Ground Noise - The new frontier

Ground Noise - The new frontier

One of my very first experiences with high-end audio involved clip leads. I was at a friends house and we were listening to his system which had quite a bit of hum. We were putting clip leads between the mono amps, between the components, and to ground. We were lifting ground pins in the power cords. What a circus, but eventually the system was dead quiet and sounded great. THe results were not always what you expected and sometime quite bizarre.

Today we are on a new frontier of performance with new multi-media sources loaded with electrical noise unlike anything we ever experienced in the past. At the same time we have made great improvements in jitter the enemy of the last decade, making ground noise which used to be lost in the jitter, the dominant problem. And again, grounding issues are back, making a huge difference, but now in harshness, focus, detail and air, instead of hum.

There is no intuition, right or wrong with high frequency ground noise.

When all we had to deal with was 60 Hz AC hum, the concept was easy to visualize. Get rid of ground loops. But now we are fighting a new animal. We have had some idea about ground noise, but our experience has shown just how tricky it is. It all started for me with the question of why the sound changed when I changed my digital cable? The DAC reclocks and all the bits arrive correctly in memory. What is different? Ground noise. Now as we do network streaming and have a Blu-ray player hooked up to an LCD monitor as a source, the matrix becomes impossible to deal with anyway but the old way. Try making changes and listen.

Just to illustrate the system dependance of this issue, in my system, when I listen to the DAC IV with the DATA CD Transport as the source using the balanced digital cable, the sound is significantly improved by connecting the MSB Network cable (a solid ground), even though it is not used. On the Universal Media Transport, with the same connections, the balanced cable sounds better without the network cable connected. The network cable makes a ground connection that may be good or may be bad depending on the system. If you have not run into this issue yet, you will before you have finished setting up your first Universal Media Transport!

The Ground Lift feature of the DAC IV is the most powerful tool available and makes a huge difference in sound - but be careful!

So we have given you all the tools to get it right. The most important is a ground lift in the DAC IV menus that disconnects the analog part of the DAC output stage from the chassis and digital ground. The idea is to avoid ground loops and if your Amps are grounded this connection SHOULD be lifted. If your AMPs float, lifting this ground connection could result in the destruction of your DAC should you accidentally discharge a lot of static to the AMP. So make sure the Amplifier case is grounded before doing the ground lift.

The next tool is the interconnect. Lets talk about the UMT. The job of the interconnect is to get the digital bits from the transport to the DAC. We want all the bits sent without errors. All the interconnect types will do this. The standard connections are limited to 24 bits and the MSB network is 32 bits. Otherwise they all do the same job, EXCEPT were it relates to ground noise. Here we have big differences. Optical has no ground and the balanced almost no ground. Coax has a transformer coupled ground and the MSB Network a solid ground. The network provides the best connection in a perfect system, but rarely are systems perfect. The MSB PROI2S Input option provides a ground isolated MSB Network input. This is by far the best of all worlds. This is the reccomended interconnect. If you do not have the PRO input and you are hooked up to video, you may well find the optical connection best sounding. There is no ground connection at all. There is no rule. Any could sound best in your system. You just have to try them.

A Real World Example - This happened to me.

When we first introduced the UMT, one of my distributors compared these two sources: a laptop feeding the USB input to the DAC IV and the UMT feeding the MSB network input. He said the USB sounded much better. Wow, that sounded like trouble, as I would expect them to sound the same. We set up a brand new Diamond DAC with volume control, M202 Amplifiers, a MAC laptop with USB connection and a new UMT straight from the box with a network cable. We played our favorite cuts for about 20 seconds. Wow, the UMT sounded horrible in comparison. It must be broken! First we ran our bit-perfect test tracks. Yes, all was fine. It was doing its job perfectly.

Rather than mess around with balanced and coax, we just made the change to a Toslink cable. Total ground isolation. Instantly we found the two sources the same. Yes, high-res source and CD source, the same on both. But why stop there. We went in the menu and lifted the DAC IV ground, as our M202 Amps are grounded. Wow, now thats what I wanted to hear. Both sources now sounded fantastic. The sound was rich, and detailed and not at all harsh. With a DAC IV we might not have seen such a jump, but the Diamond is so revealing that it just came to life.

We tried a dozen other things, but for our setup, it came down to the ground lift. Now when we went back and forth between toslink and Network, it was not at all clear which was better. The Network gives a bit more noise but a bit more resolution with SACD. Both were great, and differences involved 5% kinds of things.

So changing the network cable could make a difference. Putting a couple of turns of the cable through a ferrite ring could make a big improvement. Just moving the cables around could change things. Even the sample rate of the music played seemed to make a difference, as the digital noise generated is at a different frequency and interacts with the system differently.

So how does the UMT sound? Very good, but only if you take the time to get it that way. If you hear something harsh or lifeless right out of the box, then get to work and dial it in for your system. And do not be surprised when little changes to connections make big changes to the sound!