STX Audio STX1200.4D 4-Channel Class D Amplifier

The STX Audio STX1200.4D is a compact four-channel Class D amplifier designed to add dedicated power and tuning flexibility to a car audio system. It provides 60 watts RMS per channel at 4 ohms or 75 watts RMS per channel at 2 ohms. This makes it suited to powering compatible full-range speakers in a four-speaker installation.

For systems that need more output on fewer channels, the amplifier can bridge its channels to deliver 140 watts RMS x 2 at 4 ohms. That configuration can support two compatible speakers or subwoofer applications that meet the stated bridged-load requirement. Its four-channel layout gives installers options when planning a speaker-focused upgrade.

The STX1200.4D uses a MOSFET circuit design and Class D amplification architecture. Its SMT construction and double-sided PCB are specified to support stable operation in a compact format. The design is intended for vehicle audio systems where available mounting space may be limited.

Adjustable high-pass and low-pass filters provide useful control over which frequencies are sent to connected speakers. Both filter sections adjust from 35 Hz to 250 Hz, allowing the amplifier to be tailored for full-range speakers or low-frequency duty. This helps match the amplifier's output to the role of each speaker in the system.

Built-in overload protection and thermal protection support safer operation under demanding conditions. The amplifier is rated for a maximum current draw of 26A and lists a signal-to-noise ratio greater than 80 dB with total harmonic distortion below 1%. It is a practical option for a compatible aftermarket head unit or factory-audio integration plan using appropriate signal connections and installation hardware.

Key Features

• Four-Channel Output: Powers up to four compatible speakers from one compact amplifier.
• 75W RMS at 2 Ohms: Delivers rated per-channel power for compatible 2-ohm speaker loads.
• Bridgeable Channels: Combines channel pairs for 140W RMS x 2 at 4 ohms.
• Adjustable Crossovers: HPF and LPF controls tune frequencies from 35 Hz to 250 Hz.
• MOSFET Circuit Design: Supports efficient amplification and dependable power delivery.
• Protection Circuitry: Includes overload and thermal protection for operation under load.

Design & Installation

The STX1200.4D is built around a Class D MOSFET circuit design with SMT components and a double-sided PCB. Its compact amplifier chassis measures 4.6 x 4.8 x 2 inches, helping it fit in installations where a larger amplifier may be difficult to mount. Built-in thermal protection is specified at 176°F.

Mount the amplifier securely in a dry, ventilated location and use correctly sized power, ground, signal, and speaker wiring for the vehicle installation. Use four compatible 2- or 4-ohm speakers for stereo operation, or bridge channel pairs only with compatible 4-ohm loads. Set the HPF or LPF controls from 35 Hz to 250 Hz according to the connected speakers and overall system design.