The importance of an accurate clock signal in digital recording and playback

The importance of an accurate clock signal in digital recording and playback


From the early days of digital audio, I had the pleasure to be involved in the research & development activities of several hardware manufacturers.

In 1989, the time that I was Producer/Engineer at Channel Classics (NL), I got the wonderful task to coordinate our distribution activities for Data Conversion Systems (UK) and supply them with first hand feedback from the recording front. Their RING DAC topology proved to be far superior to any other digital converter technology in the day and it stayed like that for many years whilst being upgraded and perfected based on our audible results.

Over the following years I stayed involved closely and was at the forefront of many "World First" developments, recording the first 192kHz/24 bit recordings for SAMSUNG (1997) and persuading my friends at dCS to produce the first DSD converters by an independent company. This lead to being assigned to coordinate a project for Philip Nat. Lab (SACD development) in the early 2000’s to integrate a rare, but bit-accurate workstation (AUGAN OMX-24) with multiple dCS ADC’s and DAC’s to supply 8ch DSD recorders to studios all over the world. This for producing hundreds of the first released SACD albums. In 2005 I adapted my workflow to 352,8kHz/24 bits however, later called DXD, with custom designed “easy” filtering to make it as close as possible to the analogue realm. This gave me the ultimate transparency in digital audio and to this date the format suits all existing delivery formats including the higher rate DSD formats.

Along the way there was always a great emphasis on accurate clocking, especially for the extremely high rates. A trade off was also found regarding going “too high” in sample rate, as it overshoots other parts in the chain, like electrical parts with less tight specifications. It was clear however that “jitter” was responsible for many deformations in digital audio, but the kind of jitter and the moment it is introduced in the audio chain, from recording via post-production to play-back, made it a rather vague and abstract phenomenon to many. Not easy to put your finger on.

Clear was however that the "base rhythm' of the sampling process is crucial to start with! In the development of the first dCS 995 Master Clock, we stumbled on the effect which so called "Phase Noise" has on our perception. Our brain-ear apparatus apparently is highly sensitive for it, even to a level that most scientists would qualify it as impossible or nonsensical. Lowering it to astronomical small values however proved to be rather valuable and this was the main factor for selling quite a few of these units in both the professional and the consumer community.



When Merging Technologies started a few years back with the +CLOCK, a new chapter started. After exclusively auditioning the first 2 proto-types of this +Clock, I immediately felt that a page in the history of digital audio was turned! 

It was not just an improvement in audio quality, but a rather new phenomenon all together. It took me quite some time to grasp what was actually going on, but it dawned on me that it triggered something in me that I had long forgotten about. Listening to the microphone feed itself…!!

In the “old” days, it was normal to listen during recordings ever so often to the signal coming from the microphones directly, as opposed to what comes back from the recorded medium. Every mixing console had a direct/return switch and/or source/tape button, which gave the opportunity to compare the 2 instantaneously. Nowadays, with the ADC’s mostly on the stage and audio over IP being the standard, it is on location a rather cumbersome affair to get an  analog signal from the pre-amps into a control room far away, mostly with 5.1 monitoring as well. So the auditioning is often only after the digitizing process... As this is what becomes the end result anyway, digital feels logical to adapt the mix to anyway, but it prevented us for many years from experiencing the “real” thing. A mistake in hindsight maybe, but what can you do…digital was the new realm we lived in and so does the consumer.

Now, with this new clocking technology by MT, I immediately perceived the “flavor" of the microphone feed again, as if it was before digitizing altogether. It felt at first like a new experience, the page really turned, but it actually was a reminiscence of what used to be known and normal long ago. The difference is subtle, yet tremendous! A sense of control and ease to the sound stage and it always sounds slightly lower in volume, although this cannot be measured. Whatever sample rate, the effect is the same and consistent over all repertoire. Today the successor of the MT clocks is there and the same team that created those units proposes the Master Fidelity NADAC-C. The crystals and peripheral technology used for this new incarnation are even more accurate and however unlikely, the results keep getting better. The last version I tested is simply breathtaking.

If one has to qualify the effect on the presentation it would be the following statements:

- "A Natural Elasticity of Musical Transients and Dynamics…"

Music consists of an infinite amount of "first instances”, called transients. The ability of the electronics to follow these instances is crucial to both the dynamics and the tonal balance of the whole. With this accurate clocking, it truly feels as if every little detail within the smallest time-frame during these transients is registered and portrayed, resulting in a very elastic and realistic “attack”, however small the signal. It makes the whole much more true and elegant, without loosing authority.

- "Impeccable and Accurate Layering of the Sound Stage…

Our ear-brain relies greatly on accurate placement of sound sources, as it is inherently responsible for warning us against danger. Our ears tell us where a sound comes from, followed by our eyes seeing what it is. 

The amplitude and texture of the first instance of a sound delivers to us crucial information about a possible danger and distortions in the representation result in a warped and scrambled sound stage. The ear-brain starts searching for clues and this is tiring. (ref. many people reporting on early digital as tiresome to listen to!) Again, the result with the MF NADAC-C is an incredible accurate representation of micro-detail and placement in the sound-stage and colors.

- "The most Interactive listening Experience in musical balance and Tonal Structures possible “

Over the years mixing consoles and multi-track recorders have enabled the sound engineer with possibilities to compensate for less than ideal dynamics, tonal and sound stage deformations. Extra signals have often been added to apply “make-up” to the face of the recording. Now with this ultimate accuracy of clocking, it is possible to leave much of these “fillers" out and create a sound representation that allows for an interactive experience by the listener. The recording sounds as a whole seamless stage, but all the separate parts and individual expressions in the music can be found just by “going there” while listening, just like in real life where the transparency is optimal and all details stay alive, however big the chaos around them.


Having the Master Fidelity clocking technology available to both the recording chain and the playback is a true blessing and makes my work as a producer/engineer a lot more meaningful. 

It delivers what comes from the musicians in an incredible true fashion, whereby the gateway between them and the listener is ultimately transparent!

2024 Bert van der Wolf-Oude Avenhuis
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