AES - Word Clock Basics

[David Sturzenbecher]

I am just trying to figure out some AES interconnection basics and ran into a situation where I can't figure out if things should be working or not.

I have a SC48 and an 01V96 with a MY8-AE96 card. Both the mixers are running off of a master clock set to 48k.

I can send AES from the MY8-AE96 to the SC48 without a problem. I am guessing because there is a sample rate converter on the AES 2-Track In. However, I cannot reliably send AES from the 2-Track out to the MY8-AE96 card, when the clock is set to "Word Clock In" in the 01V. It shows up, but cuts in and out. If I set the clock source is set to "slot in" then it works fine.

This is not an actual scenario, I am just trying things out. I sure thought that if the source and the receiver were sync'ed off the same clock there wouldn't be any problems.

 

[Michael John]

Re: AES - Word Clock Basics

Try setting the 01v96 clock source to "slot." The "word clock in" means it's using the BNC.

 

[David Sturzenbecher]

Re: AES - Word Clock Basics

Yes, It works fine when the slot is set as the word clock reference. And maybe there is no logical reason to not clock to the slot input, but I sure thought that when you had a master clock connected to two pieces, they would talk happily.

 

[mackerr]

Re: AES - Word Clock Basics

Yes, It works fine when the slot is set as the word clock reference. And maybe there is no logical reason to not clock to the slot input, but I sure thought that when you had a master clock connected to two pieces, they would talk happily.

They should. Have you verified that both consoles are actually sync'd to the WC input?

In a simple system where you are only feeding digital audio in one direction you should also be fine clocking the 01v to the slot input since AES3 audio carries a good clock signal.

Mac

 

[Kip Conner]

Re: AES - Word Clock Basics

Are you using a return cable in the system or do you use a 75 Ohm terminator on the WC outs?

 

[Silas Pradetto]

Re: AES - Word Clock Basics

If a device has both WC in and WC out, I have found that many cases the WC out only works if the device is actually the clock master, not slave. If slave, the WC out doesn't do anything. You should be using those BNC T adapters and terminators for your WC run.

 

[Tim Padrick]

Re: AES - Word Clock Basics

Shouldn't the clock be run separately to each device, and be terminated at each device?

 

[David Sturzenbecher]

Re: AES - Word Clock Basics

Shouldn't the clock be run separately to each device, and be terminated at each device?

This is how my setup is, word clocks out of each device are not terminated. Is there a length limitation to word clock cable?

 

[mackerr]

Re: AES - Word Clock Basics

This is how my setup is, word clocks out of each device are not terminated. Is there a length limitation to word clock cable?

Word clock out of each device should not have to be terminated, it is not a pass through of the input, but an output of the device's internal generator. If the devices are not self terminating, you should be using a "T" connector with a terminator to connect to each device. If the device is terminating you do not need, nor want, the extra termination. There is a limit to cable length, but it is at least hundreds of feet with good 75Ω coax.

Mac

 

[David Sturzenbecher]

Re: AES - Word Clock Basics

It appears that one of the cables I was using was a 25ft piece of RG-58A/U, most likely from a wireless mic system. I replaced this with a 6ft piece of RG6 and now everything works great...and I have a little better grasp on this clocking thing.