Re: [LAU] Terrible mic ground noise

Previous message: [thread] [date] [author]
Next message: [thread] [date] [author]
To: <linux-audio-user@...>
Date: Tuesday, April 2, 2013 - 8:44 am

On Mon, 2013-04-01 at 23:06 +0000, Fons Adriaensen wrote:

2013-04-02, so no April Fools' joke.
^^

I used cheap headphones as microphones for toying. Indeed a cheap
dynamic microphone is the same, as a cheap Walkman's [1] headphone.
Regarding to this perhaps neither those cheap mics, nor those cheap
headphones are usable for serious recording.

I wouldn't connect a microphone, that is better than a supermarket
microphone to a headphone output!

Measurements inside a circuit are only useful for some tests. However,
pin 2 to pin 3 for a pseudo-Shure has got around 53 Ohm here and you
don't need to be close with an ear to hear a loud crackling. The result
is infinite between other pins, ergo no crackling.
_But_ for a GRUNDIG GDM 12, a dynamic consumer mic that is really from
the Stone Age, there's around 3K between all pins, crackling between all
pins only when measuring with to low settings for the multimeter.

To find out, if your mic is a dynamic mic or if it does need power, I
wouldn't use a multimeter, but Google.

Usually no ground = no noise and ground = possible noise. I only read
less replies and I'm scary to recommend tricks regarding to ground
issues, if the original poster is that clueless as for this thread,
since it's to dangerous to play with ground. However, it's more likely
that you get rid of noise, if you use a ground lift. At home I can do
this by completely switching of the ground connection of a device but I
don't need to do this, for the Brauner microphones we used capacitors, I
guess it's forbidden to totally cut ground and I don't remember if just
the shielding for the audio cables was lifted or also the ground cable
between wall sockets and device.

http://en.wikipedia.org/wiki/Ground_lift

FWIW, if you're living in an old house, you even can get potential
differences between devices, connected to different wall sockets, so
even if everything should be grounded, there could be a potential
difference. Don't ask me why there could be potential on ground, but it
can happen, that you can get a shock, if you touch two metal cases hat
are grounded. I guess house fires are often caused by bad electrical
things. I even don't trust earth leakage circuit breakers in old houses.

I'm living in an old house, while I don't get issues for audio, I'm
anyway scary about the house electric, but I don't have the gear to
check it.

Because the original poster already has simple questions about the usage
of a multimeter and a microphone, I recommend not to do handicrafts for
the house electric.

Regards,
Ralf

[1] In the Stone Age portable tape cassette players of all vendors were
called "Walkman", the name originally belongs to the Sony's player.

_______________________________________________
Linux-audio-user mailing list
Linux-audio-user@lists.linuxaudio.org
http://lists.linuxaudio.org/listinfo/linux-audio-user

Previous message: [thread] [date] [author]
Next message: [thread] [date] [author]

Messages in current thread:
[LAU] Terrible mic ground noise, , (Sun Mar 31, 2:06 pm)
Re: [LAU] Terrible mic ground noise, Len Ovens, (Sun Mar 31, 3:02 pm)
Re: [LAU] Terrible mic ground noise, , (Sun Mar 31, 4:25 pm)
Re: [LAU] Terrible mic ground noise, Len Ovens, (Mon Apr 1, 4:59 am)
Re: [LAU] Terrible mic ground noise, , (Mon Apr 1, 8:14 pm)
Re: [LAU] Terrible mic ground noise, Fons Adriaensen, (Mon Apr 1, 11:06 pm)
Re: [LAU] Terrible mic ground noise, Ralf Mardorf, (Tue Apr 2, 8:44 am)
Re: [LAU] Terrible mic ground noise, Fons Adriaensen, (Tue Apr 2, 10:45 am)
Re: [LAU] Terrible mic ground noise, Ralf Mardorf, (Tue Apr 2, 11:34 am)
Re: [LAU] Terrible mic ground noise, Gene Heskett, (Mon Apr 1, 1:58 pm)
Re: [LAU] Terrible mic ground noise, , (Mon Apr 1, 9:29 pm)
Re: [LAU] Terrible mic ground noise, Gene Heskett, (Tue Apr 2, 12:32 am)
Re: [LAU] Terrible mic ground noise, Ralf Mardorf, (Tue Apr 2, 9:23 am)
Re: [LAU] Terrible mic ground noise, Chris Bannister, (Tue Apr 2, 3:38 pm)
Re: [LAU] Terrible mic ground noise, Len Ovens, (Mon Apr 1, 3:44 pm)
Re: [LAU] Terrible mic ground noise, Fons Adriaensen, (Mon Apr 1, 9:51 am)
Re: [LAU] Terrible mic ground noise, , (Mon Apr 1, 9:14 pm)
Re: [LAU] Terrible mic ground noise, Fons Adriaensen, (Sun Mar 31, 8:25 pm)
Re: [LAU] Terrible mic ground noise, , (Sun Mar 31, 10:05 pm)