Nuprime AMG PRA Pre-Amplifier

Nuprime AMG PRA Pre-Amplifier

The AMG PRA went beyond being a transparent preamp with 1M Ohm input impedance and the best analog source inputs. A user-selectable 4 stage “Active Low Frequency and Harmonic Gain” control gave it distinctive characteristics to enhance the speaker performance, a world-first in preamp design.

he AMG series front panel embodies its spirit. It is milled from a 15mm harden aerospace aluminum alloy using a four-axis CNC machine with a diamond cutter through a 48 steps process. Design elements such as the 3D “floating” logo, the curved surface around the front panel switch, and diamond-cut edge bring the quality of ultra-high-end audio products to the affordable range of the AMG series.

The design goal for AMG PRA was to deliver a transparent sounding analog preamp with its distinctive characteristics. Several new design concepts were developed and used in the AMG-PRE besides 1MΩ input impedance to achieve the best analog inputs.

Users of smallish speakers would often detect a distinct drop in bass response with some audio tracks. Instead of a simple “Bass Boost” function that lifts a targeted low-frequency band, a user-selectable 4 stage “Active Low Frequency and Harmonic Gain” control compensates for the lack of bass presence. It achieves some bass extension and a more natural roll-off.
Additional features such as the 2 stage gain control and invertible phase control increase the compatibility of the AMG-PRA with other power amplifiers.

Technical Details

The layout of the AMG-PRA takes excellent care in isolating the sensitive audio signals from the power circuitry. The power circuitry comprising of a star topology power and ground layers is built on one board while a separate board houses the pre-amplification circuit. An isolation layer separates these two boards, which further minimizes interference. The effect is a highly transparent sound that is natural and not over etched.

Features

• MUSES72320 Digital Volume Control
• ONE MEGA ultra-wide bandwidth low noise JFET, single-ended Class A input design and MUSES8920 Op-amp produce harmonics similar to vacuum tube amps, which has a “warm, airy and velvety” sound characteristic.
• Non-feedback low-frequency domain Frequency Harmonic Modulation circuit provides minimum phase distortion and tone error.
• Inputs and outputs are fully balanced design.

Front Panel Settings

• Left Toggle Switch: Output Gain
• Upwards : High Gain
• Downwards : Low Gain
• Right Toggle Switch: Output Phase
• Upwards : Phase Invert
• Downwards : Phase Normal
• Left knob: Loudness Compensation
• Turn the knob to switch between Loudness Compensation
• Right Knob: Power and Input Selector and Volumes
• Briefly press for 3 sec to On/Off standby mode
• Brief press to Input Selector
• Turn the knob to adjust volume

Specifications

• Frequency Response: 10Hz to 200kHz; +-0 to -0.1dB
• THD: 0.008 %
• Input Impedance: Balanced IN: 1M Ohm @ 10 Hz ~ 200 kHz /  Line IN: 1M Ohm @ 10 Hz ~ 200K Hz
• Rated Output Voltage: 2 V (LINE) / 4V (BAL) @ 100 Ohm
• Volume level 92 is 0dB input = output
• S/N: 95 dB
• Loudness Compensation: 2.2 dB (125 Hz) /  4.5 dB (100 Hz) / 5.3 dB (75 Hz)
• Gain : 3.2 (High) / 2.1 (Low)