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HDC-SD700 producing 'crackles'/'clicks' when recording at music gigs

geoffgee's picture
Last seen: 1 year 10 months ago
Joined: 06/09/2011 - 10:31pm

I'm experiencing crackles on the audio when I make videos at some of the amplified music events at which I take video. I'm using an HDC-SD700 camcorder.

The first 30 seconds of this video should give you an idea of what I mean ...

http://www.youtube.com/watch?v=CLQ2XKWq1Yw

... and on this video the clicks heard between 27s to 32s seem to occur reasonably in 'synch' with the music ...

http://www.youtube.com/watch?v=05HsPTI7Sjc&feature=related

I only seem to get the problem at events where I'm filming near to some kind of amplifying/mixing equipment, which leads me to suspect the camera may be picking up some kind of RFI/EMI (radio frequency interference/electromagnetic interference) from the band's equipment.

Has anyone here experienced this problem (Googling hasn't so far yielded any similar reports for me)? Also do you think I'm right in suspecting RFI/EMI as the cause?  

I never had this problem with my old camcorder (Panasonic NV-GS180) at similar events. I was happy with my HDC-SD700 until this - but now???!!!

Can anyone help?


Yvon Robert's picture
Last seen: 1 year 1 week ago
Joined: 10/17/2010 - 1:35am

Hi,

I am not a specialist but you camcoder is too close from something producing interference like a mic near another mic or a camcoder near a TV interference between 2 electromagnetic source. Try to bypassthe mic inside your camcoder using a shotgun mic to test like a Sennheiser MKE400 try to loan one for testing. The camera is good but smaller size less material to block magnetic wave also you can use a metat screen like Windows screen to cover the camera like a jacket, screen can be pl ace between two cotton. You blind camera against electromagnetic wave.

Regards,

YR


geoffgee's picture
Last seen: 1 year 10 months ago
Joined: 06/09/2011 - 10:31pm

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Thanks for your (quick) reply signmax.

My experiences over the last few weeks at two different venues (indoors and outdoors) of recording this type of event does suggest that proximity is a major factor. Also I'm not sure how much metal Panasonic has incorporated in the body of the camera but I doubt there is as much as was in my old mini DV tape camera.

I don't have access to a true shotgun mic like the Senheisser you mention (I wish!) but I have adapted a metal bodied external stereo mic (from Maplin http://www.maplin.co.uk/stereo-condenser-microphone-32517 ) which I hope to try next time.

Regarding screening or shielding the camera with a metal screen, by 'windows screen' do you mean use material from a metallised car windscreen watchamacallit? I was thinking of trying alluminium cooking foil - but that would probably make a fair amount of crackling noise by its very nature! (I guess that's where the cotton comes in - also to avoid its scratching the camera possibly?)

What you say about miniaturisation of cameras is a good point. I would have VERY MUCH preferred the camera to have been a few centimetres bigger - and not merely for the purpose of adding some rfi shielding. Before I went High Definition with the SD700 I was also using a Sony DCR-TRV950E camcorder ( http://www.sony.lv/product/sdh-minidv/dcr-trv950e#pageType=Overview ) which I was finding to be of pretty much the ideal size when it came to portability and practicality.

I'm still surprised there don't seem to be others reporting this issue though. (I might even say I was even beginning to suspect a possible cover-up somewhere, hmm?)

Cheers (from a very grateful newbie to the forum).

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Rocky M's picture
Last seen: 2 months 17 hours ago
Joined: 03/12/2010 - 5:53am

Elimination is theonly means to solve thesetype of problems

- As suggestedpreviously use an external micin the same enviroment.

- If the fault condition is caused by any type of external interference on the next occasion position the camera further distance away than before. If the noises ceases or is reduced that will indicate if EMI is/was the problem. Radiation both EMI & RFI lessens with increased distance from source

- I can't see any radio equipment the band is using so highly unlikely any RFI from that source. But thats not to say some other type of equipment radiating RFI is not involvedmaybe police/security company two way radio.

