GTT Perspective · Master Fidelity
The source finally keeps the same time.
The NADAC S is Master Fidelity’s music server — built so the digital source locks to the 10 MHz reference the NADAC C master clock generates, instead of sitting outside the system keeping time of its own.
Why the server was the last problem
A music server has usually been the one box in a digital front end that keeps its own time. The converter can be clocked and the interface can be clocked, and then the source hands over its data on a schedule of its own. The NADAC S was built to close that gap. It locks to the same 10 MHz reference the NADAC D digital-to-analog converter (DAC) does — the one the NADAC C master clock generates — and that reference is carried to the clocks inside the server itself.
Master Fidelity calls the principle One System, One Time Domain — source, clock and converter working as one coordinated whole rather than as three components that happen to be connected.
Weishen Xu brought the first NADAC S to Long Valley in August. After two days of listening and comparison in the reference room, Bill bought that unit rather than let it go home on the plane.
I’ve been listening to it for two weeks, and I can’t get enough of it.
Bill Parish
What the engineering actually does
One reference, carried inside
The server synchronizes to the NADAC C’s external 10 MHz reference or runs from its own OCXO, and that reference is carried to the clocks on the motherboard and on the network and USB interfaces.
A motherboard built for the job
A proprietary motherboard driven by a custom 10 MHz clock module, with purpose-built RJ-45 and SFP network cards rather than general-purpose parts.
Power and storage kept quiet
Ultra-low-noise linear supplies feed the critical ports. Storage is enterprise-grade U.2 and SATA solid state, and the machine runs fanless, with no moving parts.
Software agnostic
The platform runs the established music-server applications rather than tying the system to one of them.
What a clock has to lock to
Timing error is more than jitter. Wander — the drift below 10 Hz — is what has to be locked, and it is what separates digital that sounds like digital from digital that does not.
What it costs to build a clock that behaves
Crystals are quality-checked, burned in for months, then checked again. Weishen Xu puts the rejection rate at roughly three in four.
Weishen Xu on the NADAC S
Questions we hear in the listening room
What does the NADAC S actually change?
It takes the last asynchronous box out of the digital front end. The NADAC C master clock generates the 10 MHz reference; the NADAC D digital-to-analog converter (DAC) and the NADAC S server both synchronize to it, so the timing discipline that governs conversion now governs the file coming off storage as well.
Does it need the NADAC C?
It can synchronize to the NADAC C’s external 10 MHz reference, or run from its own internal OCXO. The complete One System, One Time Domain arrangement is the first case.
Can I use my own software?
The platform is software agnostic and runs the established music-server applications.
Where can I hear it?
As part of a complete NADAC front end in our Private Listening Room in Long Valley, New Jersey, by confirmed appointment.
Further reading
Private Audition
Hear the NADAC S for yourself
GTT is the North American distributor for Master Fidelity. The NADAC S is auditioned as part of a complete NADAC front end in our Private Listening Room in Long Valley, New Jersey.