NotebookForums.com › Forums › Notebook Manufacturers › Dell Notebook Forums › Dell Legacy (single-core notebooks) › Audio groundloop occurs when connected to PreAmp Mixer..
New Posts  All Forums:Forum Nav:

Audio groundloop occurs when connected to PreAmp Mixer..

post #1 of 21
5/26/04 at 8:02pm
Thread Starter 
Has anyone here used their XPS/9100 with a preamped mixer?

I am using my XPS with a Vextax PCV275 mixer. When the laptop is connected to the mixer a groundloop occurs. What I have determined is that when the AC Adapter is used the loop occurs. If I only run on batteries there is no problem...this will not do!

I had DELL replace the AC Adapter to no avail. They also signed off on the issue saying its not intended to be used like this... huh?!

I am positive it is either a problem with my laptop or a general design flaw as the problem exists on all preamped mixers. lowend mixers do not experience the problem.

Anyone got the same problem or suggestions?

Thanks.
Reply
Reply
post #2 of 21
5/26/04 at 10:23pm
I used to use my old Inspiron 5000 patched into a mackie 1604 and I had the same problem. There is a ground loop that exists between the machine and the power supply of the laptop (probably because there is a transformer in the power supply).

The fix is easy - go get yourself an AC ground lift. One of those devices that allows you to plug your 3 prong AC cable in, but only has 2 prongs that plug into the wall. You should be able to get them at any electronics store or Radio Shack.

This fixed my problem right away - hope it works for you too!

Warren
Reply
Reply
post #3 of 21
5/27/04 at 6:26pm
Thread Starter 
Warren - Thanks a lot for this suggestion. I hope it is this simple!

You wouldn't believe the hell I've been going through trying to fix this; I've tried Direct Boxes, Groundloop isolators and they only result in a somewhat distorted audio signal. The thought of having to sell this unit just pisses me off...

Thanks again! I'll let you know if it works.

Jap_
Reply
Reply
post #4 of 21
5/27/04 at 9:48pm
Thread Starter 

Oh Man.....whooohooo!!!! Weeks of pain are over...

Warren - that has to be the best suggestion I've ever gotten. I've talked to literally dozens of people about this and have had several really good, really expensive suggestions made, but this is just too awesome.

Thanks for the great advice!

Paul.
Reply
Reply
post #5 of 21
6/2/04 at 10:14pm
No problem! It took me a few weeks of trying DI boxes myself before I thought to try a simple ground lift.

Warren
Reply
Reply
post #6 of 21
1/30/05 at 11:00pm
I FIXED MY PROBLEM VERY CHEAPLY AND WITHOUT THE HAZZARDS OF REMOVING THE GROUND!!!!!!!!!!!!!!
The only thing you need is two (one for left speaker and one for right, or more if you have dolby digital) BALANCED jack to jack cables to be connected from your soundcard to your amplifier or your active speakers. You will need the soundcard to have balanced outputs though and I think the amplifier has got to have balanced inputs as well. Don't know about the Audigy cards, I think the have. Mine is an RME Hammerfall.
How to check if your cable is balanced or unbalanced: Unplug the jack cable to see the plug. If it has one black or coloured line it is unbalanced, if it has two black or coloured lines it is balanced.
Also an optical connection will solve your problem

Good luck
Reply
Reply
post #7 of 21
1/30/05 at 11:25pm
same here
i bought a ground removal adapter and it works great!!
Reply
Reply
post #8 of 21
1/31/05 at 2:59am

I think a general note should be made here

Hey everybody,

I think a point should be made here. Most of us are using these ground lift "adapters" to remove the ground on our power supply, thereby removing the lowest potential point in our path and getting rid of the leak down to ground problem. For our laptops it is all fine and well. But if you are going to be doing something in a more permanent situation with a higher current load the "adapter" should be used as that a grounding adapter for outlets that only have 2 prongs. The adapter will have a metal tab that should get screwed into the outlet box via the center cover plate screw, thereby creating a ground path back to the service panel through the armored cable.

This forum is such a good source of information I feel that the above point needed to be made somewhere.