- The other possibility could be a fault in the camera (a high resistance connection) that only manifests itself with vibration, say from being too close to loud music. To test for this fault condition put the camera on a tripod in a quite enviroment press record and continually slightly tap the camera body with the index finger. Playback of the recording will determine if the problem exists in thecamera.

-Re the "27sec to 32sec in sync with the music" if that was relevent then the fault should continually occur in sync with the music.

Trust the above helps. Rocky.


CraftersOfLight's picture
Last seen: 2 months 6 days ago
Joined: 02/17/2009 - 5:42am
Plus Member

 From the first video sample, It sounded like something was going on with the camera's audio AGC curcuit trying to compensate for the volume of the drum beats to me. Almost as if its response was too fast. Can you turn off the auto gain control on your recording level in this camera and see if that helps?

Life is not a guided tour nor a destination. It is a journey. Take the time to enjoy your family, friends and surroundings. Build memories. Share experiences. Travel at sight speed not light speed. (C)


geoffgee's picture
Last seen: 1 year 10 months ago
Joined: 06/09/2011 - 10:31pm

Hi Rocky and Crafters of Light.

To answer your points ...

Distance - Good point and totally agree as a way of eliminating/confirming rfi as a possible cause. The intensity of the crackles does seem to vary depending on where I'm standing relative to the stage etc.. (If maximising the distance from the equipment is the only way I can overcome this it will severely limit my ability to capture those all important 'close-in' shots though!)

Dry joints - I did as you suggested (tapping the camera while recording in a quiet room) but, other than faint reproduction of my fingers rustling the camera, there was no other sound - and definitely none of the crackles like on the above videos.

AGC - I have (earlier in my investigations) tried testing if AGC was causing the crackles by suddenly shouting loudly while recording. As I recall the camera seemed to handle the sudden loudness change without introducing any crackle type noises though.

I just read (somewhere on this website) that it's best to work without any AGC in order to get the best sound. I must admit that, until now, I've tended to have AGC 'on' in the belief that it's safer (ie I'm less likely to end up with either distorted or too faint levels). In future I intend (whenever possible) to turn AGC off and to monitor the sound using headphones.

Thanks for your suggestions and opinions guys. I'll keep you posted in this thread about any further developments.

Cheers.


CraftersOfLight's picture
Last seen: 2 months 6 days ago
Joined: 02/17/2009 - 5:42am
Plus Member

 "... tried testing if AGC was causing the crackles by suddenly shouting loudly while recording."

I don't think that yelling would do it. The static seemed to occur with the music beats which tend to have a much faster rise time then a voice. Do you remember if the drumset was being broadcast over the bands speakers at all? You could let the little kid out and bang a pot with a spoon to simulate and see what happens.

Life is not a guided tour nor a destination. It is a journey. Take the time to enjoy your family, friends and surroundings. Build memories. Share experiences. Travel at sight speed not light speed. (C)


Charles Schultz's picture
Last seen: 1 year 2 months ago
Joined: 10/25/2010 - 10:38pm

Can you adjust the level of incoming audio? The crackling may be from the fact the internals cannot handle the level of audio at the events. If you can view the audio level on this camera, there should be a line indicating that the audio is too hot / too loud.


artsmith's picture
Last seen: 1 month 2 days ago
Joined: 03/02/2011 - 9:06pm

The time taken may be extremely brief, but any AGC reacts, not 'pre-empts' the onset of loud noise, it is only able to respond, once the first onset of the sound has reached the mic. Generally, it produces a hard 'edge' to sounds, especially those which are percussive in onset, as drums would tend to be. If you have your material on the timeline, or better yet, are able to put it into a DAW or high quality audio editor, (such that the time intervals may be greatly expanded),have a look for a loud peak on the leading edge of the wave-form, followed by a 'fall-off' (eg the AGC adjusting level to the new volume required of it). With AGC generally being pretty reactive these days, individual drum-beats, if spaced at intervals in excess of theAGC's reaction-time, could very possibly produce waves of AGC reaction in time with the music.

That said, I haven't had the opportunity to listen to your samples, because here in NZ, our internet is so slow, generally, that it would take ages for me to download them on 'dial-up' (and frequently at times of heavy loading, broadband is scarcely worth the extra expense).