noise when rolling at DVinfo.net

Mo Zee · July 7th, 2004, 10:58 PM

does anyone hear noise- hissing, and something like cardboard running though bike spokes (barely audible, though) when rolling?

i.e. there is noise only when recording.

xl1 - MA100 - crown phantom power - at4073

if i use a mixer and plug directly to the rca inputs, the noise is much less, though.

does anyone experience the same thing or is there something wrong with my camera?

Christopher Reynolds · August 18th, 2004, 07:06 AM

im not experienced with sound, but what is the impedance of the mic, the input impedance of the mixer, and the ouput impedance of the mixer? Might be that when you run it through the mixer, the impedence is then higher/lower than the mic itself, making the level more balanced between the camera and the recording equipment. Hope this helps or at least bumps your thread up for someone more experienced in sound equipment to see! Good luck.

edit: 100 ohms impedance for your mic and god forbid i look up impedance for the MA 100. Cant find a thing on it. Don't even know if this hunch is correct or not.

Don Palomaki · August 18th, 2004, 07:09 PM

The MA-100 can pick up a wee bit of power supply spatter at the syncs rates, and it appears to be a bit worse with some batteries than with others. Probably relates to how the MA-100 receives its power from the camcorder and the unbalanced output of the MA-100. Using an external mixer and feeding the RCA jacks can minimize this noise. The level is very low in absolute terms, but It can be heard in good headphones if the gain is up and you are in a quiet venue, and you can see it in the audio output waveform with the input zeroed out.

James Emory · August 21st, 2004, 03:17 PM

Yes, I have heard that white noise but it's only been in quiet rooms with little or no background noise.

Mo Zee · August 22nd, 2004, 12:38 AM

its not only white noise. there's quite a lot going on. will capture an audio sample then post a link

Mo Zee · August 22nd, 2004, 01:57 AM

here's the link:

http://www.geocities.com/moiseszee/MAINPIC03.wav

this is normalized from a channel that had nothing connected to the input.

this sound is barely audible as long as the volume is around 9:00.

bring the volume up, and you hear the sound even in a channel where a mic is plugged in.

James Emory · August 22nd, 2004, 03:38 PM

Wow. Now that's some noise. Could you make the clip about 10-15 seconds to get a better idea of the sound it's making? Could you also make the link hot by adding [url ] before and [/url ] after the link without spaces in the brackets. Thanks.

Mo Zee · August 22nd, 2004, 10:48 PM

http://www.geocities.com/moiseszee/cam1t5.wav

this is from the same clip, from the channel which didn't have a mic. originally peaked around -60dB, normalized in soundforge. there is some crosstalk from the other channel, which had a mic- AT4073 to crown phantom power to MA-100 to XL-1.

James Emory · August 23rd, 2004, 10:14 PM

In the sample that you are providing, I am mostly hearing a high pitch noise that could almost crack glass. If that's the audio your getting, then there is definitely a major problem.

Don Palomaki · August 25th, 2004, 05:14 AM

The normalized sample (cam1t5) appear to have been amplified by about 60 dB (a factor of 1000). There is a ~6 dB peak in the noise at around 15750 Hz, the NTSC horizontal frequency, and it has a ~17% DC bias as a result of the normalizing gain. If the 60 dB normalizing gain is pulled out, the RMS noise floor is about 73 dB below maximum sine wave record level.

This noise level is about what I would expect from an XL1/MA100 combo. The noise is relatively low, better than than just about any analog rcording system. But it can be heard in sensitive headphones when program material is low or silent, or if the audio signal is amplified.

BTW normalizing is not a good way to present what the camera is recording because most observers cannot easliy distinguish camcorder noise from external processing effects. Kind of like sending someone a bottle of beer that has been open for a week and asking them to confirm that the brewer produces poor beer.

The MAINPIC03 link gives a YAHOO page not found error screen.

Mo Zee · August 25th, 2004, 10:17 PM

thanks don. i won't normalize in the future. i guess there's nothing wrong with my cam/ma-100. just bothers me when the material is quiet. actually, i can hear the noise more during post than the shoot.

the mainipic link really is dead.

thanks again.

