The Bogen HTA-Series Power Amplifiers are high performance units employing Power MOSFET technology. The unique characteristics of Power MOSFET circuitry make them ideally suited to power amplifier design, providing far superior performance and reliability compared to other types of transistors. They offer higher efficiency, reduced heat, simpler overall design, reduced size and weight. The HTA125A Model supplies 125 watts and the HTA250A Model supplies 250 watts (RMS continuous output) at less than 0.5% total harmonic distortion from 20 to 20,000 Hz. An input signal of only 500mV is required for full rated output. The input impedances are: high-impedance (50k ohms) unbalanced; and low impedance (500/600 ohms, balanced or unbalanced) using the WMT1A Line-Matching Transformer accessory. Line bridging can be achieved with the optional transformer Model TL100. Residual hum and noise is at least 90 dB below rated output and the output regulation is better than 2 dB from no load to full load. The amps can drive a variety of load impedances. Outputs include 4 ohms, 8 ohms, 25VCT and 70 volts. The amplifiers are capable of safely driving any recommended load continuously. The HTA-Series amps are thermally protected to prevent damage due to excessively high temperatures. Additional failure-preventive devices include overload limiting, short circuit protection, and a SloBlo fuse. Electronic shutdown circuitry is automatically activated if an overload or short occurs and the front panel overload shutdown LED illuminates. Once the cause has been rectified, the unit automatically resets. The power ON/OFF switch, located on the front panel, illuminates when power is on. The rear panel contains an input level control, input and output connections, the AC line fuse, and an auxiliary receptacle. A low-cut filter switch is located internally.