Upgraded clock options for CH Precision digital products
By Roy Gregory
Hot on the heels of the C1.2 upgrade comes another potential performance improvement for CH Precision digital products. By now, most readers will be aware of the modular, configurable nature of the CH components. The option count on the D1.5 player/transport, C1.2 DAC and the I1 integrated amp (which of course, contains a DAC) has always included the rather opaquely named Sync I/O board, which offers one input for an external clock and two clock outputs, all on 75 Ohm BNC connectors. The board allows the use of an external master clock (such as CH’s own T1 Time Reference 10MHz clock). But its application extends beyond the use of external clocks. It also allows users with more than one digital unit to designate a Clock Master for the system and optimize the clocking topology within their digital front end – to significant musical affect.
Well, the Sync I/O is no more, replaced by the (visually almost identical) Clock Sync board: at least the name makes more sense now! Although labelling aside, the new board is almost indistinguishable from the old, it represents a root and branch reworking of the circuit’s operation and functional options.
Change for change’s sake? Before looking at the specific solutions chosen, it’s worth understanding the overall goal for the updated circuitry. The Clock Sync card promises lower levels of RF radiation and better preservation of clock signal integrity/accuracy. Both things are critical important to the overall musical performance of digital components, so you can anticipate a sonic and musical dividend on top of any measured benefits.
On the face of it, the most significant change is the adoption of a new, four-layer circuit board delivering a Low Voltage Differential output signal (LVDS). The sandwiching of the circuitry between full-surface ground planes, along with the adoption of a lower voltage, differential clock signal results in a major reduction in radiated energy. The differential signal topology also helps preserve the low jitter levels of the incoming clock stream, introducing less induced error.
Whereas the original Sync I/O board allowed users to switch the input signal between 75Ω or ‘High Z’ settings, the new Clock Sync board offers a choice of 75Ω or 50Ω, improving compatibility with third-party clocks. Finally, the new board allows users to switch off unused outputs, an obvious step that demonstrates clearly audible benefits.
With a pair of the new Clock Sync boards to hand I was able to mount them in both the D1.5 and C1.2, creating a ‘current’ digital system for direct comparison to the same pieces equipped with the older Sync I/O board. There’s nothing to stop you installing only one board in one unit and I actually started by updating just the D1.5 transport, but I soon discovered improvements that were so significant that close comparison wasn’t actually necessary, while updating a single unit constituted false economy.
Simply swapping out the older board(s) for the new Clock Sync one(s) – without disabling the unused outputs – delivered an obvious improvement in transparency, focus, depth, micro dynamic resolution, natural tonality, flow and musical expression. These were not small things. However, switching off the unused outputs produced an even bigger difference. Okay, so the benefits were cumulative, but where the first step seemed to relate more to the mid-band and up, the second was wider bandwidth, delivering a warmer, fuller balance, greater dimensionality, more immediacy, a more developed soundstage with more space within it and more natural, fluid, rhythmic articulation. Collectively, these improvements impact those areas where digital systems are traditionally weakest. They also act to make the most of the sonic benefits delivered by the C1.2 update, binding those improvements in resolution, transparency and dynamic range to the overall sense of musical structure, pattern and expression.