Amplifier Perreaux Prisma 750
New Zealand Perreaux designs amps for 40 years, using his own schematics and design principles. Monoblocks Prisma 750, the most powerful in the company directory, differ very short sound path implemented on most modern components. The main point of original concept - used in the output stages of high-field-effect transistors. Structure MOSFET, according to the New Zealand specialists combine warmth, openness and realism of sound inherent in tube amplifiers, with a high load capacity of bipolar transistors.
Energy performance of the 30-kilogram monsters are really unique - they are able to give an 8-ohm load and 750 watts to 1300 watts when operating at 4 ohms. Claimed damping factor - 700, and the maximum output current can be up to 160 A. In all likelihood, Prisma 750 designed with a huge margin to work with any acoustics and very large rooms. The task assigned to the respective power supply power supply, which occupies more than half the volume of a very large cavity. This is a huge toroidal transformer (by type kilowatt two, no less), a powerful bridge rectifier and smoothing filter with electrolytic capacitors with total capacity of 60,000 uF. That when the machine is not knocked on the electrical power (at the time of charging the capacitor amplifier consumes a huge peak current), in the design of a system for soft start, gradually increase the output voltage of the rectifier. With this energy potential was impossible to do without the scheme, breaking the speakers in case of emergencies. In Prisma 750 protection circuit are completely isolated from the audio signal by means of optocouplers.
Audio path is fully balanced monoblock, preamplification constructed using bipolar transistors, and the output - 150 watt MOSFET, four pieces in each arm. The quiescent current is chosen so that up to 10 watt amplifier operates in class A, and only then proceeds to Class AB. Cooling is provided by giant heat sinks, occupying the entire area of the side walls of the housing.
Design Prisma 750 concise and severe. The only design element - the oval window with a blue LED on the front of the colon. The back wall is much more informative. It contains input connectors XLR and RCA, as well as toggle switch for signal distribution between them. Two pairs of solid acoustic terminals are connected in parallel for the convenience of four-wire connection. There are trigger jack for integration of the amplifier in a multi-zone system and switch "lifting of the earth", isolating the internal ground signal circuit grounding cord.
After such a detailed study of the materiel does not raise any doubt about the energy potential amplifiers. Which was confirmed in the first few minutes of listening - our speakers Monitor Audio Gold Reference 20 was for their child completely load. Volume was limited only to the fear of burn dynamics, while still remained solid stock of input power. Despite the record value of SPL, the sound did not notice any dryness or roughness, or "porridge", even on fragments with rich spectrum, which indicates a low level of all kinds of distortions. Nevertheless, the "theatrical" nature of the device yet to appear. Superbly practicing low and makrodinamicheskie effects, amplifiers still tend amalgamate small parts of the sound image, but it's much better than just ignore them than often guilty kilowatt okonechniki. All of the above refers to the volume levels comparable to those that are in real life at rock concerts. And here is understandable developers love to field-effect transistors - they are instantly react to sharp peaks, and therefore the dynamics of extremely close to the one that happens in live performance. However, if some loss of filling in the lowest octave. Here, everything is just as light and airy as the mid-range, subsonic bass although it's not always a plus.
When playing audiophile records at a comfortable volume monoblocks frankly pleased. They have proven to be licked Hi-Fi integrated amplifier - sound extremely precise in the transfer of timbral colors, with the correct tonal balance and, of course, with excellent transmission peak levels at tutti. Thanks mode "A" at low power at Prisma 750 no problem "first watt" - even at the minimum volume sound remains natural and comfortable.
