SPDIF to AES

Kevin Maxwell

Kevin Maxwell

Junior
Feb 6, 2011
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SPDIF to AES

I tried connecting a CD player to an SC48 using the digital out of the CD player (Spdif) into the digital in (AES) of the SC48. I hit pay and it sounded great. Until it changed tracks. At that point it sent a rather loud glitch thru the system. Is this caused by the other data (copy protection etc?) that is on a SPDIF output? I made my own wire – RCA – pins 2-hot and 1 shield on the XLR.

Do the adapters with the transformer built in block the other stuff or does the Hosa CDL 313 strip off that data?

I plan to look today to see if there is a setting on the CD player that allows me to turn the extraneous data off.
 
Re: SPDIF to AES

Kevin Maxwell said:
SPDIF to AES

I tried connecting a CD player to an SC48 using the digital out of the CD player (Spdif) into the digital in (AES) of the SC48. I hit pay and it sounded great. Until it changed tracks. At that point it sent a rather loud glitch thru the system. Is this caused by the other data (copy protection etc?) that is on a SPDIF output? I made my own wire – RCA – pins 2-hot and 1 shield on the XLR.

Do the adapters with the transformer built in block the other stuff or does the Hosa CDL 313 strip off that data?

I plan to look today to see if there is a setting on the CD player that allows me to turn the extraneous data off.
Click to expand...

Is there a chance you could use a "lookahead" gate on the inputs that has time to automatically mute before the sync issue becomes audible? And then reopen only when the music starts?
 
Re: SPDIF to AES

kristianjohnsen said:
Is there a chance you could use a "lookahead" gate on the inputs that has time to automatically mute before the sync issue becomes audible? And then reopen only when the music starts?
Click to expand...

The Glitch is a way too loud it is louder then the program material at full blast, it pegs the meters.
 
Re: SPDIF to AES

It sounds like a clocking issue. Can the Cd player slave to the desk or vice-versa? If I have time at the show later I'll see if I can duplicate the problem and find a fix.
 
Re: SPDIF to AES

SPDIF has a lower pk-pk voltage than AES and so not all AES receivers will work when fed SPDIF. While your CD player is working when playing, your AES receiver might be on the edge of it's limits. Best get something like a HOSA CDL 313 bi-directional converter. I use one for sending S/PDIF from my 01v96 to AES on my Lake gear.
 
Re: SPDIF to AES

Michael Smithers said:
SPDIF has a lower pk-pk voltage than AES and so not all AES receivers will work when fed SPDIF. While your CD player is working when playing, your AES receiver might be on the edge of it's limits. Best get something like a HOSA CDL 313 bi-directional converter. I use one for sending S/PDIF from my 01v96 to AES on my Lake gear.
Click to expand...

So the Hosa device will fix this? And you are saying - It will handle the 44.1k out of the CD player into the AES input that then converts it to the native 48k of the console?
 
Re: SPDIF to AES

TJ Cornish said:
The Hosa device is not a sample rate converter.
Click to expand...

So for this to work right I would need a sample rate converter? It looks like the price of a sample rate converter is more then I want to spend and there is no need to replace a good Denon CD player with one that has AES 48k outputs. It sounds fine going into the console on an analog input so I guess I will just do it that way.
 
Re: SPDIF to AES

Kevin Maxwell said:
So for this to work right I would need a sample rate converter? It looks like the price of a sample rate converter is more then I want to spend and there is no need to replace a good Denon CD player with one that has AES 48k outputs. It sounds fine going into the console on an analog input so I guess I will just do it that way.
Click to expand...
I'm not sure the sample rate is the issue - it sounds like the desk is losing word clock from the CD player - either for the signal reasons as Michael mentioned which the Hosa may fix, or for deck reasons as Silas suggests.

