Exogal Comet DAC

I asked my contact at Exogal about the D to A process employed in the Comet. Part of the response I received from Jeff Haagenstad, Exogal's CEO, is worth repeating here:

The short answer to your question is "No, we won't provide answers to the questions about How We Do It. The longer version is that we don't do our D to A conversion in a conventional way. We have implemented a 6-core DSP in an FPGA (and we blew the "Read" bit, so we can write to it for upgrades but it can't be read or decompiled...) and we use some signal processing approaches that are unconventional in audio but not in wider signal processing work. We wanted to pursue patents but since it's all based on other algorithmic approaches there was too much prior art for us to do the patents. Hence the need to keep it Trade Secret.

If you look at our backgrounds, you'll see that in addition to audio experience, Jim worked on some broadband networking technologies, I've worked on GPS, Vehicle Guidance and Computer Imaging applications, and Jan has a bunch of different signal processing experience. We have all worked in applications with harsh and unforgiving computational environments so converting a relatively clean PCM signal to analog audio is actually a fairly simple thing for us to do. (Conceptually, if not mathematically)... The EXOGAL DSP platform (on which the Comet is the first of many products to exploit the technology) does have some conventional DAC chips but only the final output stages of the DAC chips are used for the final translation into analog. The main output uses PCM4104 DAC's and the headphones use PCM5122 DAC's. The outputs are buffered using TI/National LME49600 buffers. These are high-current, high-impedance, class AB buffers with no feedback. Beyond that, we ain't sayin'.

Click to expand...