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Audio-Technica BP4025

X/Y Stereo Condenser Stereo Microphone

Part of Audio-Technica’s “Broadcast & Production” series, the BP4025 is an end-address XY-stereo microphone with a unique compact dual-capsule stereo head.

Rather than mounting the capsules so their planes intersect at 90°, as one might expect would be necessary for X-Y imaging, A-T engineers have produced a realistic, wide stereo image using capsules mounted nearly parallel, back-to-back. This approach allows the headbasket assembly to be significantly smaller than if the capsules were mounted at right angles to one another.

(A-T’s “consumer” version of this mic, the AT8022, uses a similar mounting and baffling arrangement for small-diaphragm capsules; see sidebar link.)

The two capsules in the BP4025 are large-diaphragm electrets. Although originally described here as having been “designed for the AT2035 and modified for use [in the BP4025],” our source for this description has updated us that this is not entirely accurate, yet no further explanation on the BP4025’s capsules was provided.

The diaphragm material is 2-micron PPS (Polyphenylene Sulfide), a plastic resin known for its thermal and directional stability. The diaphragms’ active diameter is 24.3mm.

The output circuit is transformer-balanced.

The mic ships with a mic clip (Audio-Technica p/n AT8405a), a foam windscreen, and a soft storage pouch.

In August, 2009, Audio-Technica issued a Service Bulletin offering a free repair for all BP4025 with date codes 0844, 0850, 0851, 0852, 0904, 0907. The mics are wired out of phase, making the difficult to use in conjunction with in-phase microphones. See sidebar link for contact info.

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The mic was released in 2008.

Specifications

Frequency Response - X/Y StereoClick Graph to Compare!

Pickup Patterns	Pads & Filters
X/Y Stereo (25.1 mV/Pa; 20 - 17,000 Hz)	Pad: -10dB (Via Switch) Filter: HPF: -12dB/octave @ 80Hz (Via Switch)

Capsule Dimensions	Impedance	SPL/Noise
Diaphragm diameter: 24.3mm Capsule diameter: 26mm Diaphragm gauge: 2 microns	170 Ohms (Low)	Max SPL: 155 dB Self-noise: 14.0 dB(A)

Weight	Length	Max Diameter	Interface(s)
269g (9.49oz)	186mm (7.32'')	47mm (1.85'')	5-pin XLR male (1)

Power Specifications
Requires phantom power Phantom voltage: 11–52v

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