Phase Noise
The clock signal’s phase-noise level at a stated frequency offset from its carrier, expressed in dBc/Hz.
The unit describes noise relative to carrier power in a one-hertz bandwidth. Compare the same carrier and offset: a more negative value indicates less noise under equivalent measurement conditions.
Phase Noise — CD Transport
On a CD Transport, phase noise describes a specified internal audio clock used in its digital timing arrangement. It does not measure disc-reading errors or the receiving DAC’s complete conversion performance.
Read each value with the clock’s carrier frequency and the offset from it. Several offsets describe different parts of the noise spectrum; selecting the most negative number without its offset can mislead.
Compare equivalent conditions and the stated measurement scope. The phase noise of a compatible external clock is not the transport’s own specification, and a single spectral point does not establish total jitter or an audible advantage.
Phase Noise — Streamer
On a Streamer, phase noise characterizes a specified internal audio clock. It is separate from network timing variation and does not by itself describe the analogue performance of the receiving DAC.
Read the carrier frequency and offset, keeping separate results for different offsets. A bare dBc/Hz figure without these conditions offers limited comparison, and a jitter value in seconds is a different measurement.
Compare the clock path and conditions relevant to the output you use. An external reference’s advertised phase noise should not be substituted for the streamer’s result. Lower phase noise at one offset alone does not establish better sound across complete systems.
Phase Noise — Music Server
On a Music Server, this figure concerns the identified internal audio clock, not processor speed, network throughput or the noise of stored files. Its relevance depends on the playback and output architecture.
Read the measured carrier and offset with the number. A low-noise oscillator specification may describe a component rather than every signal leaving the server, so retain the manufacturer’s stated scope.
Compare equivalent measurement conditions and actual output use. A value borrowed from an optional external clock is not the server’s own result. Phase noise alone does not establish library performance or predict an audible difference at a separately clocked downstream converter.
Phase Noise — DAC
On a DAC, phase noise describes a specified internal audio clock rather than the entire analogue output’s noise. It can help characterize timing circuitry, but its effect depends on the complete conversion design.
Keep the carrier frequency, offset and any typical or guaranteed qualification with the value. A result at 10 Hz offset cannot be compared directly with one at 10 kHz as though they measured the same point.
Compare like conditions and the relevant clock path. An external clock’s specification is not the DAC’s internal result, and one phase-noise figure cannot be converted into a complete jitter or sound-quality rating.
Phase Noise — External Clock
On an External Clock, phase noise describes a specified timing output. A clock supplying several frequencies may have different results for each carrier, so the output signal must remain associated with the measurement.
Read every value with its carrier, offset and typical or guaranteed qualification. A 1 Hz offset result and a 10 kHz result measure different positions relative to the carrier and should not be ranked directly.
Compare equivalent outputs and conditions. Frequency accuracy and ageing are separate specifications, and phase noise at one offset is not total jitter. The receiving equipment’s clock handling also matters, so the figure alone does not prove an audible system benefit.
Phase Noise — SACD Transport
On an SACD Transport, phase noise characterizes the identified internal audio clock, with relevance determined by the selected signal path. It is distinct from supported SACD areas, DSD rates and external-clock compatibility.
Keep the carrier frequency and offset attached to each figure. A value for one oscillator or operating condition should not be assumed to apply to every disc mode or digital output.
Compare the same conditions and distinguish typical results from guaranteed limits. An external reference’s figure is not an internal-clock measurement. A lower value at one offset cannot by itself establish lower overall jitter or better sound from the complete transport-and-DAC system.