NuPrime STA-9X

NuPrime STA-9X – a Class A+D power amplifier bridgeable to 330 W mono

130 W stereo or 330 W mono from a compact chassis

The NuPrime STA-9X combines a single-ended non-negative feedback Class A preamplifier stage with a dual feedback Class D output stage. Consequently, it delivers 2× 130 W in stereo or 330 W as a bridged mono amplifier. Since the enhanced even-order harmonic circuitry mimics the warmth of valve amplification without its limitations, the STA-9X therefore sounds natural and dynamic — free from the dry, clinical character often associated with conventional Class D designs.

750 kHz switching frequency and Class A input stage

The STA-9X switches at 750 kHz — the highest switching frequency in its class. As a result, frequency response extends effortlessly to 50 kHz, well beyond the audible range. Since the Class A preamplifier stage operates without negative feedback, openness and detail resolution are therefore maximised. Furthermore, the STA-9X delivers 130% more output current than its predecessor the STA-9 — consequently driving low-impedance loudspeakers with greater authority and dynamic headroom.

Linear power supply and proprietary isolation feet

A new linear power supply with a high-efficiency toroidal transformer reduces high-frequency noise and strengthens low-frequency performance. The proprietary NuPrime isolation feet moreover absorb vibrations that would otherwise degrade audio performance. Above all, the combination of Class A input stage and high-speed Class D output delivers transient speed and dynamic impact that far exceed what the price suggests. Trigger inputs and outputs furthermore enable automatic power sequencing with other components.

The natural partner for the NuPrime DAC-9X

Since the STA-9X shares identical dimensions of 55×235×281 mm with the NuPrime DAC-9X, both components stack neatly as a visually coherent system. Together they form a complete reference-class source and amplification chain. The STA-9X is moreover bridgeable to mono for use as a monoblock in a bi-amping configuration, thereby doubling output to 330 W per channel.

Specifications

• Type: power amplifier, Class A+D, bridgeable to mono
• Output power stereo: 2× 130 W / 8 and 4 ohm
• Output power mono: 1× 330 W / 8 and 4 ohm
• Peak output stereo: 2× 170 W / 8 ohm
• Peak output mono: 1× 370 W / 8 ohm
• Switching frequency: 750 kHz
• Inputs: RCA unbalanced, XLR balanced, trigger in (12V)
• Outputs: stereo speaker, mono speaker, trigger out (12V)
• Input impedance: 47 kΩ
• Output impedance: 20 mΩ
• THD+N: 0.005%
• SNR: >90 dB
• Frequency response: 10 Hz–50 kHz
• Dimensions: 55×235×281 mm (H×W×D)
• Weight: 4 kg
• Warranty: 1 year

Frequently asked questions about the NuPrime STA-9X

How does bridging the STA-9X to mono work?

Setting the stereo/mono switch on the rear panel to mono converts the STA-9X into a 330 W mono power amplifier. The input signal is fed via the right channel, and the loudspeaker connects across the positive speaker terminals of both channels. Since output impedance remains stable, the STA-9X consequently works equally well as a monoblock in a bi-amping configuration.

What is the difference between the STA-9X and the STA-9?

The STA-9X delivers 130% more output current than the STA-9 and uses an improved Class A preamplifier stage derived from the AMG STA design. As a result, detail resolution, dynamic range and compatibility with low-impedance loudspeakers are all substantially improved.

Can the NuPrime STA-9X be used with any preamplifier?

Yes — RCA and XLR inputs make the STA-9X compatible with virtually any preamplifier or DAC with variable output. Since input impedance is 47 kΩ, it moreover works with all common source components without loading issues.