Radio Design Labs DB-TPA1A 3.5 W Audio Power Amplifier, BlackFeatures: 3.5 Watt RMS Audio Amplifier into 8 Ohms; 6.5 Watt RMS Audio Amplifier into 4 Ohms; Output Drives 4 or 8 Ohm Speaker; Setting Level to Minimum Activates Energy-Saving Sleep Mode; High-Efficiency Class D Operation; VCA Level Adjustment for Scratch-Free Long Life; Input and Power Connection on RJ45; Connects to Format-A Sender using Twisted-Pair Cable; Powered from RDL Twisted Pair Format-A Sender; Speaker Output Connection on Detachable Terminal Block; Ultra-Compact All Metal Construction; Thermal and Short-Circuit Protection; The -TPA1A modules are two pair audio amplifier modules compatible with RDL Format A twisted pair products. Each -TPA1A receives stereo audio and 24 Vdc power through a rear-panel RJ45 jack. The left and right audio signals received on pairs B and C of the twisted pair cable are summed to mono and amplified. The amplified output level is set by an internal VCA which is controlled by a front-panel volume control. The VCA attenuator provides years of scratch-free gain adjustment.The -TPA1A circuits are all designed for low power consumption. Amplification is provided by a high-efficiency Class D power stage with audio filtering tailored for crisp, pleasant audio clarity. The high-efficiency Class D output stage produces negligible heat for all levels of expected voice or music modulation. When the user reduces the audio level to minimum, the class D output stage is switched off. This sleep mode remains active until the user turns up the output level.The output drives either a 4 Ohm or 8 Ohm speaker. The speaker cable connects to the module using a detachable terminal block.The front panel does not include any illuminated indicators, making the -TPA1A ideally suited to installation in dark rooms or areas. Installation is simple and quick, requiring only the connection of the speaker leads and the twisted pair RJ45.The -TPA1A may be fed and powered from any RDL Format