SPDIF Question

[DBX160]

Hi all,

Are all SPDIF IN/OUTS equal in quality?

I would suspect they are, but wanted a 2nd opinion.

Thanx...Take care.

[brent]

Hi all,

Are all SPDIF IN/OUTS equal in quality?

I would suspect they are, but wanted a 2nd opinion.

Thanx...Take care.

No. The original spec calls for S/PDIF to max out at 20-bit. Some manufacturers support 24-bit. The voltages can vary from manufacturer to manufacturer, as the spec allows for .5V to 1V. Some say that there is no data rate specified, but I know that S/PDIF and AES can be made to work together at 3MHz.

[TotalSonic]

No. The original spec calls for S/PDIF to max out at 20-bit. Some manufacturers support 24-bit.

I'd say at this point the vast majority of spdif i/o's for both dedicated hardware and soundcards are transferring full 24bits - but check your gear's specs - obviously some things like DAT machines or older soundcards will only transfer 16 or 20 bit.

One thing with spdif though:
To make sure the transfer is as jitter free as possible always use correct cabling: for coax connections 75ohm cable with crimped (not soldered) 75ohm ends. Also - don't extend lengths beyond say around 25' - usually keeping spdif cables under 10' is a good practice - with even shorter as the limits for optical connections.



The voltages can vary from manufacturer to manufacturer, as the spec allows for .5V to 1V. Some say that there is no data rate specified, but I know that S/PDIF and AES can be made to work together at 3MHz.

Yup - plenty of spdif to AES format converters out there - I love my Z-sys Detangler digital patch bays - makes hooking up the ADC, DAC's (3), DAWs (2), and digital transports (6) a breeze.

Best regards,
Steve Berson

[Dave Labrecque]

Shortly after I bought my Ramsa/Panasonic WR-DA7 console, the local music store had Craig Anderton come through on his DA7 seminar tour. I went (won a DA7 hat, so it was well worth it :)) and watched as he took us through the paces. When he got to the stereo bus digital I/O stuff, he talked about how it could do on-the-fly converstion of AES/EBU to S/PDIF (or the other way around, I can't remember). I raised my hand and said, that's odd, cuz there's a single FORMAT toggle switch between the IN and OUT BNC jacks; you're either AES/EBU or you're S/PDIF. He kind of looked puzzled and said, well, I ran AES/EBU in and got S/PDIF out. Another guy who was there, maybe with the local store, said something about the only difference between the two formats is an extra bit in the data stream. Maybe he was saying that the AES signal going in was being truncated?

Can anyone make sense out of this curious exchange?

[Mark Stebbeds]

I raised my hand and said, that's odd, cuz there's a single FORMAT toggle switch between the IN and OUT BNC jacks; you're either AES/EBU or you're S/PDIF. He kind of looked puzzled and said, well, I ran AES/EBU in and got S/PDIF out. Another guy who was there, maybe with the local store, said something about the only difference between the two formats is a single bit in the data stream. Maybe he was saying that the AES signal going in was being truncated?

Can anyone make sense out of this curious exchange?

Can't make sense out of it, but have had similar experiences.

I had another weird experience with adjusted the output level (by taking the top off of a box) out of SPDIF out so it could drive an AES input or something weird like that. I wish I could remember that. I wrote it down, but can't find the doc.:o

mark

[brent]

Shortly after I bought my Ramsa/Panasonic WR-DA7 console, the local music store had Craig Anderton come through on his DA7 seminar tour. I went (won a DA7 hat, so it was well worth it :)) and watched as he took us through the paces. When he got to the stereo bus digital I/O stuff, he talked about how it could do on-the-fly converstion of AES/EBU to S/PDIF (or the other way around, I can't remember). I raised my hand and said, that's odd, cuz there's a single FORMAT toggle switch between the IN and OUT BNC jacks; you're either AES/EBU or you're S/PDIF. He kind of looked puzzled and said, well, I ran AES/EBU in and got S/PDIF out. Another guy who was there, maybe with the local store, said something about the only difference between the two formats is a single bit in the data stream. Maybe he was saying that the AES signal going in was being truncated?

Can anyone make sense out of this curious exchange?

No, both use bi-phase mark code. To get them to interface is a matter of changing impedence usually.

[TotalSonic]

Wiki to the rescue! - these should answer your questions -

http://en.wikipedia.org/wiki/S/PDIF

http://en.wikipedia.org/wiki/AES3

Best regards,
Steve Berson

[Dave Labrecque]

Wiki to the rescue! - these should answer your questions -

http://en.wikipedia.org/wiki/S/PDIF

http://en.wikipedia.org/wiki/AES3

Best regards,
Steve Berson

Wow. That's more than I'll ever need to know. Interesting that S/PDIF can carry four channels of audio. Anyone ever heard of this in real life?

[Mark Stebbeds]

Anyone ever heard of this in real life?

Nope. Only in my fake life.

Mark

[TotalSonic]

Wow. That's more than I'll ever need to know. Interesting that S/PDIF can carry four channels of audio. Anyone ever heard of this in real life?

I'm sure you've heard more already if you've ever been near a decent home theater set up - it can carry 5.1 via Dolby or DTS compression. But as far as 4 standard channels of PCM via a single spdif connection - I'm not aware of any hardware implementations of this.

Best regards,
Steve Berson