NuPrime Evolution STA

The Evolution STA is a stereo power amplifier from NuPrime, built on a dual-mono architecture that separates the amplification circuits of the two channels. It is aimed at those seeking a Class D electronic capable of driving a pair of speakers directly with a high level of precision.

The heart of this amplifier relies on a design that NuPrime calls Only Distortion Cancellation (ODC). Unlike a conventional error correction that reinjects the inverted output signal into the input signal to generate a corrective signal, ODC derives the error signal directly from the MOSFET devices and the output filter. This approach greatly reduces reliance on negative feedback, which translates into very low harmonic distortion when listening: NuPrime states a THD+N rate of 0.002% at 1 kHz for a power of 5 W, and less than 0.005% over a range from 2 W to 100 W at the same frequency.

In terms of power, the Evolution STA delivers 2x230 W RMS into 8 ohms and rises to 2x310 W RMS into 4 ohms, with respective peaks of 2x270 W and 2x360 W. The gain of x21 combined with a sensitivity of 2 Vrms and an input impedance of 47 kOhms make it easy to pair with a preamplifier or a source with a standard line output. Its frequency response extends from 10 Hz to 50 kHz at -3 dB, a wide range that comfortably covers the audible spectrum with margin at the extremes.

This amplifier suits a demanding stereo setup, where one seeks to get the best out of speakers able to handle substantial power, including under a 4 ohm load which is harder to drive. Its compact size of 430 x 372 x 66.5 mm and modest weight of 10.5 kg make it an electronic component that is easy to fit into a cabinet or shelf, without the constraints of a traditional Class A/B amplifier of equivalent power.