Real-time hum removal

  • Thread starter Thread starter Roger Bourne
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Roger Bourne

Hello all,

When I use my computer mic to chat online or to record a sample opf my
voice, or simply to record anything, I get a loud background hum (I
suspect it the 60Hz power line is the culprit) . Is there any
software/freeware that can filter the microphone input before it is
received by chatting-software ? I suspect recording software will have
a hum removal feature, however I am interested in real-time hum
filtering for when I am chatting online. (The people on the receiving
end of the chatting software -the ones who get the pleasure of hearing
me ;) -complain that the hum is loud and distracting).

Regards,
Roger Bourne
 
try this...

Put your hand ON the computer casing with all the palm down,
and see if this decreases the hum....

if it does tell me...
 
When I use my computer mic to chat online or to record a sample opf my
voice, or simply to record anything, I get a loud background hum (I
suspect it the 60Hz power line is the culprit) . Is there any
software/freeware that can filter the microphone input before it is
received by chatting-software ?
Click to expand...

You have a hardware problem, so solve the hardware problem. Solving
it in software is like putting a really tight band-aid on a severed
artery - it'll stop the bleeding, but ...

Either the mic is bad or it's not the correct type for the sound card
- there are two types of input and mic, and using the wrong type can
result in weak or no audio or hum. (Unfortunately no manufacturer
tells you which type of audio input you have and which type of mic
they're selling - you have to figure it out for yourself.)
 
Ok,

I put my palm on the laptop's (computer is actually a laptop)
keyboard-side casing and recorded myself. The playback did not show
any evidence of the hum decreasing.

-Roger
 
oh this is a laptop?

hmm... I have noticed hum decrease on many systems (desktops)
when you place your hand on the metallic part of the case...
it seems that that creates better grounding and noise is reduced.

But what you are doing is on plastic, right?

so since your sound chip is built in, is it perhaps c-media?

see in your control panel if its cmedia or you have another icon
for your sound. These sometimes have a built in software equalizer that you
can adjust the low frequencies....

tell me if this is the case...
 
question1, if you run the laptop from the batteries does the hum continue?

question2 what sound drivers are you using? xp, laptop specific or the
yamaha ones from the yamaha site?

there are actually 2 ways of seeing the mixer, one is for playback and the
other is for recording
to get the recording mixer, go to the normal mixer then to OPTIONS>
Properties>
select the RECORDING radio button

question3 if you disable all other inputs from the sound mixer, do you still
get the hum?

question 4 does the mic in the mixer record settions have an advanced button
for mic boost?
You will need to go to OPTIONS> ADVANCED CONTROLS to make this show.

if yes try that and lower the general sound volume... see of that makes the
signal to
noise ratio better
 
Thank you John Jay (and Al) for the feedback. Unfortunately, I cannot
get the answers for you for at least a couple hours since I am posting
from work (for the previous answers, I had called home).

Thanks again
-Roger
 
When I use my computer mic to chat online or to record a sample opf
my voice, or simply to record anything, I get a loud background hum
(I suspect it the 60Hz power line is the culprit)...
Click to expand...

Under conditions where the hum is present, if you _only_ remove the mic
from the laptop does the hum disappear?

If this is the case, then perhaps the mic is wrong for the machine or
perhaps the cable is broken or mis-wired.
 
You have a hardware problem, so solve the hardware problem. Solving
it in software is like putting a really tight band-aid on a severed
artery - it'll stop the bleeding, but ...

Either the mic is bad or it's not the correct type for the sound card
- there are two types of input and mic, and using the wrong type can
result in weak or no audio or hum. (Unfortunately no manufacturer
tells you which type of audio input you have and which type of mic
they're selling - you have to figure it out for yourself.)
Click to expand...

There are other things that can cause hum. :)

In particular, laptops are notorious for having badly designed mic and
line-input channels. They often pick up hum or noise. Sometimes this
goes away when running off batteries, because you no longer have the
AC input and the charging circuitry is not running. Other times it
does not go away, and the noise to be related to CPU use, this is
probably cross-talk on the motherboard.

