The requirements imposed upon modern power amplifiers are enormous: they are expected to combine very high power, minimal weight, outstanding audio performance, absolute reliability,
remote monitoring and control, and networking.
In order to realize power levels of 2500 W / 4 Ω, power amplifiers must be able to supply peak output voltages between 180 V and 200 V. This requirement limits the number of plausible topologies to two:
Class D and Dynacord's Linear Grounded Bridge Class-H.
After extensive research, the Dynacord engineering department decid- ed against the use of Class D designs: the besetting evils of Class D technology – primarily, distortion and a clear load-dependence in the frequency response – cannot be overcome, even by modern designs, and the result is an un-wanted discoloration of the output signal.
Linear push-pull designs with Class-H topology are acceptable solu- tions for output levels up to 1500 W / 4 Ω and are used in many Dynacord power amplifiers. The limitation of the Class-H push-pull approach is the 250 V specification of typical audio power transistors and their second breakdown restrictions. Even exceeding the speci- fied peak voltage or the second breakdown limit for a short period leads directly to failure of the power transistors and the power ampli- fier. The use of exotic 350V-specified transistors presents no reliable solution in view of their second breakdown behaviour, their perform- ance and also their availability.
Higher power classes require different solutions! Dynacord's Linear Grounded Bridge designs (e.g. L 2400/P3000) have proven extreme- ly reliable over many years as well as outstanding in terms of audio performance. One of the key advantages of Grounded Bridge solu- tions is the considerable reduction in 'voltage stress' for the power transistors. This permits the design of high-power power amplifiers with peak output voltages in excess even of 200 V. A logical step in the direction of lowering power dissipation while increasing the out- put power at the same time was the development of a linear Grounded Bridge topology using Class-H technology with a three- stage switching, floating power supply. The use of an extremely sta- ble switching power supply makes a decisive contribution to the very low weight of these power amplifiers: 7 kW packed into 2 rack- spaces and weighing less than 15 kg!
PowerH power amplifiers are ready for integration into IRIS-Net™- based audio systems and networks. Retrofittable remote control modules, e.g. the RCM-26, make possible complete system supervi- sion and remote control combined with digital controller functions including ultra-precise FIR filters and optimised loudspeaker protec- tion algorithms
