My new engineer, Bob Stadtherr, had come up with a fascinating idea that would potentially solve our big hurdle. He called it the Intelligent Buffer.
The problem was the variable speed at which a CD or DVD player delivers data and the system's master clock. Sometimes the data and clock came out quickly, other times they would slow down as the laser mechanism tried to read a scratched or dirty part of a CD.
Bob's idea for this buffer was relatively "simple". Because the CD player provided both the musical data and the master clock (this clock tells us how much data to expect and at what speed) Bob would read the master clock's frequency and then adjust the length of the buffer to accommodate the expected data. And here's the trick. We don't want this buffer (our water tank) to run out of data or to get so full we can't accept more. If we run out of data then we get a pause in the music. If we overrun the data and it chokes, we get a tick or blip in the music.
Because we are using a fixed frequency output clock, a simple on-the-fly math calculation can set the difference between the incoming master clock frequency and the output fixed frequency of our fancy low jitter clock. Thus, the buffer's length changes on the fly (intelligently) to make sure we never run out of data and never get too much to clog the system.
The only downside is a phenomena we call latency. The signal is delayed from real time play, something that matters if you're watching a movie or trying to synch a person's lips with their speech, but hey! This is an audiophile device designed for music. Screw the video guys.
It took Bob two months to design, build, test, and deliver to us a working Digital Lens.
And at this juncture, it is again instructive to recall that we don't yet know if this whole exercise was worth it. What if, after all this trouble and ingenuity we would put it in the system and get meh results? Honestly, given that we could hear differences in the CD/DAC systems of the day by coloring a CD's edge with a green pen, I wasn't too worried about hearing improvements.
Arnie and I listened to the first Digital Lens and were absolutely stunned. Not only did it make an improvement, it took the digital audio experience to a place we had only dreamed about. The increased openness, depth, and spaciousness we heard on that day recalibrated everything we had ever imagined possible. Suddenly, our vinyl had been bested in ways we never dreamt about.
Over the years, the Digital Lens became a standard bearer for standalone digital interfaces. Even today, if you find one on eBay, it is swooped up instantly.
Lastly, every digital product we have made at PS Audio in the ensuing 30 years and up until today, has a version of this exact intelligent buffer/fixed output clock and wave shaper built into our digital products.
And its inventor, Bob Stadtherr, is still cranking out beautifully designed innovative products to this day.
Go Bob!
