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Old March 2nd, 2006, 12:56 PM   #1
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Stereo vs 2 Channel

At the risk of sounding like a dumb question, can someone tell me what the difference is between recording with a stereo shotgun microphone vs recording with 2 mono mics on separate camera channels?
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Old March 2nd, 2006, 01:47 PM   #2
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Originally Posted by Bob Harotunian
At the risk of sounding like a dumb question, can someone tell me what the difference is between recording with a stereo shotgun microphone vs recording with 2 mono mics on separate camera channels?
A stereo mic is just two mono mics inside the same shell. Good stereo requires more than simply recording two channels - it also requires attention to the levels and phasing of the left and right channels in order to provide the brain with the cues it needs to create the illusion of space. The main difference between using a stereo mic instead of two mono mics is you don't need to worry so much about mic placement and matching with a stereo mic. The downside is you don't have as much flexibility either.
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Old March 2nd, 2006, 02:00 PM   #3
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Thanks Steve, good explanation.
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Old March 2nd, 2006, 04:15 PM   #4
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Actually, the most important factor is probably in the physical arrangement of the two mics (and the exact specs of the two mics used). Stereo mics (or stereo techniques with two separate mics) involve mic capsules that are carefully chosen for how their frequency response and pickup patterns interact, and placed in a very specific configuration that allows them to capture spatial information.

Two channel just means you're recording using two sound-gathering devices - often placed on different sources. Stereo means you're using 1 specifically-configured 2-channel sound-gathering device, both aiming to capture the same sound source.

Stereo shotguns are not the best approach to stereo! You can get a much better stereo image using a good pair of microphones in a proper configuration than you'd get from a stereo shotgun. You can also use non-shotgun stereo mics to better effect. What are you trying to record?
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Old March 2nd, 2006, 05:02 PM   #5
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Quote:
Originally Posted by Barry Werger
...

Two channel just means you're recording using two sound-gathering devices - often placed on different sources. Stereo means you're using 1 specifically-configured 2-channel sound-gathering device, both aiming to capture the same sound source.

...
Depends on what you mean by "1 ... device." I'd consider 2 cardioids or hypercardioids in an X-Y coincident array to be two devices, not one. Likewise a cardioid and a figure-8 in an M/S configuration or a pair of figure-8's in a Blumlein Array would be 2 devices or even a pair of omnis in an A-B spaced array but all of them are well-known mic arrangements for recording true stereo.
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Old March 2nd, 2006, 07:00 PM   #6
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Quote:
Originally Posted by Barry Werger
Stereo shotguns are not the best approach to stereo! You can get a much better stereo image using a good pair of microphones in a proper configuration than you'd get from a stereo shotgun. You can also use non-shotgun stereo mics to better effect. What are you trying to record?
I brought up the question due to a discussion on another forum. I always thought I was recording stereo using 2 mono mics into my PD-170's audio channels. Someone else told me it wasn't true stereo prompting my question here for the experts. I'm a wedding videographer and this question applies to capturing reception music and ambient sounds.
Thanks for the input.
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Old March 2nd, 2006, 08:13 PM   #7
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Quote:
Originally Posted by Barry Werger

Stereo shotguns are not the best approach to stereo! You can get a much better stereo image using a good pair of microphones in a proper configuration than you'd get from a stereo shotgun. You can also use non-shotgun stereo mics to better effect. What are you trying to record?
And plased be advised that the term is Stereo/Shotgun, as in stereo OR shotgun. There is no such thng as a Stereo Shotgun.

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Old March 2nd, 2006, 09:14 PM   #8
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Bob, to clarify a bit more--
In the most common usage, especially around here, the word stereo means recreating the sense of relative placement of sounds a single head would hear at a point in the room--a stereo image.

But two mics that provide different signals two the two channels, directional mics pointed differently or nondirectonal mics located differently, can often give a spacious and pleasing sound. I don't think you're wrong to call that stereo sound in the dictionary sense. You wouldn't get a true stereo image, but that is probably not important for a wedding reception.

