The AKG SPR 4 Bodypack Transmitter is one of the core components of the AKG IVM 4 wireless in-ear monitor system. The AKG IVM 4 is the first wireless system ever to combine all the features required for professional in-ear monitoring in a single, compact device. The IVM 4 system features an integrated dbx compressor, an equalizer offering a large number of EQ presets and in-ear-optimized binaural room simulations that provides musicians, vocalists and presenters with outstanding high-performance signal processing flexibility for a natural listening experience with more life-like imaging.

The IVM 4 allows the input signal to be processed individually to meet the requirements of both the artist and the sound system environment. Unique integrated signal processing for a natural listening experience and a complete set of inputs and outputs make the IVM 4 an ideal tool for professional applications.

The SPR 4 bodypack receiver features a rugged die-cast magnesium case. Auto Setup and Environment Scan functions for finding clean frequencies make setting up extremely easy. The 30 MHz bandwidth allows manual selection of 1200 frequencies or the system chooses from preprogrammed frequency preset banks. The SPR 4 wireless receiver provides a backlit display and jog control for ease of use. The display indicates the received signal strength and battery status along with other parameters. Integrated charging contacts allow the optional BP 4000 battery pack to remain inside the receiver whilst being charged on the CU 4000 charger (optional). The BP 4000 will be charged to capacity in only one hour, and can power the SPR 4 for about seven hours.

The only control the artist needs to operate is an ergonomically shaped volume control with integrated on/off switch. Placed in the center of the SPR 4 top panel, the volume control with its clearly discernible detents can be operated intuitively even if it is positioned outside the user's field of vision. An Individual mix function allows a personalized monitor mix to be set up even where only a small sound system with no separate monitor mixer is available. To accommodate the individual preferences of users, the SPR 4 has been designed to drive a large number of different types of earphones.