The answer to that question is going to depend on the system, the situation and the architecture (of both the building and its AC supply). However, it’s a question that’s well-worth answering and one that can be approached by stages and in nice, reversible, bite-sized chunks. The beauty of working with the AC and ground arrangements within a system is that whatever you try can always be reversed, making ABA comparisons quick, simple and effective. You can listen to literally everything (assuming that you have the patience): from the order in which you’ve plugged in the main system to AC polarity for each unit; from the number of ground connections to their optimum location. The array of options sits somewhere between daunting and mind-boggling so a few ground rules (no pun intended) are essential.
As far as this exercise goes, I’m going to use my standard Nordost AC and signal cable loom as an example, not because of any perceived, inherent superiority but because the company has considered the issues and its products present a sensible and pretty representative approach. The key elements here are the QB distribution blocks and in my case, the use of Schuko sockets. Even in the UK, I preferred to use Schuko power cords, because the plugs sound better than the 13A UK standard and they are also reversible, allowing easy optimization of the AC polarity for each separate component – as mentioned above. I’m also going to discuss the specifics of system grounding in the context of the CH Precision 1 Series products, simply because they offer users an additional level of easily accessible system grounding options. However, the basic logic holds good for any system, whether it offers ground lift options or not.
By now, many an eye-brow will have been raised at the idea of running the whole system through a single AC feed, via a distribution block, but the object of the exercise here is two-fold: firstly to achieve the lowest possible ground potential and secondly, to ensure that every unit in the system sees that same ground potential. Start using separate AC feeds to supply power to the different elements in the system and you risk creating a ground differential between them, a sure route to undermining system performance.
Look at the back of a CH Precision 1 Series component and you’ll see a trio of 4mm banana sockets, with two of them linked by a jumper. The lowest socket is connected to the chassis ground, the middle goes to the signal ground; place the jumper across them and you tie the two together. But place the jumper between the signal ground socket and the upper ‘parking’ socket and you separate the two (without risking the loss of the jumper itself). It’s a well thought out feature, albeit one that seems to cause some confusion. So how should you configure the grounding within a typical CH system (or any other system that affords a similar facility)?
Continuity, continuity, continuity…
Let’s start by thinking about a classic four-box system: P1 phono-stage, L1 line-stage, X1 power supply and M1.1 stereo power amp. In this set up, you’d start by connecting all four boxes and the record player to a star-grounded distribution block, with all five power cords being grounded and, ideally, exactly the same length (remember, we’re trying to achieve identical ground potential for every unit). The units should be connected in reverse system order, with the L1’s AC feed (!) connected to the Primary Earth at the centre of the ground star. In this case that means that the M1.1 power amp connects to the third socket, the X1 power supply to the Primary Earth the L1 itself to the fourth, the P1 to the fifth and the record player to the sixth socket. The signal should be star-grounded via the line-stage – meaning that you lift the jumpers (park them in the upper position) on the P1 and M1.1 and tie the signal ground to chassis ground on the L1. The ground terminal on your distribution block should be connected to the parallel clean ground. For most of you who are unfamiliar with the CH components, it’s also worth noting that the X1 has no ground jumper as it carries no audio signal.
