The Sennheiser EW-D SKM-S R4-9 BASE SET is a core digital wireless system package centered around a handheld transmitter body with a mute switch, operating in the R4-9 frequency band (552 to 607 MHz). This "Base Set" provides the essential wireless electronics—a handheld transmitter body (without a microphone capsule) and a compatible single-channel rackmount receiver—but allows the user to select their own microphone capsule. This configuration offers ultimate flexibility for professionals who already own high-quality capsules or wish to choose a specific model for their application. The integrated mute switch on the transmitter body is a crucial feature for broadcast and live presentations.

The system delivers the full performance of the EW-DX platform: pristine 24-bit/48 kHz digital audio, ultra-low latency, and 128-bit AES encryption. The receiver features Intelligent Antenna Diversity for robust RF performance. This set is ideal for sound companies, rental houses, and engineers who require the premium digital wireless performance of the EW-DX series but need the versatility to pair it with a wide range of interchangeable microphone capsules for different vocalists or uses.