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Aardvark Aardsync II

Master Digital Audio Sync Generator By Mike Collins
Published October 1997

Got the jitters? Aardvark's external sync unit could be the answer. Mike Collins investigates.

Many of today's project studios will be using a combination of digital equipment: a Yamaha 02R mixer, perhaps; Digidesign Pro Tools or Sonic Solutions recording and editing systems, outboard digital signal processors and converters, and other digital audio sources and destinations.

All this equipment has to be synchronised to one master clock source, and normally it can be slaved to a sync signal that's either embedded in the digital audio signals, or supplied as a separate signal. The internal clocks used in these systems are adequate when the devices are used standing alone, but when they're linked together, clock‑timing variations known as 'jitter' can arise, and these may cause noticeable degradation of the audio quality.

To achieve the highest sound quality with digital audio, the master clock in your system — to which all the devices are locked — should, ideally, have a jitter rating down in the picoseconds range. Most of the equipment you use is unlikely to achieve such low‑jitter performance, though: its jitter will normally be measured in nanoseconds or even microseconds. So for rock‑solid sync you need to use a high‑quality external sync unit such as the AardSync II.


The AardSync II is supplied as a compact black box measuring 7" by 9" by 11&2"; it uses an external 12V power supply. With the rotary switch on the front panel, you can set the sampler rate to just about anything you're likely to come across between 32 and 50kHz, including the pull‑up and pull‑down frequencies needed for film and video transfer — and an option is available to provide double these rates if you need to work at the new 88.2 and 96kHz sampling rates. Indicator LEDs are provided to show video input, video frame rates and system lock; there's a front‑panel On/Off switch, and an associated LED to show when the power's on.

...the ultimate timing reference for everything in your studio...

The back panel has two XLRs for AES/EBU sync output, three BNCs for word‑clock output, and one BNC for the Digidesign Superclock output used by Pro Tools and Avid systems. There's also a BNC for video sync input: the AardSync can be locked to PAL/SECAM's 50 frames per second or NTSC's 59.94 or 60 frames per second, or to video black‑burst signals.

Sync'Ing To Video

The synchroniser features very fast lockup to SMPTE timecode using proprietary digital techniques. To sync to video, you could just feed a video signal from your VCR to the Aardsync and lock to that, but the timing of the video signal would vary because of wow and flutter in the VCR transport — so, ideally, you need to use a video black‑burst signal from a house sync generator and lock both the VCR and the Aardsync to this. A similar situation applies if you want to use an analogue multitrack recorder and have this synchronised to your digital audio. Typically, one of the audio tracks on your video recorder or audio multitrack will contain SMPTE timecode, which you can feed to a SMPTE/MTC converter connected to a personal computer. On the computer, you may be running Pro Tools or some other digital audio workstation, possibly with a MIDI sequencer as the front end. The software on the computer will synchronise to the MIDI Timecode signal, but the digital audio in the Pro Tools system still needs a sync signal to keep the audio locked to the same clock source as the tape‑based machines. These machines may also need additional machine synchronisers to vary the speed of the transport motors, so that they keep in step with the video frames coming from a house‑sync black‑burst source.

The synchroniser features very fast lockup to SMPTE timecode using proprietary digital techniques.

In case you were wondering, a black‑burst video signal is simply a video signal with no picture content — just the timing signals, to which you can synchronise. Such a device is often referred to as a 'house sync' source because these devices are typically used by video facilities 'houses' when they need to synchronise several video sources for editing or broadcast. Conveniently, a video black‑burst board is available as an option for the Aardsync II; with this, you can make the Video BNC and one of the wordclock BNCs output video sync signals, which you can use to sync a VCR and an analogue audio multitrack recorder.


If you're new to the issues discussed here, you may not have realised how important it is to use the highest‑resolution clock source for best results, or have appreciated that all your digital devices (along with any MIDI and audio software) need to be locked to a common clock. Also, starting your video, analogue and digital audio and MIDI from the same SMPTE location doesn't guarantee that all this equipment will stay in sync!

This is where the AardSync II enters the scenario — acting as the ultimate timing reference for everything in your studio, whether it's digital audio, analogue audio, video or MIDI.

Highly recommended!


  • Low‑jitter AES/EBU and word‑clock sync.
  • Supports a very wide range of sample rates.
  • Suitable for use with Yamaha 02R, and Digidesign and


  • Manual could be a little more comprehensive.
  • Project‑studio users are unlikely to encounter the wide range


The AardSync II is the answer to all your synchronisation requirements — whether you work with audio, video or film, or even at the latest 88.2/96kHz sampling rates. It has exactly the right combination of features to let you hook up all the devices commonly used in professional project studios and high‑end home studios.