Soundcraft Ghost 24 + Otari MX5050 8 tk 1/2" - Pin Hot

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bbmelanson
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Soundcraft Ghost 24 + Otari MX5050 8 tk 1/2" - Pin Hot

Post by bbmelanson » Thu Jun 10, 2010 1:00 pm

Just checking to see if anyone has used this setup together before (or currently).

I have an older Soundcraft Ghost 24 console and an Otari MX5050 8 track 1/2" machine.

I'm currently awaiting a set of recording snakes to test everything out... but I'm mainly concerned about phasing probs or 'pin hot' conflicts.

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Dakota
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Post by Dakota » Thu Jun 10, 2010 1:09 pm

My Otari MX5050 mkIIIB 2tk is pin 3 hot, and when initially connected with normal cabling was unpredictable how it would interact with other gear, sometimes fine sometimes not. I made custom i/o cabling to it with pins 2 and 3 flipped, and now it's always fine. If I get around to it, I may rewire the Otari internally at the jacks.

The Ghost I'd guess to be pin 2 hot, but that's a guess.

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Post by bbmelanson » Thu Jun 10, 2010 1:21 pm

Thanks Dakota.
I do have a multi-meter, but I'm unsure how to measure to find out which pin is hot and what not.

I took out one of the output XLR jacks (FEMALE) and looked at it.
Looks like the solder is original... Pin 3 Orange, Pin 2 White, Pin 1 had rubber sheilding.

Image

Only problem is that I do not know what color/sheild means what.
I usually do not work on electronics, so my knowledge is very limited.

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Post by Dakota » Thu Jun 10, 2010 1:49 pm

You're very welcome, bbmelanson.

A multimeter is not really the easy way to tell if gear is pin 2 or 3 hot. Get a manual for the Ghost, it should specify.

"Hot" in this case means that line is carrying the "real" polarity of the signal. Example: a synthesizer or tone generator set to "up" sawtooth, on viewing the waveform on an oscilloscope or in a DAW waveform view, you'd see the waveform ramping up, then dropping steeply, then ramping up again. The "cold" line carries a mirror opposite, inverted polarity version of the signal, exactly the same but upside down. The idea of a balanced line like this is that the cold is flipped (inverted) again when it gets to where it's going, the two signals mixed, and any noise that got in along that line is therefore canceled out. Pin 1 is always "ground", the shield and reference and path to ground if needed.

If you need to test the ghost or anything else for pin 2 or 3 hot, send in a known signal (like the up sawtooth described above, from a synth or tone generator or DAW) on an unbalanced input to the board (to make sure there's no way anything could be flipped). Send from a balanced output on the board to an oscilloscope or record it into a DAW with known modern pin 2 hot inputs, look and see if the waveform has flipped.

Older gear is half pin 3 hot, half the other way. The convention eventually standardized on pin 2 hot, and almost everything recent is pin 2 hot.

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Post by doctari » Wed Jun 16, 2010 7:42 pm

I had the same situation between My 5050 and Mackie analog 8 bus. I have pretty humble soldering skills and was able to switch the wires on the Otari connectors. It just seemed an easier fix than having multiple snakes.

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Post by Brian » Fri Jun 18, 2010 7:17 pm

Didn't it used to be british stuff was always pin 2 hot and american stuff was pin 3 or vice-versa?
Either way, the above directions are good.
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Post by honkyjonk » Wed Jun 23, 2010 12:08 pm

For folks re-wiring their tape machines to reflect Pin2 hot, or anything else for that matter, I would suggest putting an indicator on the machine itself that this is the case because potential future owners will generally assume it's wired as the manual says.
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