Shure RPM181/BI – Bidirectional Capsule for Beta 181 Microphone

Product Overview

The Shure RPM181/BI is the bidirectional (figure-8) replacement capsule for the Beta 181 small-diaphragm side-address condenser microphone, suited to broadcast studios, recording facilities, and live sound engineers who require figure-8 polar pattern capability for mono drum overhead placement, dual instrument capture, or mid-side microphone techniques. It snaps onto the Beta 181 body and converts the microphone to a bidirectional pickup pattern, providing textbook polar response in the compact Beta 181 form factor. This capsule is sold individually for users who already own a Beta 181 body.

Product Description

The Beta 181 platform uses interchangeable capsules to deliver multiple polar pattern options from a single microphone body, a configuration well-suited to broadcast studios, commercial recording facilities, and live performance venues that need to adapt a microphone to different placements without additional equipment. The RPM181/BI bidirectional capsule is ideal for mono overhead drum applications that benefit from rejection at 90° and 270°, capturing two instruments simultaneously on a single channel (one source in front, one behind), or constructing mid-side stereo configurations. The capsule installs without tools and maintains the consistent Beta 181 small-diaphragm condenser performance standard. AV system designers specifying flexible microphone inventories for multi-purpose rooms, broadcast studios, or house of worship installations can use the capsule system to reduce hardware overhead while maintaining pattern versatility.

Key Features

• Bidirectional (Figure-8) Polar Pattern — Captures audio from front and rear while rejecting sound from the sides, enabling mono drum overhead, dual-source, and mid-side stereo applications.
• Beta 181 Capsule System Compatibility — Installs directly onto any Beta 181 microphone body with no tools required, providing polar pattern flexibility from a single hardware investment.
• Small-Diaphragm Side-Address Design — The compact Beta 181 form factor allows close placement in tight configurations such as drum kits, piano lids, and instrument clusters.
• Consistent Polar Response — Maintains textbook bidirectional polar response across the frequency range for predictable, accurate placement in professional recording and live applications.
• Professional Recording and Live Reinforcement — Designed for both studio and live sound environments where pattern accuracy and consistent frequency response are required.

Typical Applications

• Broadcast studio instrument recording
• Auditorium and performing arts overhead microphone placement
• House of worship instrument miking with mid-side stereo techniques
• Multi-purpose room and training room instrument capture
• Drum overhead in mono figure-8 configuration

Technical Specifications

Frequently Asked Questions

Which microphone body does the RPM181/BI fit?

The RPM181/BI is designed exclusively for the Shure Beta 181 side-address condenser microphone body. It is not compatible with other Shure microphone bodies.

Can I switch capsules in the field?

Yes. Beta 181 capsules are designed for field installation without tools, allowing sound engineers and AV technicians to change polar patterns between setups.

What is the primary use case for the bidirectional capsule?

The bidirectional pattern is most commonly used for mono drum overhead placement, capturing two instruments on a single channel, and mid-side stereo recording configurations.

Does the capsule require phantom power?

Yes. As a condenser capsule, the RPM181/BI requires 48V phantom power supplied by the connected preamp or mixing console.