User manual ACCUPHASE C-222

[. . . ] These central DSP functions are handled by four 40bit floating point SHARC processors from Analog Devices. The display of the C-222 is a supremely large, wideformat color LCD that is configured as a touch panel. It lets you simply draw a desired frequency curve with the supplied stylus pen and immediately hear the results. Control of other functions is also easily accomplished with this panel. [. . . ] A spectrum analyzer function has been newly incorporated, providing a visual representation of the spectral content of any source in real time. The C-222 can be connected to other digital Accuphase components such as the DP-100/DC-101, DC-330, DP-85, and DP-77 via the HS-Link interface. Analog components can be accommodated by installing suitable analog input/output option boards. C-222 Features n Fully digital Voicing Equalizer with 40bit floating point DSP devices for digital signal processing. n 192 kHz/24 bit input/output interface n Two equalizing modules: sound field compensation (VOICING) and sound field creation (EQUALIZER) n Large, wide-format color LCD panel (154 × 58 mm) n Touch panel and supplied stylus pen ·Allows direct drawing of response curve on screen ·Cursor keypad can be called up for pinpoint operation and touchup Call up cursor pad to select frequency and adjust level by moving cursor right and left or up and down. ·Control functions by tapping or dragging symbols displayed on screen n 20 memory slots to store entire patterns including target curve, pre-compensation curve, postcompensation curve, equalizer curve etc. Data sets can be given a name and called up or modified at any time. Call up input panel for character input or editing n RS-232 connector for interfacing with a computer n Sound field measurement microphone AM-28 supplied Supplied stylus pen can be used to draw any desired response curve. n Supplied Remote Commander RC-30 Controls input selector, equalizer on/off, memory recall, memory number up/down. Fig. 1 C-222 Block Diagram Two main circuit as semblies with four high speed 40bit floating point DSP chips, Ultra Jitter-Free PLL circuit, tone generator, HSLink en-coder/decoder, digital input/output connectors etc. Sound field compensation (voicing) Sound field creation (Equalizer) Because the C-222 incorporates both measurement and adjustment functions, accurate sound field compensation can be carried out easily. 68 IIR type filters with 1/6 octave spacing are used for measuring the sound field, and the resulting data provide the basis for accurate compensation. This screen gives access to various functions including microphone setup, target curve setup, auto compensation, display of frequency response before and after compensation, and calling up or saving frequency response curves. When power to the C-222 is turned on, the Equalizer screen shown here appears. In this mode, the user can create a desired sound field by drawing a frequency response curve. This can be done with the supplied stylus pen directly on the display screen. Based on the measured characteristics before compensation, a target curve for achieving balanced L/R response at the listening point is created automatically. The curve can be further modified on screen to reduce small peaks and dips. L/R channael characteristics example for performing sound field compensation with the "flat" target curve. Peaks and dips caused by listening room acoustics and speaker characteristics are evened out, resulting in approximately flat response. Auto compensation is performed based on the created target curve. By harnessing room characteristics and speaker characteristics, it is possible to counter the effect of standing waves and achieve well balanced compensation for the right and left channels. Ultra Jitter-Free PLL circuit The operation of a D/A converter must be synchronized with the input signal. For this purpose, a phase-locked loop (PLL) circuit generates a master clock which is used as system reference. In the C-222, the so-called Ultra JitterFree PLL circuit developed by Accuphase is used. As shown in the illustration, this circuit consists of a detector for the preamble component (a kind of start marker for the L/R signal) and a voltage-controlled oscillator (VCO) using a quartz crystal element. The master clock produced by this PLL circuit is totally free from the effects of pulse distortion and jitter. Preamble detector ~Accuphase original digital interface~ HS-Link: High Speed Link HS-Link is an ultra high-quality digital audio interface developed by Accuphase. It supports send/receive verification for copyright protection. The LVDS (Low Voltage Differential Signaling) principle allows a single dedicated HS-Link cable to transmit signals using advanced formats such as 2. 8224 MHz/1 bit or 192 kHz/24 bit. Conventional digital formats are also supported. [. . . ] Conventional digital formats are also supported. Because digital audio data are transmitted with utmost fidelity, the sound quality achieved by HS-Link is simply outstanding. DAI signal input Preamble signal (pulse distortion removed) Phase comparator Loop filter Divider Principle of Ultra Jitter-Free PLL circuit Master clock output HS-Link Block Diagram Connections between C-222 and other components The C-222 is a Voicing Equalizer with many functions. By incorporating it into an existing audio system, the entire reproduction chain including the speakers and the listening room can be measured and optimized to achieve the best possible playback quality. The C-222 can be connected to digital components such as the DC-330, DP-85, or DP-77 (with DO2-HS1 installed) via HS-Link. [. . . ]