Don Palomaki · August 26th, 2004, 08:03 PM

You may be able to use a decent audio editing program, sample the noise, and then run a noise reduction filter to reduce it by on the order 4-6 dB without hurting the rest of the audio excessively.

Mo Zee · August 28th, 2004, 09:05 PM

<<<-- Originally posted by Don Palomaki : You may be able to use a decent audio editing program, sample the noise, and then run a noise reduction filter to reduce it by on the order 4-6 dB without hurting the rest of the audio excessively. -->>>

thanks.

do you mean filtering out using EQ or taking the sample and inverting it to cancel out the noise?

or is there software which will make a noise reduction filter from a sample?

Don Palomaki · August 29th, 2004, 08:50 AM

Program like Adobe Audition (formerly Cool Edit Pro) and Sound Forge to name a couple can do it. They use the noise sample to create the filter parameters, and give control over how much filteration is applied. EQ can work if the noise is at a frequency you are not interested in for progam material.

Mo Zee · August 31st, 2004, 11:11 PM

<<<-- Originally posted by Don Palomaki : Program like Adobe Audition (formerly Cool Edit Pro) and Sound Forge to name a couple can do it. They use the noise sample to create the filter parameters, and give control over how much filteration is applied. EQ can work if the noise is at a frequency you are not interested in for progam material. -->>>

thanks

i use soundforge and really couldn't find it- unless you're talking about the acoustic mirror?

July 7th, 2004, 10:58 PM	#1
Mo Zee Regular Crew Join Date: Jan 2002 Location: manila, philippines Posts: 102	noise when rolling does anyone hear noise- hissing, and something like cardboard running though bike spokes (barely audible, though) when rolling? i.e. there is noise only when recording. xl1 - MA100 - crown phantom power - at4073 if i use a mixer and plug directly to the rca inputs, the noise is much less, though. does anyone experience the same thing or is there something wrong with my camera?

August 18th, 2004, 07:06 AM	#2
Christopher Reynolds Regular Crew Join Date: May 2004 Location: North Canton, Ohio Posts: 109	im not experienced with sound, but what is the impedance of the mic, the input impedance of the mixer, and the ouput impedance of the mixer? Might be that when you run it through the mixer, the impedence is then higher/lower than the mic itself, making the level more balanced between the camera and the recording equipment. Hope this helps or at least bumps your thread up for someone more experienced in sound equipment to see! Good luck. edit: 100 ohms impedance for your mic and god forbid i look up impedance for the MA 100. Cant find a thing on it. Don't even know if this hunch is correct or not. __________________ The only thing worse than quitting is being afraid to start. Get off your bum and go shoot something!

August 18th, 2004, 07:09 PM	#3
Don Palomaki Wrangler Join Date: Sep 2001 Location: Northern VA Posts: 4,489	The MA-100 can pick up a wee bit of power supply spatter at the syncs rates, and it appears to be a bit worse with some batteries than with others. Probably relates to how the MA-100 receives its power from the camcorder and the unbalanced output of the MA-100. Using an external mixer and feeding the RCA jacks can minimize this noise. The level is very low in absolute terms, but It can be heard in good headphones if the gain is up and you are in a quiet venue, and you can see it in the audio output waveform with the input zeroed out. __________________ dpalomaki@dspalomaki.com

August 21st, 2004, 03:17 PM	#4
James Emory Regular Crew Join Date: Aug 2002 Location: Atlanta, Georgia Posts: 1,892	Noise Yes, I have heard that white noise but it's only been in quiet rooms with little or no background noise.

August 22nd, 2004, 03:38 PM	#7
James Emory Regular Crew Join Date: Aug 2002 Location: Atlanta, Georgia Posts: 1,892	Now that's noisy! Wow. Now that's some noise. Could you make the clip about 10-15 seconds to get a better idea of the sound it's making? Could you also make the link hot by adding [url ] before and [/url ] after the link without spaces in the brackets. Thanks.

August 22nd, 2004, 12:38 AM	#5
Mo Zee Regular Crew Join Date: Jan 2002 Location: manila, philippines Posts: 102	its not only white noise. there's quite a lot going on. will capture an audio sample then post a link

August 22nd, 2004, 01:57 AM	#6
Mo Zee Regular Crew Join Date: Jan 2002 Location: manila, philippines Posts: 102	here's the link: http://www.geocities.com/moiseszee/MAINPIC03.wav this is normalized from a channel that had nothing connected to the input. this sound is barely audible as long as the volume is around 9:00. bring the volume up, and you hear the sound even in a channel where a mic is plugged in.

