ADAT ports!  Nearly all of the new breed of USB3 or Thunderbolt equipped audio interfaces have them, a lot of older interfaces have them too. But how many of us actually use them?  

The first time I encountered the ADAT Optical cables with Toslink connectors on was back when I was working in pro audio sales in London. The new, must have interface was a Korg 1212 card which offered 2 analog audio inputs, 2 analog output and 8 channels of ADAT optical I/O. WOW 8 channels over a tiny fibre optical cable. What's not to like? We sold Korg 1212 cards like they were going out of fashion. I sold dozens of the things. 

Fast forward getting on for 20 years and I find that much of the gear I have in my studio has the option for ADAT connectivity. So why have I not been using it? 

Understanding Digital Clocking

Any devices linked together digitally in the studio must be locked together. If you don't do this and allow the units to run to their own internal clock you are going to get major clicks and pops in the audio.  If you are linking just 1 ADAT device to your main interface  you can use the clock signal that is built into the ADAT optical connection. Follow the instructions on your devices to make one the ADAT Clock Master (normally the device like a Mic Pre which is sending the signal) and the other the Slave.  Now normally I do not like doing this as I believe that better "Master" clock will be in the interface not a mic pre.   You can of course use Word Clock if both your devices have  Word Clock BNC terminals. The problem here is that not all devices that can lock to Word Clock have 2 WC terminals (In and Out) making using multiple digital devices at best tricky. 

ADAT Sample Rates

'Back in the day'  the Korg 1212 card supported sample  rates of 44.1KHz and 48KHz.  Nothing to shocking there but these days we demand our gear to support 96KHz and often 192KHz (even if we don't work at such high sample rates).  This is where we find a problem. The 8 channels of the ADAT format is maxed out at 48KHz. Working at samples rates of up to 96KHz cuts the track count in half meaning our 8 channel mic pre becomes a 4 channel mic pre and who likes the sound of that?

How I Have Configured My Studio (For Now) 

I have added the 'for now' as my studio is always changing.  Gear comes in and gear goes out. I like to keep changing it up and learning new pieces and learning what my ears and my instruments sound best through. 

I may have mentioned on many a podcast that at the moment I am using a  Focusrite Red 4 Pre as my main interface for my Pro Tools HDX rig.  The Red 4 Pre offers me 2 sets of ADAT ports. So a maximum of 16 channels of I/O at up to 48KHz. I am driving the two ADAT inputs with two Audient ASP 8 channel mic pres (ASP008 and ASP800). I am running a TOSLINK cables from the ADAT out of the Audient pre-amps into the Ins on the Red 4 Pre. I want to keep the Red 4 Pre as my digital clock master as I do not have a master clock for the studio. So I need to run word clock cables from the WC out of the Red 4 Pre to the WC IN on the two Audient Mic pre-amps but there is a problem. The Audient pre-amps only have a WC input BNC terminal.  Having consulted some of my pro-audio friends in high places we came up with a solution. The BNC T terminal (which you can see in the image on the right). This is hooked onto the WC out on the Red 4 Pre then two  cables run to the two Audient pre-amps.  These are then set to receive sync via Word Clock.  However, we still have this 48KHz issue. Well the truth is for right now for me this is not much of an issue. If I need to record at 96KHz I can live with only 8 channels plus the built in pre-amps that the Red 4 Pre has.

So that's how I do it. How is ADAT optical working for you?