Digital audio binary data, represented by ones and zeros, records the amplitude of sound samples. However, the integrity of the digital signal is not solely dependent on the accuracy of these amplitudes. Timing plays an equally vital role and the timing of the signal is created by the music server used. Imagine a turntable with high frequency wow and flutter distorting the signal’s timing and you begin to realise that the ones and zeros are only half of the picture.
In digital audio, unlike its analogue counterpart, timing inaccuracies can be reduced during playback. This is achieved through buffering and regenerating the digital signal, and synchronising it with a low phase noise clock, in a circuit that is well designed to maintain its stability. This process enhances the quality of the digital signal in the time dimension, and therefore it enhances the sound quality of the resulting analogue audio.
This characteristic of digital audio leads to a common misconception that as long as one possesses a high-quality DAC, with a high precision clock, then the quality of the music server is inconsequential. The rationale behind this misconception is that this DAC will be able to perfectly time the data just before the digital-to-analogue conversion.
Of course, there are individuals that are absolutely vehement that it is all just ones and zeroes, so a music server-streamer cannot make a difference. This is so easily dis-proven by listening that it is hard to understand how this fallacy persists. The writings of Neuroscientist Iain McGilchrist on left and right brain thinking give us a clue: “the left hemisphere sees truth as internal coherence of the system, not correspondence with the reality we experience.”; “Meaning emerges from engagement with the world, not from abstract contemplation of it.”; “The only certainty, it seems to me, is that those who believe they are certainly right are certainly wrong.”
Just because perfect digital is theoretically possible, does not mean that real-world circuits can so easily achieve a perfect, or even a good result. In practice, good results require excellent circuit design and multiple stages, amongst other real-world factors. In practice, achieving precise signal timing before the DAC always improves the resulting analogue audio quality.
We have previously used the analogy of cleaning a very dirty car. While it is theoretically possible that a single step might do a good job of cleaning the car, a multi-stage process of pressure cleaning, wiping-down with soap and water, rinsing, waxing and polishing, yields a far superior result in practice.
As an example, a clock stage is only as good as the circuit it is used in and the power supply that powers the circuit. And the re-clocking stage needs to receive a low-noise signal with high-bandwidth, before it can re-clock the signal accurately. If the signals before and after the re-clocking stage are polluted by noise below the bit-rate (such as from employing linear power supplies) then the re-clocking will be largely ineffective. Anyone that claims that digital is ‘just ones and zeroes’ has not applied their knowledge to demanding real-world problems.
The necessity for high-end audio equipment to perform the music server stage stems from at least three factors:
- Noise Reduction: Music servers can be engineered with sufficient power, specialised power supplies and circuit designs that isolate the digital signal from electrical noise. Noise, prevalent in general-purpose computers and networks, can significantly degrade audio quality.
- Isolation: Isolating processor-intensive digital signal processing from analogue signals is crucial. What will yield the best digital signal will interfere with analogue signals and vice versa.
- Dedicated Audio Optimisation: High-end music servers can be optimised for audio playback. This includes the use of high-quality components, optimised operating systems and software applications, and optimised management of services to avoid time-based distortion of the signal.
DACs play a pivotal role in digital audio playback, and so too do Music Servers. It is the quality of both the Music Server and the DAC that delivers the quality of the resulting analogue audio signal.
Referring back to the cleaning car analogy, the OLADRA has two steps, the K50 one step.
