An audio RCD: sense or nonsense?

Readers of Alpha-audio have known this for a long time: power supply is crucial for sound quality. But an RCD – isn’t that going a bit too far?

Adding an audio RCD to the power circuit

Through reading extensively, experimenting and gradually gaining wisdom, you think you’ve got the power supply well organised. A separate audio circuit in the fuse box, fitted with an AHP sound module and two Hifi Tuning Diamond fuses. From the fuse box, a cryo-treated Hifi Tuning power cable runs to a Furutech socket, followed by an Audes DC blocker and a Shunyata Venom mains filter.

The amplifier and the streamer are connected with Yeti power cables and the Melco switch with the Furutech DPS-4.1. The amplifier and the streamer also contain audiophile fuses from QSA and Synergistic Research respectively. Of course, there’s always room for improvement, but that usually means it immediately becomes a fair bit more expensive.

Then the Peacock Audio newsletter arrived, and what did I read there: finally an affordable audiophile RCCB, the HiFi-Tuning Supreme RCCB (‘Residual Current Circuit Breaker’). Hmm, I was in two minds – would that really make a difference?

My simple reasoning was: the further away from the system, the less it’s going to help. But a hobbyist is always on the lookout for improvements, so I placed the order anyway. There is a standard version for € 499 and a Diamond version for € 1,099. I opted for the standard one.

How an earth leakage circuit breaker works

In your meter cupboard, you will find three types of switches:

1. The main switch, which simply allows you to switch your home’s power supply on and off.
2. After the main switch are several residual current devices (RCDs) placed, which protect against electric shock.
3. Behind the RCD are the fuses, which are designed to prevent fires in the event of a short circuit or if too much current is drawn.

Many hi-fi enthusiasts have already replaced the standard fuse with an audiophile variant (also known as a sound module). However, this is even less common with RCDs, mainly because, until recently, only a very expensive one from Doepke was available.

An RCD compares the incoming and outgoing current. If there is too great a difference, current leaks to earth. If this passes through a person, it is literally life-threatening. If the difference exceeds 30mA, the circuit breaker will trip. Inside the RCCB is a measuring coil (toroidal transformer) through which the live and neutral wires pass. As long as the currents are equal, the magnetic fields cancel each other out. But if there is a difference, a magnetic field is created which activates the tripping mechanism.

The magnetic fields, that inevitably occur within the circuit breaker as a result of this mechanism, disrupt the sine wave of the alternating current. The HiFi-Tuning Supreme RCCB utilises large, solid copper/silver contact materials, anti-magnetic stainless steel screws, and everything has been cryogenically treated. Due to the resulting low impedance, this should lead to improved conduction and the prevention of stray fields, resulting in less voltage loss and an optimal sine wave.

Installation

Peacock Audio provides an installation diagram with your order. It is relatively straightforward and I did it myself, but you do need to know what you are doing. If in doubt, or if you have two left hands, it is better to have an electrician do it; safety is at stake here.

You install the HiFi-Tuning Supreme RCCB in a free space next to your other residual current circuit breakers. It is connected at the bottom using 6mm² installation wire from another RCD. At the top, you connect it to the sound module for your audio circuit using 6mm² installation wire. It is best to connect only your audio circuit and no other circuits to the HiFi-Tuning Supreme RCCB.

Listening

After installation and switching on the main switch, I powered up the audio components one by one. Without any break-in period, it was immediately clear that the system was performing at a higher level. Absolutely everything was better: the bass was tighter, there was more detail, better spatiality, and the dynamics were improved. The system played with greater ease and could also play louder without sounding harsh. But what struck me most was that the sound became purer.

I’d like to highlight one track in particular: “Love Day” from the album “The Los Angeles Session” by Richard Galliano and Charlie Haden. Galliano’s accordion sometimes produces long, sustained high notes; it demands a lot from your system to reproduce these accurately. At the same time, a double bass, piano and drums are playing. Everything remains beautifully separated, sounding detailed and clear.

The setup was a breeze and I had other things to do that day, but because I was so captivated by the music, I spent the rest of the day lazing about, going through all my playlists. And whatever I play, everything sounds better. I hear details in some tracks that I’ve never heard before. For example, the subtle electric guitar on ‘Gasthaus Zum Lachenden Stalin’ by Jan Delay amidst the heavier sounds of drums, bass and synthesiser. Colin Meloy’s acoustic guitar on “Caroline Low” by The Decemberists can be followed in minute detail. The bass on Matt Simons’ Deepend remix of “Catch & Release” is tight, whilst the details of all the background strumming are beautifully preserved.

On several occasions I found myself uttering the Lord’s name aloud because I could scarcely believe it. The hushed and restrained “If It Be Your Will”, a Leonard Cohen cover by Jennifer Warnes, moves me as never before. I never thought a RCD could do this to a grown man.

And back to the old situation

Now, a first impression isn’t always reliable; sometimes you really want something to sound better, and your brain can play tricks on you.

Perhaps you recognise this: back when you used to go to the record shop to listen to a carefully compiled list of LPs, and then you’d have one of those days where everything sounded good to you. You’d come home with far too many LPs, which, on closer listening, really weren’t all that good.

It is probably wise to keep listening for another week or two and then see if your opinion stands. The problem, however, is that you get used to good sound quality, and after two weeks you can hardly imagine what the previous situation sounded like. So I grabbed my screwdriver and reconnected the sound module to my old RCD.

Back to the old setup, it was immediately clear: everything I’ve described above, but in reverse. The bass was less tight, there was less detail, less space around the instruments and less dynamics. The feeling from day one remains intact.

Conclusion

You should always be careful with overly bold statements, but these 500 euros are among the most efficient I’ve spent on my system. If you want to achieve the same improvement by, for example, upgrading your amplifier or your speakers, you generally won’t manage that for 500 euros. Highly recommended.