Laptop power supply causing nasty digital buzz

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electricfuzz
Posts: 21
Joined: Sun Jun 01, 2008 8:02 pm

Laptop power supply causing nasty digital buzz

Postby electricfuzz » Sat Mar 14, 2009 1:16 pm

This isn't a Forte related question other than all my gear is ran by the program. The problem I am having (and have had in the past with other applications) is that when hooked up to the P.A. and amps etc.., I got a nasty, computery sounding buzz/noise through all the monitors (probably the mains also, be we did not have those set up for practice last night). The noise is instantly fixed by removing the power cord from the rear of my laptop and letting the batteries take over. I have been building my new rack with the new forte and incorparating my new Yamaha Motif Rack, a new sound card (Edirol FA-66), and a different laptop (not new, i have experienced the issue with this laptop with all different hardware hooked up). At home, with all the same gear exept the outputs of sound card are hooked up to a small desktop mixer which is in turn hooked up to studio monitors, i did not get this problem at any output.
Since I have had this problem on and off, depending on my setup, I can only assume that the only way to solve this is to isolate my laptop's power supply from everything else. I have tried running power from different circuits to no avail. I even ran an extension cord to a circuit that was from a different breaker box all together but to be fair the breaker box i was bypassing/avoiding was directly wired to the breaker box in the house that i ran an extension cord to. I'm not an electrician and I have no idea what all that means. I would think that if I ran a chord to a neighbors house, I would prolly not get the noise but that is speculation.
I guess my question is, are there power conditioners that would isolate this plug from the rest somehow? A small one outlet converter would be much more suitable than a whole rack unit, unless multiple things could all be pluged into it and still be isolated from each other. What about a piece of ferite on the power cord, my edirol came with such a device attached to its power cord and the manual said it was to kill noise/interference. As I type this I realize that I should remove my power conditioner from my PA rack and test out a standard run of the mill type and see if that works. I have a couple other things to try today, if any work I will reply to this post with my successful treatment. Thanks in advance.
-Cory

Angel
Posts: 362
Joined: Wed Aug 04, 2004 1:00 pm
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Re: Laptop power supply causing nasty digital buzz

Postby Angel » Sat Mar 14, 2009 2:48 pm

This is a common problem with laptop power supplies that have a three prong mains plug. Try to get a replacement power supply with a two-prong plug without earth contact. These supplies are double-insulated and have a sign on their housing that looks like a small square in a larger.

The other solution is using ground-loop isolators in every connection to the PA.

Angel

Dirk Offringa
Posts: 3508
Joined: Sat Mar 06, 2004 3:44 am
Location: Sainte Anastasie, France
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Re: Laptop power supply causing nasty digital buzz

Postby Dirk Offringa » Sun Mar 15, 2009 4:02 am

Most common cause of this sort of problems is a BS-FFUN* error. It has been reported that changing his UN from "electricfuzz" to "silentnight" or something similar got rid of it altogether. Don't forget to reboot for the change to take effect.

Dirk

*ForteForumsUserName Error :lol: :lol: :lol:
Life would be much easier if I had the source code.

Juergen Koehler

Re: Laptop power supply causing nasty digital buzz

Postby Juergen Koehler » Fri Aug 28, 2009 3:19 am

I'm using a Palmer Isolation Box PLI-03 to eliminate this buzz. Works perfect. The Palmer PLI-02 or any other DI-Box does not.

Juergen


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