Sennheiser EW-D SK BASE SET (R4-9) Digital Wireless Microphone System with Bodypack, No Mic (R4-9: 552 - 608 MHz) - 508742

Product Overview

The Sennheiser EW-D SK BASE SET (R4-9) is a professional digital wireless bodypack system designed for integrators and system builders who supply their own lavalier microphone, headset, or instrument cable. The set includes the EW-D SK bodypack transmitter and the EW-D EM single-channel rackmount receiver operating in the R4-9 band (552–608 MHz) — delivering 24-bit audio, 134 dB of dynamic range, and ultra-low 1.9 ms latency on Sennheiser's premium EW-D platform. No microphone or lavalier is included, making this the ideal starting point for AV integrators, broadcast engineers, and production companies who specify their own transducer. The result is a highly flexible, future-proof wireless bodypack foundation at a professional price point.

Product Description

The EW-D SK BASE SET (R4-9) places the full capability of Sennheiser's EW-D wireless platform in the hands of integrators who want to define every element of their signal chain. The EW-D SK bodypack transmitter accepts microphone, instrument, and line-level sources via its 3.5 mm locking TRS input, making it compatible with a wide range of lavalier microphones — including the Sennheiser ME 2-II omnidirectional lavalier, the ME 4-II cardioid lavalier, the MKE 1 miniature condenser, and compatible third-party transducers. A mute switch on the bodypack gives users discreet on-body control, while Bluetooth 5.1 enables quick pairing with the EW-D EM receiver.

The companion EW-D EM receiver is a 1 RU half-rack unit that installs cleanly into any standard rack infrastructure. Intelligent Switching Diversity protects signal integrity across two removable BNC rear-mount antennas, while the equidistant tuning grid across 2240 available frequencies in the R4-9 band (552–608 MHz) allows up to 90 simultaneous wireless channels without complex intermodulation coordination. The Sennheiser Smart Assist app (Android and iOS) connects via Bluetooth to streamline setup, frequency scanning, gain adjustment, and remote monitoring from a smartphone — eliminating the need to physically access rack-mounted gear during a show. The receiver outputs a full-range 20 Hz to 20 kHz audio signal through both a balanced XLR and an unbalanced 1/4" TRS connector, with receiver gain adjustable from -3 to +42 dB in 3 dB steps. The bodypack runs up to 8 hours on two AA batteries or 12 hours on the optional Sennheiser rechargeable battery pack.

Key Features

• No Microphone Included (Integrator Base Set) — Attach any compatible lavalier, headset, or instrument cable via the 3.5 mm locking TRS input; compatible with Sennheiser ME 2-II, ME 4-II, MKE 1, and more.
• EW-D SK Bodypack Transmitter — Lightweight metal-housing bodypack with mute switch, accepts mic/instrument/line inputs; ideal for discreet wireless applications.
• R4-9 Band (552–608 MHz) — UHF operation in the R4-9 band with 56 MHz of usable bandwidth and 2240 tunable frequencies.
• 24-Bit Digital Audio, 134 dB Dynamic Range — Professional digital audio quality with no companding artifacts and an ultrawide dynamic range.
• Ultra-Low 1.9 ms Latency — Transparent wireless performance with virtually imperceptible delay for live performance and broadcast use.
• Up to 90 Simultaneous Channels — Equidistant tuning grid from the Digital 6000/9000 platform eliminates complex frequency coordination for large multi-channel deployments.
• Intelligent Switching Diversity — Dual BNC rear-mount antennas with automatic diversity switching guard against RF interference and dropouts.
• Bluetooth Smart Assist App (Android & iOS) — Remote setup, frequency scan, gain control, and battery monitoring from any smartphone without touching rack equipment.
• 8 / 12-Hour Battery Life — 8 hours on 2x AA alkaline batteries; up to 12 hours with the optional Sennheiser rechargeable battery pack.
• 328 ft / 100 m Operating Range — Robust UHF range for stages, houses of worship, broadcast studios, and large installed AV systems.
• Rack-Mountable EW-D EM Receiver — Half-rack 1 RU unit with XLR balanced and 1/4" TRS outputs; rackmount hardware included.
• OLED Display on Receiver — Clear at-a-glance status readout for frequency, gain, and battery level on the receiver front panel.

Typical Applications

• Lavalier wireless systems for presenters, lecturers, and corporate event speakers
• Houses of worship where clergy wear discreet clip-on microphones
• Broadcast and TV production with integrator-specified lavalier transducers
• Theater and performing arts productions requiring bodypack wireless
• Fitness and aerobics instructors needing headset wireless freedom
• AV integration projects specifying a custom lavalier or headset solution
• Instrument wireless for guitarists, bassists, and keyboardists (line/instrument input)

Technical Specifications

Frequently Asked Questions

Q: Does this base set include a lavalier microphone or headset?

No. The EW-D SK BASE SET (R4-9) ships with the bodypack transmitter and receiver only. You connect any compatible lavalier or headset microphone using the 3.5 mm locking TRS input. Compatible Sennheiser microphones include the ME 2-II omnidirectional lavalier, the ME 4-II cardioid lavalier, and the MKE 1 miniature condenser, all sold separately.

Q: What does the R4-9 band designation mean?

R4-9 is Sennheiser's designation for the UHF frequency range spanning 552 to 608 MHz. This band is widely used in professional wireless audio and is coordinated in most markets. If you are unsure whether R4-9 is appropriate for your region or venue, we recommend contacting Creation Networks for frequency coordination advice before purchasing.

Q: How does this differ from the EW-D SK BASE SET (R1-6)?

The two sets are identical in every feature, specification, and capability. The only difference is the RF operating band: R1-6 covers 520–576 MHz while R4-9 covers 552–608 MHz. Both overlap slightly, so band choice should be driven by available spectrum in your specific deployment environment. Do not mix R1-6 and R4-9 transmitters with the wrong receiver band — they are not cross-compatible.

Q: How many EW-D SK systems can I run simultaneously?

The EW-D platform supports up to 90 simultaneous transmitters per frequency band, enabled by the equidistant tuning grid inherited from Sennheiser's Digital 6000 and 9000 series. Large venues such as stadiums, conference centers, and theaters can deploy dozens of channels without complex intermodulation calculations.

Q: Can I control the system remotely without touching the receiver?

Yes. The EW-D EM receiver uses Bluetooth 5.1 to connect with the free Sennheiser Smart Assist app on Android and iOS. From the app you can scan for clean frequencies, assign channels, monitor battery status, and adjust receiver gain — eliminating trips to the equipment rack during setup or performance.

Q: Is this bodypack suitable for instrument wireless use?

Yes. The EW-D SK bodypack transmitter accepts microphone, instrument, and line-level input sources via its 3.5 mm locking TRS input, making it compatible with electric guitar, bass, keyboard, and other line-level instruments in addition to lavalier and headset microphones.

Q: What audio outputs does the EW-D EM receiver offer?

The receiver provides one XLR 3-pin balanced output and one 1/4" TRS unbalanced output, with receiver gain adjustable from -3 to +42 dB in 3 dB steps. Both outputs are active simultaneously, so you can feed a mixing console and a direct recording interface at the same time.

Q: What are the physical dimensions and weight of this system?

The EW-D EM receiver measures 7.4 x 1.7 x 8.3" (189 x 44 x 212 mm) and weighs 2.2 lb (1 kg). The EW-D SK bodypack transmitter measures 2.5 x 3.1 x 0.8" (63 x 80 x 20 mm) without antennas and weighs 4.2 oz (120 g) without batteries.