Jesse
Reply
Reply
post #9 of 21
1/31/05 at 3:11am
Ok here is the bad news....

The onboard sound ports have a flaw with the grounding. I went through hell with dell (poetic )... and 4 fans with no help in quality. It has to do with the fan. The faster the fan the worse it gets. The power for the fan is bleeding through the audio ports.

There is no fix other than to get the WONDERFUL SB Audigy 2ZS PCMCIA... There is an active thread on it, and it works beautifully. And.... no more ground loop problems. You will also be able to fully use the audio programs that are out like Cakewalk and Pro Tools to their fullest extent. Try that with the onboard sound... I dont think it even supports midi. How sad for such a nice machine...

The only downside is that it will not play through the onboard speakers ( I dont use mine much anymore... ).

Running your laptop is psycho without proper grounding. So many potential bad things... lightning, power surges, brownouts... I know the lappy better protected but you can blow power adaptors, and bad power adaptors can blow laptops...
Reply
Reply
post #10 of 21
1/31/05 at 3:14am

actually I had to gournd lift the audigy card

wack,

I have the audigy 2 zs notebook and love it. The other day at work coming out of a midas Venice console - I had to ground lift the ac adapter to get rid of the hum coming into the line in.

J
Reply
Reply
post #11 of 21
1/31/05 at 3:24am
really.... that sucks my mackie 24 channel works good.... I wonder where the difference lies....
Reply
Reply
post #12 of 21
1/31/05 at 3:26am
well I was doing a 150' run out to foh, in a new venue I hadn't been to. I'll have to try it out later in one of my usual venue with the midas again or the gl3300.

j
Reply
Reply
post #13 of 21
2/1/05 at 11:22am
i am an audiofile, though i have never used my 9100 with my pre amps i do have the same problem anytime i connect a player or any other equipment to my preamps. the fix is to make sure that all grounds are coming from the same outlet so that you do not get in a loop. this fix is simple and no equipment needed, just connect all grounds to the same origin.
Reply
Reply
post #14 of 21
2/1/05 at 11:30am
awesome thread

I got my audigy last week and everytime I try to record through line in i get some nasty ground loop.. interesting to hear of other peoples issues with it
Reply
Reply
post #15 of 21
2/1/05 at 12:36pm

wardo, I did :)

When I had the problem I did have everything (mixer, dsp, effects, amps, band power) connected to the same ground source, and still had hum in the laptop but not in any of the other equipment. I am still interested to see what happens at other venues with other boards.

J
Reply
Reply
post #16 of 21
2/1/05 at 12:53pm
hey Jesse, have you tried to ground your computer to the pre amp yet? this is what i have done for equipment that didn't have a ground wich is what i think the problem might be. the ground that is on the adapter is probly only for the adapter since it is the only high voltage part of the computer, and there would need to be a 3rd wire going to the computer if it had a isolated ground. try grounding the computer to the preamp. i would do it by the connector screws on the back.
Reply
Reply
post #17 of 21
2/1/05 at 1:40pm
i remember doing that with my turntables back in the day... it worked too...
Reply
Reply
post #18 of 21
2/1/05 at 8:26pm
Ok I used the 3 to 2 prong adapter to remove the ground. My systems groundloop is now gone. Is this dangerous in anyway to me or my laptop?
Reply
Reply
post #19 of 21
2/1/05 at 9:23pm
The safest solution is to simply use an isolation transformer. Check this Link..
http://www.hammondmfg.com/171.htm
Get the 200VA.

This definitely NOT the cheapest solution but is is the safest.

This way there will be NO connection between the laptop and the wall outlet.
So any external equipment can be used whether they are grounded or not.

An alternative is to use one of those lightning and surge protectors. Most of them are isolated from the wall outlet.

Regards
HD
Reply
Reply
post #20 of 21
2/1/05 at 11:52pm
that too would work
prob better cause ground is good protection for your pc
whats happening is a ground loop
Reply
Reply
New Posts  All Forums:Forum Nav:
  Return Home
NotebookForums.com › Forums › Notebook Manufacturers › Dell Notebook Forums › Dell Legacy (single-core notebooks) › Audio groundloop occurs when connected to PreAmp Mixer..