We explain the proven technique for optimizing grounding in a Hi-End or Home Cinema sound system.
Section 1: Understanding the grounding system
What is the difference between Safety Grounding and System Grounding?
(If you just want to learn how to set up the system grounding system, skip to Section 2)
It is important to make a clear distinction between safety ground and sound system ground. The two are often confused so it helps to understand what each does.
Safety grounding
Earthing is the term we use to refer to a connection that includes the electrical safety wiring in a mains-powered (230 V AC) home power installation or mains-powered equipment. It is the wire that provides a safe path for a fault current, preventing electric shock in the event of a fault link coming into contact with exposed metal parts.
In other words, if a fault occurs in a component, causing a live part of the internal circuitry to touch the outer casing, the ground wire safely carries that current away from the component to earth. Theoretically, you shouldn’t get a shock (or worse) when you touch the chassis of your audio equipment in the event of a fault.
This wire is a yellow/green wire of sufficient size to carry the potential fault current. It requires low resistance and a direct path to ground or earth somewhere outside your home, usually provided by the electricity company.
However, not all mains-powered HiFi/HiEnd audio devices have this connection. More on that later.
Sound system grounding
Audio system grounding is the term we use to talk about providing an effective path to “drain” the degrading RFI (Radio Frequency Interference) signals received from the various exposed metal parts of your audio system.
These connections are not safety-related and are best connected with cables that you run between the chassis – or spare signal jacks in some cases – and the router, which are specially tuned to these high-frequency signals. The router output is then connected via a low-resistance, low-inductance cable to a grounding pin. Alternatively, you can use the grounding pin on one of the wall sockets via a Router socket, which provides the sound system grounding with a path through your network’s normal grounding.
Why should the chassis of hi-end devices be grounded?
So why do we recommend grounding the metal case of audio equipment?
It is important to understand how the musical signal passing through the circuits in your source components and amplifiers relates to the metal casing of the equipment surrounding them.
In a single-ended audio system, that is, one where connections are made with RCA (phono) connectors, at least two wires are required, one for the music signal and one for ground: both are required for the signal to flow properly in a circuit. The outer part of the phono plug is the ground connection and the center pin is for the signal.
Now, this signal ground is usually (but not always) connected inside the audio equipment to a ground point… a ground point that is also connected to the mains ground and the equipment enclosure.
If you have a balanced circuit (with XLR connectors), the signal itself is split into positive and negative, but the third pin is essentially the same as the audio signal ground in a single-ended circuit. Like this circuit, the signal ground is connected through the ground point on the equipment chassis.
You can now see that the audio equipment chassis is connected to the signal ground: therefore, any high-frequency RF noise on the signal ground also appears on the chassis. Because the chassis is connected to the signal ground, this also means that it is relatively easy to connect the signal ground (via the chassis and router) and dump the noise that is on it.
Audio benefits
The benefits of grounding the signal in this way are profound. On first listen, you’ll be impressed by how much lower the bass goes. How much tighter and clearer it is. Then, how much more distinct it is, how much easier it is to hear the notes being played.
Then you realize that the instrument has a defined character, tone, and presence as a distinct instrument. You may know the musician who plays that instrument, their technique, and their musical skills.
What’s true for bass is true for every instrument and every voice. Everyone seems to play better than you’ve heard before.
After hearing all these changes, you may realize that the whole concert is much more real, as if you were there.
Wow… don’t you want any of these?
Why sound system grounding is especially important now
Rejecting RFI from your audio system has never been more important than now. The RFI fog we endure in the name of “staying connected” is a serious issue for audiophiles and is only likely to get exponentially worse in the future.
As we move through 3G, 4G and 5G, the density of networks in the environment increases and the power and frequencies of the transmission increase to achieve the area coverage and data density that we all demand. We now expect extremely fast broadband speeds. Emergency Services are enhancing their communication networks to give police, ambulance and fire service personnel better control of live voice and video via computer.
You may not use Ethernet-over-Mains devices, but your neighbors probably do because they don’t want to use cables to connect all their audio/video kit. Our need to protect our musical enjoyment from the degrading effects of 21st century lifestyles is urgent and increasingly important. Rest assured. we will continue to work harder and harder to find effective solutions for all of us!
When to introduce grounding into your audio system
We have found that the effects of grounding are so great, at all levels of the sound system, that we have promoted Sound System Grounding in the hierarchy of our Audio Upgrade Steps, right at the top alongside the others.
