• Registered: 2013-02-14
  • Posts: 8

Topic: hdsp cardbus + rme rpm "ground loop" problem

Hello.

I bought a laptop with pcmcia port + HDSP cardbus card plugged into a "RME RPM" and I have a big problem of ground noise.
As soon as I remove the AC adapter from laptop, no more problem.

The problem is therefore the AC adapter of my laptop.

How to solve this problem ?

Thank you in advance for all your help.

  • From: Toronto
  • Registered: 2007-05-01
  • Posts: 95

Re: hdsp cardbus + rme rpm "ground loop" problem

I've been having that problem with an RPM and a Multiface 1. There are a bunch of threads in the MF forum about this. Some people have fixed it by isolating the card from the case using electrical isolation tape. Not sure how this would apply to a PCMCIA card though.
For me it took me a while to get my one RME AC adapter in the same place as the HDSPe based MacPro but now that I have, there is nice clean output. No buzz. In the long run it's not a big deal for me to leave it plugged in and I would always need the AC if I was using the express card in a MacBookPro so it doesn't affect portability but it does mean I would need another adapter if I had to use the MF and RPM on two different systems at the same time.

It might be me or the confusing number of posts that seem to be about the same thing but I couldn't find a definitive answer from RME as to what is the cause of this.

  • Registered: 2013-02-14
  • Posts: 8

Re: hdsp cardbus + rme rpm "ground loop" problem

Thank you for your reply.
But I'm french, my english is not very good, and I don't really understood how do you solved this problem.

"to get my one RME AC adapter in the same place as the HDSPe based MacPro"?

  • From: Toronto
  • Registered: 2007-05-01
  • Posts: 95

Re: hdsp cardbus + rme rpm "ground loop" problem

Sorry.
I have an RPM and a Multiface as well as laptop and desktop Mac systems, but only one AC adapter. The systems move around to different locations and generally the AC adapter is with the laptop, as it is required for any operation.
When I got both systems in one location ( by a chance of scheduling) I was able to eliminate the buzz/blips by connecting the AC to the desktop. Even though it's plugged into a MacPro and doesn't need the adapter for power.

I can survive with one AC adapter at the moment. I am the only operator for both systems so I'll just have to take it with me when I move back and forth.

On a Cardbus system, does the RPM still require external AC power? or can it draw from the card?
(My laptop uses an Express34 card which can't provide power to the RPM)

  • Registered: 2013-02-14
  • Posts: 8

Re: hdsp cardbus + rme rpm "ground loop" problem

Yes, my "hdsp cardbus pcmcia" require the external AC power.
And I have plug it, but the problem is still there for myself.

  • Registered: 2013-02-14
  • Posts: 8

Re: hdsp cardbus + rme rpm "ground loop" problem

My soundcard is useless because of this ed:
I'm sad.
Nobody has a solution ?

7 Reply by jbgeluid (edited by jbgeluid 2013-02-22 04:20:37)

  • Registered: 2008-01-20
  • Posts: 7

Re: hdsp cardbus + rme rpm "ground loop" problem

I have this probem when I connect my laptop adaptor in a "grounded" powersocket, together with other "grounded" things (powered monitors with grounded power cables) that are also connected to the soundcard. "Ungrounding" the laptop adaptor solves the issue.

By úngrounding I mean putting the laptop adaptor (mine has a power-plug with grounded connector) into an ungrounded power socket.

Hope this helps..

  • Registered: 2013-02-14
  • Posts: 8

Re: hdsp cardbus + rme rpm "ground loop" problem

Yes, it solves the issue.
I don't know if it's safe for me anb my laptop "security".
But it's the only one solution, I have no choice, I have to do like this...
Thank you.