Hello,

At my home, some wall outlets have ground connection while others don't. (And I'm not sure if outlets with ground are really connected to ground).

Is it important to plug the DA11 into an outlet with ground connection? Will it affect sound quality? Or is it just for safety reasons in case of voltage variations? (may I fry the device?...)

And, by the way, what do you think about the noise in AC power lines? Is the DA11 isolated from it, should we use some kind of filter? Or we don't need to bother about it?

Thank you very much,
Ferran

Whenever possible, we strongly recommend that you connect the DA11 to an outlet with the third pin grounded. There are a number of reasons for this, including the possibility of a voltage developing on the case of the unit if it is not properly grounded. Another important reason is so that the other equipment in your system share a common ground other than the signal connections with the DA11. To accomplish this, you can use an AC "power strip" as the source for the AC power for equipment in your system so that the equipment's AC power ground pins are connected together.

Although it is not likely that damage would occur to the DA11 if it were connected to an un-grounded outlet, it could cause "hum" or noise in the audio as well as the possibility of a shock hazard. So I would strongly recommend that you use a grounded outlet as the AC source for your DA11/system.


Unless you have a situation where there is an unusual amount of "noise" on the AC power line, the DA11's power supply is actually capable of dealing with typical voltage variations. At the minimum, it is a good idea to use a "de-spiking" power strip to help prevent very high voltage "spikes" from getting to the DA11's power supply. In cases where the AC power is unreliable, you can use a standard computer battery back-up. The better quality battery backups quite often offer constant voltage regulation as well as the battery operation for more serious voltage variations or black-outs.

The combination of regulation in the power supply and additional filtering on the main circuit board of the DA11 should provide isolation from all but the worst noise in the AC power.

Brad Johnson
Lavry Engineering Technical Support

Thanks a lot Brad,

If my outlets are not grounded (I have to figure it out), will a computer battery be enough to avoid the noise in the audio?

By the way, Dan was more optimistic about grounding problems:
Taken from: http://www.head-fi.org/forums/f158/lavr ... ndex7.html

What do you think about that?

Thanks again!

I think you may be combining or confusing more than one issue here...

I believe most Battery back-up units designed for "home" computers have grounded AC plugs and warn against using them without the ground connected; I was not suggesting using one as a "solution" to lack of proper AC grounding. The best thing you can do is establish which outlet(s) are properly grounded and use one that is grounded for your AC power source. I was suggesting the use of such a unit if your AC power has large voltage variations or interruptions.

Also, regarding Dan Lavry's answer on the Head-Fi forum- he speaks of ground issues that can affect the audio, but this does not mean he advocates operating equipment that has a ground pin on the AC plug without connecting it to a grounded AC outlet. There is a big difference between a little noise in the audio and an electrical "shock" hazard.

So I would suggest addressing your grounding issue first, then see if there are any other issues that could be addressed by AC line filtering or power conditioning. Chances are that other equipment in your system will either be more sensitive to AC power issues than the DA11, or the AC power disturbances will be so bad that it will affect all of your equipment and can only be solved by use of something like the battery backup.

Brad Johnson
Lavry Engineering Technical Support

Ok, so I understand I might hear noise if my outlets are not grounded.

By the way, have you considered a battery powered DA11?

Thank you!

Do you also understand the implications of creating a "shock hazard?"

In some cases, operating equipment with a ground pin on the AC cord that that is not connected to a proper ground can result in a voltage being present on the case or other metal parts of the equipment. This is why we do not recommend operating our equipment (or any other equipment that has a ground pin on the AC cord) with the ground pin NOT connected to a proper AC ground.

Brad Johnson
Lavry Engineering Technical Support

Yes, I know. That happens when touching my computer while going barefoot...