Sadie 96k cable issue

matthewd · 5th January 2009

I had a problem today monitoring 96kHz out of a sadie system. I have a Presonus Central Station on which I use the digital input on SPDIF which claims to be up to 192K. I only have a AES card on this particular Sadie so I use a female XLR to phono cable which is fine a 44.1kHz and 48kHz but at 96kHz it just got ridiculous digital spitting sounds. Having troubleshot things methodically I tracked it down to the particular XLR to Phono lead - I have three. The one that I replaced it with which is not fine I think was bought specifically as a digital cable but I was interested to know the explanation for this as a producer more on the musical than technical side.

Thanks

Matt

huub · 5th January 2009

So your other 2 cables were fine?

matthewd · 5th January 2009

Yes, the other two were fine. I haven't taken them apart yet to have a look. None of the cables are more than a year old and thing which freaked me out is how it worked fine at standard resolution but played up at higher res.

I have read about cables specifically for digital audio which in the case of van damme are usually purple or light green and have difference impedance or something. Forgive my ignorance but I come from more the musical than engineering side and should have paid more attention at school!!!

Matt

huub · 5th January 2009

'Officially' you have to use a special adapter to convert SPdif to AES/EBU or vice versa.. I think it changes the impedance. A normal phono to XLR adapter usually works fine, but especially at higher samplerates it will be more critical.

BLP · 5th January 2009

Quote:

Originally Posted by huub

'Officially' you have to use a special adapter to convert SPdif to AES/EBU or vice versa.. I think it changes the impedance. A normal phono to XLR adapter usually works fine, but especially at higher samplerates it will be more critical.

Correct you are; the adapter is a transformer, which changes the impedance. AES3 (specifically the AES3 terminating in XLR connectors) is spec'd at 100 ohms, while S/PDIF (and AES3id, terminating in BNC connectors) is spec'd at 75 ohms. But this could just be part of the problem. While the actual data carried by the two formats is identical, the header/status data used in the format is different. I know that most new boxes don't seem to mind one way or the other, but I've heard rumors that some older systems can glitch due to this.

As for why some would work and others would not, it could be a manufacturing tolerance thing. Cables, just like any other gear, seem to have a wide range of manufacturing quality and spec tolerances depending on the company or the line.

Sorry to get techy, but there isn't much of a musical explanation for this one...

Plush · 5th January 2009

The problem may not be your cable at all. It depends on what SADiE system you are using. The SADiE 24/96 uses a double wire system to record and output 96K material.
For example to play back a 96K edl, one uses TWO AES cables. One side carries LFT ch. and the other cable carries RT ch. You plug into ch 1 and 3 AES out on the SADiE.

The current SADiE workstation, Version 5, uses a single AES cable to record and play back 96K material.

AES to SPDIF conversion can indeed be done with an inline transformer. You will have to check on which SADiE editor it is you are using in order to know what to do.

matthewd · 6th January 2009

It was recorded on my LRX and is being post produced on my H64, both running V5. I am aware of a tick box in the setup for output format SPDIF or AES but this didn't make a difference in this instance. I am of course on internal sync and the Dual Wire mode seems to be blanked out so I can't choose it anyway. No I have a working cable it is actually fine but I was just curious and worried that my reliance upon outputting via the AES card because I can't justify a grand for a 16 ch analogue output card I would only ever use two channels of leaves me a bit vulnerable on location. At lease I know which cable to take with me in future!!!

Matt

mpdonahue · 7th January 2009

Matt,
I would take an ohm meter and test the cable. What I suspect is that one of the cables in question has pin 3 floating and one has pin 3 tied to ground (Pin 1).
When you're not using a balun to transformer match the 110 to 75 ohm, is is best to ground the other side of the balanced driver, as most AES outputs are transformer isolated.
All the best,
-mark

5th January 2009	#1
matthewd Gear maniac Joined: Feb 2008 Posts: 162 Thread Starter	Sadie 96k cable issue I had a problem today monitoring 96kHz out of a sadie system. I have a Presonus Central Station on which I use the digital input on SPDIF which claims to be up to 192K. I only have a AES card on this particular Sadie so I use a female XLR to phono cable which is fine a 44.1kHz and 48kHz but at 96kHz it just got ridiculous digital spitting sounds. Having troubleshot things methodically I tracked it down to the particular XLR to Phono lead - I have three. The one that I replaced it with which is not fine I think was bought specifically as a digital cable but I was interested to know the explanation for this as a producer more on the musical than technical side. Thanks Matt

5th January 2009	#6
Plush Lives for gear Joined: Jul 2003 Location: EARS/Chicago Posts: 4,274 2 Reviews written	The problem may not be your cable at all. It depends on what SADiE system you are using. The SADiE 24/96 uses a double wire system to record and output 96K material. For example to play back a 96K edl, one uses TWO AES cables. One side carries LFT ch. and the other cable carries RT ch. You plug into ch 1 and 3 AES out on the SADiE. The current SADiE workstation, Version 5, uses a single AES cable to record and play back 96K material. AES to SPDIF conversion can indeed be done with an inline transformer. You will have to check on which SADiE editor it is you are using in order to know what to do. __________________ Atelier HudSonic, Chicago EARS-Chicago (Engineering And Recording Society) visit me at https://public.me.com/hudsonic1 to hear recordings and ephemera

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5th January 2009	#2
huub Lives for gear Joined: Apr 2005 Location: amsterdam Posts: 1,208	So your other 2 cables were fine?

6th January 2009	#7
matthewd Gear maniac Joined: Feb 2008 Posts: 162 Thread Starter	It was recorded on my LRX and is being post produced on my H64, both running V5. I am aware of a tick box in the setup for output format SPDIF or AES but this didn't make a difference in this instance. I am of course on internal sync and the Dual Wire mode seems to be blanked out so I can't choose it anyway. No I have a working cable it is actually fine but I was just curious and worried that my reliance upon outputting via the AES card because I can't justify a grand for a 16 ch analogue output card I would only ever use two channels of leaves me a bit vulnerable on location. At lease I know which cable to take with me in future!!! Matt

7th January 2009	#8
mpdonahue Gear addict Joined: Dec 2002 Location: Boston, MA Posts: 495	Matt, I would take an ohm meter and test the cable. What I suspect is that one of the cables in question has pin 3 floating and one has pin 3 tied to ground (Pin 1). When you're not using a balun to transformer match the 110 to 75 ohm, is is best to ground the other side of the balanced driver, as most AES outputs are transformer isolated. All the best, -mark