“Now that I’ve lived with the CAD [Ground Controls] for another couple of months, I can render my verdict : I can’t live without it. After listening for weeks, I pulled it out of my system, listened for a few minutes, put it all back immediately, then wrote a check” – Michael Fremer, Analog Corner, Stereophile September 2020

The CAD Ground Controls

Less noise. More Music.

The brand new GC1.1 and GC3.1 are now available!

Please read the many reviews and testimonials on this page and you will find similar comments
coming from many different reviewers and CAD customers.  Hearing a Ground Control yourself is our best sales technique. 

Contact a CAD dealer near you. 

The GC1 Ground Control resting on top of the GC3 Ground Control

The Ground Control interconnects

The new CAD GC-R Reference Ground Control

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.

Click here for the new:   Ground Control Top Tips

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.


A picture of the rear of the GC3 showing the six connectors
There was considerably more detail on offer and in that respect the upgrade was of a similar level to an upgrade of a streamer, DAC, preamp or other key component. But more importantly, it all just sounded much more musical, and has encouraged me to spend more time listening. Paul G, London, UK

I hooked the GC1 Ground Control up to the Melco server via the ground post and WOW, did it smooth and clean the sound up.  Just an amazing improvement in the overall quality of sound.  I’m amazed by how the stereo sounds with the GC1…Simply fantastic!!  Frank Goldfarb – Owner of Cane Creek Audio, North Carolina, USA

I just wanted to tell you about an interesting revelation I had during my last recording with Ilonka Kolthof on piccolo flute and Raloh van Raat on piano. I was really afraid of the piccolo, being such an extremely high-pitched instrument, getting super sharp and brittle, especially with my very broadband microphones. But it really wasn’t, which surprised me greatly. I then unplugged the CAD GC1 and oh my, what a difference! Of course, I had already experienced the difference the GC units can make, but I was floored by the sheer difference between having it plugged in vs not. It was incredible. My assistant engineer, who’s worked for Channel Classics and Pentatone Classics as well, said he never heard anything like it and also wants to purchase a unit.  Brendon Heinst – Recording & Mastering engineer, https://trptk.com

The GC1 Ground Control received the Recommended Product Award from Net Audio Magazine in Japan:

“I connected the GC1 to a RCA coaxial digital input of my SACD player to see how it would work. The result was an outstanding change in sound quality, noise was reduced, more details were heard, especially in reproducing weak notes. I haven’t experienced such a significant noise reduction with any other audio accessory in the past.”  Net Audio Magazine, Japan (translated from Japanese)

“Connected the GC1 to the SPDIF on my CD player, it’s so good it’s overwhelming!  Totally transformed my system.”  Alester Kells, Designer at Quadraspire audio racks

“The difference the Ground Controls make is so profound in my system – a system that already has a fully realized, dedicated AC supply and two parallel clean grounds – that they have become indispensable.”   HiFi+ Magazine

“I’m loving it – tunes are so much easier to follow and bass is so much more detailed; timing is incredible. Everything hangs together in a much more coherent fashion; every aspect of the performance is improved. The system is starting to take on some of the dynamics of real music.  Really shocking. In summary, all I can say is ‘wow’!!”   Evan S. – Massachusetts, USA

“I have one GC1 for a test in our home, I must say it is like the Holy Grail for me!  I have been looking for this solution for thirty years! And now I have found it! Remarkable, I nearly can’t believe it.”   Rickard S. – Stockholm, Sweden

“I have wired up the GC3 Ground Control and all I can say is Holy ****!”  Nick S. – Hong Kong

“WOW the improvement was astonishing.  If I had not heard it I would never have believed the improvement this little box can make” Philip – United Kingdom

“If I’m honest, I get slightly cold feet with stuff like this, as I’m not exactly wealthy and I start to try to justify spending ££££££ on a small black box? ( I’d never even try justifying it to my wife ! ) Then I listen to what it does and there’s just no getting away from it.” Stuart – United Kingdom

GC1 Dimensions are:
322 (L) x 111 (W) x 89 (H) mm
Weight : 4.65 Kg

GC3 Dimensions are:
356 (L) x 458 (W) x 89 (H) mm
Weight: 16KG

GC-R Reference Ground Control Dimensions:
469 (L) x 400 (W) x 231 (H) mm
Weight:  50Kg

The GC1 & GC3 Ground Controls can be demonstrated at any of our dealers. Please contact CAD directly if you do not have a dealer in your area:
Europe: +44 (0) 203 397 0334
USA:  (541) 728-3199