XPS Series Amplifiers
Class-DH Switch Mode Power Amplifiers with Crossover and OVP Power Converter
The XPS-series amplifiers are two-channel class-DH amplifiers 2U (rack space).
All models are equipped with a high-efficient SMPS (switch mode power supply), which ensures optimum performance whilst remaining light weight. The front panel houses the two gain controls with round LED displays which displays the condition of the amplifiers. The rear of the amplifier has two XLR input connectors and two XLR output connectors (link). The input sensitivity (gain) is 32 dB. 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.
All the XPS series amplifiers can be switched into three different modes of 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 of the amplifier. 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 via 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.
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 depending on the signal. At high power output levels the class-H design is used to reduce the voltage drop and dissipation of power in the output transistors. 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 higher voltage level. The efficiencies of class-H amplifiers are between 60% to over 80%, depending on the circuit design.
Dynamic adaptive voltage regulator
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 typical for class-H amplifiers. 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.
► Distortion-free sound due to continuous control of the supply voltage
► Higher efficiency and less power consumption
► Less heat by very low power loss
POWER CONVERTER – Full Output Power at any Impedance
In theory, an amplifier that delivers 500 watts into an 8-ohm load, offers analogous to Ohm’s law 2.000 watts to a 2-ohm load. In practice, many amplifiers deliver 65% -77% of the theoretical 4-ohm power at 2 ohms only. The resulting losses come from the voltage power supply and from the current limitations of the output stages. The current limiter in the output stage generates additional distortion, this is due to the impedance curve of the loudspeaker connected. The speaker represents a dummy load to the amplifier. A large part of the energy is returned to the amplifier and may activate the current protection circuit (current limiter) externally.
The OVP Power Converter
The NOVA Over-Voltage Protection (OVP) is a special power converter that delivers more power than it has previously taken from the power supply. Due to this, it delivers the required current even at lower impedances. To drive a higher impedance (such as a speaker with an impedance of 8 ohms) a higher voltage is required. Using the OVP switch (not included on the XPS 900 model), the user can adjust the NOVA XPS amplifiers exactly to the impedance of the loudspeaker connected.
► Full power output even at low impedances
For larger and more complex speaker systems, we recommend using a digital loudspeaker management system, which takes over the function of a crossover. For smaller systems, such as a system consisting of two 18″ subwoofers and two 2-way mid/high loudspeakers users often rely on cost efficiency and flexibility. Therefore, all NOVA XPS amplifiers are equipped with a high pass filter (120 Hz / 18 dB / Butterworth) and a low-pass filter (120 Hz / 18 dB / Butterworth). The x-over filter type can be selected on the rear of the XPS amplifiers by using a switch. The crossover function is disabled in position FULLRANGE.
Advantage of X-over function:
► High flexibility and cost-effective configuration
of smaller systems
At the core of NOVA XPS amplifiers is the variable SMPS switching power supply, which provides stable performance even with voltage fluctuations from the mains supply (~230V +/-10%). The power supply is designed specifically for the NOVA class-DH amplifier technology. It provides a stable power supply for uncompromising performance even at full load and low-impedance. The use of this highly efficient power supply also allows the XPS amplifiers to remain lightweight.
Advantages of variable switching power supply:
► Stable performance at full load & fluctuating voltage from the mains supply
► Stable bass reproduction even at full load
The safety circuits protects the connected speakers in case of component failure . All NOVA XPS series amplifiers are equipped with following safety circuits:
► Back EMF protection
Speakers are a complex and reactive load for an amplifier. Because of the high damping factor of all NOVA amplifiers the EMF effect figures not during normal operation. In case of a defective speaker the energy could be sent back to the amplifier. This energy could potentially damage the amplifiers transistors and this is why All NOVA amplifiers are equipped with back EMF protection.
► Short circuit protection
A short circuit in a speaker or cable could damage the transistors of an amplifier. All NOVA amplifiers are equipped with a short circuit protection. This protects the amplifier.
► Overheating protection
All NOVA amplifiers are equipped with sensors at the transistors and transformers. The constant monitoring of the amplifiers temperature ensures the built-in fans sufficiently cool the amplifier.
► HF protection
Extremely high frequencies could damage the voice coils of the connected loudspeakers. All NOVA amplifiers are equipped with HF protection circuits and filters.
► DC protection
DC (direct current) at the amplifiers output stage could damage the voice coils of connected loudspeakers. All NOVA amplifiers are equipped with DC protection circuits, which avoid DC at the outputs of the amplifiers.