The Nordost QB8 Mk. III Distribution Block
By Roy Gregory
There’s an old adage in the world of audio cables: Which is the most important cable in the system? The one coming out of the wall.
It’s both a riposte to those who dismiss the significance of proper power cables and a statement of easily demonstrable fact. After all, in a very real sense, what you are hearing is a repurposed version of your AC supply. But while it makes clear where the cable comes from, it’s less clear as to where it goes – and that should be to an audio-grade distribution block. That star-earthed distribution block will provide the foundation stone of your system’s AC supply, unifying ground impedance and delivering the bedrock for natural musical coherence. The cable coming out of the wall might be the most important cable in your system, but its significance only becomes fully apparent once it’s able to feed the whole system.
Nordost’s QB8 has been my go-to power block since it first appeared, some 15 years ago. That’s partly because it matches the cables I use for the majority of the time (I have Crystal, AudioQuest, Russ Andrews and Chord Co. alternatives as required) but it also reflects its sheer practicality. With eight Schuko sockets (you can specify US or Australian sockets as an alternative, or UK 13A – although in that case you only get six outlets) it has sufficient outlets for all but the most extravagant set ups, it allows easy correction of AC polarity for each individual unit in the system (by simply flipping the plug through 180 degrees) and its footprint is wide enough for stability, narrow enough to fit behind a rack.
Outwardly, the QB8 has remained almost unchanged: The Mk. II added the option of a 20A input and adopted different, more secure sockets; The Mk. III has black end-caps to its extruded aluminium chassis, largely one suspects, to differentiate it from previous versions. Along the way, the company has also devised a cradle to allow users to support their QB8 on SortKones, although a full complement of Odin 2 power cords is going to challenge the stability of that arrangement!
What sets the QB8s apart from the crowd is less than obvious. The first and most significant difference is the use of a passive, parasitic resistance to raise the ground impedance on all but the socket at the centre of the star, forcing ground paths to that central point. The second, arguably more contentious difference is to do with the chassis itself. From Golden Ratios through to the ‘magic numbers’ deployed by Shun Mook and 47 Labs (amongst others) it has long been recognised – if not fully understood – that employing key dimensions allows you to mechanically ‘tune’ the musical performance of a component. The benefits are far from subtle and, with up to eight individual power supplies and the national grid all shaking and rattling the distribution block, the QB8’s specially selected dimensions help it roll with the punches.
The Mk. III version introduces the biggest change yet. Rather than a single internal board to carry the AC current, the latest QB8 uses two separate boards, one for live and neutral, the other carrying the ground. This helps minimise cross-talk between the inputs and ground, in line with current thinking on the importance of ground quality. It also introduces wider and much heavier tracks to increase the incoming current capacity – a criticism levelled at earlier QB8s when they were used with really current hungry amplifiers. With C20-equipped Mk. II units already feeding my main system, it was the perfect opportunity to gauge whether the new version offered a step up in performance – or not.