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Author Topic: Connecting Board to Camera  (Read 4030 times)

Aaron McQueen

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Connecting Board to Camera
« on: May 08, 2007, 08:33:30 pm »

Sunday I attempted to video record our service for the first time.  I ran a TS connector out of aux4 to the mic input on the camera.  I was using a 1/8" stereo cable to 2 RCA (camera side) to a RCA to TS  (board side) from the aux going only to the left side (white connector = left side of camera input).  The recorded sound on the camera came out terrible.  It was very distorted.  It sounded like I was overdriving one of the stages.  The camera is a Canon GL2 and it has a level meter on the screen.  The channel level, aux level, board level, and camera level all looked good on the meters.  It's not a problem with the aux because we have been using for CD recording with no problems.  Can I not use a TS cable on the aux?  Any other ideas as to what is going on hear?  How do others feed the board to the camera?  I would like to keep on an aux to get a separate mix.

Here is breif clip of the audio.
http://www.laurelfirstassembly.org/media/070506.mp3
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Jon Murray

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Re: Connecting Board to Camera
« Reply #1 on: May 09, 2007, 12:37:18 am »

We have a special adapter for that purpose. Not sure what it is I'll go in tomarrow and find out what it is and where it comes from. Get back to you tomarrow PM. Something to do with the line level being to high. I had the same problem and the guy at my music store got it for me.
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Jon Murray
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North East Community Church
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Ira White

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Re: Connecting Board to Camera
« Reply #2 on: May 09, 2007, 07:25:29 am »

If it is a balanced TRS aux output, the problem you should experience is left and right camera feed out of phase. A balanced signal sends one phase down the hot wire (tip) and another down the neutral (ring). Splitting to stereo gives you incompatible left/right, not normal stereo or mono operation. Using a mono-1/4" to split RCAs would eliminate that problem.

Impedance problems may also arise going from pro XLR or TRS low-impedance outputs to consumer RCA high-impedance inputs. I have heard this sound like distortion, a very "thin/tinny" response, or level problems, though I'm not versed on the technical ramifications involved. You may need a direct box or interface designed to convert the signals from low to high unless your camera has XLRF inputs and switching from mic to line level. (Most direct boxes are high to low. Passive models will often go either way, but you would need to accommodate an XLRM input.)

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Ira White
Sanctuary Sound, Inc.

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Scott Vystrcil

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Re: Connecting Board to Camera
« Reply #3 on: May 09, 2007, 02:25:01 pm »

We have a camera that has XLR inputs on them so we don't have that issue.  We go from AUX4 to the camera.  Do you have a headphone jack on the camera?  Did you monitor the sound during the recording and did it sound bad?  Did you have the audio on manual or automatic?  if on auto, the meters will look fine as they are tying to compensate for the audio being too hot, but it can only do so much.  You might also try looking at an XLR adapter.  There is one from Canon, but a better variety (and quality) with the BeachTek adapters.

http://dvcreators.net/beachtek-xlr-adapters

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Scott Vystrcil
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Aaron McQueen

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Re: Connecting Board to Camera
« Reply #4 on: May 09, 2007, 02:41:09 pm »

Quote:

Do you have a headphone jack on the camera? Did you monitor the sound during the recording and did it sound bad?


There is a headphone jack, although I didn't monitor on the camera, only on the board.  I figured if the meters where out of clip then it was fine.

Quote:

Did you have the audio on manual or automatic?


I had it on manual.

Quote:

You might also try looking at an XLR adapter. There is one from Canon, but a better variety (and quality) with the BeachTek adapters.


I used one of these in the past, maybe 3 years ago.  It seemed to add some low hum to the audio.  I returned it, and they sent me a new one with the same problem.  I guess I could try it again. This is a different camera so maybe it won't have the same problem.
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Allan Stevenson

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Re: Connecting Board to Camera
« Reply #5 on: May 09, 2007, 03:37:27 pm »

Hey Aaron,
I took a quick look at the GL 2 Manual.  It will only take a Mic level input on those connectors.  On some cameras you can select line or mic input.

