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Old March 13th, 2007, 12:16 AM   #1
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hooking up two mics to create stereo

I need to connect a stereo boom mic to an XL1 camera.

My first thought was: extend the cord on the stereo mic that comes with the XL1. But I understand a long cord would pick up stray magnetic signals and create buzz.

My second thought was to get a new stereo mic that comes with an XLR connection & heavyduty cord and connect it to an MA100. However good
stereo mics are so expensive.

And the third idea: Use two mono condenser mics...
-Put one mono mic stage left (call it LM)
-Put the other mic stage right (RM)
-Connect both mics to a generic mixer
-On the mixer, turn PAN dial for LM channel all the way to the left
-Turn PAN dial for RM all the way to the right
-The mixer has two outputs: "main out left", and "main out right"
-Connect each to XL1's two RCA jacks (one red, the other white) in back of camera (Audio 1)
And finally:
- Select "Audio 1" for input select (on side of camera)
- And in menu select "audio 1 in line" ??? or "mic"? .

Is the second and third option OK? Thanks for reading this l-o-n-g post!!!
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Old March 13th, 2007, 03:25 AM   #2
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You may want to be more specific as what you intend to record that leads you to believe you need a stereo mic on a boom, perhaps there are other solutions. For example, I've used a well positioned Sony ECM-MS957 and a mini-disc recorder for recording a concert rather than running a long cable to the camera, and then synced the sound in post...

A 'good' mic does not necessarily imply just the quailty and cost of the mic itself, but how suited it is for the specific situation. There are supringly good mics on the market a relatively low prices, but here again we would need to know the specifics of your particular situation to make suggestions.

Sound equipment is usually a long-term investment, however if your need is one-off, then you alternatively want to hire gear and/or a sound person.

Given the number of XL1 owners that have switched to more recent cameras, you may find a used MA100 for very little... perhaps someone in you're area can dig one up and lend it to you.

You may also want to check out www.equipmentemporium.com, they have a lot of good information about the merits of specific stero mics (sales - mics).

best of luck
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Old March 13th, 2007, 04:17 AM   #3
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Quote:
Originally Posted by Darin Clarke View Post
I need to connect a stereo boom mic to an XL1 camera.

My first thought was: extend the cord on the stereo mic that comes with the XL1. But I understand a long cord would pick up stray magnetic signals and create buzz.

My second thought was to get a new stereo mic that comes with an XLR connection & heavyduty cord and connect it to an MA100. However good
stereo mics are so expensive.

And the third idea: Use two mono condenser mics...
-Put one mono mic stage left (call it LM)
-Put the other mic stage right (RM)
-Connect both mics to a generic mixer
-On the mixer, turn PAN dial for LM channel all the way to the left
-Turn PAN dial for RM all the way to the right
-The mixer has two outputs: "main out left", and "main out right"
-Connect each to XL1's two RCA jacks (one red, the other white) in back of camera (Audio 1)
And finally:
- Select "Audio 1" for input select (on side of camera)
- And in menu select "audio 1 in line" ??? or "mic"? .

Is the second and third option OK? Thanks for reading this l-o-n-g post!!!
Well, your proposed third method will record two tracks but it won't be a true stereo recording and using it could present some major headaches for you down the road. If you do decide to go that route I'd use the Tape Out RCA jacks on the mixer instead of the Main Outs. (Tape out is usually consumer -10dB line level which is what the audio in on your XL1 expects to see.) But in either case, spaced microphones like that have the problem that the same sound arrives at each mic at slightly different times. If the resulting tracks are mixed to mono, the sound waveforms mix together and selectively reinforce and cancel each other at various frequencies to produce a type of distortion called 'comb filtering.' While you may be shooting and releasing in stereo, depending on where it's to be shown and what sort of viewing equipment your audience happens to have, this mixdown to mono might occur anywhere along the chain after the program leaves your control, even occuring in the air between the stereo speakers and the listener in some cases. Also, widely spaced microphones like that need very careful positioning, and perhaps a third mic to fill in the centre (called a 'Decca Tree' arrangment), to produce a satisfactory stereo image. You'll probably have better luck with a pair of cardioid mics positioned together at about the centre of the stage and out in the audience a ways. They would be placed at an angle of about 105 degress crossing each other with the capsules as close together as possible without actually touching, called 'X/Y stereo.' Good stereo imaging and far fewer phase issues. Even better for video is a technique called Mid-Side or M/S stereo that uses a pair placed centre stage and back a ways as before but this time a cardioid aimed at stage centre is combined with a figure-8 mic place at 90 degrees. Unfortunately this requires special decoding in the mixer to monitor properly on-set and special handling in post production to create the actual Left and Right stereo channels from the two recorded channels, not a major problem for NLEs like Vegas or Premiere but it is an additional layer of complexity to deal with.
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Last edited by Steve House; March 13th, 2007 at 11:17 AM.
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Old March 13th, 2007, 10:10 AM   #4
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To add a few details about the XL-1, you would set the input to "Line" in your 3rd proposal where the camera is hooked to a mixer.
Even some Tape Outputs from mixers such as the Mackie VLZ models are hotter than -10db and can overdrive the camera's RCA inputs even when they are set to Line. If the mixer you use has hot tape outputs but also has two independent Aux Sends, you can use the Aux Sends instead and adjust their output level independent of the main/tape outs to match the camera inputs if you need the mains to be at normal level for feeding other devices.
The MA-100 can't handle full line-level signals either and doesn't provide phantom power. It can also be prone to interference from its power connection with the camera.
If you keep your pair of mics closely spaced (read about "coincident pair" stereo mic technique) and properly placed, configure a mixer correctly and use appropriate cables and camera settings, you can make a worthwhile stereo recording with the XL-1 using the RCA connectors.
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Old March 13th, 2007, 09:44 PM   #5
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thanks Jay, Steve, and Kalunga

