2. digital
  3. 177172-20253

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.

erik_squires
painter24's avatar
painter24
212 posts
 

@erik_squires Hi Eric, I bought these from Amazon a while back; they are not manufactured for audio, more an installation product to protect against surges/lightning strikes. Made a very subtle difference in clarity for me. There is a review out there somewhere, from Germany I think it was, from someone who stumbled across these and tried them in their hifi system. There is some kind of isolation built in to them which may be what’s giving beneficial results.

Worth a punt at 20 odd quid (£)

DeLOCK 62619 - cable interface/gender adapters (RJ-45, RJ-45, Female/Female, Grey, Polybag) https://amzn.eu/4WEPwOi

 

erik_squires OP
15,657 posts
 

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.

anzaanimalclinic's avatar
anzaanimalclinic
239 posts
 

@erik_squires 

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.

kavogel
5 posts
 

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. 

erik_squires OP
15,657 posts
 

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:

 

 

More to discover