MacBookPro - nDAC - chassis/floating

Posted by: gav111n on 07 October 2010

I have read several comments over the months about selecting the ground switch on the nDAC to ‘chassis’ or ‘floating’. I remember js suggesting a few times to play around with this to decide which sounds best. Until now I have not bothered and left it set to the default of chassis because:

(1) The naim manual says you may need to change it to floating if you are connecting to a HiFi system incorporating another earthed component. I use MacBookPro>HiFace>DC1>nDAC+PS and listen to music with the MBP on battery, so no earthed component right?

(2) The naim manual says you may need to change it if you hear humming through the speakers. I get no humming.

(3) What difference can a tiny little switch on the back of the nDAC really make?

The other night I had the urge to fiddle and flipped it over to floating. I should have followed js’s advice months ago! It has improved the sound quality and it isn’t subtle, an effect not unlike adding the PS to the nDAC – more ‘real’ sounding – more focussed – more engaging. I don’t understand why though. Am I going mad?

Gav.
Posted on: 07 October 2010 by AMA
quote:
What difference can a tiny little switch on the back of the nDAC really make?

Huge -- in some systems. It can "switch off" the noise. Put source on pause and crank the volume knob at max and listen if ground switch removes the hiss/hum.
The removed noise was not explicitly audible at normal volumes but produced a very unpleasant detrimental effect on the music.
Posted on: 07 October 2010 by gav111n
I guess I was (mistakenly) assuming that the ground switch is all about obtaining one stable ground from the mains earth connection. So with a battery powered source you would need the ground switch set to chassis.

Well whatever the theory, I am happy to have discovered the benefit, eventually. I am interested to hear if other MBP / coax / nDAC users have found similar results. Or perhaps I am the only prat to have not sorted it out from day one.

Gav
Posted on: 07 October 2010 by js
If you have other bits connected to your pre, this may be why you get this particular result. From your description of things, I suspect that's the case. If not, it may just be a flavor thing with your source possibly preferring a softer partner. At the end of the day, whatever sounds the best to you, is.
Posted on: 08 October 2010 by jlarsson
The ground/earth is the reference your system use so you should have only one such connection from your system. You know like Naim prefers to distribute this reference from box to box with one DIN cable (one ground connection) rather than two RCA:s (two ground connections).

At least this is my understanding of this - some expert will probably come and whack me deep into the ground/earth now :-)

Earthing is rocket science.

The Hiface Evo has its BNC output galvanically isolated (so it doesnt matter if the mac is grounded or not, will not affect the naim system reference) but I dont know about the smaller model.
Posted on: 08 October 2010 by js
It's not rocket science and could be dumbed down like other manufacturers do. You would just lose the opportunity to make things a bit better. Another aspect of grounding that hasn't been mentioned is that if your wall earth is a poor or noisey one, you may be better off without it. Not common but it does occur.
Posted on: 08 October 2010 by Hook
quote:
Originally posted by AMA:
quote:
What difference can a tiny little switch on the back of the nDAC really make?

Huge -- in some systems. It can "switch off" the noise. Put source on pause and crank the volume knob at max and listen if ground switch removes the hiss/hum.
The removed noise was not explicitly audible at normal volumes but produced a very unpleasant detrimental effect on the music.


Hi AMA -

Nice post! Very worthy of the "Hints & Tips" thread.

Just tried your method and now, for the first time, can clearly hear that "Floating" is more quiet for my setup.

Thanks a lot -- really appreciate the free upgrade! Smile

Hook