thank you Jay, Steve, and Kalunga (moito obrigado). I was researching this further with a sales guy from B&H Photo today, and he brought up the same question as Kalunga: "Why do you need a stereo mic to record a dude giving a seminar inside a classroom?" Apparently I don't!

He suggested a mono shotgun mic he sells for $250 called Rode NTG-2 which he says would work well on a boom and would attach via a $20 adapter (XLR to mini) to the MINI-PLUG on my XL1. This guy however is an audio person –and unfamiliar with video cameras. So when I asked him if the "mini plug" is the same plug that the manufacturer provided mic connects to –he couldn't tell me. So I'm back to you guys!

This sounds like a good (simple) solution for me because I wouldn't have to mess with a mixer and the camera's audio monitor would automatically regulate the sound so it's not too hot –but I'd like to be sure I'm not going to pick up buzzing AND be sure that this is how it hooks up. And on the side of the camera I assume I choose "MIC" for input select? Finally, I'm wondering why the salesman suggested a shotgun mic instead of a cardioid? To capture ambient noise? What do you think is better for my
application?

Again, my thanks for sharing your knowledge. -Darin
.

Last edited by Darin Clarke; March 13th, 2007 at 09:47 PM. Reason: correction
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Old March 13th, 2007, 10:42 PM   #6
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No, you don't need a stereo mic to record a lecture in a classsroom, but you also don't want a shotgun mic. Better to get a wireless lav and put it on the lecturer. A sennheiser G2 will do.

Regards,

Ty Ford
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Old March 14th, 2007, 07:09 AM   #7
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Quote:
Originally Posted by Darin Clarke View Post
thank you Jay, Steve, and Kalunga (moito obrigado). I was researching this further with a sales guy from B&H Photo today, and he brought up the same question as Kalunga: "Why do you need a stereo mic to record a dude giving a seminar inside a classroom?" Apparently I don't!

He suggested a mono shotgun mic he sells for $250 called Rode NTG-2 which he says would work well on a boom and would attach via a $20 adapter (XLR to mini) to the MINI-PLUG on my XL1. This guy however is an audio person –and unfamiliar with video cameras. So when I asked him if the "mini plug" is the same plug that the manufacturer provided mic connects to –he couldn't tell me. So I'm back to you guys!

This sounds like a good (simple) solution for me because I wouldn't have to mess with a mixer and the camera's audio monitor would automatically regulate the sound so it's not too hot –but I'd like to be sure I'm not going to pick up buzzing AND be sure that this is how it hooks up. And on the side of the camera I assume I choose "MIC" for input select? Finally, I'm wondering why the salesman suggested a shotgun mic instead of a cardioid? To capture ambient noise? What do you think is better for my
application?

Again, my thanks for sharing your knowledge. -Darin
.
You didn't mention in your original post that your subject was a lecturer at a podium. The BH guy is right, you don't need and probably shouldn't use stereo for that sort of scene anyway. But as Ty says, rather than a shotgun this is the classic place to use a lav on the presenter, perhaps with a cardioid on the other channel aimed at the audience to capture the ambience of the room.

"Mini-plug" and "3.5mm plug" and "1/8 inch plug" are all terms for the same thing so the Rode XLR to mini adapter would work just fine. You are correct tp be wary of long cable runs since that means the cable is unbalanced, even on the XLR side of the adapter, but up to 10-15 feet should be safe if you don't run it near florescent lights or power cables.

But as for eliminating a mixer and letting the camera's audio automatically control the sound, not a good idea. Camera AGC has its uses but generally speaking you want to control the audio levels manually. What happens is the AGC is a very stupid slave. When the speaker pauses or takes a breath it thinks the sound is fainter and turns up the gain to try to hear something that isn't there. Then when he starts to talk again, the gain is up too high and it has to turn it down again. It doesn't take long but it's noticable that the start of the sound is hotter than the rest. It also leads to a noticable 'pumping' in the level of the background ambience. You might not need an external mixer, though they're a good idea, but try to shoot on manual when possible to avoid this pumping effect.
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Old March 14th, 2007, 11:54 PM   #8
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I second Steve on turning the AGC off - the AGC on my camera drives me nuts. My next camera MUST have manual audio controls.
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