NAT Audio Magneto Hybrid Amplifier: Single Stage NuFET in OTL and OCL Circuitry
Serbian NAT Audio has released Magneto – a hybrid single-stage power amplifier operating in dual-mode class A. The ideology of the novelty is a proprietary amplification system OTL (without an output transformer) and OCL (without an output capacitor). The circuitry of this monoblock power amplifier is based on the NuFET (nuvistor-FET) combination.
A subminiature triode nuvistor radio tube in a sintered body is connected to two electrodes of the field-effect transistor and acts as a linearization device for the entire system. The design of the lamp, originally intended for military use, is also aimed at minimizing the “microphone” effect and negative vibrations. Another advantage of the nuvistor is claimed to be a service life of up to 10,000 hours.
The potential of the output field-effect transistor used in Magneto was 1800 watts of power dissipation. In Magneto, up to 13% of the maximum is used – as planned by the developers, this increases the reliability of the system. The amplifier works with speakers with impedance from 4 to 8 ohms, its bandwidth is 5-100,000 Hz. According to NAT staff, the Magneto power supply is a high-tech, quiet, sealed device. The peak parameters of the module are quite high – the capacitor bank of the audio class has a total capacity of 141,000 μF. Teflon (PTFE) capacitors are optional. For noise cancellation, the power supply has a coreless inductance that does not introduce magnetic contamination.
At the same time, the efficiency of the system is quite high: at 250W of power consumption, Magneto produces a maximum of 100W of pure class A. The output power of the amplifier is made switchable, options with a maximum of 30W or 100W. Magneto is compatible with true balanced (XLR) or unbalanced (RCA) connection options. The standard version of the amplifier uses a purely balanced input implemented with an input transformer with a nanocrystalline core. The system can be upgraded to the SE version, which uses an input transformer with a nanocrystalline core – silver wound OFC and Teflon insulation. In addition, the SE version has a larger input inductor.
The amplifier is assembled in a black metal case with a 15mm thick aluminum front panel. The basic version of Magneto power amplifiers from NAT Audio was priced at €14,900 per pair. In the SE version the price per pair is increased by €3,900.
