Предусилители — Nuprime Audio PRA-9X

The PRA-9X is a fully balanced preamplifier from NuPrime Audio that combines a line stage, a moving magnet phono input and a headphone amplifier in one compact case. NuPrime designed it around very low distortion, quoting THD+N of 0.0004%, and the same figure is repeated for the four new amplifier modules that do the gain work inside.

Key specs that matter

The rear panel offers one XLR stereo input, two RCA stereo inputs and the MM phono pair, while the outputs comprise a balanced pair and a single-ended pair. On the line side, input resistance is 20 kohm and output resistance is 10 ohm. Line gain is 17 dB at 1 kHz, the frequency response stays within 0.2 dB from 0 Hz to 50 kHz and reaches its -3 dB point at 200 kHz, with noise more than 115 dB below the reference level. The distortion and noise figures are taken at a 7.5 V output. The phono section provides 50 dB of gain with a sensitivity of 4.0 mV at 1 kHz. A 6.3 mm socket on the front drives headphones with 560 mW into 32 ohm or 110 mW into 600 ohm, at 0.004% and 0.0015% THD+N respectively, while its noise floor sits more than 110 dB down at 32 ohm and dynamic range is above 115 dB. The case measures 55 x 235 x 281 mm and weighs 3 kg.

Engineering and use context

NuPrime credits the low distortion to its next-generation current booster circuit. The phono amplifier works in two stages to apply the RIAA curve, using NJR MUSES8820 operational amplifiers so the equalisation stays accurate at high gain. DIP switches select an input resistance of 32, 47 or 100 kohm and a capacitance of 100, 220 or 320 pF, allowing the load to be set for the cartridge in use. Inputs are switched by relays, and volume is controlled digitally in fine 0.5 dB steps with the last setting stored in memory. One front knob handles power and input selection, the volume control mutes the output with a short press, and a display shows the current status. The remote covers power, display on and off, volume, mute and direct access to each of the four inputs. A selector sets the unit for mains of 90 to 130 V or 210 to 250 V AC. The warranty period is one year.

Pairing

Balanced cables are the natural link to a power amp that has XLR sockets, and single-ended leads serve the rest. Vinyl playback with a moving magnet pickup goes straight to the phono input, leaving the XLR and two RCA line inputs for a DAC, streamer or CD player.

Alternatives

The NuPrime AMG PRA is a fully balanced line-only preamplifier with a 1 Mohm input impedance and a four-step low frequency and harmonic gain control.