Re: [Ardour-users] Re: Hardware Questions

From: Joern Nettingsmeier (nettings_at_folkwang-hochschule.de)
Date: 01/18/04 14:56 EST


Message-ID: <400AE50B.3010706@folkwang-hochschule.de>
From: Joern Nettingsmeier <nettings@folkwang-hochschule.de>
Subject: Re: [Ardour-users] Re: Hardware Questions
Date: Sun, 18 Jan 2004 20:56:59 +0100

Eric Halbert wrote:
> [quote]
> "This sounds like a problem that can happen when
> things are
> not properly grounded.  Make sure you're not using any
> 3 prong converters, that your mixer uses a 3 prong
> plug, and
> that your outlet is properly grounded."
> 
> ""You might also check the instrument cables and
> grounding
> there if applicable."
> 
> ""I'm not really up on this - it might have something
> to do with trying
> to run professional signal level (+4dBu) into a
> consumer card (-10dBu) 
> -
> another good reason to get a pro card.  It might be a
> grounding issue. 
> As I said, I'm not an expert.""
> 
> I know it's not the card.  I can plug an instrument in
> radio-station problem.

for radio stations to leak through, you need some sort of hf demodulator 
that converts the ubiquitous hf noise back into audible frequencies.
some input circuits are more prone to function as a demodulator than others.

iirc, you can alleviate the problem by soldering a capacitor in the 
picofarad range from the signal wire(s) to ground. it will 
"short-circuit" the hf garbage but have practically no effect on audio 
frequencies. mackie designs do that on their mixers by default, i'm told.

> The grounding issue seems likely.  Unfortunately, my
> apartment only has two-prong outlets, so I have no
> choice but to use a three-to-two prong convertor if I
> want to use any of my music equipment at all.  Oh
> well, at least when I'm shopping for a new apartment,
> I'll make sure the outlets are three-prong. 

if you have central heating, heating pipes can make decent grounding in 
some cases. just scrape off the paint a little and connect them to your 
gear with a hi-gauge copper lead (at least 6 mm^2, the more, the better).
another option is to use the plumbing for ground.


-- 
"I never use EQ, never, never, never. I previously used to use mic
positioning but I've even given up on that too."
	- Jezar on http://www.audiomelody.com


Jörn Nettingsmeier
Kurfürstenstr 49, 45138 Essen, Germany
http://spunk.dnsalias.org (my server)
http://www.linuxaudiodev.org (Linux Audio Developers)





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