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Old June 11th, 2008, 07:35 PM   #1
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Connecting Wireless transmitter to sound board

Hi all,

I have a Telex ENG100 wireless system that I would sometimes like to connect to a sound board to transmit the house mix to my camera. Usually, I use the transmitter with a electret lav mic that requires +5 VDC. It uses a four pin T4A connector.

I would like to make T4A to XLR cable and be able to connect to the sound board. I've soldered my own cables before, so I'm not afraid of that. But are there any gotchas I should watch out for when soldering 4 pin T4A to 3 pin XLR? The manual says the four pins are:

1. Ground
2. Mic
3. +5 V bias
4. +5 V bias fed though a 3K Ohm resister for 2 wire electrets.

How would these connect to the XLR pins? Ground to ground, Mic to negative, 5V to positive? Do I leave pin 4 unconnected?

Question two is, once I have the cable, how do I connect to a sound board. Is it as simple as asking for an XLR mic level output, and adjusting my levels? Or are the XLR outputs on most sound boards line level?

Last question, for those of you who hook up to house systems in this way. What do you find the optimal XLR length is? I'd like to go short, so it fits more easily in my camera bag, but I'm wondering if you often need to be hiding the transmitter a distance away from the sound board.

Sorry if these are basic questions, but my web searches were futile, kind of like resistance to the Borg...

Any input would be most appreciated. Thanks in advance.
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Old June 11th, 2008, 07:57 PM   #2
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Hi Vito...............

The first problem I think you might find is the XLR O/P of the sound board being balanced.

That can be got 'round using a balanced to unbalanced transformer, available as a tiny plug in unit with an XLR at each end.

Once you've got unbalanced out of the board, my logic says XLR ground to 4 pin pin 1, "Live" to pin 2. Finish. Pins 3 & 4 are redundant.

My limited knowledge of sound boards (er, try non existant) thinks the answer could be either mic or line, as long as your transmitter can be set to match each, everythings rosy.

As for optimum cable length, as a complete guess, say 2 feet? Just long enough to let you duct tape the transmitter to the underside of the board.

If you want to verify any of this I would suggest you Google "connecting to sound board" or somesuch and wadeing through the 17,000 hits you'll get, mostly from knowledgeable people here on DVinfo.


CS
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Old June 11th, 2008, 08:45 PM   #3
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Hi Chris

Quote:
Originally Posted by Chris Soucy View Post
The first problem I think you might find is the XLR O/P of the sound board being balanced.
Right, and without a return, I can't have balanced. That never even occurred to me.

Quote:
Once you've got unbalanced out of the board, my logic says XLR ground to 4 pin pin 1, "Live" to pin 2. Finish. Pins 3 & 4 are redundant.
Yes, of course! Pins 3 and 4 provide power to the mic, which I don't have to worry about?

Quote:
If you want to verify any of this I would suggest you Google "connecting to sound board" or somesuch and wadeing through the 17,000 hits you'll get, mostly from knowledgeable people here on DVinfo.
Yeah, I tried that. Hence my reference to the Borg...

As I feared, this is getting scarier and scarier.

Thanks, Chris.
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Old June 12th, 2008, 04:19 AM   #4
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Check the levels coming out of the board. I don't know if the Telex transmitter has a mic/line switch but you've been talking about connecting to its mic input which would obviously be expecting a mic level signal. The board, OTOH, will most likely be putting out line level. If so, the board will seriously overload the transmitter and you'll need to look at converting the levels as well as simply wiring an adapter.
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Old June 12th, 2008, 05:13 AM   #5
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Er, Steve.......

Vito never said anything about Mic level, in fact he doesn't know what to expect (funnily enough, neither do I).

Maybe, if you actually read my post thoroughly, you'll see this "sort of covered" in a "well, if it don't work, don't blame me" sort of way.

I agree with you, the board will, from reading this Forum, most likely be outputing Line, but no guarantee.

The question about the input to the transmitter was covered.

I do not know what the Telex can take or not, that's for Vito to determine.

CS
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Old June 12th, 2008, 10:03 AM   #6
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I don't know of too many soundboard that use a mic feed on the output side of things. In fact, I don't think I've ever run into one in my years of recording. That's not to say they don't exist, but that they are quite rare if they do.

I would plan for and expect a line output. The real trick is to have the right connector combos. Some boards will have RCA outputs, some 1/4" outputs, and others XLR outputs. As long as you have adapters, you should be fine.

As far as length goes, I made my own cables years ago. One set is 1/4 to XLR, the other RCA to XLR, both are unbalanced (most boards tend to be unbalanced), and I have two sets of each. One is 1 metre in length, the other set is 20 feet in length. I've been using these cables for years without problems. But it's a crap shoot trying to figure out what the output of the board is going to be connector-wise.

Wayne
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Old June 12th, 2008, 10:22 AM   #7
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Thanks, Wayne. I have several adapters, so that shouldn't be a problem.

Looks like I can make the cable using Chris's pinout suggestions, and need only be concerned with attenuating the line output for my transmitter's mic input, as mentioned by him and Steve. Does this make sense? Do I really need to be worried about going from balanced to unbalanced for such a short cable?

Is it that rare to try and do what I want? I thought tons of videographers would want to do this. Perhaps I should have asked the question in the event video section.

You guys have all been a great help.
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Old June 12th, 2008, 11:32 AM   #8
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Quote:
Originally Posted by Vito DeFilippo View Post
...Is it that rare to try and do what I want? I thought tons of videographers would want to do this. Perhaps I should have asked the question in the event video section.....
Others options...

1) Get a 2 track 24 bit recorder at sound board using "tape out" to line level input. Sync it up in post production.

2) Get a "butt" plug transmitter that can connect either to an xlr balanced out from the sound board. Try to convince the sound board operator to give you your own "aux out" (post fader) and dial down the aux master send closer to mic level.
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Old June 12th, 2008, 11:45 AM   #9
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Quote:
Originally Posted by Wayne Brissette View Post
I don't know of too many soundboard that use a mic feed on the output side of things. In fact, I don't think I've ever run into one in my years of recording. That's not to say they don't exist, but that they are quite rare if they do.

I...
Wayne

Just to keep it interesting, my Mackkie 1642 has both XLR and TRS main outputs plus tape out on RCA's. The TRS are +4dB line, the RCA's are -10 dB line, and the XLR's are switch selectable between +4 line and -30 mic
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Old June 12th, 2008, 12:14 PM   #10
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Quote:
Originally Posted by Jim Boda View Post
Try to convince the sound board operator to give you your own "aux out" (post fader) and dial down the aux master send closer to mic level.
A better option is to get them to give you a feed out of the matrix output if at all possible (maybe that is the aux out on some boards???).

Steve - yes, but I've yet to run into a Mackie at live music events. Maybe smaller halls, but then I'm not usually asked to record there.

Wayne
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