The silver/piano black A-S1100 from Yamaha is a dedicated single-ended integrated audio amplifier and receiver with 320W RMS. The A-S1100 features a symmetrical design, as well as floating and balanced power amplifier technology with MOSFETs. A large capacity power supply enables fast response, while an all-stage fully discrete configuration provides strong reproduction of high frequencies, and a low-impedance design produces powerful bass. The amplifier offers electronic volume control for optimum sound dynamics, a discretely configured phono preamp, and level meters that visually reflect the dynamics in the music. It additionally includes original speaker terminals and real wood side panels.
Floating and Balanced Power Amplifier with MOSFETs
The basic design of the power amplifier circuit uses a floating and balanced power amplifier technology developed by Yamaha. The output stage achieves a symmetric push-pull operation by adopting output elements with the same polarity on the plus and minus sides of the output stage, and completely separating the negative feedback (NFB) circuit and power supply into a total of four plus and minus sides of the left and right channels. Completely floating the entire power amplifier circuit from the ground removes any negative impact of minute voltage fluctuations or ground noise. Moreover, the output elements are comprised of MOSFETs. The use of MOSFETs, which have the same polarity on the plus and minus sides, further evolves the symmetrical design to eliminate sound quality variations due to difference in polarity, a major distinguishing characteristic of the floating and balanced power amplifier.
Dedicated Single-Ended Amplifier for All Types of Audio Sources
Since this device employs a dedicated single-ended amplifier, it provides amplification of single-ended analog sound from all kinds of audio sources such as CD players and D/A converters, including those made by other manufacturers.
All-Stage Full Discrete Configuration for Strong Reproduction of High Notes
This amplifier adopts an all-stage, fully discrete configuration. The slew-rate of the audio signal has been improved to bring strong response to high musical notes. Moreover, the tone control circuit lets you switch to the defeat state and enable a full discrete configuration that bypasses the op-amp IC of the internal circuit, simply by setting the bass/treble knobs to their center points.
Low-Impedance Design for Powerful Bass Response
By strengthening the capacity of the high-current route, pursuing low-impedance design, and forming screw-clamped wire connections of major ground points, the A-S1100 boasts speaker drive power with a damping factor of more than 250. Along with the large capacity power source transformer equipped with an EI core, this design delivers strong bass reproduction.
Electronic Volume Control for Optimum Sound
The A-S1100 utilizes a digital volume control designed by New Japan Radio Co., which consists only of ladder-type resistance, removing the impact of slew-rate decline or coloring of the sound. This delivers high purity sound and fast response to large volume changes and steep transients. Moreover, the tone controls employ a triple-parallel method, minimizing the detrimental impact on sound quality seen with straight-line tone controls. The bass, treble, and common circuits each use simple construction in which the NFB of the amp is not used and the CR elements are simply fixed in a straight line. This maintains sound reproduction quality even when tone control is applied. When tone defeat is applied, straight signal flow from one volume circuit to a discrete configuration buffer amp is achieved.
Large Capacity Power Supply Unit for Fast Response
The A-S1100 Amplifier employs an original EI transformer, customized for optimum compatibility with the chassis, that combines four large capacity carbon sheath block capacitors. Since the control amp and control system are equipped with twelve shunt-type local regulators that prevent deterioration caused by current fluctuation, a clean and stable power supply is achieved. The EI transformer is mounted on the chassis using a brass washer, restricting internal vibration that would result in noise.
For greater separation of the left and right channels, the A-S1100 features left-right symmetrical construction with the power supply in the center and in the ends of the power amp blocks. This is necessary for proper two-channel stereo reproduction and ideal weight balance. The fine-tuned center frame extends from the front to the back of the casing. With metal legs (selectable from spike or pad), the A-S1100 has mechanical rigidity and installation stability that lessens the impact of external vibrations on sound quality.
Discretely Configured Phono Preamp
The phono preamp is comprised of an MC head amp and an equalizer amp, each of which are discretely configured. The A-S1100 can be used to play vinyl records with both MC and MM phono cartridges.
Level Meters Visually Reflect the Dynamics in the Music
The center of the main unit features level meters that provide rapid, delicate movement of the needles. The meter is illuminated softly from inside by LEDs. The meter indicators, along with VU display, can be switched to show peak power as well, according to the user's preferences. The meter's window has been precision-fit to the panel and lies completely flat with no gaps.
Body Design with Real Wood Panels
This amplifier offers a metal front panel and side wood panels that have been integrated together. The dials and tone controls are machined aluminum knobs.
Original Speaker Terminals
The screw-type terminals with originally-designed handles are created by cutting pure brass, enabling a secure connection with no reduction in sound quality. Contoured to the shape of human fingers, they can be turned easily and fastened tightly with minimal effort. They are also compatible with connections that use banana plugs.
The supplied remote control features a design complementary to the aluminum front panel of the amplifier with a simple, easy-to-understand button layout and a metallic texture. In addition to the basic volume adjustment and input switching controls of the A-S1100, it can also be used to operate Yamaha CD players.