Accuphase DF 45 Brochure

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Multi-channel divider with fully digital signal processing – High-speed 40-bit floating point DSP provides the processing power for four channel units supplied in standard configuration. Choice of 59 cutoff frequency points ensures total flexibility. Highly accurate digital filters enable 96 dB/octave slope characteristics. Time alignment function adjustable in 1-cm steps, plus delay compensator for offsetting filter circuit delays ensure superb spatial accuracy. HS-Link capability provides SA-CD support. Unbalanced Balanced Buffer Digital Inputs Analog Inputs Left Analog Outputs Right Analog Outputs Unbalanced Balanced Master LevelDigital Filter Master LevelDigital Filter Frequency Level Phase Subwoofer Slope Delay Delay Comp Output DSP Floating Point DSP : Digital Signal Processor DAI Decoder Encoder Clock Distributor Micro- computer Digital Output Channel A Channel D Display Coaxial Transceiver Coaxial Receiver Optical Receiver HS-Link Receiver A/D Converter A/D Converter Channel C Channel B BalancedHS-Link UnbalancedCoaxial Coaxial Optical Coefficient Memory Buffer Sampling Rate Converter Analog Attenuator ON/OFF Analog Attenuator ON/OFF MDS++ D/A Conversion System X4 MDS++ D/A Conversion System X4 Channel dividers based on fully digital signal processing The central task of a multi-amp system is of course the division of the frequency spectrum into multiple bands or channels. The channel dividers in the DF-45 feature an impressive array of sophisticated digital technology based on a DSP chip with amazing power. The high-speed 40-bit floating point design of this device makes it possible to implement all filtering and delay functions as well as phase and level control in fully digital form. With minimal temperature drift and excellent long-term stability, this ensures filtering performance of the highest order. High-speed 40-bit floating point DSP assures precision digital filtering As a crucial circuit element, the digital filter is configured with a high-speed 40-bit DSP that has a 32-bit mantissa and 8-bit exponent section. The floating point principle enhances calculation accuracy and results in dramatically improved dynamic range. This allows the implementation of extremely steep filter slopes of up to 96 dB/ octave. 59 selectable cutoff frequency points Filter frequency points can be set over the range from 31.5 Hz to 22.4 kHz in 1/6-octave intervals. Same as Channel A (no Subwoofer in DSP ) Fig. 1 DF-45 Block Diagram Same as Channel A (no Subwoofer in DSP ) Same as Channel A (no Subwoofer in DSP ) In addition, 10, 20, and 290 Hz points are also provided, resulting in a total of 59 points. Each divider unit is fully flexible and allows free selection of the lower and upper cutoff frequency, for configuration as a low-pass, bandpass, or high-pass filter. Six filter slope characteristics up to 96 dB/ octave The filter attenuation characteristics can be set to 6 dB/octave, 12 dB/octave, 18 dB/octave, 24 dB/octave, 48 dB/octave, or 96 dB/octave. Within each unit, separate settings for lower and upper slope are possible, resulting in a wide variety of combinations. Time alignment function allows adjustment in 1-cm steps When multiple speaker units are used, differences in sound source location (diaphragm position on the front/back plane) will lead to different arrival times of the sound at the listener's ears. Time alignment is a function designed to compensate for such Multi-amplification is regarded as the pinnacle of the audio world. The term refers to dividing the musical spectrum into several distinct bands and handling each of these using a dedicated power amplifier and directly connected speaker unit. When configured and adjusted properly, such a system can achieve sound reproduction on a scale that is not possible by any other means. Sonic definition and spatial imaging can be optimized by the user to obtain exactly the desired result. Configuring a multi-amplified system affords truly one of the greatest pleasures of audio. The Digital Frequency Dividing Network DF-45 repre- sents a further evolution of the model DF-35. Only the latest digital technology is employed throughout, and all inter- nal signal processing occurs fully in the digital domain. High-speed 40- bit floating point DSP chips allow super-precise high-order filtering with a slope of 96 dB/octave. This in turn enables the digital input to handle sources up to SA-CD quality. In addi- tion, balanced and unbalanced analog inputs are also provided, and the unit comes as a 4-channel device (for 4-way amplification) in its standard configuration. Each channel in the DF-45 is handled by a dedicated unit. A full array of functions including frequency dividing filters (low-pass, band-pass, high-pass), attenuation slope characteristics, delay and delay compensator function, level control, and phase switching are implemented in the digital domain. To store parameter settings for various scenarios, five memory positions are