2 audio channels, one mic?

M

Metrolens

Well-known member
Is it possible with the A1 to use an XLR Y-adapter, such as the one below, to feed sound from one mono shotgun mic to both audio channels simultaneously? The point being to set the audio levels with one channel slightly higher than the other, so that you could have a "hot" channel and a "safety" channel?

http://www.guitarcenter.com/Monster-Cable-Female-XLR-to--2--Male-XLR-Y-Adapter-330069-i1172772.gc

Would this degrade the sound quality somehow?

And would phantom power become problematic? (I'm using a Rode NTG-1.)
 
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Why not connect the shotgun to Channel 1 and set the switch to channel 1/2? Then both channels are fed with the signal coming in on channel 1.
 
But doesn't this just gang the signal together, meaning you can't set different levels for each channel?
 
this makes no sense. why record a mono signal twice? with digital audios post processing possibilities you can do all the compression and volume games you want. ganging 2 channels to 1 mic will most probably alter the impedance load on the inputs and possibily add noise.
 
timbook2 said:
this makes no sense. why record a mono signal twice? with digital audios post processing possibilities you can do all the compression and volume games you want. ganging 2 channels to 1 mic will most probably alter the impedance load on the inputs and possibily add noise.
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Because if it allowed you to set a "hot" level for CH1 and a "safety" level for CH2, it would be great. I think this is partially how pro audio guys record with a mixer; in case the sound becomes suddenly louder than anticipated and peaks/clips, (e.g. if they suddenly laugh), you'll have that safety channel recorded at a lower level.

The A1 already allows you to gang CH1+CH2 from one mic, but AFAIK you can't have a "hot" channel and a "Safety" channel; the level stays the same for both.
 
... but AFAIK you can't have a "hot" channel and a "Safety" channel; the level stays the same for both.
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I just confirmed on my A1 that this is true.

So back to my original question - might the XLR Y-adapter work? Phantom power problem?
 
I would like to know if this works as well. I am about to order my first xlr mic for my A1 and this is one of the things I'd like to be able to do to guard against spikes.

Unfortunately I'm no expert, but I think that as long as you only set one of the channels to supply phantom power, your mic should get the power it needs, while the Y-splitter will send the signal from the mic to both inputs which can be adjusted independently. That's what I hope, anyway.

Can anyone confirm that this works?
 
you must try it out yourself....IMO the impedance needs to be matched when doing this. I am a pro audio guy and would never do this ....I also never heard of anybody doing this before...
 
Timbook2, I don't understand what you mean when you say the impedance needs to be matched (as I mentioned I've never recorded with an xlr mic before).

I know that recording the same mono signal to two different channels, at two different levels, was mentioned by Barry Green in his comparison of the HVX and the A1. I'll quote the relevant part:

"If you’re used to routing one microphone to both channels (a common HVX/DVX technique), be aware on the Canon that you can’t set the volume level for those channels individually! The same volume gets recorded to both, which defeats the popular technique of recording one channel lower than the other (to provide some protection against sudden loud spots in the audio being driven into overmodulation/clipping)."

The A1 will allow two external mics to have independent volumes, so the hope is that the Y-splitter will trick the A1 into thinking it has two separate mics. Does that sound possible?
 
timbook2 said:
you must try it out yourself....IMO the impedance needs to be matched when doing this. I am a pro audio guy and would never do this ....I also never heard of anybody doing this before...
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On many low-budget films where they really can't afford to do re-shoots or a whole lot of post sound, this is often done. I've seen it done dozens of times. It was standard operating procedure when I was in film school (as recommended by all of our sound teachers).

I don't understand why the A1 allegedly can't do this. Nearly every camera I've used can mix one channel at a different audio level than the other while using a single microphone.
 
It does work, nearly perfectly, with the small exception that the sound is very slightly "thinner" or has slightly less drive. Just be sure to only use one phantom power on the A1 - using two could blow the mic, camera, or both.

Here are my results, posted in another thread:
http://www.dvxuser.com/V6/showthread.php?t=145901&page=2

"So I just got a XLR Y-splitter... and it works beautifully. I am now able to independently set levels.

The question I have left is, is there any reason the splitter would change the sound quality? I think I hear a slight difference between the splitter and just going straight into the camera. I could very well be imagining it, but straight to cam sounds somehow minutely fuller.

Could it be that the signal has been somehow "thinned" because of the the splitter? Might it mean the single phantom power isn't strong enough to produce the 2 signals? (I haven't dared to turn on both phantom powers at once; I'm scared that'd blow the mic and/or cam.)

Or, am I imagining the difference?
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timbook2 said:
you must try it out yourself....IMO the impedance needs to be matched when doing this. I am a pro audio guy and would never do this ....I also never heard of anybody doing this before...
Click to expand...


I read through this older post that you use an A1 and your a pro audio guy. I am getting a feedback sound (like the room static sound is what I'm talking about) when I use my XLR mic on the A1, and it is killing me at the festivals. They play it so loud the room static sound is way louder than when I watch it on my computer. Can you tell me what your exact settings are, do I need to lower the audio gain? Other films show just fine. Thanks in advance.
 
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