Stefan Kiessling – organist
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Calculator for Stereo Imaging and Coincident Polar Patterns


If you find this tool useful, I would be pleased with a donation.
As an autonomous recording organist I am interested in microphone setups that are quick to set up and give some flexibility to adjust the stereo image and/or polar patterns in post-processing (compared to arrangements like AB and ORTF, that are fixed). Dealing not just by experimenting but also with the theory, led me develop this calculator and some microphone setups, that might not be so well-known. Also, a number of standard setups are shown.
Simple and well-known examples are MS- and XY-Stereo. Extending MS and combining more than one MS-Setups leads to Stereo with time-of-arrival imaging and also Surround sound.
You can combine up to microphones. Select the polar pattern, angle and phase of each, and play with its signal strength to see the influence on the resulting pattern.
Example: For MS-Stereo select e.g. “Cardioid” in the first column, “Figure 8” and -90° in the second column. Adjusting the signal strengths gives you the resulting pattern and its on-axis angle. The off-axis will be indicated graphically, too.
More Examples here.
For minimalistic 2-microphone-setups take a look at the Stereo Adviser as well.

Show realistic patterns (usually the polar response is frequency dependent).

This is a user-created setup.

Input


This calculator is currently able to process coincident and AB-setups only.
Air temperature: °C
Distance between sound source and Mic(s): 0cm
Distance between sound source and Mic(s): 0cm

Output


Power Sum Front
Power Sum Back
Mono compatibility ?
Frequency response of the front setup as a whole, free/diffuse field ?

Examples


click to put the configuration into the calculator
Omni plus Fig. 8 at 0° to create an arbitrary type of cardioid. Mono.
This works better when a wide cardioid is used instead of an omni, as an omni polar pattern is highly frequency dependent.
XY-Stereo. Adjusting the levels of the summed signal and the subtracted signal allows to change the stereo width in post-proc.
Blumlein-Stereo (special form of XY). Adjusting the levels of the summed signal and the subtracted signal allows to change the stereo width in post-proc.
MS-Stereo: Cardioid plus Fig. 8 at -90°, resulting in XY-Stereo, where angle and cardioid type of the resulting virtual mics are not independent.
MS-Stereo: Omni plus Fig. 8 at -90°, resulting in XY-Stereo, where the angle of the virtual mics is always ±90°, cardioid type is adjustable.
Double-MS, also for Surround: Fig. 8 plus 2 cardioids, one directed backwards (180°) for MS-stereo with independent cardioid type and angle; surround with any number of virtual mics of any angle and cardioid type. Also Blumlein can be emulated.
Double-MS plus omni: like before, supplemented by an omni for better capture of low frequencies. The back-facing cardioid is theoratically not necessary as the omni-mic picks up the sound coming from behind as well. However, high frequencies from the back are usually attenuated by omnis. The back-facing cardioid is helping here.
MMS: Mid-Side with two Mid-Microphones: an omni and a figure of eight. Simple MS has the disadvantage that the resulting patterns and the powersum are dependent from the gain relation between the microphones. Here this is no longer the case and it is possible to create intensity stereo of almost any recording angle with any resulting pattern (also Blumlein) or for instance an equal power sum.
MXY: XY plus Omni. Like MMS the stereo width can be adjusted independently from the power distribution in the stereo image. It avoids Fig. 8's, which are usually more expensive and have less low end. This example uses Supercardioids with an angle of 50°. Appropriately mixed you can virtually get a Blumlein setup.
Stereo-Setup with spaced omnis. Two additional Fig.8's allow to introduce an arbitrary amount of intensity stereophony, which also widens the stereo image.
Like before, but with the Figure 8's turned 45°. Allows to adjust the intensity stereophony, different behavior in the frequency dependence of the stereo image and different shape of the power sum graph (with a stronger center).
Like before, using Wide Cardioids instead. Power Sum graph less frequency dependent.
Spaced MS, also for Surround: Two MS-Setups turned by 90° outwards, resulting in an adjustable surround with time-of-arrival and intensity stereo image between L and R. Each MS-Setup is providing a virtual Mic towards the front and back. The more the virtual mics are pointing to the front/the back, the more they are turning into supercardioids.
Like before, using super-cardioids, supplemented with omnis. This allows to adjust the pattern of the resulting mics independently from their angle. Moreover the omnis can be high-cut mixed in to provide better bass. The recording angle can be freely set while still keeping a very good front-back-separation.
„Flex-ORTF“; adjustable intensity stereo by using super cardioids and wide cardioids.

Examples for setups that are not adjustable in post-proc


AB-Stereo, which delivers time-of-arrival-stereo only. The recording angle depends on the distance of the mics.
ORTF; with partly time-of-arrival stereo and intensity stereo.
Faulkner-Array

Equipment


Affiliate-Links
Fig. of 8 microphone capsule: Schoeps MK 8 Cardioid microphone capsule: Schoeps MK 4 Super cardioid microphone capsule: Schoeps MK 41 Wide cardioid microphone capsule: Schoeps MK 21 Microphone amplifier for the capsules: Schoeps CMC 1U Cardioid microphone (capsule incl. amplifier) for mid: Sennheiser MKH 8040 Wide cardioid microphone (capsule incl. amplifier) for mid: Sennheiser MKH 8090 Omni microphone (capsule incl. amplifier) for mid: Sennheiser MKH 8020 plastic clips to clip two microphone bodies together: Rycote MS Stereo Clip Field recorder, suitable for on-location recording, with 6 channels: Zoom F6

Cheaper options:

Røde NT5 Omni capsule for the NT5: Røde NT45-O Fig. of 8 microphone: t.bone SC 1100 for mid and side Field recorder with 4 microphone inputs: Zoom H6

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