Sound system grounding and cables
An essential part of the grounding system are the Grounding Routers.
A change in wiring regulations in 2008 meant that it would no longer be possible to connect additional grounding pins directly to the house ground ring – a technique that can improve system performance. Fortunately, there is a way to effectively connect a grounding pin while remaining compliant with the latest regulations.
The product needed to enable this has a circuit that is frequency optimized to provide an easy path for RFI to exit the audio equipment chassis down to the ground. Please note that the grounding router should not be used on a safety ground.
Grounding circuit
After extensive testing, we came to very important conclusions:
- Getting it right was absolutely essential. Small differences in exactly what was connected to what, in what order, were very important.
- The results were consistent, repeatable, and predictable.
- Although our first priority was the musical virtues, we could also see the benefits in the image quality displayed on the Home Cinema screens.
We tested the application on very modest audio systems to prove that it was a general solution for ground correction and not just specific to a very specialized complex or Hi-end system. And it was!
Fortunately, the correct grounding path is very simple: follow the sign.
The preamplifier or integrated amplifier is used as a “hub” and the enclosure of all the equipment that makes up the music sources is connected directly to it with grounding cables. The preamplifier or integrated amplifier is then connected to the grounding Router.
In systems with a separate amplifier or power amplifiers, the power amplifiers are also connected directly to the Router. If you have speakers with chassis ground connections, connect both of them directly to the Router. The router output is then connected to the main ground ring.
Section 2: How to set up the grounding system
The concept of grounding is very simple. The basic components are some grounding cables, some means of connecting the cables to the housing of the audio devices, a Router, and a way to ground your Router.
Choosing audio system ground cables
The way your audio equipment is electrically wired will determine how best to integrate it into the grounding ecosystem and which grounding wire to use. Your options are either to connect to the metal enclosure or via the grounding of an unused signal outlet.
All specialized grounding cables have a directional arrow to indicate best performance – when you connect your device to your router, the arrow should always point towards the router. Similarly, if the cable is used to connect the router to a grounding point, such as a grounding bar or wall outlet with a grounding pin, the arrow should point towards the ground.
Is my audio device grounded?
The easiest way to tell if your audio equipment is grounded or not is to look at the IEC socket – if it has 3 pins then it is most likely electrically grounded and you should connect the ground wires to the housing. If the power cord is bonded (i.e. connected directly to the back of your component) then look to see if there is the symbol for ‘double insulation’ printed on the back panel. If there is no symbol then it is safe to say that it is grounded.
An audio device with double-insulated construction is wired with only Line and Neutral connected and has no connection to ground. This type of design is extremely common, but because the internals are completely insulated from the enclosure, connecting a ground wire to the enclosure is less successful in grounding RFI. The solution is to use the ground connection of an unused signal jack.
Double-insulated audio equipment – usually denoted by the symbol shown below right – has a “floating” metal or plastic enclosure that is not electrically connected to the internal circuitry of your component. The device’s power supply is contained within its own insulated shield, and its input is likely an IEC two-pin, or IEC three-pin, or cloverleaf-type plug with the ground pin not connected internally.
What if there are no screws or spare grounding contacts?
In some cases, you may find that your audio equipment simply has no way to connect a ground wire. Some older Naim equipment, for example, has an aluminium (non-magnetic) sleeve with no visible screws. If this is the case, then either leave it out of the grounding system or, if you feel confident and have the necessary skill, add a grounding terminal.
If your audio device is an amplifier (which we would normally recommend as a hub), simply choose another device, preferably one that is grounded, to act as a hub. If your audio system consists of just a few devices, connect them directly to the router.
Power amplifiers should be grounded independently and directly to the Router. Additional power amplifiers should be grounded directly to the Router with their own cable. The preamplifier becomes the “hub” for your sources.
Choose the appropriate grounding cable and connection depending on whether your audio equipment is grounded or double insulated.
Speakers and grounding
You can ground the metal speaker units of your speakers in the same way you would the enclosure of your audio equipment (and it’s worth doing so). Some speakers have grounding terminals, or you can install your own. Do not connect a ground wire to the positive or negative terminals.
Some speaker manufacturers – for example, some Tannoy models – provide an additional terminal that allows you to ground.
If your speakers don’t have grounding terminals, you can try the principle quite easily yourself without having to modify the speakers. When you remove the speaker grille, you will probably find that the speaker units are held in place with screws. Drivers and tweeters that have plastic frames do not need grounding of course.
