Fidelity Imports
Matrix Audio SC-1 Reference Clock | 10MHz OCXO | TweekGeek
Matrix Audio SC-1
A clock source is a product category that requires some explanation before it becomes obvious why it matters. The short version: every digital audio device — streamer, DAC, CD transport — runs on a clock. The quality of that clock determines how accurately the device can reconstruct audio timing. Jitter, which is variation in the clock signal's timing, is directly audible as smearing of fine detail and spatial information. A better clock produces lower jitter. The SC-1 is a purpose-built 10MHz reference clock that connects to compatible equipment and replaces their internal clock reference with something considerably more precise.
This is Matrix Audio's first clock source product. They built it as the natural completion of the N Series and M Series ecosystem — the SC-1 is what the clock inputs on the NT-1, ND-1, MS-1, and MS-1c are waiting for.
The oscillator
At the centre of the SC-1 is a custom OCXO — an oven-controlled crystal oscillator. The crystal uses an SC cut, a more complex and expensive cutting geometry than the standard AT cut used in most oscillators. The SC cut offers lower phase noise and better aging characteristics — the frequency drifts less over time as the crystal ages. The oven chamber maintains the crystal at a precise operating temperature, which eliminates the frequency variation caused by ambient temperature fluctuations. Warm-up time to rated specification is under five minutes at 25°C.
Frequency accuracy when shipped is better than ±0.01ppm. Temperature stability across the full -40°C to +70°C range is better than 0.003ppm. Short-term stability is better than 5×10⁻¹³ at tau equals one second. These are numbers that are difficult to contextualise without comparison, but the short version is that the SC-1's oscillator is operating at a level of precision that exceeds what any consumer audio device's internal clock is likely to achieve.
Phase noise and jitter
Phase noise is the relevant measure for audio clock quality. The SC-1 achieves better than -118dBc/Hz at 1Hz offset from the carrier, measured at the output port — not at the oscillator itself, which is an important distinction. The output buffering circuit always degrades the signal somewhat; Matrix have designed the buffer stage well enough that the output measurement remains better than -118dBc/Hz at 1Hz, dropping to -140dBc/Hz at 10Hz, -150dBc/Hz at 100Hz, -160dBc/Hz at 1kHz, and a noise floor better than -170dBc/Hz.
Jitter at the output is 20 femtoseconds, measured over 1–100Hz. For reference, the NT-1's internal femtosecond clock system — which is already exceptional — produces a clock the SC-1 can improve upon. That improvement is what Matrix's own measurements of the NT-1 and MS-1c in external clock mode are designed to demonstrate.
Four independent outputs
The SC-1 has four BNC outputs, each with its own independent buffer circuit. They all derive from the same oscillator source, so they are phase-synchronised. The independent buffers mean each output has stable 50Ω impedance and sufficient drive capability regardless of whether one output or all four are in use simultaneously. This matters for anyone building a system with multiple components that accept a reference clock — a transport and a DAC, for instance, or a full N Series stack with NT-1, ND-1, and a future addition.
Output waveform — sine or square wave — is fixed at the factory to customer specification at the time of order. Square wave is recommended by Matrix for higher locking accuracy. Sine wave output is 0.5Vrms; square wave is 1Vrms. Both at 50Ω output impedance.
Calibration and long-term accuracy
Even an SC-cut OCXO drifts slightly over time. The SC-1 includes a 1PPS reference signal input on the rear panel for connection to an external seconds-based reference — GPS disciplined oscillators are the common source for this. When a 1PPS reference is connected, the SC-1 calibrates automatically, with calibration status shown on the front panel LED. Matrix also offers free factory calibration service for the SC-1 as a longer-term maintenance option.
Power supply
The SC-1 runs on a linear power supply with automatic voltage detection and switching — it adapts to 100–120V and 220–240V without manual configuration. The supply uses dual multi-stage regulators, with the oven control circuit and the clock circuit on separate independent regulated rails. The reason for the separation is specific: the oven control circuit draws variable current as it maintains temperature, and that variation would introduce noise into the clock circuit if they shared a regulator. Keeping them independent eliminates that interference path. Maximum power consumption is under 20W.
Where it fits
The SC-1 connects via BNC to the 10MHz clock input on any compatible Matrix Audio product — NT-1, ND-1, MS-1, or MS-1c. Non-Matrix equipment with a 10MHz reference input will also work, provided the input accepts the SC-1's signal level and impedance. The same 330mm width and 97mm height as the NT-1 and ND-1 means the SC-1 stacks cleanly in an N Series system.
Whether the SC-1 is worth adding depends on how far you have taken the rest of the system. If you are running a NT-1 into a ND-1 with good cabling and a capable amplifier, the SC-1 is the next logical step. It is not the first upgrade to make — the transport, the DAC, the power amplifier, and the speakers will each have more impact individually. But in a system that is already well sorted, the SC-1 addresses the last remaining variable in the digital chain.
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Specifications
- Type: 10MHz reference clock source
- Oscillator: Custom OCXO, SC-cut crystal
- Output frequency: 10.000MHz
- Frequency accuracy (shipped): <±0.01ppm
- Frequency stability vs temperature (-40°C to +70°C): <0.003ppm
- Short-term stability: <5×10⁻¹³ @ tau = 1s
- Warm-up time: Under 5 minutes @ 25°C
- Phase noise @ 1Hz offset: ≤-118dBc/Hz
- Phase noise @ 10Hz offset: ≤-140dBc/Hz
- Phase noise @ 100Hz offset: ≤-150dBc/Hz
- Phase noise @ 1kHz offset: ≤-160dBc/Hz
- Noise floor: ≤-170dBc/Hz
- Jitter: 20fs (measured 1–100Hz at output port)
- Output ports: 4 x BNC, independent buffer circuits
- Output impedance: 50Ω
- Output level: 0.5Vrms (sine wave) / 1Vrms (square wave)
- Output waveform: Sine or square wave (factory configured to order)
- Reference input: 1PPS for external calibration
- Power supply: Dual-regulated linear supply, auto-ranging (100–120V / 220–240V, 50/60Hz)
- Power consumption: Under 20W maximum
- Isolation: CBVB vibration-absorbing foot pads
- Dimensions: 330mm W x 267mm D x 97mm H
- Weight: 4.4kg
- Manufactured: China
