The Bogen HTA Power Amplifier Series 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 W and the HTA250A Model supplies 250 W (RMS continuous output) at less than 0.5% total harmonic distortion from 20 to 20000 Hz. An input signal of only 500 mV is required for full rated output. The input impedances are: high-impedance (50k ohms) unbalanced; Low impedance (500/600 Ohm, balanced or unbalanced) with optional accessory transformer Model TL600. Line bridging can be achieved with 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 Ohm, 8 Ohm, 25 VCT and 70 V. 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.