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About the NS6U
Part of CelAudio’s Signature Series, the NS6U can serve as both the library hub and playback source of a digital audio system.
It supports local music playback through CelPlayer, library management through Roon Server and UPnP Server, and network playback through Roon Bridge, UPnP, AirPlay and HQPlayer NAA. This flexibility allows it to operate as a self-contained music server or as a playback endpoint within an existing system.
The NS6U adds a dedicated USB audio, digital-output and clock module to the NS6 platform, providing USB, I²S, AES and coaxial S/PDIF connections.
CelHeart-G1: A Dedicated Hardware Platform
The CelHeart-G1 motherboard is designed specifically for audio applications. Its architecture separates computing and I/O power domains, provides dedicated PCIe connections for expansion modules and incorporates a layout developed for passive cooling.
The CPU and NVMe storage—the platform’s principal heat sources—are positioned to simplify heat transfer into the cooling structure. Passive cooling avoids the acoustic noise of a cooling fan.
Dedicated USB & Digital Output Module
The NS6U’s audio card provides a dedicated PCIe-connected USB 2.0 interface with linear power and clock signals supplied by the CelCLK II system.
XMOS and FPGA circuitry implement the additional I²S, AES and S/PDIF outputs. The USB controller and digital-output circuitry share the card’s clock architecture.
For USB connection to a DAC, CelAudio recommends the dedicated audio-card socket rather than the motherboard’s general-purpose USB connections.
OCXO Clocking & External Synchronisation
The output card incorporates a 50 MHz oven-controlled crystal oscillator and CelAudio’s CelCLK II PLL system, operating with a 1 Hz locking bandwidth.
Separate BNC and SMA inputs accept compatible external 10 MHz references. This allows the NS6U to integrate with the NWX clock switch or another suitable reference source. CelAudio recommends the SMA connection when pairing it with the NWX.
Two-Stage Power Architecture
CelAudio’s power architecture combines a primary linear supply stage with further linear regulation on the motherboard. The CPU and memory retain switching regulators to accommodate their dynamic voltage requirements. The I/O circuits—including PCIe, Ethernet, SATA, USB and NVMe—use dedicated linear supplies, with power-domain separation intended to limit interference from the computing section.
This approach treats power delivery as part of the motherboard design, extending regulation beyond the main supply to the circuits handling storage, networking and audio output.
Technical Overview
Network Connection
1 × RJ45, 10/100/1000 Mbps
Software-configurable speed and duplex mode
Operating Voltage
110V / 230V / 50-60Hz
Fuse
5 × 20 mm, 2.5 A, slow-blow
Size
Width 37.0cm / 14.5’’
Depth. 21.0 / 8.5’’
Height. 12.0cm / 4.7’’
Weight
11.0kg. / 24.2lbs
Chassis
Machined Aluminum
Product Type
Music streamer, server and digital transport
Hardware Platform
CelHeart-G1 motherboard with x86 processor
Passive cooling
Playback & Server Functions
CelPlayer
Qobuz Connect
Roon Server and Roon Bridge
UPnP Server and renderer
AirPlay
HQPlayer NAA
Playback Software & Control
Linux-based CelMusperOS
Config. through nManager app for iOS/Android or web browser
Internal Storage
1TB NVMe drive installed (870 GB available to the user)
Two additional drive bays for 2.5-inch SATA drives up to 7 mm thick
Dedicated Audio Outputs
1 × USB Audio, USB 2.0
1 × I²S via HDMI connector
1 × AES
1 × coaxial S/PDIF via RCA
External Reference Clock Inputs
1 × BNC: 10 MHz, 50 Ω, minimum 0.6 V RMS, sine or square wave
1 × SMA: 10 MHz, 3.3 V LVCMOS square wave