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Post by Golgoth on Jun 20, 2016 7:07:39 GMT -6
Hi guys, I recently built a couple of TRS to XLR cables for patching outboard gear and I'm having phase issues. The signal comes back swapped. Which of these schemes is right?   I'm sure my XLR's are ok (2hot 3cold 1ground), but I don't know about the TRS's. I wired them hot in the middle, cold on top and ground on the bottom like in the first pic. |
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Post by mulmany on Jun 20, 2016 7:30:46 GMT -6
That's correct. It's how I have wired all my trs.
What gear are you patching in? Is it a older piece with pin 3 hot?
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Post by Golgoth on Jun 20, 2016 7:46:37 GMT -6
Hi Patrick,
Patching a VP28 (a second one is on the way) with these cables. The lunchbox has pin 2 hot.
Tried all four cables I made in different slots configurations.
Could the problem lie in the VP? I recently replaced the transformers to Litz's but the wiring is correct.
I observed the phase flipping while testing the cables by recording through the module in mono.
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Post by mulmany on Jun 20, 2016 14:07:39 GMT -6
I would look at the transformer wiring again and double check.
Do you have another factory made 500 unit?
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Post by Golgoth on Jun 20, 2016 14:26:30 GMT -6
Transformer wiring checked ok. Unfortunately no factory made 500 module on hand at the moment.
I am expecting a second VP28 kit to be delivered in the next few days. I'll try again with the new one and while I'm at it maybe reflow the Litz's solders?
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Post by mulmany on Jun 20, 2016 15:50:59 GMT -6
Transformer wiring checked ok. Unfortunately no factory made 500 module on hand at the moment. I am expecting a second VP28 kit to be delivered in the next few days. I'll try again with the new one and while I'm at it maybe reflow the Litz's solders? Check it with continuity on your DMM. The cable and VP28. Go through the card edge pin out and verify, with cables plugged in and no cable. Do you have a 500 series test jig? |
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Post by Golgoth on Jun 20, 2016 16:32:33 GMT -6
I do have a test jig. What would be the procedure?
Thanks for helping Patrick.
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Post by mulmany on Jun 20, 2016 17:25:05 GMT -6
Use the 500 series pin out diagram that Jeff has on capi-gear.com. Put your DMM in continuity mode, the one that beeps. Test the XLR'S against the card edge pinout. Then plug in your trs/xlr cables and do the same. You can do the same with the test jig and test the xformer pins.
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Post by jayson on Jun 20, 2016 17:34:31 GMT -6
Is that a Canare 1/4" TRS? I really loathe the connectors that have the pos & neg poles less than a millimeter apart like that. It's almost like they want the connector to either short or break so they can sell you another one. They don't seem to me like the solder cups have anywhere near enough capacity to give you a durable connection - especially if the insulator on the cable your soldering tends to shrink away from the heat of the solder even the tiniest bit. I'll take a even a used Switchcraft 297 over that style connector any day - they actually have enough room to work on them.  |
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Post by Golgoth on Jun 21, 2016 3:47:43 GMT -6
Thx guys. I tried recording in and out through the cables only. Here's the result:  Same result with every cable I own, DIY or factory made. I suspect the problem comes from my audio interface. I will get in touch with the brand today. |
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Post by Golgoth on Jun 21, 2016 5:41:17 GMT -6
Alright got an answer from them, this is a bug in the current release of the audio interface firmware.......  |
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Post by mulmany on Jun 21, 2016 6:41:27 GMT -6
Alright got an answer from them, this is a bug in the current release of the audio interface firmware....... Was not expecting that! What Daw? |
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Post by Golgoth on Jun 21, 2016 6:58:42 GMT -6
I wasn't either!
The bug is in the Audient's ID firmwire. That's not the first problem I got with them unfortunately.
I'm currently struggling for stability since I bought that iD22 interface...
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Post by Golgoth on Jun 21, 2016 7:24:05 GMT -6
Quick and final update:
I got another email from the Audient support team. They provided me with a special manual update to apply to the software including some terminal commands and a patch file attached to the mail, with very detailed instructions. No more phase flipping!
I think they have one of the best customer care around, the problem was solved in 2 hours from the moment my request was initially sent. I just hope there will be no more issues in the future with the unit, that was my third experience with their technicians in two months!
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Post by svart on Jun 21, 2016 7:29:20 GMT -6
Folks, there is NO standard in the industry that dictates signal polarity relationships between devices.
In other words, if you had a sine wave file that started at 0:00 with a positive going voltage, one manufacturer might have a positive going signal, another a negative going signal.
It's not phase per se, it's polarity, since phase is only related to a single point in time. Hardware and software propagation delay will cause phase slip anyway.
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Post by Golgoth on Jun 21, 2016 7:48:06 GMT -6
You're right! Polarity.
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ericn
Temp
Balance Engineer
Posts: 16,107 
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Post by ericn on Jun 29, 2016 20:35:31 GMT -6
Folks, there is NO standard in the industry that dictates signal polarity relationships between devices. In other words, if you had a sine wave file that started at 0:00 with a positive going voltage, one manufacturer might have a positive going signal, another a negative going signal. It's not phase per se, it's polarity, since phase is only related to a single point in time. Hardware and software propagation delay will cause phase slip anyway. Luckily it's the easiest problem in audio to solve! If you don't have a simple polarity switch a simple adaptor cable , barrel plug or my favorite do it on the patchbay! |
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