Computer Audio Design Ground Control-Reference grounding box

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Computer Audio Design Ground Control-Reference

I was fortunate enough to have a complete suite of CH Precision electronics in-house when the GC-R arrived: fortunate not just because they afforded the necessary multi-box digital front-end and eye-watering system cost, but because each component also offers the ability to separate the analogue signal and digital control grounds. With star-grounded QB8 distribution blocks and a separate, parallel AC ground I was able to really ring the changes when it came to grounding arrangements – so much so that I’m going to skip the long and convoluted step-by-step analysis and cut straight to the conclusions. Along the way I compared (by stages) connecting just the digital, just the analogue or all of the system components to the GC-R: I rang the changes on the individual component grounding arrangements and I compared connecting the QB8s to the parallel AC ground, the GC-R and strapping all three together in every conceivable arrangement. Yep – it took a while… but the results are in and they’re pretty unequivocal save the one big caveat I’ll save for last.

The upshot of the component connection is pretty straightforward. Connecting the analogue units to the GC-R brought a worthwhile benefit in terms of lower noise floor, focus, dimensionality, stability and a more natural, communicative quality to performances. Connecting just the digital components was actually less successful. It reduced the grain and noise in the soundstage and improved the sense of order and focus, but it did little to help the sense of musical pace or purpose. However, connecting both digital and analogue components to the GC-R resulted in a really significant step up in performance, with gains not just in terms of detail, separation and focus, but more natural colours, greater presence and more immediate presentation. In terms of bringing performers and their performance into the room this was a huge step up. 

As to the connections themselves (the GC-R offers eight ground points as standard, although the number of ground points and the necessary ground cables can be specified to suit a given system and are included in the price) I found that connecting to a single digital input on the DAC – the USB proved best – was better than multiple connections to the transport and various inputs. The dual-mono line-stages and the power amps each required a signal-ground wire and in all cases I left the signal and digital control grounds tied together with the units’ jumpers. Which brings me to the second counter-intuitive result (the first being the superiority of combining as opposed to separating the grounding of digital and analogue components): on the face of it, having separate ground paths for the digital control circuitry looks like a heaven sent opportunity to reduce system noise, but in practice, pulling the jumpers and running separate ground wires to the GC-R was a case of slightly different rather than better, while running those ground wires to a separate GC3 was definitely worse. The two exceptions to the findings so far, both involve the C1 DAC. This was the one instance where separating the digital ground proved beneficial, improving the sense of musical flow and phrasing, delivering more natural diction and greater expressive range. The other (slightly odd) connection that proved worthwhile was grounding the USB Firmware Upgrade port. I have no idea why that would be, but repeat comparisons left me with a firm preference and the ground cable in place. 

Finally, there was one other external component that really benefited from additional grounding – and it’s not even an audio device. Anybody relying on network replay (or network control in this instance) will likely be using a network switch. Although audiophile grade switches with linear power supplies are becoming more common, most people will be using generic, computer industry items – in my case a stock Netgear unit. Grounding one of the vacant ports to the GC-R removed a persistent glaze from the soundstage that had been lightening the blacks and filling the intra-instrumental space. Although I intuitively knew that the switch would be noisy, I wasn’t ready for the scale of the improvement and in any file replay system this is clearly a place to start, not just with grounding but the choice of switch (and its PSU) in the first place.

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