[LAU] Terrible mic ground noise

Len Ovens len at ovenwerks.net
Mon Apr 1 04:59:11 UTC 2013


On Sun, March 31, 2013 9:25 am, jonetsu at teksavvy.com wrote:

>> From what you have said above and from looking up the HW you are
>> using,
>> you should not be getting any audio through the mic at all. So if you
>> turn
>> the gain up high enough you might get hum.
>
> That must be the problem then.  The higher the volume, the higher the
> 'ground' noise.
>
>>>    The electric plug has only two prongs.  I though of getting some
>
>> What electric plug?
>
> The one to which the computer stuff is connected.  The house plug.
> Which is not a plug, but a box. That one does not have a ground wire as
> others do.  The two-AC plastic socket unit has no ground wire.

Is this the way the whole house is wired? (or garage or whatever) This may
very well be some of your problem. It would seem that your whole setup is
floating. I would feel comfortable fixing the wiring to make sure I had
proper grounding even if it just meant running one wire for that purpose.
If there are any grounded outlets in the building (washing machine for
example), I would run an extension cord from there. I have not had hum
like that from a mic. If you have no grounded outlets at all in your
house... In North America that would be over 50 years old... then running
a good thick wire (14 gauge would be good) to the chassis of your computer
from the cold water pipe if you are on city water and it is metal all the
way out of the house... or a 6 foot piece of re-bar pounded into the
ground would work too. If you are on well water the whole water system may
be above ground or plastic. Also check the main power panel as the power
company may have that grounded regardless of the rest of the house. A
friend who is an electrician would be a great asset at this time :) They
could probably figure things out in less time than it took you to read
this.

You are getting sound from your mic... therefore it must be a dynamic mic.
It is quite possible that whatever I looked up on m-audio's website is not
what you have. So it is not worth worrying about getting phantom power to
it if it is working without it.

> Obviously I know nothing about those phantom power units.  Which one
> would you recommend ?  Will it simply be in the XLR path: mic -> power
> -> 1010LT ?

That would be the way, but if you are getting sound at all, your mic
either has power already or doesn't need it. If it was indeed a phantom
powered mic you would get no audio from it at all, so I think you have a
dynamic mic of sorts.

> Also, now the passive DI box can be put to some other use.  Would it
> accept the 1/4" output of a small VOX guitar amplifier ?  What would be
> the difference in sound characteristics between using a DI box to the
> 1010LT 2nd XLR input vs. not using one and connecting the same VOX
> output to a regular 10101LT input ?

:) I suspect you will not hear much if any difference. The transformer in
the DI may pull some of the high end sharpness if you run the amp into
distortion all the time. Not knowing if the VOX you have is tube or
transistor, where you are getting the output from, etc. I really don't
know. The value of a DI is in long cable runs often found in a live
situation or in the case you only have balanced inputs. If your amp has a
direct out, it should work fine into one of your line ins. If it is a
speaker out, the DI may do a better job of matching things. In any case
your ears are the best judge of this.


-- 
Len Ovens
www.OvenWerks.net



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