NuPrime AMG PRA

Nuprime AMG PRA is the latest addition to the family and one of Nuprime’s finest preamplifiers. A stripped-down, clean preamplifier with no built-in DAC, focused on careful handling of the music signal. We strongly recommend using dual AMG STA power amplifiers to avoid limiting the reproduction; the Evolution One is also an excellent partner for this preamplifier.

A new and unusual feature on the market is four-step tonal adjustment to match your taste and equipment. It is not a traditional tone control and does not affect sound quality.

The AMG PRA is more than a transparent preamplifier with 1 MΩ input impedance and first-class analog inputs. A selectable four-step control, “Active Low Frequency and Harmonic Gain,” gives the preamplifier its own character and enhances speaker performance. It is a world first among preamplifiers.

The front panel is milled from 15 mm thick aircraft-grade hardened aluminum alloy on a four-axis CNC machine with diamond tools, in 48 steps. Details such as the “floating” 3D logo, the curved surface around the power switch, and the diamond-cut edges give the affordable AMG series the same sense of quality as truly high-end hi-fi.

The goal with the AMG PRA was to create a transparent analog preamplifier with its own character. In addition to the 1 MΩ input impedance, several new design solutions were developed to provide the best possible analog inputs.

With smaller speakers, the bass often seems to drop off on some recordings. Instead of a simple bass boost that raises a particular frequency band, the four-step control compensates for the lack of bass presence, with slightly deeper bass and a more natural roll-off at the bottom end.

Two-stage gain and switchable phase make the AMG PRA compatible with a wider range of power amplifiers.

Technical description

The circuit boards in the AMG PRA are carefully designed to isolate sensitive audio signals from the power supply. The power circuitry, with a star topology for the power and ground planes, is on its own board, while the amplifier circuitry is on a separate board. An insulating layer separates the boards and further minimizes interference. The result is highly transparent sound that is natural and not overly sharp.

Front panel controls

Left toggle switch: gain

• Up: high gain
• Down: low gain

Right toggle switch: phase

• Up: inverted phase
• Down: normal phase

Left knob: loudness compensation

• Turn to select the loudness compensation level

Right knob: power, input selection, and volume

• Hold for 3 seconds to turn on or enter standby
• Press briefly to switch inputs
• Turn to adjust the volume

Specifications:

• Frequency response: 10 Hz - 200 kHz, +0 to -0.1 dB
• THD: 0.008%
• Input impedance:
  • Balanced input: 1 MΩ at 10 Hz - 200 kHz
  • Line input: 1 MΩ at 10 Hz - 200 kHz
• Nominal output voltage: 2 V (line) / 4 V (balanced) at 100 ohms
• Volume level 92 corresponds to 0 dB (input = output)
• Signal-to-noise: 95 dB
• Loudness compensation:
  1. 2.2 dB (125 Hz)
  2. 4.5 dB (100 Hz)
  3. 5.3 dB (75 Hz)
• Gain: 3.2 (high) / 2.1 (low)