DAC loud hum/funny noise. No music.

Posted by: warwick on 24 August 2010

For the past couple of weeks my new Musical Fidelity V-DAC has been hooked up to my desktop computer and it's sub sat TDK speakers without any problem.

Yesterday, in a different room [where my hi-fi is] I hooked the DAC up to my brand new laptop {Windows 7) with a usb cable and and a phono to din cable from the DAC into my Naim Nait 1 amp tuner and tape inputs.

With the usb cable plugged in and the power cable for the DAC plugged in there was the funny noise comming mostly from the right channel. When I unplugged the DAC's mains cable there was still the funny noise coming from the right hand speaker (hum/ short wave radio interference sound]. So it's not an earthing issue.

When I press play on a music file or BBC Iplayer the music comes out of the laptop speaker and not at all from my hi-fi. Again only an even worse funny noise comes out of the speakers (mostly right channel).

I am perplexed. One of the main benefits of getting a laptop was to get into lossless computer audio.

Any suggestions?

Thanks.

Posted on: 24 August 2010 by garyi

I am willing to bet its your laptop. It does not understand there is a dac connected and therefore nothing is being passed to it. The consequence is all you get is like a dead connection on your amp end resulting it crappy noise and the music coming out of your laptop.

Posted on: 24 August 2010 by {OdS}

warwick,

have you set up your usb device as the default sound output in Windows? Seems like it's still using your onboard card and not passing the signal through the usb port.

Posted on: 24 August 2010 by warwick

Thanks Ods,

I have changed the default sound output in Windows to the USB DAC. I can now hear music. It sounds good but on quieter parts of songs I can still hear the persistent hum/ funny noise on the right channel.

This is odd.

Posted on: 25 August 2010 by {OdS}

warwick,

this might be an earthing problem after all. I'm no specialist but after all, USB cables carry quite a bit of current. Who knows what might happen when connecting many devices together.

Christian

Posted on: 25 August 2010 by gone

Is your laptop plugged into the mains? If so, try it on batteries. Maybe that's it.
Some laptops have dreadful earthing problems when used with their switched mode power supplies, and the Nait 1 has some 'unusual' grounding arrangements

Posted on: 25 August 2010 by warwick

Thanks guys. This morning, after doing a search on computer audiophile forum, I set everything up with the laptop powered by it's battery.

Bingo! Music with no hum or nasty noises.

Last night I sent a message about the hum to the laptop producer's customer service team. Interesting to see what they'll say. I'd rather have laptop powered from mains to save battery re charging faffing around. But if that's the way it is then c'est la vie.

Laptop should be finished recharging after 2 hours now. So now in the digital groove. WE7 (like Spotify but free version streams at 192) sounding much better than through normal pc set up. Burned CD of hi-fi quality. Not had time to listen properly yet.

Posted on: 25 August 2010 by garyi

For many reasons there is a real benifit to having something dedicated to the task. if you decide that the tunes is worth it I would recommend as uitable computer just for audio.