Schoeps BLM 3g Boundary Layer Microphone Capsule with Pressure Transducer in 8?€? Square Plate Matte Black

Since the plate of the Schoeps BLM3G Boundary Layer Microphone Capsule with Pressure Transducer in 8” Square Plate | Matte Black is only 5 mm thick and the transducer is not mounted at its center, the edges of the plate have very little effect upon the sound pickup. The BLM 3g does not interfere with the natural sound field; off-axis sounds thus encounter very little frequency discrimination. Sound coloration is low, even for moving sound sources, because the frequency response is essentially the same for all angles within the hemispherical pickup pattern.

Microphones used near sound-reflecting surfaces ordinarily produce comb-filter effects. This does not occur with the BLM 3g, since at the boundary in which the transducer is mounted there can be no phase difference between the direct sound and its reflection.
Ordinary pressure transducers show a difference in sensitivity between direct and diffuse sound at high frequencies. In a properly placed boundary-layer microphone, however, this difference occurs at all frequencies. The sound pressure for direct sound is doubled at an acoustic boundary (6 dB increase), while the essentially random phase relationships of reflections in the diffuse sound field cause the boundary-layer microphone's sensitivity to increase by only 3 dB. Thus a boundary-layer microphone will suppress diffuse sound somewhat, even though it is not directional. It will pick up less “room sound“ and the recording will be slightly “drier“ than it would be with an omnidirectional microphone.

The capsule itself is a classic electrostatic pressure transducer, which assures accurate reproduction of even the lowest frequencies along with the high signal-to-noise ratio and stable performance typical of professional condenser microphones.
This type of transducer is inherently insensitive to wind and vibration and the BLM 3g is comparatively heavy, so it picks up very little solid-borne noise. For example, when footsteps are recorded, most of the sound reaching the microphone will be conducted through the air rather than the floor.

Key Features

• Microphone capsule designed for placement at an acoustic boundary

• Particularly frequency-independent, hemispherical directional pattern

• Very low off-axis sound coloration

• Very good reproduction of low frequencies

Technical Specs

Frequency range

20 Hz - 20kHz

Sensitivity

19 mV/Pa

Equivalent niose level (A-weighted)

12 dB-A

Equivalent niose level (CCIR)

23 dB

Signal-to-noise ratio (A-weighted)

82 dB-A

Maximum Sound pressure level at 0.5% THD

128 dB-SPL

Dimensions

200 × 200 × 5 mm

Weight

570g (with CMC6) - 1.26 lbs

Surface finish

matte black