STX Audio STX2000.5D 5-Channel Class D Amplifier

The STX Audio STX2000.5D is a five-channel Class D car amplifier designed to power a complete speaker-and-subwoofer system from one compact chassis. It provides four full-range channels for front and rear speakers plus a dedicated subwoofer channel. This layout helps simplify a system upgrade when separate amplifiers are not desired.

At 4 ohms, the amplifier is rated for 80 watts RMS across each of its four full-range channels and 200 watts RMS for the subwoofer channel. At 2 ohms, it is rated for 130 watts RMS x 4 plus 400 watts RMS for the subwoofer channel. Its 2,000-watt maximum-power rating describes its peak output specification.

The STX2000.5D is intended for listeners who want independently amplified door or component speakers along with a subwoofer. Adjustable high-pass filtering helps remove deep bass from the full-range speakers, while the dedicated low-pass filter sends bass-focused frequencies to the subwoofer channel. Separate front, rear, and subwoofer gain controls support level matching within the system.

Its circuit design uses MOSFET technology along with a double-sided FR-4 circuit board and SMT components. The Class D platform is specified at over 80% efficiency, helping make the amplifier suitable for installations where available space and heat management matter. Thermal protection is specified at 80°C (176°F).

The amplifier accepts RCA inputs for front, rear, and subwoofer signal paths, making it appropriate for an aftermarket head unit with preamp outputs. A remote bass-level control is included for adjusting subwoofer output from the listening position. With adjustable crossover controls and five amplified channels, it provides a focused foundation for a conventional full-range-plus-subwoofer car audio system.

Key Features

• Five-Channel Layout: Powers four full-range speakers and one subwoofer channel.
• 2-Ohm RMS Output: Delivers 130W x 4 plus 400W subwoofer RMS.
• Adjustable HPF: Helps protect full-range speakers from excessive low bass.
• Adjustable LPF: Directs low-frequency content to the subwoofer channel.
• Remote Bass Control: Allows convenient adjustment of subwoofer level.
• Thermal Protection: Protection threshold is specified at 80°C (176°F).

Design & Installation

The STX2000.5D uses a compact enclosure measuring approximately 8.6 x 4.8 x 2 inches. Its electronics are built around a double-sided FR-4 PCB with SMT components, and the amplifier includes power and protection status indicators. The chassis should be installed in a dry location with clearance around it for ventilation.

Use the +12V, ground, and remote-turn-on terminals for vehicle power connections, and connect RCA cables to the separate front, rear, and subwoofer inputs. Connect full-range speakers to channels 1 through 4 and the subwoofer to the dedicated subwoofer output, keeping connected loads at or above the stated 2-ohm minimum. Set gain conservatively, then use the HPF, LPF, and bass-boost controls to suit the speakers and subwoofer in the system.