provided. The DF-45 allows the user to select cutoff frequency settings for adjacent bands from 59 choices, plus six different attenuation slope settings (max. 96 dB/oct). This unprecedented flexibility makes it possible to elicit optimum performance from every speaker unit, achieving a smooth transition between bands and ensuring exactly the desired overall energy balance. A high-quality multi-amp system built with the DF-45 will sound its very best. [Hz] [dBr] PASS 6dB/oct 6dB/oct 1 2 d B /o c t 12dB/oct 18dB/oct 18dB/oct 24dB/oct 24dB/oct 48dB/oct 48dB/oct 96dB/oct 96dB/oct PASS Frequency Fig. 2 Divider unit slope characteristics (bandpass filter)[Cutoff frequency setting 100 Hz for lower and 1 kHz for upper range] differences. The DF-45 incorporates this in the form of a DELAY function that electrically adjusts the time when the sound from each driver reaches the listener. In Figure 3, the sound from the two speaker units [L and H] at the start exhibits a time difference of t seconds due to the front/back distance d (cm) of their respective diaphragms. In order to eliminate this difference, the delay function delays the sound of the (H) unit by t seconds. Normally, a delay would be expressed as a time value, but since the delay here is caused by a spatial distance (of the two diaphragms), the DF-45 converts the delay into a distance value (cm) and shows this value on the display for easier understanding. High-speed 40-bit floating point Digital Signal Processor (DSP) Circuit assembly with high-speed DSP

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t=34,000d d cm L Delay Delay H H L DAC 1 DAC 2 DAC 3 DAC 4 (seconds) Inputt seconds t seconds Delay function delays H wavefor m by t seconds B Time Start time Speaker units L and H (diaphragm) are d centimeters apart Delay ensures that Land H signals arrive at the ear at the same time Fig. 3 Principle of time alignmen t Speed of sound = 331.5 + 0.607 T [ms] T: temperature (°C) Consequently, at 14°C, sound travels at about 340 m/s. In the example above, when DELAY function for H is set to d cm, the signal start for H will be delayed by t seconds (✽), causing the sound from L and H to reach the listener at the same time. (✽) Further Improved MDS++ D/A Converter MDS (Multiple Delta Sigma) is a revolutionary design which employs several delta sigma type converters in a parallel configuration. In the combined output of these multiple converters, conversion errors cancel each other out, resulting in a drastic improvement in all relevant aspects of conver ter performance, such as accuracy, S/N ratio, dynamic range, linearity, and THD. In the DF-45, four delta sigma type D/A convert- ers (AD1955 from Analog Devices) are driven in par- allel. Compared to a single converter, this results in an overall performance improvement by a factor of 2 (= √4 ). As shown in the diagram, the MDS++ features an enhanced current-to-voltage (I/V) converter for processing the D/A converter output current. To reduce the load on the current adder, a combination of current Block diagram of MDS++ converter (Normal phase output) (Reverse phase output)I (current) / V (voltage) converter Current summing Voltage summingSubtractionDAC output Other Functions and Features nIndividual output ON/OFF control for each channel. nIndividual 4-position phase control for each channel. nDigital attenuator with setting range from -40.0 dB to +12.0 dB (in 0.1-dB steps) allows precise level adjustments for left and right channel. nMemory for five sets of parameter and function settings in each channel. nUnused channels can be set to OFF (all display elements and LED indicators are out). nSafety Lock prevents inadver tently changing any settings. nFull Level Output Protection function safeguards the speakers if a digital signal without volume control data is input (output level is reduced by 40.0 dB). nVersatile input connector array comprises coaxial, optical and HS-Link inputs for digital signals and balanced and unbalanced inputs for analog signals. n5-way and higher configurations can be realized by using more than one DF-45 unit.nAnalog ATT function ( –10 dB) can be activated for specific channels to reduce residual noise when using high-efficiency midrange or high range speaker units. nDisplay indication can show predefined strings or custom strings entered by the user (max. 8 characters, character set with 97 characters). nEasy selection of Subwoofer (3D) mode using dedicated switch in channel A. nAnalog output for each channel supports balanced connection.nThe DF-45 incorporates four units named CHANNEL A - D (4-way configuration). The assembly shown here carries the coaxial digital input and output connectors, unbalanced analog input connectors, MDS++ D/A converter modules for 4 channels, and unbalanced analog output connectors. summing and voltage summing is used. The overall result is further improved stability and top- notch performance. The music emerges from a totally silent background, with breathtaking detail resolution and accurate spatial information.