Class-DH switch mode power amplifiers
The XPS-series amplifiers are two-channel class-DH amplifiers at a compact size of 2 HU (rack spaces). All models are equipped with a high-efficient SMPS (switch mode power supply), which ensures top performance and light weight. The front panel shows two gain controls for easy access and the main switch. Two round LED displays inform about the condition of the amplifiers. The rear side shows two XLR input connectors and two XLR output connectors (link). Two SPEAKON© outputs and four binding posts are mounted at the rear side. The SPEAKON© connector of the output channel 1 (left) is connected with all four poles. This connector offers additionally the output signal of channel 2 (right) at the pins 2 (+/-). This enables an efficient four-pole connection of two-way speaker systems with one speaker cable only. The XPS-series amplifiers can be switched into three different modesof operation: stereo, parallel and bridge mode. The integrated crossover is equipped with a high-pass filter and a low-pass filter (each 18 dB / Butterworth). The filter type can be set and activated by a switch on the rear panel. The function of the crossover is switched off in position FULLRANGE. The XPS models are equipped with a switchable impedance matching function (except XPS 900 = class-D). This power converter can be set by the OVP switch on the rear panel. The OVP function ensures that the amplifiers deliver full output power even at low impedances. All models are equipped with a switch-on delay function to protect the connected speakers.
Class-DH | Sounds like “Class-H” – Efficient like “Class-D“.
A class-H amplifier is basically a class-AB amplifier, the supply voltage can be changed in dependence on the signal. At high power output levels of the amplifier, the class-H design is used to reduce the voltage drop and dissipation power in the output transistors considerably. The voltage increase is split at class-H amplifiers in 2 or 3 stages in the power supply. Disadvantages of class-H are the higher circuit complexity and low distortion when switching to the higher voltage level. The efficiencies of class-H amplifiers are between 60% to over 80%, depending on the circuit design. Class-DH is the evolution of the class-H technology. Class-DH has all the advantages of the class-H technology, but without switching to any higher or lower voltage level(s). Class-DH amplifiers are equipped with a dynamic adaptive voltage regulator that regulates the supply voltage continuously. The usually occuring distortion when switching to the higher supply voltage, is typically for class-H amplfiers. This kind of distortion does not occur in class-DH amplifiers at all. The efficiencies of the class-DH amplifiers are over 90% at full load.