Air gaps

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The long-awaited PS Audio music server, Octave, is inching closer to making its debut in late 2019. Since I’ve not written much about it recently, I thought you’d enjoy an update about one of its innovations, a new invention called the Air Gap Audio Interface or AGAI.

The AGAI solves a big problem in digital audio servers, contamination by noise and electrical detritus.

Inside a server, you have a noisy computer. As it chugs away at its tasks it jitters and pollutes the output signal feeding the DAC. This is why, we believe, FLAC sounds differently than WAV even though the bits are identical. A FLAC file (for example) requires far more bit crunching to extract the original bits than does a WAV file. Those crunched bits contaminate the final output signal through mutually shared power, ground and physical signal traces.

How can we fix that?

Imagine that the noisy computer inside the server was not in the server box and was instead far away (as we are doing in the upcoming Ted Smith Signature DAC). Its noise and ground contamination would not be a problem as long as we took its distant output and regenerated it in a Digital Lens.

Since our goal is to build a one-box server, the next best thing is to physically isolate the two systems within a single chassis. To do that we need separate power supplies, ground planes, physical boards, and at the end of the proverbial day, a physically isolated connection between the internal computer and the output Digital Lens. That’s where the AGAI comes into play. By bridging the gap between the internal noisy computer and Digital Lens by nothing more than light traveling through air, we get excellent isolation.

(In the upcoming TSS DAC the problem is solved with two chassis: a digital and analog separated too by light using a fiber optic cable between the two.)

We’re all familiar with digital data transmitted through lightwaves using a TOSLINK cable but that won’t work for either of our applications because of TOSLINK’s bandwidth limitations. But that isn’t a show stopper. It just means we have to step up our use of technology. Some of the highest speed data in the world travel on beams of light.

Whichever method is used, AGAI or high-speed fiber, transmission of digital data over lightwaves offers the possibility of getting noise and jitter out of the signal and gets us that much closer to musical perfection.