NuPrime STA-9X Class A+D Stereo Power Amplifier

STA-9X Class A+D Stereo 130W x2 / 330W x1 mono Power Amp

The NuPrime STA-9X, a 2 X 130W Class A+D stereo amp, bridgeable into a 330W mono amp, is designed with enhanced even-order harmonic circuitry that mimics the most attractive features of tubed and Class-A amp sound without incurring their drawbacks and limitations. The STA-9X’s frequency response to 50 kHz elevates vocals into emotional experiences; similarly, instrumental upper registers mimic a live performance’s shimmering heights.
  
Completing the ensemble is NuPrime’s new linear power supply with its high-efficiency toroidal transformer for reduced high-frequency noise and strengthened low-frequency performance. The damping effect of the NuPrime proprietary isolation feet absorbs and cancels vibrations that degrade audio performance. The overall result is unprecedented transient speed and an almost shocking level of dynamic impact.
In summary, NuPrime STA-9X has a sound characteristic that is spacious, transparent, dynamic, luxuriously textured with extended high-frequency.

Features:

• .Stereo mode bridgeable into mono mode.

• .Enhanced even-order harmonic (H2) circuitry creates warmth and natural sound characteristic.

• .Highly reliable under no-load condition and enhanced short circuit protection.

• .130% higher output current drive capability than STA-9 allows low impedance speakers to have better dynamic and power.

• .Operating at 750 kHz switching frequency, it produces high resolution with extended frequency.

• .A new linear power supply with a high-efficiency toroidal transformer reduces high-frequency noise and strengthened low-frequency performance.

• .The signal path avoids cross-linking capacitors, thus achieving a frequency response at the DC level for pure musical enjoyment.

• The NuPrime Sound:

• .Wide, lightning-fast dynamics

• .Ultra-low distortion and noise

• .Music emerges from a pristine background, with delicate details and nuances intact

# Class A+D Stereo Amp bridgeable into a 330W mono amp

 The STA-9X amplifier improved upon the ULCAM (Ultra Linear Class A Module)+Class D design of STA-9 with the design concept from AMG-STA. By joining a robust high impedance singled-ended non-negative feedback amplifier circuit in the preamp stage with a dual feedback Class-D power stage, the STA-9X sounded warm and dynamic with remarkable speed and clarity. NuPrime amplifier improves on traditional Class-D switching design by using a self-oscillating circuit to generate pulse-width modulation. STA-9X switches at a frequency of 750kHz (highest on the market), well beyond the compact disc’s 44.1kHz sampling rate. Most class-D amps switch at 300kHz or lower.

• Improved over STA-9, the STA-9X Single End Non-Negative Feedback Class A and Dual Feedback Class D amplifier design derives from AMG STA. This design allows STA-9X to produce more details and higher resolution than STA-9.
  
• Vast soundstage
  
  

In summary, NuPrime’s sonic character stands well apart from – and indeed above – the soft, cushy sound we often associate with most tubed amplification or the dry, clinically edgy sound we often associate with solid-state and switching technology. Rarely does an amp achieve an ideal balance of richly textured timbres and harmonics, bottom-end authority, startling dynamics, exquisite low-level detail, and a fully revealed, fully dimensional soundstage against a backdrop of mile-deep silence.

Specifications

Inputs:

.RCA: Un-Balanced input x 1
.XLR: Balanced input x 1
.TRIGGER IN (12V)

Outputs:

• .Stereo Speaker Out x 1
• Mono Speaker Out x 1
• TRIGGER OUT (12V)

• Power: 2 X 130W / 1 X 330W @ 8 Ohms
• Peak Output Power: 2 X 170W / 1 X 370W @ 8 Ohms
• Input Impedance: 47k Ohms
• Gain: x 28.5
• Signal to Noise Ratio: > 90dB at 1W, 10W, 100W
• THD+N: 0.005% (Stereo) / 0.005% (Mono)
• Frequency Response: 10Hz to 50kHz
• Worldwide AC voltage: (115 VAC / 230 VAC) with Voltage Select Switch
• AC Fuse: Slow-blow, 3A, 250VAC
• Dimension: 235 mm W x 281 mm D x 60 mm H (including feet)
• Weight: 4 kg
• Color: Black or Silver

Public Awards and Reviews

HiVi Winter 2024 Audio Visual Magazine Best Buy Product: https://nuprimeaudio.com/best-buy-products-by-hivi-winter-2024/

….."A stereo power amplifier featuring a compact design with a width of 235 mm. Built into its body is a single-ended A-class first stage and a high-efficiency, high-S/N D-class power stage, giving it a driving force that is hard to imagine from its cute appearance. A supple and bouncy sound. There is no roughness."….. – by Fujiwara

Stereo Best Buy Components 2023: https://nuprimeaudio.com/best-buy-components-2023-results-announcement-by-stereo-january-2024/

Power amplifier under ¥550,000 JPY

HIFI-IFAS:https://hifi-ifas.de/test-d-a-wandler-und-vorstufe-nuprime-dac-9x-mit-endstufe-nuprime-sta-9x#/ 

 …..”The sound that the NuPrime chain creates for fans is worthy of all honor: the basses are impulsive, the details are clearly worked out and the vocals are also on point – as the spoken vocals in “Diesel Power” show. The owner of the NuPrimes will not have to be picky when choosing music. That’s why “Need Some 1” from the last album No Tourist is also available . It’s good that we’re not a specialist magazine for selected audiophile music enjoyment. Gentlemen (and ladies) – that’s fun! Just one more trip to the “Wild Frontier”, which I can listen to without any noise – and then something completely different at the end.”….. - by  FALK VISARIUS

What's HiFi 5 Stars review: 

https://www.whathifi.com/reviews/nuprime-dac-9x

 ….."The NuPrime DAC-9X is a talented and versatile product that is capable of delivering pleasing results in a wide range of systems. Match it with the care a product at this level deserves and it won’t disappoint"……