When it comes to transforming a digital signal into an analog form digital to analogue converters (DAC) are used. Sometimes in High End Audio Systems stand alone DACs can be found. In addition to upsampling a digital signal the clock signal that causes each number to be latched in sequence is drawing attention among “digital audiophiles”.
The clock used in a digital chain needs to be reasonably accurate and consistent so that the music plays evenly and at the right speed. Transmitting signals between more than two digital devices – as I do in my dCS system – may cause inevitably slight variations in the devices` clocks. Therefore the dCS Scarlatti clock takes the role as a clock master for the whole system.
While the Scarlatti clock does a pretty good job in my system I was advised by an audio friend trying an external rubidium clock in addition. Ok! I thought a little more precision behind the comma could bring a little (!) difference to my ears, instead of +/- 0.1 ppm. (Scarlatti) maybe ending up with +/- 0.05 ppm.
Atomic rubidium clocks (they do not carry any radioactive material) used to be very expensive, some units went for 20.000 $. They were more or less designed around commercial off-the shelf rubidium clocks designed for the communications market – not audio. And while these rubidium clocks may have good long-term stability, they were never designed to provide low short-term jitter. In the meantime rubidium clocks wear more reasonable price tags, e.g. Isochrome 10M Rubidium Atomic Clock of Antelope Audio, Mio Audio La Clock etc.
I decided to go for a Perfection 10 Rubidium Clock of Stanford Research Systems (SRS) as it comes with eight outputs built around their own PRS10 rubidium oscillator, so being able connecting to the dCS Scarlatti, Esoteric XO1-Limited and eventually to the Accuphase DP-800.
As a vinyl affcionado my digital chain hasn`t seen me very often in the last days. It took me some thoughts and time to find out about the correct connection of all the cables and time clocking directions between the four dCS units and the SRS atomic clock. In the end I succeeded in “convincing the Verona clock” serving as a route director giving the SRS clock the master role.
Now, was it worth the investment and the installation work? Can I hear a difference? Does it make me happy?
First of all I can hear a difference. The built in PRS10 is an ultra-low phase noise, 10 MHz rubidium-disciplined crystal oscillator, enabling the system an absolutely quite and controlled processing. This leads to a wonderful three dimensionality and natural presence I need to admit I have never listened to in a digital chain before. CDs and SACDs do sound absolutely dynamical, moving and pushing me forward while listening. Against all odds as a vinyl guy I am really overwhelmed about the capabilities of Atomic Digital. And I am happy!