Does the SC48 have sample rate conversion on the digital inputs? I'm not familiar with that desk and can't find the answer with a quick search. If not, and if your Denon deck doesn't have the ability to output at 48K (and accept a wordclock input from the SC48 so the board stays as the clock master), then I agree with you - analog inputs are a lot simpler.
 
Re: SPDIF to AES

TJ Cornish said:
I'm not sure the sample rate is the issue - it sounds like the desk is losing word clock from the CD player - either for the signal reasons as Michael mentioned which the Hosa may fix, or for deck reasons as Silas suggests.

Does the SC48 have sample rate conversion on the digital inputs? I'm not familiar with that desk and can't find the answer with a quick search. If not, and if your Denon deck doesn't have the ability to output at 48K (and accept a wordclock input from the SC48 so the board stays as the clock master), then I agree with you - analog inputs are a lot simpler.
Click to expand...

The SC48 does do sample rate conversion on the digital ins. The CD player doesn’t have the capability to output 48k and it doesn’t have a word clock connection.

Someone from Avid has been asked this question and is supposed to get back to me. So for now it is analog in.
 
Re: SPDIF to AES

If the sample rate conversion is set up correctly, which I think it must be as you can hear good audio then it's a clocking issue probably the CD player stopping the digital transmission then the pop is re-sync try using pause rather than stop if you must use the digital ins, somehow I think it's not worth the effort G
 
Re: SPDIF to AES

gordon mcgregor said:
If the sample rate conversion is set up correctly, which I think it must be as you can hear good audio then it's a clocking issue probably the CD player stopping the digital transmission then the pop is re-sync try using pause rather than stop if you must use the digital ins, somehow I think it's not worth the effort G
Click to expand...

In case I didn’t make this clear the glitch happened when the CD went on its own from track 1 to track 2. It may have also glitched when I stopped it. After that I stopped playing it thru the system. When I played the same CD when plugged into the analog inputs it played just fine.

I may revisit this later and see if I can figure out the behavior and see what it seems to be related to.

When building some radio station control rooms a few years ago the guy I was working for had us connect from the SPDIF out of the CD players to the AES inputs of the digital Radio station console by just connecting the hot and shield and ignoring the pin 3 on the AES. And it worked just fine. But both pieces of equipment where at 44.1k.
 
Re: SPDIF to AES

The CD player is a Denon that I think sold for about $500. So its not a cheap piece of junk and hard to justify changing out. But the plot sickens.

Well I need to do a little bit more testing. I was all alone in the church today and I put the CD on, it is being feed into a Direct box and then into an analog preamp into the console. The CD that I had played belongs to the church and it looks like a standard production CD but it only has 3 tracks on it. This is the only CD I had tried because I didn’t have anything I though was appropriate to play in a church with church people around. I do have Christian music I just didn’t think I had any with me. And this is the first time I actually listened to the whole thing. And it has a glitch on it that is rather noticeable at the start, at the track changes and I think even at the end. It seemed louder when I was connected digitally but that might have been because I was playing it louder.

Buy do I really feel like an idiot. It just seems to be a bad CD.
 
Re: SPDIF to AES

Kevin Maxwell said:
The CD player is a Denon that I think sold for about $500. So its not a cheap piece of junk and hard to justify changing out. But the plot sickens.

Well I need to do a little bit more testing. I was all alone in the church today and I put the CD on, it is being feed into a Direct box and then into an analog preamp into the console. The CD that I had played belongs to the church and it looks like a standard production CD but it only has 3 tracks on it. This is the only CD I had tried because I didn’t have anything I though was appropriate to play in a church with church people around. I do have Christian music I just didn’t think I had any with me. And this is the first time I actually listened to the whole thing. And it has a glitch on it that is rather noticeable at the start, at the track changes and I think even at the end. It seemed louder when I was connected digitally but that might have been because I was playing it louder.

Buy do I really feel like an idiot. It just seems to be a bad CD.
Click to expand...

That's the kind of stuff that really pisses you off. Hopefully that's the end of the story for you.
 
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