But for recording a stage concert, you might want to take two directional mics, say cardioid pattern mics, line them up with one directly below the other pointed at the stage, then rotate them while keeping the front ends lined up so that one points toward the front left and the other toward the front right. They still receive the same sound waves at the same time over all frequencies, but each one's response is strongest in the direction it's pointed. Meanwhile, the response of each mic to the sounds coming from the front center is weaker, BUT it's heard from both speakers on playback. The relative loudness and locations of the sounds, aka the stereo soundfield, is reasonably reproduced. This arrangement of mics is called the x-y coincident pair.

A lot of stereo mics use a pair of fixed X-y coincident elements, but in return for the convenience you trade away the flexibility of being able to change the angle to get the balance you want. There are other arrangemets that reproduce the soundfield also.
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Old March 8th, 2006, 03:16 AM   #9
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Originally Posted by Steve House
Depends on what you mean by "1 ... device." I'd consider 2 cardioids or hypercardioids in an X-Y coincident array to be two devices, not one. Likewise a cardioid and a figure-8 in an M/S configuration or a pair of figure-8's in a Blumlein Array would be 2 devices or even a pair of omnis in an A-B spaced array but all of them are well-known mic arrangements for recording true stereo.
Well, I thought I made that clear in my post - that my definition of "1 2-channel device" included "two seperate mics in a specific configuration" as opposed to "2 separate devices" which don't have a specific relative configuration.

Just semantics... but even when I'm using a spaced pair, or a Decca Tree, I consider the whole setup to be one stereo device, because of the various types of constraints (on mic matching, placement, levels, etc.) that tie the system together. MENTALLY, I mean, a stereo pair is a single device working on 1 consistent image, while "2 mics" can also be 2 unrelated devices working on 2 unrelated images.
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Old March 8th, 2006, 04:58 AM   #10
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Then there's creating a stereo image with non-symetrical mics; like using a Schoeps CMC641 and a Neumann U 89 on the top and bottom bouts of an acoustic guitar, respectively. Semantics preclude some from calling this "stereo" due the dissimilar mics, but the stereo field created can be quite nice.

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Old March 8th, 2006, 06:50 AM   #11
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Quote:
Originally Posted by Ty Ford
And plased be advised that the term is Stereo/Shotgun, as in stereo OR shotgun. There is no such thng as a Stereo Shotgun.

Regards,

Ty Ford
Scratching my head on this one and looking at my A-T 835-ST.
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Old March 8th, 2006, 10:56 AM   #12
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the 835ST is EITHER a stero mic OR a shotgun. Not both at the same time.

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Old March 8th, 2006, 02:19 PM   #13
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Originally Posted by Ty Ford
the 835ST is EITHER a stero mic OR a shotgun. Not both at the same time.

Ty Ford
I am missing something Ty. In the definition of Shotgun, does it only specify mono? On narrow or wide, it is stereo. It has the 'reach' of a shotgun (rejection is the better term, I believe). There is also the M/S, which is different.
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Old March 8th, 2006, 03:15 PM   #14
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I am missing something Ty. In the definition of Shotgun, does it only specify mono? On narrow or wide, it is stereo. It has the 'reach' of a shotgun (rejection is the better term, I believe). There is also the M/S, which is different.
Not to put words into Ty's mouth but what I think he meant by that is that a "shotgun" typically is picking up from directly where it is aimed and has relatively little pickup away from the centre axis. A stereo mic, OTOH, pickups from a broad area in front of the mic in order to create the stereo soundstage. The focussed directivity of the shotgun is conceptually the exact opposite of the broad pickup pattern (when both channels are considered) of a stereo mic. The "stereo shotgun" when used as a shotgun would not be creating a stereo image even though sound might be present on both channels - the left and right signals would be substantially the same unlike the case with the same mic set for stereo where the two channels are quite different.
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Old March 8th, 2006, 03:23 PM   #15
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Originally Posted by George Ellis
I am missing something Ty. In the definition of Shotgun, does it only specify mono? On narrow or wide, it is stereo. It has the 'reach' of a shotgun (rejection is the better term, I believe). There is also the M/S, which is different.
Yes, mono only for shotgun. Otherwise the added side stereo capsules (X/Y or M/S) make it a stereo mic.

The more stereo you have the less rejection you have, by definition.

'
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