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Old August 9th, 2008, 10:45 AM   #1
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Balancing an unbalanced cable

What's the best way to do this? I'd like to use this adapter cable -- http://www.trewaudio.com/store/produ...&cat=25&page=2 -- to take a feed from the tape out on my SD302. Problem is, the signal is unbalanced (at least I think it is). Could I add a transformer or something to the chain to balance the signal?
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Old August 9th, 2008, 12:00 PM   #2
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According to my info the SD302 mix/tape out is unbalanced, -10dBv, TA3F stereo with pin 2=left, pin 3 = right, pin 1 = ground.

If you *really* need to balance it for a very long cable run you'd need some inline transformers but frankly I wouldn't worry about it for any reasonable distance, especially since you're carrying a line level signal instead of mic level. I'd expect the device you're feeding will be as happy with unbalanced on the XLR, pin 3 connected to ground, as it would be with a balanced connection. Is this for your Red shoot in a few days?
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Old August 9th, 2008, 12:11 PM   #3
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Yup. this is for a scratch track back to camera as hopefully we will now be doing double system. Cable length is probably going to be 50 feet. It would be great if I could balance the signal. I'd like to feed the recorder with the XLR outs on my mixer.
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Old August 9th, 2008, 01:42 PM   #4
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I could run down there with my 442 <grin>. With 3 pair of outputs, 2 pair of which are switch selectable for mic/-10/+4, plus the direct outs on each channel and the tape/mix out, it's easy to do what you needing.

How about sending the 302's XLR outs to the camera and its tape out to the recorder?
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Old August 9th, 2008, 01:45 PM   #5
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Quote:
Originally Posted by Marco Leavitt View Post
Yup. this is for a scratch track back to camera as hopefully we will now be doing double system. Cable length is probably going to be 50 feet. It would be great if I could balance the signal. I'd like to feed the recorder with the XLR outs on my mixer.
The XLR outs on the 302 are balanced.
The TA3 tape out on the 302 is not balanced.

I use the tape out on the 302 to a small recorder with this cable from Sound Devices (the second one in the list):
http://www.bhphotovideo.com/bnh/cont....y=0&Go=submit

Sound Devices is very helpful, and if you telephone them they can tell you what to do for your specific situation.

Probably, from what you described, you want to go from the unbalanced tape out, change the signal to balanced with a DI box, then do your 50 foot run to the camera.

There is a thread somewhere on DI (Direct Inject) boxes. However, what you would want is a dual box, not too expensive.

Here are a couple of them:
http://www.bhphotovideo.com/c/produc...ction_Box.html
http://www.jr.com/sdir-series-stereo.../SAU_SDIRPLUS/

You have to figure out the levels. I don't remember without looking how or if you can adjust the tape out level on the 302.

What kind of recorder are you sending the XLR outputs from the 302 to? Does the recorder have balanced outputs you can send to the camera?
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Old August 9th, 2008, 01:53 PM   #6
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"How about sending the 302's XLR outs to the camera and its tape out to the recorder?"

Yeah, I'm considering it. Oh, and I promise you, you want nothing to do with this shoot! :) Just kidding. I hope they aren't reading.
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