11R SPDIF to MBox 3 Clock Question
 

I'm starting a new thread because the one I started yesterday was too general. I've got it working now except for one problem that I'd like to solve.

I'm connecting a 11R to a MBox 3 through SPDIF.

It works this way:

MBox 3 main interface
Clock set to external SPDIF

11R connected SPDIF
Clock set to internal.

I set up a track in Pro Tools, set input to SPDIF...all is good. I can hear and record guitar through the 11R.

The problem is I want to use the internal clock of the MBox 3 because I believe the A/D conversion in that is better, and the clock is a part of that.

But If I set the MBox 3 clock to internal and the 11R to external/SPDIF I get no guitar sound.

Is this normal or am I doing something wrong?

Re: 11R SPDIF to MBox 3 Clock Question
 

Yep - that's the way it is, - for a digital transfer, PT must be clocked to an ext source, which is the Eleven in your case. And don't be misled by the AD conversion - "AD" is analog to digital, but you're not dealing with analog signal between the two devices here, it is strictly an exact digital copy you are sending from Eleven.

Re: 11R SPDIF to MBox 3 Clock Question
 

Thats how i set mine up. 003R as the main interface. 11R hooked to it via SPDIF, set the clock on the 11R to internal and set the clock on the 003R to SPDIF.

Re: 11R SPDIF to MBox 3 Clock Question
 

Thanks guys.

Then I guess I'm all set.

Re: 11R SPDIF to MBox 3 Clock Question
 

I am reading this with great interest as I am having a different experience doing the same thing and maybe I am missing something or doing something wrong.

I have 11R set into the MBOX 3 through SPDIF Cables

I have 11R Set to use EXTERNAL CLOCK and SPDIF (as per page 72 of the 11R manual)

In ProTools I am using the Internal Clock and this is also reflected in the MBOX 3's Driver Settings.

11R comes through no problem. Sound is clear and crisp.

If I switch the clock in PRO TOOLS to use External and the R11 to use internal I get sound, but I also get a constant ticking noise.... ( I am assuming that changing it in PROTOOLS would also change it in the MBOX 3?)

Am I doing something wrong?

Sorry if I am missing something obvious....

Thanks
SBS

Re: 11R SPDIF to MBox 3 Clock Question
 

The 'ticking' sound usually comes from a mismatch of sample rates between the devices. make sure they're still set to the same sample rate.

Beyond that, i'd say stick with what works!

Re: 11R SPDIF to MBox 3 Clock Question
 

I hear ya on that…

However I would like to understand what I am doing….

I guess the bottom line question is:

Which Unit (11R or the MBOX 3) should be the Clock source? Does it matter?

Would there be a preference and why?

I did some more testing and to be honest it seems to work either way I set the clock source even though according to the MBOX 3 and 11R Manuals it shouldn’t work….

Here is the reason why I am getting confused as to which way is the right way.

The 2 different manuals (11R and MBOX 3) say two complete different and contra ways to hook up SPDIF and the clock source. I realize these are generally referring to PT 8 but that doesn’t appear to be relevant.

According to the 11R Manual you should set the clock external to the ProTools System (PG72-73) either through the USER INPUTS on the 11R itself or if it is hooked up with USB to the PRO TOOLS System, then you should use the 11R Control Panel Applet in Windows to set the Clock Source to External and Sample Rate to match the project.

Now According to the details in the MBOX 3 Manual (Bottom of Page 46 Top of 47) it says that the “EXTERNAL DEVICE” (in this case 11R) should be configured to supply the “Clock Source (if relevant to your device)” This is the complete opposite to what the other manual is saying.

Then it says to go into Pro Tools >Setup>Hardware and set the clock source to SPDIF.

It then goes on to say:

“Setting the Clock Source to S/PDIF is the only way to utilize S/PDIF input.”

“Selecting any other Clock Source (Internal, or Word Clock) disables S/PDIF input.

My confusion is that it is working for me either way in Pro Tools. Even though the manual says it won't. I can set it to Internal or SPDIF and it does work.

So my question is does this make a difference to me as to which I use?

Is there a technical reason or any kind of ramifications by setting the clock source to one or the other?

Am i missing something here as I am new to this?

Sorry I would just like to understand the technical reasons behind this….

Thanks
SBS

Re: 11R SPDIF to MBox 3 Clock Question
 

Whatever works/sounds best in your setup should be fine. As far as the contradictory info in the manuals, they're probably making certain suppositions about general system setups or something. Nothing to worry about.

Re: 11R SPDIF to MBox 3 Clock Question
 

Cool thanks....

Re: 11R SPDIF to MBox 3 Clock Question
 

Exactly. I'm glad you mentioned that as I failed to in my posts.

Just so Avid is aware, I had the same problem....the manuals are opposite in their instructions of how to set the clock when using SPDIF.

I wanted to use the clock in the MBox 3 because I understand the A/D conversion is better in that unit, and clocking is a part of that process. But I guess when I'm recording through the MBox 3, I can just swith it back to Internal clock.

I wonder why your units work both ways and mine don't? I'm told that if you don't use an external clock source, that the SPDIF port should shut off as mine does.

Anyway, thanks to all that helped out with advice.