Remove one screw from each speaker and clean the metal around the screw hole to remove any paint. Strip the end of a piece of wire long enough to reach your Router, make a small loop in the stripped end and reinsert the screw through it so that it makes a good tight connection to the chassis. If there is more than one speaker in each speaker, you can connect them together or use independent lines of wire.
Alternative way:
Make a connection at the back of the speaker (inside the cabinet) and run the ground wire to an extra connector on the back plate, next to the regular speaker terminals. Then use this to permanently connect to your router
The benefits of using a grounding rod:
The whole point of grounding is to reject RFI/EMI from the sound system and into a good, low-impedance ground. How do you get a good, low-impedance ground? I know many of you connect your Router to the safety ground: this works well and is easy to achieve, but for best performance you should connect your Router to an external ground spike or rod, buried in the ground outside.
This assumption is not simple, I’m afraid, because the quality of your land depends on the resistivity of the soil which varies with type and condition. If you are lucky, a simple copper spike will do a good job, but you may find it more difficult in dry urban situations.
It pays to get it right, so seek help from a good electrician who has the measuring equipment to ensure that, whatever lengths you have to go, you have a reliable, low-resistance ground.
Where soil conditions are good (very wet, agricultural, clay and loamy soils), a single ground rod may well prove sufficient to achieve a good, low-resistance ground connection.
Choose a suitable spot away from the house (the soil is usually drier near the house) and hammer the rod into the ground – avoid buried pipes and cables! If you have found a good spot, it will be easy to install. If not, then the soil is probably full of rocks or stones that will not make good ground. If this is your case, look for a spot without rocks. If you cannot find any soft and easy place, you should consider installing a star network of rods connected together.
Each rod should be longer than it is deep. Another alternative is to bury a long copper plumbing pipe horizontally about 1 meter down in a trench. This could be under a lawn, but do it about 1 m. down
Finally, connect the ground wire to an easily accessible location so you can check the connection regularly.
Whichever technique you use, consider treating the soil around each rod or pipe with a treatment such as magnesium sulfate, copper sulfate, common rock salt, or conductive concrete such as Marconite®. The best technique is to dig a circular trench around the rod, fill it with the soil treatment material, and cover with soil.
Your electrician can solve these problems for you and guarantee the result. The connection to the ground rod should be made with a thick copper ground wire (10mm’ or 16mm’). Remember to protect the wire in some way to prevent accidental damage that may go unnoticed (gardeners use shovels and other sharp tools!).
It may also be wise to place a plastic tube in the wall to protect the cable. It is then easy to seal it with mastic.
FAQ's
1. What is Safety Grounding? Safety Grounding is the connection of electrical safety wiring to the home network. It provides a safe path for fault current, protecting against electric shock in the event of a fault that comes into contact with exposed metal parts.
2. What is Audio System Grounding? Audio System Grounding is about providing an effective path for draining RFI signals from your Hi-Fi or Home Cinema system, improving the dynamic range and sound quality.
3. How does Safety Grounding differ from Audio System Grounding? Safety Grounding is related to safety and preventing electric shock, while Audio System Grounding aims to improve sound quality by draining RFI signals.
4. Why is Sound System Grounding Important? Sound System Grounding reduces radio frequency noise, improving sound clarity and clarity, while enhancing dynamic range and bass accuracy.
5. What are the benefits of Grounding a Sound System? Benefits include improved sound clarity, increased dynamic range, better bass quality, and an overall more vibrant musical performance.
6. How do I set up the grounding system? The setup involves connecting grounding cables from the enclosure of your audio devices to the Grounding Router, and from there to a ground (e.g. grounding stud or wall outlet).
7. How do I choose the right grounding cables? Choose cables with directional arrows pointing towards the Router or ground. Check if your equipment is electrically grounded (3 pins on the IEC socket) or double insulated.
8. What if my equipment doesn’t have obvious ground connections? If your audio equipment doesn’t have obvious connections, you can add a ground terminal or leave it out of the grounding system.
9. What is the difference between grounded and double-insulated audio equipment? Grounded audio equipment has a connection to ground through the mains, while double-insulated equipment does not have a direct connection to ground and the ground connection is made through unused signal sockets.
10. Can I ground my speakers? Yes, you can ground the metal speaker drivers in the same way you ground other metal parts of the sound system.
11. How can I protect my audio system from RFI? RFI protection is achieved through effective grounding, the use of specialized grounding routers, and proper connection of grounding cables.
