The new CAD GC-R Reference Ground Control

Over the past 10+ years the amount of high frequency noise on our Mains power has increased dramatically due to the use of computers, routers, modems, wifi, switch mode power supplies, etc. The high frequency noise that is generated within our audio systems has also increased: DACs, Servers, Computers, NAS drives, Routers, WiFi, etc. are all connected directly to our audio systems.

CAD believes that one of the key reasons so many digital audio products “sound digital” is due to this high frequency noise. From the very beginning of CAD we have worked hard to reduce unwanted noise in all our products. Materials and technologies that are used in our 1543 MKII DAC, USB Cables and CAT are included in the GC1, GC3 and GC-R Ground Controls.

The Ground Control contains a mixture of materials that converts high frequency energy into heat. Our research has found that to achieve the best sound quality the GC1, GC3 & GC-R needed to be effective over a large frequency range. This was not easy to accomplish! The CAD Ground Controls will reduce noise from about 1MHz up into the GHz range.

There are two independent voltage references in any audio system:

1) Signal Ground
2) Earth

Earth is what the third pin on your mains plug is connected to and what your copper pipes in your house are connected to. Earth is not typically (but occasionally is) connected to the Signal Ground in higher quality audio components.

Signal Ground is the negative side of an RCA, XLR, USB etc. connector.

Most audio engineers put a lot of effort into making sure the positive and negative rails of their DC power supplies have low ripple and noise, adequate bandwidth, etc. but typically not much thought is put into the signal ground plane.

CAD believes that reducing high frequency noise on Signal Ground and Earth improves sound quality.

Unfortunately there isn’t a common industry accepted technique for measuring noise levels on Signal Ground or Earth. A common measurement is Signal to Noise (S/N) ratio. S/N is the maximum output of a device (0dB) divided by the minimum output of a device (the noise). The reference for both of these measurements is Signal Ground. S/N measurement is not the whole story because it does not tell you anything about noise on the Signal Ground. You can have a very good S/N measurement and in reality the system can have considerable noise on the Ground side.

The CAD GC1, GC3 & GC-R Ground Controls can be connected to any audio product that has an unused output or input connection. If your DAC, streamer, computer, phone stage, preamplifier, amplifier, CD Player, NAS, etc. has a spare output/input connector like an RCA, XLR, Spade, USB or BNC you can connect the Ground Control to that. We supply a range of interconnects with various connectors. The other end of the connector has a single 4mm banana plug that attaches to the Ground Control.

There are two 4mm banana sockets on the back on the GC1, six on the back of the GC3 and eight on the GC-R.

The GC1, GC3 or GC-R Ground Control can also be attached to Earth. If you have any type of Earth connection on your audio system or power distribution CAD can supply you a cable with an appropriate connector that will fit. The outside case of any audio component that is made from metal by law must be connected to Earth for safety. So another option is to attach a Ground Control to the case directly by loosening a case screw and inserting a Ground Control cable with a spade connector.

We typically get the best results connecting the GC1 Ground Control to the device in your system that has the highest noise levels: components like computers, audio servers, DACs, CD players, NAS, routers etc. or by connecting the GC1 Ground Control to mains Earth. These are the best places to first try connecting the GC1 to. The GC3 & GC-R work exceptionally well connected to your mains Earth connection and directly to the cases of your amplification.

We also have had very good results connecting a Ground Control to phono preamplifiers. The gain on these devices is large and the reduction of noise that the Ground Control provides has brought some amazing results.

Note: Amplifiers

We do not recommend attaching Ground Controls to the output of audio amplifiers unless you completely understand the technical design, or the amplifier can be damaged

Our results have shown that better sonic results are typically obtained by connecting Ground Controls to source components, preamplifier or an unused input of an amplifier.

But, if this is not possible and you wish to connect a Ground Control to the output of an amplifier (especially a balanced design) you must follow these rules:

• Never connect a Ground Control to a positive output.

• If you connect a Ground Control to the negative output NEVER connect the Ground Control to anything else. It is safe if you connect a Ground Control to the negative output of your amplifier only if the Ground Control is NOT connected to anything else.  If you also attached the Ground Control to another component or to Mains Earth you may short your amplifier and damage will result.

We are excited to announce that an interconnect company (that CAD really likes) called Bibacord is now making interconnects so that a Ground Control can be linked directly to the shield/screen inside the cable.  In this arrangement you have a Ground Control connected to the screen/shield along the entire length of the cable.  The reduction in high frequency noise in the interconnect produces what we feel is a more natural, larger sound stage with increased detail of an already amazing cable.