DAC's and the Two Ground Loop Types
Quick topic. So everyone knows, there are 2 possible types of ground loops a DAC can be subject to. Still.
The first is the normal, audible hum caused by a ground loop. This can happen when the source is on a different AC branch circuit for instance. It's exactly like every other ground loop problem most of us are familiar with. Just like them, this requires metal to metal signal transmission. In my mind it's very disappointing that this even happens anymore since USB isolator chips, and coax S/PDIF transformers are plentiful and cheap. My Mytek Brooklyn absolutely shows this problem when I run a long USB cable to my PC, something I only do for audio testing. Fixed it by switching to a laptop.
The other type of ground loop issue is in the digital domain and evidences itself as excess jitter sidebands. I have seen measurements for this, I think in Stereophile. Again, same exact cause but we don't hear it the same way. There's no audible humm.
Even a cheap, hospital grade USB isolator would fix either issue, but in the case of the Mytek, these won't work. I haevn't tried an iFi with it's own additional power supply though.
If you have Ethernet you should not have any ground loop at all. Because Ethernet is meant for long runs, with equipment at various ground potentials to begin with, it is galvanically isolated at each end. However! A 4kV hospital grade isolator is inexpensive and often used for lightning protection. If you try one and it helps youyr audio quality do let me know.
That’s kind of how I stumbled across them, I was reading some technical articles about surge protection for Ethernet. The article discussed the difference between protection that isolates vs. those that shunt to ground and it made the point that generally speaking the isolators performed better in real world surge events. In theory, Ethernet is isolated already, but I can see how extra isolation could reduce the noise transmission. The devices can be really cheap, as you point out. |
I just invested in Computer Audio Designs GC1 and GC3 for grounding. There brochure advises using a GC for either earth ground or the other ground. I am using the GC1 to earth ground my Server/Streamer and the GC3 to sort of star ground several other components and remove high frequency electrical noise. Honestly I have no idea how it works but it does. Its hard to describe the benefit except as a vanishing noise floor I was unaware of. I am very pleased with the the effect. |
I've looked at a lot of component surge and noise protectors including Panamax and Furman. Of the ones that support Ethernet surge protection with RJ45 connectors in and out, most of the units on the market are only 10/100, if they tell you at all the pass through speed. Many do not. My new Panamax M5400-PM and Panamax MR4000 are only 10/100. Given that I use my systems to watch streaming movies, can someone tell me if the slow surge protector speed creates a data bottle neck on the download speeds and effects the viewing? All of my cable is CAT 6, as is the router and switch? There are a few stand-alone ethernet surge protectors on the market which advertise gigabit speed 10/100/1000. |
Hi @kavogel Inside the home you want Ethernet isolators as opposed to surge protectors. The latest literature I read says that having a shorting type of Ethernet surge protector (ESP) actually is more likely to cause problems when a surge happens. They create a path to ground with a lower spark-over voltage than there was before. So as a result yo have massive currents trying to run through tiny wires. An isolator INCREASES the spark-over voltage needed for a surge. This minimizes the damage downstream from the point of entry of the surge. If at all possible, put shorting surge protectors like a gas-discharge tube outside your home. Use Ethernet isolators inside, as close to the cable modem as possible, and if you have any runs ~ 30’ or longer. Alternatively you can air-gap with fiber converters, but those require extra power supplies which are subject to surge paths and noise. Here is what I use, and it’s good for up to Gigabit-E:
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Hi @erik_squires . Thank you for your suggestion. I purchased the unit that you recommended. It's more expensive than others on the market, but cheap compared to the cost of replacing a component that might get fried by a power surge. I skipped using the integrated Lan protector in the Panamax (10/100) in lieu of the EverStar. My Lan wire goes into a switch, which then connects to several components - AV Denon Receiver; Sony BlueRay; Sonos; and Apple TV. What surprised me is that the directions recommend using a separate EverStar on every port of the equipment side of the Hub or one on going into the Hub and one on each outgoing port side into each component. I'm curious how you wired yours? I bought 3 - one to protect the Hub and one each on the outgoing side into the receiver and DVD. I wonder if that's underkill or overkill? Given that the signal come out of the AV receiver to the components by the HDMI cable, and I'm not directly streaming any audio or video from the internet without passing through the receiver, I wonder if realistically there is any noise that needs filtering on the ethernet side into the other components? I was thinking, perhaps wrongly, that any surges would be stopped before hitting the switch and that the only benefit of doubling up on the outside is noise? Thank you. |
