Author Topic: noisy audio  (Read 7812 times)

dpcam1

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noisy audio
« on: September 10, 2012, 11:28:58 AM »
I've just installed the latest version of magic lantern on my 5d. Im getting terrible hiss and hum through my headphones both with the internal and external mics. It sometimes improves if i reboot the camera. The worst thing is that the noise is being recorded. Is there something im doing wrong here?

Malcolm Debono

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Re: noisy audio
« Reply #1 on: September 10, 2012, 12:01:46 PM »
Do you have digital gain set to a positive value (greater than 0) in the audio menu?
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dpcam1

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Re: noisy audio
« Reply #2 on: September 10, 2012, 02:00:28 PM »
thanks for your reply...I've taken ml of my camera because I was afraid it had done something to the audio circuit of my camera but the horrendous noise when I plug in the headphones is still there and if I plug in my external mic the resulting recording is full of hiss and static.

dpcam1

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Re: noisy audio
« Reply #3 on: September 10, 2012, 02:07:40 PM »
I am right in thinking that I should be able to use the a/v to listen to camera audio?

dpcam1

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Re: noisy audio
« Reply #4 on: September 10, 2012, 02:11:05 PM »
I'm also noticing that when I plug in the headphone jack to the camera the liveview picture disappears.

Malcolm Debono

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Re: noisy audio
« Reply #5 on: September 10, 2012, 03:05:47 PM »
I am right in thinking that I should be able to use the a/v to listen to camera audio?

Yes. Make sure headphone monitoring is turned on from the Audio menu. You can use the miniUSB to 3xRCA cable supplied with the camera, and then use a 2xRCA to 3.5mm converter (connected to the red & white sockets) to connect your headphones.

I'm also noticing that when I plug in the headphone jack to the camera the liveview picture disappears.

That's because headphone monitoring is turned off (see above), and therefore the camera is using the video out (the default usage of the cable in use).

thanks for your reply...I've taken ml of my camera because I was afraid it had done something to the audio circuit of my camera but the horrendous noise when I plug in the headphones is still there and if I plug in my external mic the resulting recording is full of hiss and static.

Not quite sure about what's causing the noise. Is there any noise without any cables attached (i.e. using built-in mic), or just an external mic connected? Or does it happen only when you have headphones attached? You can also try deleting the ML config to reset all the values to default in case you accidentally changed any audio settings.
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ZeroUnityGain

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Re: noisy audio
« Reply #6 on: September 10, 2012, 08:56:51 PM »
I am right in thinking that I should be able to use the a/v to listen to camera audio?

As Malcolm said, make sure you use the correct colour plugs--as in red and white for audio, because if you use the yellow plug (video) in an audio circuit it will certainly give you a similar kind of noise.  Also, the general blurbs say that you must only use the Canon supplied AV connector.  Canon say that the USB connection is a 'digital terminal' but to me that doesn't make any sense because those red, white and yellow leads deliver an analogue signal.  I can't believe that there is some little D/A converter in the plug, so I'm thinking that the only reason Canon say to use their cable is cause of the pin configuration.  I'm guessing it's all analogue and they just used a USB for convenience.

nanomad

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Re: noisy audio
« Reply #7 on: September 10, 2012, 08:59:05 PM »
There's probably a chip on the camera that senses the USB voltage and re-routes the A/V signals if it's not there
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dpcam1

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Re: noisy audio
« Reply #8 on: September 10, 2012, 09:11:38 PM »
I think I've located the problem. After freaking out that I'd damaged my camera I read in the manual that you have to use the canon a/v cable coupled with an adapter to hear anything out your headphones. I wasn't doing that and was trying to go directly into a/v jack with my headset.
The issue of very crackly audio being recorded on the mic circuit with new rode video mic may have something to do with using old batteries. Im going to try out a new one tonight and see if that improves the situation. Thanks heaps for the kind responses.

ZeroUnityGain

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Re: noisy audio
« Reply #9 on: September 10, 2012, 11:27:41 PM »
I think I've located the problem. After freaking out that I'd damaged my camera I read in the manual that you have to use the canon a/v cable coupled with an adapter to hear anything out your headphones. I wasn't doing that and was trying to go directly into a/v jack with my headset.
The issue of very crackly audio being recorded on the mic circuit with new rode video mic may have something to do with using old batteries. Im going to try out a new one tonight and see if that improves the situation. Thanks heaps for the kind responses.

It might also be worth checking some other stuff -- especially when you might have had 2 separate problems, which is often hard to solve  unless you deal with one at a time.  I'm not sure how the 5D works but you'd certainly want to disable the AGC because that not only causes noise (mostly hiss) but adds a heap of gain.  I'm saying this because I'm not sure if you have the Rode Video Mic pro, which also has a +20db gain switch.  And to add to that if you left the ML's analogue gain up around 23db it might all be overloading the input. 
I would start by reinstalling the ML. Disable the AGC, and also zero all gain including the ML output gain -- especially the digital gain, which is noisy.  Then try the rode -- if it's got the 20db gain switch it on.  If it hasn't got that you might need to add some analogue gain on the ML.

dpcam1

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Re: noisy audio
« Reply #10 on: September 10, 2012, 11:49:39 PM »
I think there is two issues. I was thinking they were linked. I'll  reinstall ml and see what happens..

dpcam1

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Re: noisy audio
« Reply #11 on: September 11, 2012, 12:26:53 AM »
I did have the Mic gain up to minus 23db.

ZeroUnityGain

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Re: noisy audio
« Reply #12 on: September 11, 2012, 03:13:31 AM »
I did have the Mic gain up to minus 23db.

Hi,
I'm not being pedantic, but for those following this, that's +23db.  That's ok if the AGC is off, but if the AGC is on it's going to give you a lot of gain.  Do you remember what the meters were doing, and was the AGC on or off?

dpcam1

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Re: noisy audio
« Reply #13 on: September 11, 2012, 03:24:37 AM »
The meters were never hitting full peaking....i think the peak issue was probably bad batteries in my rode....will test that out soon

dpcam1

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Re: noisy audio
« Reply #14 on: September 11, 2012, 09:38:26 AM »
I'm starting to think the Rode Video Mic has something wrong with it as I've put a new battery in it and the hiss and static remained the same. I've also plugged a of computer headset, with microphone, into the 5d and the recorded audio is clean as so the 5d mic input is fine. I've tested the mic on 0db, -10 and -20 and the result is always the same; lots of hiss and static...all these tests were done with the cameras audio in manual mode.

RowanMachine

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Re: noisy audio
« Reply #15 on: May 24, 2014, 03:33:17 PM »
What happened in the end with your 5d? I've been having similar issues lately, I think something's broken in my camera. With and without ml on my 5d3 I have crackly audio using an external mic...