Your Aux feed is at line level, so a quick fix for you would be to put a DI box between your Aux out and your camera input.  This should get you going.

Hope this helps.
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Allan Stevenson
Peoples Church Hamilton
Ontario, Canada

Ira White

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Re: Connecting Board to Camera
« Reply #6 on: May 09, 2007, 04:35:28 pm »

A DI box will not change the level from line to mic. Level will still be too strong for a mic input, but the stereo RCA inputs you said you were using are typically -10dB consumer line level. The Aux out is typically 0dB to +4dB line level, but the consumer line level will usually handle it if you just adjust the aux out master for it.

DI or not (depending on the need for impedance matching), you still need an unbalanced signal split to your stereo inputs to avoid an out-of-phase signal. It may sound fine through headphones since the elements are isolated, but as soon as you run it through speakers stereo or mono, you will hear the phase cancellation.
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Ira White
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Aaron McQueen

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Re: Connecting Board to Camera
« Reply #7 on: May 09, 2007, 04:56:30 pm »

Quote:

DI or not (depending on the need for impedance matching), you still need an unbalanced signal split to your stereo inputs to avoid an out-of-phase signal. It may sound fine through headphones since the elements are isolated, but as soon as you run it through speakers stereo or mono, you will hear the phase cancellation.


I don't think this is my problem.  I'll try to clearify the connections.  Out of aux4 -> mono TS to female RCA cable -> male RCA (left side of stereo cable, white connector only, red connector left open) to stereo mini 1/8" cable -> mic input on camera.

So I wasn't sending the negative to the left and positve to the right.  There was nothing on the right side of the recording.

A few things I don't understand.  Plugging in the mono TS cable into the aux4 will ground the negative side of the balanced output.  Is this a problem? All the levels were fine.  Maybe the level meters on the camera are not on the premamp?
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Brad Weber

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Re: Connecting Board to Camera
« Reply #8 on: May 09, 2007, 06:16:41 pm »

Ira White wrote on Wed, 09 May 2007 07:25

If it is a balanced TRS aux output, the problem you should experience is left and right camera feed out of phase. A balanced signal sends one phase down the hot wire (tip) and another down the neutral (ring). Splitting to stereo gives you incompatible left/right, not normal stereo or mono operation. Using a mono-1/4" to split RCAs would eliminate that problem.

Maybe I misunderstood it, but I took Ira's setup to be an aux out > TS 1/4" to RCA cable > the left connector of of dual RCA to 1/8" TRS into the camera.  If this is correct then it is a mono signal through the chain with the audio only going to one channel of the camcorder.

As far as I can tell from the GL2 manual there are two audio inputs on the camcorder, an external mic input and an AV input/output.  The external mic input is for an unbalanced stereo mic  The A/V connector is a stereo line input, but it requires a special breakout cable (STV-250N) that comes with the camera as that connector also has the video signal on it.  You can select between AUDIO IN and MIC IN in the VCR Setup Menu, however it appears that this selection is only available for dubbing in the VCR Mode and from the manual it appears as though in Camera Mode the only input available is the external mic input.  So you might need something like the Beachtek DXA-4p, about $180-$190 online, that not only has XLR inputs, but also a mic/line switch and that then plugs into the external mic input.

There is also an Attenuator setting in the VCR Setup menu, with it out the nominal input levels are -55dBV for the external mic input and -10dBV for the A/V input, with the attenuator engaged the levels are -35dBV and 0dBV.
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Brad Weber
muse Audio Video
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Ira White

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Re: Connecting Board to Camera
« Reply #9 on: May 09, 2007, 07:28:31 pm »

Sorry, I thought your post had TRS in there somewhere. (I guess that's called miss-lexia.) You should be fine on the unbalanced signal, and the grounding of the neutral ring is not a problem.

You normally don't want to use the mic input which usually doesn't favor a line input level. I'd recommend using whatever adapter cables you need to get to the line input. If your levels are fine as they are with no noise or hums, I would guess impedance problems. You're feeding a low impedance into a high with your setup. Someone else here might recall which one is the problem: high to low, or low to high.
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Ira White
Sanctuary Sound, Inc.

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