In either case, there may not be much you can do about it. Try the
above suggestions, as wel as those of the other folks -- they may
work. Certainly try another microphone, to eliminate that as the
culprit. Also try moving the microphone cable around to see if that
affects the amount of hum.

If no luck, then to get good sound input, you may be forced to use an
external sound device -- you can get USB ones now, which are easy to
use, but I don't think they are cheap (the ones I have seen are aimed
at people doing serious recording ).

Terry
 
Roger said:
Hello all,

When I use my computer mic to chat online or to record a sample opf my
voice, or simply to record anything, I get a loud background hum (I
suspect it the 60Hz power line is the culprit) . Is there any
software/freeware that can filter the microphone input before it is
received by chatting-software ? I suspect recording software will have
a hum removal feature, however I am interested in real-time hum
filtering for when I am chatting online. (The people on the receiving
end of the chatting software -the ones who get the pleasure of hearing
me ;) -complain that the hum is loud and distracting).

Regards,
Roger Bourne
Click to expand...

Is the hum still there if you mute the mic input with the windows audio
panel controls?

John.
 
I had the same problem when I tried to hook up my PC to our Cables tv
DVR so I could use my 5.1 surrond sound. Loud hum, I checked everything
I replaced the drivers in my realtech sound card, checked the cables,
bought new one's. At a loss I dissconnected from the DVR.

Sigh it would have sound so good too.

I just can not figure where the hmm was coming from, I even triend a
ferrite core on the line in and out still did not work.
 
I had the same problem when I tried to hook up my PC to our Cables tv
DVR so I could use my 5.1 surrond sound. Loud hum, I checked everything
I replaced the drivers in my realtech sound card, checked the cables,
bought new one's. At a loss I dissconnected from the DVR.

Sigh it would have sound so good too.

I just can not figure where the hmm was coming from, I even triend a
ferrite core on the line in and out still did not work.
Click to expand...

Try a pair of isolation transformers, also called a ground loop
isolator.
 
Roger said:
I had the same problem when I tried to hook up my PC to our Cables
tv DVR so I could use my 5.1 surrond sound. Loud hum, I checked
everything I replaced the drivers in my realtech sound card,
checked the cables, bought new one's. At a loss I dissconnected
from the DVR.

Sigh it would have sound so good too.

I just can not figure where the hmm was coming from, I even triend
a ferrite core on the line in and out still did not work.
Click to expand...


I agree with the Al's post to you. It sounds quite possible that this
could be an earth loop between the tv equipment and the PC.

Inhibitors like the one below are likely to have the audio line-
isolation transformers Al mentions plus a few passive components to
match the lines and minimize frequency losses.

http://www.radioshack.com/sm-see-all-needs-and-wants--pi-2062214.html

"Solving the humming problems of computer soundcards and home theatre
systems" may be of use to you.
<http://www.epanorama.net/documents/groundloop/home_solving.html>
 
Question to the experts... could switching to a USB mic be helpful?

I picked up the cheap Logitech model and it records cleaner than
anything I ever tried in the mic jack.
 
I had the same problem when I tried to hook up my PC to our Cables tv
DVR so I could use my 5.1 surrond sound. Loud hum, I checked everything
I replaced the drivers in my realtech sound card, checked the cables,
bought new one's. At a loss I dissconnected from the DVR.

Sigh it would have sound so good too.

I just can not figure where the hmm was coming from, I even triend a
ferrite core on the line in and out still did not work.
Click to expand...

Near;y all sound cards do that. I tried wiring mine to my cassette
deck, and it did likewise. You have to install some kind of noise
filter. I don't what it's called-ask an electronics technician (a
computer tech probably won't know, either). Get back to us when you
find out, because I have a feeling Radio Shack has it.

Dan
 
Question to the experts... could switching to a USB mic be helpful?
Click to expand...
I picked up the cheap Logitech model and it records cleaner than
anything I ever tried in the mic jack.
Click to expand...

I use the mVox I picked up at Radio Shack for $10. It's a USB
speaker-mic, works great in both directions and is USB.
 
I had a noise problem once. I discovered that I had 3 microphone jacks
on the back of my computer. I switched to the one that connects to my
sound card and the noise went away. You can identify the sound card
jack as it will be aligned in the same row as your audio output jacks.
 
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