August 22nd, 2004, 10:48 PM	#8
Mo Zee Regular Crew Join Date: Jan 2002 Location: manila, philippines Posts: 102	http://www.geocities.com/moiseszee/cam1t5.wav this is from the same clip, from the channel which didn't have a mic. originally peaked around -60dB, normalized in soundforge. there is some crosstalk from the other channel, which had a mic- AT4073 to crown phantom power to MA-100 to XL-1.

August 23rd, 2004, 10:14 PM	#9
James Emory Regular Crew Join Date: Aug 2002 Location: Atlanta, Georgia Posts: 1,892	In the sample that you are providing, I am mostly hearing a high pitch noise that could almost crack glass. If that's the audio your getting, then there is definitely a major problem.

August 25th, 2004, 05:14 AM	#10
Don Palomaki Wrangler Join Date: Sep 2001 Location: Northern VA Posts: 4,489	The normalized sample (cam1t5) appear to have been amplified by about 60 dB (a factor of 1000). There is a ~6 dB peak in the noise at around 15750 Hz, the NTSC horizontal frequency, and it has a ~17% DC bias as a result of the normalizing gain. If the 60 dB normalizing gain is pulled out, the RMS noise floor is about 73 dB below maximum sine wave record level. This noise level is about what I would expect from an XL1/MA100 combo. The noise is relatively low, better than than just about any analog rcording system. But it can be heard in sensitive headphones when program material is low or silent, or if the audio signal is amplified. BTW normalizing is not a good way to present what the camera is recording because most observers cannot easliy distinguish camcorder noise from external processing effects. Kind of like sending someone a bottle of beer that has been open for a week and asking them to confirm that the brewer produces poor beer. The MAINPIC03 link gives a YAHOO page not found error screen. __________________ dpalomaki@dspalomaki.com

August 25th, 2004, 10:17 PM	#11
Mo Zee Regular Crew Join Date: Jan 2002 Location: manila, philippines Posts: 102	thanks don. i won't normalize in the future. i guess there's nothing wrong with my cam/ma-100. just bothers me when the material is quiet. actually, i can hear the noise more during post than the shoot. the mainipic link really is dead. thanks again.

August 26th, 2004, 08:03 PM	#12
Don Palomaki Wrangler Join Date: Sep 2001 Location: Northern VA Posts: 4,489	You may be able to use a decent audio editing program, sample the noise, and then run a noise reduction filter to reduce it by on the order 4-6 dB without hurting the rest of the audio excessively. __________________ dpalomaki@dspalomaki.com

August 28th, 2004, 09:05 PM	#13
Mo Zee Regular Crew Join Date: Jan 2002 Location: manila, philippines Posts: 102	<<<-- Originally posted by Don Palomaki : You may be able to use a decent audio editing program, sample the noise, and then run a noise reduction filter to reduce it by on the order 4-6 dB without hurting the rest of the audio excessively. -->>> thanks. do you mean filtering out using EQ or taking the sample and inverting it to cancel out the noise? or is there software which will make a noise reduction filter from a sample?

August 29th, 2004, 08:50 AM	#14
Don Palomaki Wrangler Join Date: Sep 2001 Location: Northern VA Posts: 4,489	Program like Adobe Audition (formerly Cool Edit Pro) and Sound Forge to name a couple can do it. They use the noise sample to create the filter parameters, and give control over how much filteration is applied. EQ can work if the noise is at a frequency you are not interested in for progam material. __________________ dpalomaki@dspalomaki.com

August 31st, 2004, 11:11 PM	#15
Mo Zee Regular Crew Join Date: Jan 2002 Location: manila, philippines Posts: 102	<<<-- Originally posted by Don Palomaki : Program like Adobe Audition (formerly Cool Edit Pro) and Sound Forge to name a couple can do it. They use the noise sample to create the filter parameters, and give control over how much filteration is applied. EQ can work if the noise is at a frequency you are not interested in for progam material. -->>> thanks i use soundforge and really couldn't find it- unless you're talking about the acoustic mirror?