EMU 0404 Ground Hum

Posted by: MarkAz on 26 July 2009

Hi

I've searched previous posts but i don't think this Q has been covered. Apologies if it has.

I just bought a EMU 0404 USB interface from Andertons in Guildford, UK (great shop if you're ever in the area) with the hope of improving on the dac performance of my Samsung NC10. Problem is, when I connect the unit to my Nait 5 (+FC2) via Chord Chrysalis I get quite an audible ground hum (not talking about the familar naim amp hum - this is much, much louder).

fyi, the RCAs on the Chrysalis are fitted with mono adapters to fit the 1/4 inch output sockets on the EMU 0404.

I've tried:

* the other inputs in the nait rear panel
* swapping the jack adapters
* unplugging the usb connection to the laptop (hum remains, i.e. it's not the lappie)

Can anyone help on this?

Thanks in advance.

Mark
Posted on: 26 July 2009 by james n
Does this use a power adapter ? - what happens if you pull this too - does the hum dissapear ?

James
Posted on: 26 July 2009 by MarkAz
Hi James

Yes it does! Hum stops as soon as I pull the power cord out...do you think this means the unit is generating the hum?

Mark
Posted on: 26 July 2009 by james n
Hi Mark,

Sounds like a ground loop - what else is plugged into the Nait ?

James
Posted on: 26 July 2009 by MarkAz
Nothing - well, just a flatcap 2.
Posted on: 26 July 2009 by james n
Looking at the specs of that unit, the 1/4 jacks are balanced outputs so you could be running balanced outs into the unbalanced input of the Nait.

Also - Ground Loops

The E-MU 0404 USB 2.0 contains built-in “ground lift” switches for both analog
inputs in order to safely break the loop if a ground loop occurs in your setup.
The ground-lift switches are located on the bottom of the unit, close to the front
panel. The input ground is lifted when the A or B slide switch is closest to the GND
LIFT label. These are for the analogue inputs only though.

The manual shows balanced 1/4 jacks to unbalance RCA adapters - are you using these ?

James
Posted on: 26 July 2009 by MarkAz
Thanks James - great spot!

I checked the specs before purchasing, but in my clearly blind excitment did not pay attention. Back to the drawing board on the afordable d/a a/d then...

Thanks again James
Posted on: 26 July 2009 by james n
You should be able to get some adapters to convert the balanced to unbalanced quite easily. Looks a neat unit.

Enjoy

James
Posted on: 26 July 2009 by MarkAz
Thanks - if I get the hum sorted I'll report back on how the thing sounds. Hum aside, it looks promising.
Posted on: 27 July 2009 by Mike Smiff
The Nait 5 from my experience will hum when it has only a non earthing source connected due to the fact it has no earth screen, as soon as you connect a Naim cdp without even switching on the cdp on and connecting the mains cable the hum stops.
Likewise the same happens when you connect a Linn lp12 which has a Mains connected reference earth.