Antelope Isochrome OCX external clock with a Digidesign Digi 002 pro tools interface.

Posted on July 28, 2009

by Brian Petersen

It’s no doubt that the Digi 002 is now an industry standard interface and has been featured on numerous records. Its smaller size combined with the ability to portably record to pro tools makes for a win win combination. The units come in either a 3U rack mount version or a table top automated mixer version that I personally prefer. The only problem is that the stock A/D converters and the clock in the unit are not the same quality that would you hope to have on a major record using a more high end pro tools studio interface. Some companies provide modifications on the clock and the converters with the digi 002 units, but you can also do well by making these modifications yourself. I use higher end vintage mic pres and nice large diaphragm mics to compensate for the stock pres and the converters on the 002. More on the converters later, but one way to overcome the clock issue is to use a high end external master clock for your interface. Many clocks are available and widely discussed, but I have gone with the recommendation of engineers that are much more skilled and discerning than I am in the studio world. This article is a brief detail of how to use an Antelope Isochrome OCX external clock with a Digidesign Digi 002.

Just a brief side note here but the main connection used for the external clock with the Digi 002 is a RCA S/PDIF port on the back of the interface. Later Digi 003 models came with upgraded stock BNC clock connections. S/PDIF = Sony/Phillips Digital Interchange Format

Step One

Acquire a Digi 002 interface, an Isochrome OCX clock, and a S/PDIF cable from your favorite dealer, studio, or music buddy. I bought my clock from Joe Gilder at Sweetwater. You will also need the necessary gear and connections for setting up your monitor mix, computer, mic pres, and so on. This is assuming you already have your studio setup.

Step Two – Warning

I would highly recommend turning off your gear and muting your monitors before you start any of this. Also a warning here as I found that my interface and monitor setup emitted loud white noise when I tried to set the clock to a sample rate above 96k. The 002 unit does not work above 96k even though your clock will be able to go up to 192k. Do yourself a favor and mute your monitors.

Step Three

Connect a S/PDIF cable from your clock to your Digi 002 interface. You do this by plugging in the S/PDIF cable to the S/PDIF OUT on the OCX clock and connect the other end of the cable to the S/PDIF IN on the Digi 002 RCA S/PDIF port. It’s recommended that you keep your clock within 10 ft (3 meters) of your interface when using a S/PDIF cable.

Step Four

Connect the IEC power cable to the OCX and power it on. Set the sample rate by pressing the rectangle buttons just to the left of the main red LED readout.

Step Five

Connect the IEC power cable to the Digi 002 and power it on. Open pro tools. Choose Setups on the top right tab. Under Setups choose Hardware Setup. Now select the S/PDIF clock source in the lower box on the left side. Click OK.

Your external clock should now be setup. Make sure that your sample rate on the clock matches your pro tools session sample rate. Begin making beautiful music.

More about the OCX clock…

Antelope’s Isochrone OCX emerges as the new quality standard in professional master clocks. A master clock is the heart of the digital studio, essential to maintaining stability and preserving sonic integrity. It is crucial that a master clock be flawless, and the Isochrone OCX exists to meet this need. Uncompromised design has created the most stable, best sounding master clock available.

Oven Controlled Discrete Transistor Crystal

Oscillator for lowest jitter

Atomic clock input resolves to Rubidium clock for perfect stability

Jitter Management Module improves sonic performance

Sample Rates 32-192 kHz

Factory calibrated to better than +/- 0.02PPM accuracy via Atomic Clock

Can be recalibrated in the field to an Atomic Clock for better than +/- 0.02PPM accuracy

W/Cx256 “Superclock” output for Digidesign Pro-Tools systems

Outputs multiple, divisible sample rates

8 Word Clock outputs

2 AES/EBU outputs

2 S/PDIF output

http://www.antelopeaudio.com/en/products_iso_ocx.html

More about the Digi 002…

Digi 002 combines the features of a high-quality audio interface, a MIDI interface, a touch-sensitive control surface, and a stand-alone digital mixer, all in one unit.

Digi 002 provides the following input and output capacity:

• 8 analog audio inputs (4 with mic preamps), with A/D converters supporting up to 24-bit, 96 kHz audio

• 48V phantom power on mic preamps, switchable in channel pairs

• –10 dBV input pair for direct monitoring of tape or CD input sources

• 8 analog audio outputs, with D/A converters supporting up to 24-bit, 96 kHz audio

• Monitor Output pair (+4 dBu) mirrors Main Outputs 1–2 with dedicated volume control for direct connection to powered speakers

• Alternate Main Output pair (–10 dBV) mirrors Main Outputs 1–2 for direct output to –10 dBV devices.

• Stereo headphone output with level control

• Optical connectors for 8 channels of ADAT I/O (up to 48 kHz) or 2 channels of Optical S/PDIF I/O (up to 96 kHz)

• RCA connectors for 2 channels of S/PDIF digital I/O supporting up to 24-bit, 96 kHz audio

• 1 MIDI In port and 2 MIDI Out ports, providing up to 16 channels of MIDI input and up to 32 channels of MIDI output

Control Surface Features

Digi 002 provides an integrated control surface for software control that includes the following:

• 8 touch-sensitive moving faders and dedicated solo, mute and channel select/record arm controls

• 8 multi-function rotary encoders for operating pan, send, and plug-in controls

• Transport and navigation controls

• 10 scribble strips for channel information display

• Footswitch jack for punching in and out while recording