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Mimics the Most Attractive Features of Tubed and Class-A Amp Sound
The NuPrime STA-9X is a 2 X 130W Class A+D stereo amp, bridgeable into a 330W mono amp. It's 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, while instrumental upper registers mimic a live performance’s shimmering heights.
The STA-9X amplifier improves upon the ULCAM (Ultra Linear Class A Module) + Class D design of the STA-9 with a design concept taken from the high-end NuPrime AMG-STA amplifier. 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 sounds warm and dynamic with remarkable speed and clarity.
<h4"Exceeds Its Peers by a Wide Margin"
"NuPrime has struck gold with the premium and affordable 9X Series. The optics and construction of the compact DAC-9X, STA-9X and Stream-9 hi-fi components are formidable. Thanks to the many features, the equipment level and the available connections, this NuPrime series occupies a unique position," observes Harro Tillema, hifi.nl, January 8, 2024.
"When it comes to the music experience, it exceeds its peers by a wide margin. The sound quality is phenomenal. As the NuPrime itself indicates: 'Beyond Ordinary,' and this is not a lie."
Improves Upon Traditional Class-D Designs
This NuPrime amplifier improves upon the 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.
The 130% higher output current drive capability than the STA-9 allows low impedance speakers to have better dynamic and power with the STA-9X. Plus, it is highly reliable under no-load condition and features enhanced short circuit protection.
An Almost Shocking Level of Dynamic Impact
Completing the upgrades is NuPrime’s new linear power supply with its high-efficiency toroidal transformer for reduced 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 damping effect of the NuPrime proprietary isolation feet absorbs and cancels vibrations that degrade audio performance. The result of all this advanced technology is unprecedented transient speed and an almost shocking level of dynamic impact.
In summary, the sonic character of the STA-9X stands well apart from – and indeed above – the soft, cushy sound we often associate with most tubed amplification or the dry, clinically edgy sound associated with solid-state and switching technology.
Enhanced even-order harmonic (H2) circuitry creates warmth and natural sound characteristic. According to NuPrime, "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."
"Remarkably Coherent"
"With the STA-9X NuPrime have pushed their proprietary Class D design to its highest switching speed within the entire line up – at 750kHz the ‘9X stands above even the Evolution models. You can hear this in the speed and agility during complex passages," reports totallywired.nz.
"Conventional thought is that amplifier output should double when you halve impedance. But when you consider that most speakers vary in impedance over a range of frequencies this is possibly not so great. Also distortion levels can vary over this range. The STA-9X has a completely stable output regardless of the speaker impedance it is connected to. This is one of the reasons the new STA-9X sounds remarkably coherent."
