[musickid]

For Rob could you kindly look at these situations and let me know if ground loops or leakage currents could arise, assuming all devices are plugged into the same mains strip.

1)H2 optical in from desktop computer or battery powered laptop usb and also charging while playing and listening to headphones.

2)blue 2 with battery powered laptop usb connected to h2 which is playing and charging ie intelligent desktop mode in use. (here the fact that blu2 and h2 are both connected to the mains puzzles me)

3)same as just described in point 2 but with mains powered usb source for blu2.

thanks alot mk.

 

[Rob Watts]

Situation 1 would technically have a ground loop via the mains - but in practice it is OK, as I have not heard a SQ change with the charger connected with a grounded source and headphones.

Don't worry about Blu 2, as the galvanic isolation on the BNC outputs eliminates the problem.

 

[musickid]

many thanks Rob. just one point. i always thought galvanically isolated optical into mojo/h2 from either a grounded source or a battery powered laptop makes no difference. am i wrong here as you mention ground loops via the mains as still being a potential problem.

 

[Rob Watts]

Yes I could hear a difference between grounding the OP phonos with USB against optical; but could hear no difference when using the supplied PSU. I guess the RF filtering I put on the charging input removed that potential ground loop problem.

 

[musickid]

i follow you fully here. the rf filtering on the charging input basically neutralises the problem i was trying to put into perspective. with blu2 the galvanic isolation on the bnc output also eliminates any potential sound degradation from occurring by blocking any electrical "pollution" from entering h2/dave. out of interest is it possible for a ground loop to occur between two devices plugged into the same mains strip? i was under the impression that is why people do plug everything into the same strip which is my practice too. i'm surprised that you hinted this may not always be the case? thanks again mk

 

[Triode User]

out of interest is it possible for a ground loop to occur between two devices plugged into the same mains strip?

The clue is almost in what you have written. You have created a loop.

 

[musickid]

in that case why do countless online sources recommend plugging everything into one strip to avoid ground loops? could you help me fill in the gaps in my understanding here? thanks mk

 

[Rob Watts]

What is happening in plugging into one strip is not avoiding ground loops, but reducing the area of the loop, hence reducing magnetic pick-up (hum) - it's only of benefit for low frequencies only.

But as soon as effective isolation happens, there are no ground loops, even if both are connected via the mains.

 

[musickid]

a great sunny saturday to all.......mk

 

[Deftone]

a great sunny saturday to all.......mk

Feels like the first bit of sun I’ve seen here in 9months

 

[Rob Watts]

It's a shame to be stuck indoors coding... Still Wales v Ireland rugby after lunch!

 

[musickid]

which sunny county are you in deftone? oh and why did you sell h2?

 

[plsvn]

just bought a Qutest and tried it in my secondary system
looks this amp (RWA Signature 15) doesn't like 3v line in as all is fine as soon as I set Qutest line out to 2v

plan was to replace the 2Qute in my main system with the Qutest and move the 2Qute to my secondary one
question: anything I can do ("easily": might consider some simple DIY) to lower 2Qute's line out voltage, please?

 

[musickid]

i think its fixed

 

[plsvn]

I actually mean: is there "something" (ready-made or DIY) I can put between 2Qute's line out and amp's line in?