Cayin C9ii Flagship Portable Headphone Amplifier

Cayin C9II: Reinventing Portable Audio Amplification with Nutube Technology

The Cayin C9II redefines portable audio, building on the legacy of its predecessor, the C9. This innovative amplifier introduces groundbreaking features like no-feedback operation, local feedback adjustment for its dual 6P1 Nutubes, and adjustable anode voltage, offering unparalleled sonic versatility.

Uncompromised Circuit Purity and Performance

At its core, the C9II is a testament to circuit purity. In its "rawest form" – with no global feedback and minimal local feedback around the Nutube voltage gain stage – it delivers an exceptionally clean and natural sound. This simple yet effective design outperforms more complex circuits, especially within its portable form factor.

Hyper Mode and Balanced Differential Operation for Maximum Performance

Cayin has engineered the C9II for peak performance in every mode of operation. "Hyper mode" pushes the operating voltage and bias to their linear open-loop maximum, while fully balanced differential operation ensures optimal signal integrity.

Customizable Sound Signatures with Nutube Technology

The C9II empowers listeners to precisely tailor their audio experience. Adjustments to parameters like tube anode voltage and the feedback loop around the Nutubes unlock up to five distinct sonic signatures. In "Classic mode," the Gen 5 Nutube circuit eliminates global negative feedback, resulting in a more immersive, faster circuit free from time lag and transient intermodulation distortion. While this may show a theoretical increase in distortion, it's of a low-order, less jarring variety compared to the complex intermodulation caused by excessive feedback.

Superior Linearity and Distortion Control

The C9II's linear open-loop circuit, combined with immaculate parts gain matching, sets a new standard for audio fidelity. Class A bias and high operating voltages further enhance its performance, allowing for remarkably audible sonic outcomes by adjusting Nutube anode voltage. The C9II maintains excellent linearity even without error correction due to inherently fewer errors in its design. Cayin's differential, balanced operation excels in common-mode rejection, amplifying the signal while effectively blocking non-linear distortion and noise.

Hybrid Design: Nutube and Solid-State Excellence

While the 6P1 Nutubes are the star, the C9II's solid-state input deserves equal recognition. Four channels of single-ended Class A Toshiba JFETs operate in a unique quasi-complementary fashion, utilizing only NPNs to avoid PNP mismatches, and leveraging even-order harmonics and square law for a distinctive portable differential circuit.

Advanced Volume Control and Discrete Signal Path

After selecting your preferred sonic permutation, the input signal passes through JRC's MUSES 72320 resistor ladder volume controls. Strategically placed after the driver stage, these controls preserve fragile small-signal integrity and maintain an excellent signal-to-noise ratio. The entire signal path is handled by discrete transistors, ensuring uncompromised resolution, a clear departure from typical op-amp ICs. Cayin's dedication extends to its discrete, differential analog stage for superior common-mode rejection.

Optimized Driver and Headphone Power Amplifier Sections

The C9II's driver section benefits from a discrete FET & bipolar design, offering low open-loop gain, reduced negative feedback, high slew rates, excellent current handling, and unity gain stability. Cayin's headphone power amplifier section is inherently stable, avoiding oscillation, and meticulously designed for optimal performance.

True-Balanced Design for Unparalleled Linearity

Unlike many amplifiers that rely on op-amp layouts for THX-certification with excessive gain and feedback, the C9II achieves exceptional linearity in the open-loop due to its high operating voltages and bias. This ensures individual transistors operate optimally, keeping distortion and noise low without resorting to excessive negative feedback. The true-balanced differential amplifier design further enhances linearity, providing best-in-class common-mode rejection when connected via a 4.4mm output, preserving every detail.

Deep Bass and Effortless Dynamics

The direct-coupled output stage significantly improves low-frequency performance, allowing the C9II to audibly plumb the lowest bass depths. This extended low-end, combined with excellent phase reproduction in the human hearing range, results in taut, hard-hitting, and remarkably lifelike dynamics.

Robust Power Delivery and Natural Sound

The power stage features large bipolar devices in a parallel emitter-follower configuration, ensuring excellent beta and current handling. This design fully leverages Cayin's quad of 18650 batteries, providing direct DC without voltage boost conversion. These power transistors are highly linear in the open loop, operating with full bias and high voltages, allowing them to be removed from the global feedback loop with a single button press. This reduction to local feedback for small-signal gain control results in a more natural, faster, simpler, and responsive circuit that presents musical information effortlessly.

A Portable Future of Linear Amplification

The Cayin C9II represents Cayin's latest achievement in old-school linear amplification, expertly adapted for the portable future. It offers uncompromising sound quality, perfectly managing the complex crossovers of flagship IEMs. The C9II's versatile tuning options reflect the growth of the portable audio market, promising to adapt and enhance your evolving transducers and portable sources, giving you complete control over your audiophile nourishment.

Keywords: Cayin C9II, portable amplifier, Nutube, tube amplifier, audio amplifier, high-resolution audio, balanced output, audiophile, portable audio, linear amplification, discrete design, no feedback, anode voltage adjustment, sonic signatures, IEM amplifier, headphone amplifier.