Speaker terminals are the final step in the music signal I/O process, and these large screw-type terminals are compatible with banana plugs.

The R-K731 features the latest digital technology to convert and amplify the music signal more accurately. In order to eliminate “voice data conversion loss” and the “influence of external noise” that occur in existing circuit architecture, the R-K731 features a “full digital amp” to perform all signal processing digitally from the signal input to the final step in the amp. In addition, the “Lch amp” and the “Rch amp” each have independent architecture. When combining these with power-supply circuits that have also been made independent, it enables accurate signal amplification with excellent channel separation and reproduction of sound faithful to the original audio.

The power-supply circuit supports accurate signal conversion and features independent architecture for the “digital circuit,” the “CD mechanism,” the “analog circuit,” and for the “amp.” This suppresses interference from the power of the mechanism parts and improves playback of weak signals. In addition, power is supplied independently to the Lch and Rch amps, and the right and left amps have independent digital amp architecture. Rectified power provides an even more stabilized power supply, thereby removing ripple noise and realizing stable operational amplification.

The power supply features a large EI core transformer to support sound quality. In order to suppress interference from the operating current between each circuit, each part is supplied power separated by windings to support the basic sound. In addition, the sound quality has the high-quality bass reproduction expected of an analog transformer.

The supporting legs use a specialized insulator that absorbs unnecessary vibrations.

The handsomely designed front panel is constructed of 4.5mm thick aluminum that increases the rigidity of the entire structure to suppress the influence of external vibrations and helps create even more realistic sound.

The R-K731 features a new, uniquely shaped chassis not only to suppress external vibrations that influence music playback, but also to control the vibrations that cause sound quality degradation. This effectively reduces vibration sound wave harmonic and fluctuation levels. In addition, a rigid case is used in the unit to suppress the influence of external vibrations and create an even smoother sound.

The speaker cabinet, the most important part that affects sound quality, features a high-density MDF material has high rigidity for excellent sound. The front baffle is 18mm thick and supports the correct vibration amplitude of the speaker unit. In addition, we’ve gently rounded the top part of the baffle to greatly reduce unnecessary diffraction waves that result in a secondary sound element, and to improve treble characteristics while also enabling　natural and beautiful sound field reproduction.

These tweeters feature a silk diaphragm with natural tonality that can clearly reproduce treble-range signals up to 65kHz. By combining this with an aluminum die-cast frame, that controls radiation characteristics, we created a more nuanced reproduction and at the same time improved the reproduction of weak signals.

The woofer unit now features a diaphragm that makes use of high-quality pulp and a rubber edge with little loss. These create mid-range reproduction with a natural tone and powerful but comfortable bass reproduction. In addition, the magnetic circuit that drives the diaphragm features a low-strain magnetic circuit which uses a copper cap and aluminum short rings. The aluminum short rings absorb the alternating current produced by the vertical motion of the voice coil, and when combined with the copper cap added to the bottom plate, they reduce distortion of the vocal band and improve musical expression.

The speaker terminals feature large terminals compatible with banana plugs. These also enable a secure connection with thick speaker cables that are commercially available.