Esoteric Grandioso C1X Solo Preamplifier

There are two main methods of volume control system employed in preamplifiers. The “stepped attenuator circuit,” which switches multiple fixed resistors to adjust the volume, is an ideal method for a preamplifier that pursues sound quality because of high reliability at the contact points and bringing out pure and direct sound quality. However, since the volume is defined by switching resistors, the circuit scale becomes too large for smooth volume adjustment. In contrast, another method, “variable resistor (potentiometer)” allows smooth, step-less volume adjustment. However, the signal path is longer, and the potential of deterioration of crosstalk between the left and right channels and deterioration of contact points exists due to aging. The newly developed “Ultra Fidelity Attenuator System” is the fruit of our pursuit of an ideal attenuator circuit that realizes smooth, step-less volume control of the “variable resistor”, while maintaining the excellent sound quality of the “stepped attenuator circuit”.

The core of the Ultra Fidelity Attenuator System is the UFA-1792, our proprietary module that integrates a stepped resistor attenuator into an integrated circuit. The internal resistors can be switched in 0.1dB/1,120 steps, which means that the volume can be adjusted in astonishingly fine, nearly infinite steps, compared to a typical attenuator module which offers about 0.5dB/100 steps. In addition, as an original module, everything from materials, layout and internal circuit patterns has been uncompromisingly scrutinized to achieve the resolution and tone quality befitting a top-of-the-line preamplifier.

The heart of the preamplifier’s amplification circuit is our proprietary module “Integrated Discrete-Amplifier Module IDM-01”. Carefully selected materials, circuit patterns, and layout, thoroughly implement the Esoteric’s sound philosophy, just like a discrete amplifier, and the extremely short signal path which is the beauty of integrated circuits, allows dynamic and delicate amplification of musical vibrancy.

Based on two original new module technologies (UFA-1792, IDM-01), a lot of materials suitable for a flagship model are employed. The Grandioso C1X solo is configured with a dual balanced preamplifier circuit that employs four Ultra Fidelity Attenuator System per channel. All input signals are balanced and internally transmitted with low impedance to minimize noise effects, while the dual balanced configuration employing the best module technology is completely free from channel crosstalk and level balance issues; powerful, and above all, firmly transmits the vibrancy of music to the power amplifier.

Many audiophiles have experienced the speakers started to “sing” immediately after changing the preamplifier. Audibly, the preamplifier has a great influence on the drive power of the speakers, and a good preamplifier will drive and control the speakers to the maximum level.
The Grandioso C1X solo maximizes the driving of the power amplifiers by applying the largest possible amount of material to the output buffer amplifiers. The output buffer amplifier employs the Esoteric-HCLD (High Current Line Driver), which is renowned for its excellent drive capability and 180MHz wide range, and boasts an astonishingly high-speed slew rate of 2,000V/μs. This powerful buffer amplifier is installed in a parallel configuration for a single signal line, while the output buffer amplifier has an independent power supply section, – with two dedicated large toroidal power transformers in independent left and right configurations. The C1X solo’s output buffer amplifier, which boasts the powerful current output capability befitting a flagship, fully powers the amplifier and the speakers, conveying to the audience an unprecedented level of vibrancy.

We believe that 70% of the sound quality of a preamplifier is determined by the design of the power supply section. The C1X solo consists of a total of five main components: left and right input/output amplifiers and a control section. All five of these are powerfully driven by five independent power transformers for each section (audio system: toroidal core, control system: R core).
By separating the power supply components for each section and investing far more amount of materials than intrinsically required, mutual interference between circuit blocks is fundamentally eliminated, resulting in extremely pure and dynamic sound quality. In addition, carefully selected parts appropriate for a flagship model, such as the high-capacitance Grandioso custom block capacitors and Schottky barrier diodes, are employed in pursuit of high sound quality.

With the flagship Grandioso amplifier models, Esoteric is breaking new ground by pushing the limits of fidelity in pre-preamp-to-amplifier signal transmission. Esoteric’s unique current transmission system “ES-Link Analog” is the ideal method for preamp to amplifier transmission where the signal level is extremely low. Compared to the conventional voltage transmission, it transmits approximately 100 times more current, making it less susceptible to noise and sending the full energy of the music to the amplifier.
Also, it is not affected by the impedance of the interconnects running between the preamp and amplifier, so it maintains a perfect integrity between the output signal of the preamp and the input signal to the amplifier.

The input amplifier section, as well as the output amplifier section, is configured with complete dual mono/dual balanced circuits with independent left and right power transformers and rectifier circuits. Input signals are transmitted without loss by using Esoteric-HCLD buffer amplifiers for signal transfer from the input amplifier to the output amplifier. For the input switching, a switch with an FET element is employed instead of the conventional mechanical relay system. The FET element allows 12A instantaneous current and 3A constant current,and minimizes current loss.
The conventional mechanical relays add sonic coloration by using rare earth materials at their contact points, emit operation noises, and wear over time – the FET elements are totally free from these negative factors, sound neutral and are reliable all the time.

The logic control section, which controls operation and display, is shielded and housed in the front panel, isolated from the audio circuits. A photo-coupler that converts the control signal to optical signal for transmission is employed for connection to the preamplifier section to ensure physical and electrical isolation.
Furthermore, by completely shutting down the control circuitry except during operation, low-noise operation is achieved without affecting the audio circuitry. We improved operability by having the built-in program automatically lower the volume level to zero when the preamplifier is turned off, and automatically restore the level when the power is turned back on. We also aimed for a high-end operability that is full of elegance and a pleasure to use, such as fading out/fading in the music signal when switching inputs.

To achieve the unique design goal of “reproducing the master sound,” the C1X solo chassis optimally controls all vibrations that can affect sound quality. The sleek and clean form of this sports car-like mechanical engineering, to pushes the limits of its balance between rigidity and flexibility, and speaks to its high degree of perfection.
For example, the enclosure, which requires rigidity, makes extensive use of aluminum blocks and is thoroughly non-resonant, while the top panel, which needs to be free of vibration for an open sound, has a semi-floating structure. Esoteric’s unique patented isolation foot, which integrates a spike and a saucer, also has a special mounting structure that reduces mechanical stress and enhances sound quality.

The volume control and input selector employ solid construction knobs machined from an aluminum block. By adopting a bearing mechanism developed in the design of VRDS drive mechanisms for the rotary axis, extremely precise rotation without core shake is achieved. By adjusting the rotational torque to the optimum level, a smooth, analog-feeling operation is achieved, befitting Esoteric’s flagship preamplifier.

A compact and simple remote control is included that can also operate Esoteric digital source devices. The functional design features buttons used for each operation scenario on both sides of the remote control, and the smartphone-sized aluminum body, which fits comfortably in the hand, is achieved through advanced metal processing. Esoteric’s new approach is a design that allows you to experience thoughtful operability and craftsmanship every time you pick it up.