring the connectors together without any other components. Some do have balancing and/or impedance matching transformers or other stuff going on.
What about DI boxes like Brooke Siren's AR116 that can be phantom powered by their optional AR117 phantom power module and include a ground lift switch?
The basic AR116 can house two 9 volt batteries, one powers it with the second taking over seamlessly if / when the first's voltage falls below a certain level.
Alternately you can install their optional AR117 phantom powering module in the first slot with a fail safe battery to seamlessly maintain operation if / when your phantom power fails.
Toodleoo!
Ron Hebbard
 
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DrewE

Well-Known Member
What about DI boxes like Brooke Siren's AR116 that can be phantom powered by their optional AR117 phantom power module and include a ground lift switch?
The basic AR116 can house two 9 volt batteries, one powers it with the second taking over seamlessly if / when the first's voltage falls below a certain level.
Alternately you can install their optional AR117 phantom powering module in the first slot with a fail safe battery to seamlessly maintain operation if / when your phantom power fails.
That would depend on where the phantom power supply--such as one of the DI boxes you mention-- is in relation to the disconnected shield wire. You need all three connections between the source of phantom power and the microphone being powered. If you have a power supply on the microphone side of the shieldless cable, then it stands to reason the shield connection is irrelevant in the snake (for that phantom power purposes, at least), as you aren't trying to send phantom power through it. If, for some strange and perverse reason, you had the phantom power/DI box on the opposite end of the shieldless cable from the phantom powered microphone, things wouldn't work.
 

FMEng

Well-Known Member
Fight Leukemia
Microphones that use phantom power (basically, most condenser microphones) won't work at all without the shield, or at least a separate wire connecting the shield pins at each end. The phantom power voltage is applied between the shield and both of the balanced audio connections (through current limiting resistors).

Microphone signals over unshielded twisted pair apparently can work reasonably well. A fair number of the boxes that have three or four channel audio snakes over Ethernet cable are simply wiring the connectors together without any other components. Some do have balancing and/or impedance matching transformers or other stuff going on.
I think you'll find the Cat cable snake box manufacturers universally recommend shielded cable.

If the camera cable doesn't have at least an over-all shield, then the level of risk goes up considerably. This falls into the category of things that will work fine until you really need it for a big show.
 

Jay Ashworth

Well-Known Member
Well, it looks like the CCZ isn't as standardized as I'd thought, and it's also *right at* the Event Horizon of the Internet.

Here's a partial pinout:


You're probably going to have to locate a service manual for a camera or CCU that used it to find a full one -- which would lead you to a rundown of what's in the cable.

You can still *buy* CCZ cable too, looks like, that might also get you there.

But there's a *strictly* limited amount of labor it's worth investing in doing anything besides using it as a pull-rope to pull in a 12x4 snake. :)
 

TimMc

Well-Known Member
Premium Member
The quick answer is you're on a fool's errand. The theater is being penny-wise but pound-foolish.
 

lscherrer

Member
UPDATE: Thank you all for your responses! We've decided not to try to repurpose it (agreed that for the amount of time and labor it makes more sense to just buy new cable) but for educational purposes we cut open the CCZ cable to see what was inside. There were two runs of twisted pairs (we theorize these were the audio feeds to and from the camera) and the rest of the wires (unshielded and shielded) were spirally wrapped around the core. The more you know.
 

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