Noise that goes away when touching the chords and the mixer at thesame time

[Carlos]

Hello,

I made a rehearsal on a room of an old house. We had one mixer withe
Firewire output connected to a laptop for recording, one bass and one
guitar connected to a active DI box then to the mixer and one
microphone directly connected to the mixer. But we had this noise,
captured by the amplification system and recorded by the tracks on the
DAW, that disappeared every time one of us touch the chords of the
instrument and the metal chassis of the mixer at the same time. As
that was an old house the electric power does not have a ground
connection. Is this the cause of the problem? If it is, is it possible
to eliminate the problem even if it's impossible to get a ground
connection? And by the way, is it dangerous for the persons not having
this ground connection?

Thank you very much in advance for your help

Cheers

[Laurence Payne]

On Sat, 15 Dec 2007 10:59:41 -0800 (PST), Carlos
> wrote:

>Hello,
>
>I made a rehearsal on a room of an old house. We had one mixer withe
>Firewire output connected to a laptop for recording, one bass and one
>guitar connected to a active DI box then to the mixer and one
>microphone directly connected to the mixer. But we had this noise,
>captured by the amplification system and recorded by the tracks on the
>DAW, that disappeared every time one of us touch the chords of the
>instrument and the metal chassis of the mixer at the same time. As
>that was an old house the electric power does not have a ground
>connection. Is this the cause of the problem? If it is, is it possible
>to eliminate the problem even if it's impossible to get a ground
>connection? And by the way, is it dangerous for the persons not having
>this ground connection?

Any house can have a ground connection. Even if you have to bury a
copper rod outside and run a cable to it. In the dry season, throw
an occasional bucket of water over it.

[Peter Larsen[_2_]]

Carlos wrote:

> Hello,

> I made a rehearsal on a room of an old house. We had one mixer withe
> Firewire output connected to a laptop for recording, one bass and one
> guitar connected to a active DI box then to the mixer and one
> microphone directly connected to the mixer. But we had this noise,
> captured by the amplification system and recorded by the tracks on the
> DAW, that disappeared every time one of us touch the chords of the
> instrument and the metal chassis of the mixer at the same time. As
> that was an old house the electric power does not have a ground
> connection. Is this the cause of the problem? If it is, is it possible
> to eliminate the problem even if it's impossible to get a ground
> connection? And by the way, is it dangerous for the persons not having
> this ground connection?

Does the issue go away if you run the laptop on its battery?

There is probably some advice on this on the rane website.

You may need a qualified electrician that knows the local safety code. A
ground connection can indeed under some circumstances increase the risk -
usually some type of fault current relay also needs to be installed.


Kind regards

Peter Larsen

[Hal Laurent]

"Carlos" > wrote in message
...

> DAW, that disappeared every time one of us touch the chords of the
> instrument

Heck, I'm impressed that you do something as metaphysical as "touching a
chord". :-)

Cords, on the other hand, are another story.

--
Hal Laurent
Baltimore

[[email protected]]

On Dec 15, 1:59 pm, Carlos > wrote:
> But we had this noise,
> captured by the amplification system and recorded by the tracks on the
> DAW, that disappeared every time one of us touch the chords of the
> instrument and the metal chassis of the mixer at the same time. As
> that was an old house the electric power does not have a ground
> connection. Is this the cause of the problem? If it is, is it possible
> to eliminate the problem even if it's impossible to get a ground
> connection? And by the way, is it dangerous for the persons not having
> this ground connection?

Yes to all your questions, there are too many unknown facts to further
advise on possible solutions.
and the fact that you posted here means no one in your group has the
knowledge to DIY the problem.
Get a local person with an electrical background to help.

[Peter Larsen[_2_]]

Hal Laurent wrote:

> "Carlos" > wrote in message
> ...

>> DAW, that disappeared every time one of us touch the chords of the
>> instrument
>
> Heck, I'm impressed that you do something as metaphysical as
> "touching a chord". :-)

> Cords, on the other hand, are another story.

Ah, you didn't know that chords also means strings in gp international
english, at least since yesterday ... brush up your english Hal, because the
language is changing. You gotta learn to read through such stuff.


Kind regards

Peter Larsen

[Scott Dorsey]

Carlos > wrote:
>
>I made a rehearsal on a room of an old house. We had one mixer withe
>Firewire output connected to a laptop for recording, one bass and one
>guitar connected to a active DI box then to the mixer and one
>microphone directly connected to the mixer. But we had this noise,
>captured by the amplification system and recorded by the tracks on the
>DAW, that disappeared every time one of us touch the chords of the
>instrument and the metal chassis of the mixer at the same time. As
>that was an old house the electric power does not have a ground
>connection. Is this the cause of the problem? If it is, is it possible
>to eliminate the problem even if it's impossible to get a ground
>connection? And by the way, is it dangerous for the persons not having
>this ground connection?

What did the ground lift switch on the DI box do?
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Peter Larsen[_2_]]

Soundhaspriority wrote:

> If you look at the name of this group, it's rec.audio.PRO.

NNTP-Posting-Host: 66.175.215.121 ... yawn ... buzzard morein impersonator
again, and drunk this time.


Kind regards

Peter Larsen

[D C[_2_]]

Peter Larsen wrote:

>> If you look at the name of this group, it's rec.audio.PRO.
>
> NNTP-Posting-Host: 66.175.215.121 ... yawn ... buzzard morein impersonator
> again, and drunk this time.

I didn't see it until now.

[[email protected]]

On Dec 15, 10:15 pm, "Soundhaspriority" > wrote:
> "Carlos" > wrote in message
>
> ...
>
>
>
> > Hello,
>
> > I made a rehearsal on a room of an old house. We had one mixer withe
> > Firewire output connected to a laptop for recording, one bass and one
> > guitar connected to a active DI box then to the mixer and one
> > microphone directly connected to the mixer. But we had this noise,
> > captured by the amplification system and recorded by the tracks on the
> > DAW, that disappeared every time one of us touch the chords of the
> > instrument and the metal chassis of the mixer at the same time. As
> > that was an old house the electric power does not have a ground
> > connection. Is this the cause of the problem? If it is, is it possible
> > to eliminate the problem even if it's impossible to get a ground
> > connection? And by the way, is it dangerous for the persons not having
> > this ground connection?
>
> > Thank you very much in advance for your help
>
> > Cheers
>
> The problem description resembles another, posted perhaps six weeks ago. As
> I recall, the poster complained of pickup noise that vanished if he grounded
> himself. Some of the replies suggested techniques of shielding the pickup.
> It appears that the player's body increasing the capacitive coupling of the
> pickup to something else nearby, creating a second, spurious, ground. When
> the player touches the mixer, he is at signal ground potential, and he acts
> as a capacitive shield. If this old house has hot water heating, Carlos
> might try clipping a wire to the mixer which he would run to the water pipe
> using a standard plumbing ground clamp.

and he might wire up a quad box with said grounding so that all the
electrical connections for all the equipment to be plugged into, but
then he would be stepping out of his knowlwdge base.
Hence my "find a friend" to help