Audio problem with PD150, noise follows recorded sound at DVinfo.net

Sverrir Fridriksson · April 26th, 2009, 09:32 AM

I'm just recently starting to use my PD150 which I bought used, and I am experiencing audio problems. I'm doing tests for a short film which will have people singing the whole time, the problem is that everytime someone sings a line, there is a notable rise in the noise just after the final note. This dies out again in a second but is extremely annoying.

The manual says something about the ND filter being able to cause noise when changed mid-recording, I've switched the camera off and on again for every nd setting but no change. Otherwise I have found nothing which could cause this. The mic is the supplied ECM NV1. Both channels are used, input level is on mic and it's set on +48.

Please let me know if you have any ideas how to fix this.

Bob Hart · April 26th, 2009, 08:20 PM

Are you using manual or auto control of audio levels? If you are using auto, at the end of a period of intense sound into a lower background ambience, you might be getting an overshoot of gain-up and then adjustment back down to a stable setting.

If this is happening with manual control of audio levels, something else will going on that I can't help you with.

John Cline · April 27th, 2009, 05:35 AM

Get into the Audio Menu and make sure that both "Wind" and "Mic NR" are turned OFF. I'm pretty sure that the effects of MIC NR are your problem. The MIC NR is a dynamically floating notch filter that filters out the slight whine of the motors and heads if the microphone is mounted to the camera and you are trying to record extremely quiet situations. It doesn't do its job very well, so just shut it off and never use it again.

Also, the PD150 is known to have much higher noise in the manual recording level mode. The AUTO mode has significantly less noise than the Manual mode. Its automatic mode is more of a limiter than a traditional "automatic level control" which will bring up the audio gain during quiet passages. On the PD150 specifically, it is better to use the AUTO mode for the lowest audio noise floor and the limiter is fairly transparent in its operation.

The warning about potential audio and video noise when switching the ND Filter is for strictly mechanical reasons. When you change the ND setting, it takes moment for the camera to adjust to the different amount of light now hitting the CCD sensor block. Also, when you change the ND filter, the mechanical movement of the ND filter can be picked up by the microphone if it is attached to the camera.

Finally, since you just got the camera, make absolutely certain that the audio sampling rate is set to Fs48k and not Fs32k, which for some reason, is its default.

Sverrir Fridriksson · April 27th, 2009, 06:19 AM

Thanks for your advice, guys :)

I did a quick test with the Mic nr off and it seems to have fixed the problem. I need further testing to be sure but it seems that that the annoying sound has been eradicated.

This will save my project if it works so thanks a lot!

Sverrir

John Cline · April 27th, 2009, 06:34 AM

Quote:

Originally Posted by Sverrir Fridriksson

I did a quick test with the Mic nr off and it seems to have fixed the problem. I need further testing to be sure but it seems that that the annoying sound has been eradicated.

I am 99.999% certain that the MIC NR setting was your problem.

Sverrir Fridriksson · April 27th, 2009, 07:34 AM

I hope you are right, John, and it certainly seems that way, you can imagine my dismay, after hearing of all the benefits of xlr mics and sound, testing the camera and hearing some awful noise in the recording. The manual seems to be rather vague about sound settings but thankfully there are people out there like yourself willing to help.

Thanks again.

John Cline · April 27th, 2009, 08:35 AM

Glad, I could help. By the way, Iceland is on my short list of places I would really like to visit.

Sverrir Fridriksson · April 27th, 2009, 10:31 AM

Nice to hear that. It's actually a pretty good time to do so now, since the Icelandic currency is very weak.

April 26th, 2009, 09:32 AM	#1
Sverrir Fridriksson Regular Crew Join Date: Jan 2009 Location: Iceland Posts: 58	Audio problem with PD150, noise follows recorded sound I'm just recently starting to use my PD150 which I bought used, and I am experiencing audio problems. I'm doing tests for a short film which will have people singing the whole time, the problem is that everytime someone sings a line, there is a notable rise in the noise just after the final note. This dies out again in a second but is extremely annoying. The manual says something about the ND filter being able to cause noise when changed mid-recording, I've switched the camera off and on again for every nd setting but no change. Otherwise I have found nothing which could cause this. The mic is the supplied ECM NV1. Both channels are used, input level is on mic and it's set on +48. Please let me know if you have any ideas how to fix this.

April 26th, 2009, 08:20 PM	#2
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,476	Are you using manual or auto control of audio levels? If you are using auto, at the end of a period of intense sound into a lower background ambience, you might be getting an overshoot of gain-up and then adjustment back down to a stable setting. If this is happening with manual control of audio levels, something else will going on that I can't help you with.

April 27th, 2009, 05:35 AM	#3
John Cline Major Player Join Date: Oct 2002 Location: Albuquerque, New Mexico USA Posts: 333	Get into the Audio Menu and make sure that both "Wind" and "Mic NR" are turned OFF. I'm pretty sure that the effects of MIC NR are your problem. The MIC NR is a dynamically floating notch filter that filters out the slight whine of the motors and heads if the microphone is mounted to the camera and you are trying to record extremely quiet situations. It doesn't do its job very well, so just shut it off and never use it again. Also, the PD150 is known to have much higher noise in the manual recording level mode. The AUTO mode has significantly less noise than the Manual mode. Its automatic mode is more of a limiter than a traditional "automatic level control" which will bring up the audio gain during quiet passages. On the PD150 specifically, it is better to use the AUTO mode for the lowest audio noise floor and the limiter is fairly transparent in its operation. The warning about potential audio and video noise when switching the ND Filter is for strictly mechanical reasons. When you change the ND setting, it takes moment for the camera to adjust to the different amount of light now hitting the CCD sensor block. Also, when you change the ND filter, the mechanical movement of the ND filter can be picked up by the microphone if it is attached to the camera. Finally, since you just got the camera, make absolutely certain that the audio sampling rate is set to Fs48k and not Fs32k, which for some reason, is its default.

April 27th, 2009, 06:19 AM	#4
Sverrir Fridriksson Regular Crew Join Date: Jan 2009 Location: Iceland Posts: 58	Thanks for your advice, guys :) I did a quick test with the Mic nr off and it seems to have fixed the problem. I need further testing to be sure but it seems that that the annoying sound has been eradicated. This will save my project if it works so thanks a lot! Sverrir

April 27th, 2009, 07:34 AM	#6
Sverrir Fridriksson Regular Crew Join Date: Jan 2009 Location: Iceland Posts: 58	I hope you are right, John, and it certainly seems that way, you can imagine my dismay, after hearing of all the benefits of xlr mics and sound, testing the camera and hearing some awful noise in the recording. The manual seems to be rather vague about sound settings but thankfully there are people out there like yourself willing to help. Thanks again.

April 27th, 2009, 08:35 AM	#7
John Cline Major Player Join Date: Oct 2002 Location: Albuquerque, New Mexico USA Posts: 333	Glad, I could help. By the way, Iceland is on my short list of places I would really like to visit.

April 27th, 2009, 10:31 AM	#8
Sverrir Fridriksson Regular Crew Join Date: Jan 2009 Location: Iceland Posts: 58	Nice to hear that. It's actually a pretty good time to do so now, since the Icelandic currency is very weak.