A theoretical appraisal of the Samson Zoom H2
Samson states that "The H2 is the only portable recorder with 4 mic capsules on-board for 360° recording. [...] For maximum flexibility, you can record from the front of the H2 in a 90° pickup pattern or the rear of the H2 in a 120° pickup pattern [...]" [Link]
A view of the capsules can be found here.
As can be seen from the graphics Samson provides they expect the pair of forward-facing cardioids, arranged at +-45° off axis (for a total of 90°), to result in a stereophonic recording angle of 90°. This is not correct. According to Eberhard Sengpiel the recording area is much wider at 196°.
For the rear-facing microphones the arrangement of +-60° off axis (for a total of 120°) is said to result in a recording angle of 120°. This again is not correct. The calculated recording angle is 158° --less than the 196° found in the frontal configuration.
The fact is: a greater off-axis angle results in a smaller recording angle! This is not only mathematically correct but can be easily verified in practice.
In sum, the total recording area of the 4-Mic-setup in the Zoom H2 covers 354°, composed of a larger forward-facing and a smaller rear-facing area.
What should it sound like?
Both (near-) coincident pairs employ cardioids, which will result a high degree of diffuse-field correlation, perceptually compressing both the frontal and the rear-facing soundstage. Whereas I have not personally experimented with this recorder I believe a more complex setup is required to capture a realistically enveloping experience.
I find both the coincident approaches (Soundfield, Double-M/S) and runtime-based solutions (Atmos, Surround Decca-Tree, OCT/OCT2) interesting. My XYtri features a composite approach. But all of these are definitely way more involved than a compact, handheld solution. As such it might meet many user's needs.
[All © by their respective owners]
A view of the capsules can be found here.
As can be seen from the graphics Samson provides they expect the pair of forward-facing cardioids, arranged at +-45° off axis (for a total of 90°), to result in a stereophonic recording angle of 90°. This is not correct. According to Eberhard Sengpiel the recording area is much wider at 196°.
For the rear-facing microphones the arrangement of +-60° off axis (for a total of 120°) is said to result in a recording angle of 120°. This again is not correct. The calculated recording angle is 158° --less than the 196° found in the frontal configuration.
The fact is: a greater off-axis angle results in a smaller recording angle! This is not only mathematically correct but can be easily verified in practice.
In sum, the total recording area of the 4-Mic-setup in the Zoom H2 covers 354°, composed of a larger forward-facing and a smaller rear-facing area.
What should it sound like?
Both (near-) coincident pairs employ cardioids, which will result a high degree of diffuse-field correlation, perceptually compressing both the frontal and the rear-facing soundstage. Whereas I have not personally experimented with this recorder I believe a more complex setup is required to capture a realistically enveloping experience.
I find both the coincident approaches (Soundfield, Double-M/S) and runtime-based solutions (Atmos, Surround Decca-Tree, OCT/OCT2) interesting. My XYtri features a composite approach. But all of these are definitely way more involved than a compact, handheld solution. As such it might meet many user's needs.
[All © by their respective owners]
posted by Andrew Levine at Wednesday, February 25, 2009
2 Comments:
do you know of an article in english explaining why the wider mic angle results in a narrower pickup area?
You can find some graphics of the relationship @ Recording angle of an XY-setup with cardioid microphones.
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