Infinity Kappa 5004A 4-Channel Powersports Amplifier

The Infinity Kappa 5004A is a compact four-channel Class D amplifier designed for powersports, marine, and other mobile-audio installations where space is limited. It provides dedicated amplification for up to four full-range speakers, helping an upgraded speaker system play with more headroom than a source unit alone can provide. Its compact form factor is intended for installations where a conventional amplifier may be difficult to mount.

This amplifier is suited to riders and vehicle owners building a multi-speaker system, replacing an underpowered factory setup, or adding amplified front and rear channels. It delivers 75 watts RMS to each of four channels at 4 ohms, with increased output available at 2 ohms. Two pairs of channels can also be bridged for systems that require higher power to fewer compatible speakers.

The KP5004 is built around Class D amplification, a practical choice for efficient output in electrically demanding mobile environments. Its full-range frequency response covers 20Hz to 20kHz, allowing it to support speaker-focused systems across the audible range. Adjustable input level controls help match the amplifier to the connected source.

Selectable crossover controls make the amplifier adaptable to different system layouts. The front channels offer off or high-pass filtering, while the rear channels can be set to off, high-pass, or low-pass operation. Crossover points of 60Hz, 80Hz, and 120Hz help direct bass away from smaller speakers or configure the rear channels for a subwoofer application.

An aluminum chassis and conformal-coated circuit board support use in harsh outdoor-oriented installations. Both speaker-level and low-level inputs are provided, allowing integration with a range of factory and aftermarket audio sources. The amplifier can serve as the foundation for a four-speaker upgrade or as part of a mixed speaker-and-subwoofer system when wired and configured within its rated limits.

Key Features

• Four-Channel Class D Power: Supplies 75W RMS x 4 at 4 ohms for amplified multi-speaker systems.
• 2-Ohm Capability: Delivers up to 125W RMS x 4 at 2 ohms.
• Bridgeable Channels: Configures as two 250W RMS bridged channels at 4 ohms.
• Selectable Crossovers: Helps tailor bass filtering for speakers or subwoofer channels.
• High- And Low-Level Inputs: Supports connection to factory or aftermarket audio sources.
• Conformal-Coated PCB: Adds protection suited to demanding powersports environments.

Design & Installation

The Kappa 5004A uses an ultra-compact aluminum chassis with a curved body, angular end caps, and inset brushed-aluminum Infinity branding. Its circuit board is conformal-coated, and the package includes cover plates plus stainless steel mounting hardware for a clean, durable installation. Power and protect indicators assist with basic operating-status checks after installation.

Use 10 AWG power and ground wiring as recommended, and install the battery-side fuse and fuse holder within 18 inches of the battery. The amplifier accepts high-level or line-level signal inputs and supports 12V or DC-offset turn-on modes. Set the gain conservatively, select the appropriate crossover mode for the speakers being powered, and confirm that all speaker loads and bridged wiring arrangements remain within the amplifier's rated configurations.