Audio Database

The

Accuphase DC-300
980,000 yen(November, 1996 release)

Description

The digital preamplifier which combined the new circuit which made full use of the DSP technology of carrying out high-speed operation processing for an advanced digital technology to a foundation, and was developed as the first in the world.

The same axle and the optical input terminal can input the digital signal up to sampling frequency 32/44.1/48kHz and 24 bits. The automatic lock of the inputted signal is carried out in a sampling frequency with a DAI (Digital Audio Interface) decoder,The high precision of 44.1/48kHz in this and the incoming signal of a level I extract the master clock which has neither pulse transmission distortion nor a Jitter by an ultra Jitter free PLL circuit, and make it the standard of the system.
After changing all the signals with the other low accuracy into the signal of 48kHz and a level I by SFC (Sampling Frequency Converter), they extract a clock.
By DSP (Digital Signal Processor), a signal processes a tone control function [ weight / for preamplifiers, such as tone control a Compensation, and a monophonic phase change, ] by digital operation after this.
Then, it uses independently at a time the signal which changed the sampling frequency 8 times with the digital filter for one channel of one of the two, and it goes into ultra high-speed DSP. Here, by the digital gain control by special noise shaper processing, little volume control of sound quality degradation is carried out to -95dB. By this DSP, balance adjustment and an Attenuator are processed simultaneously.
Next, after an ultra high-speed optocoupler separates digital one / analog part completely electrically, it changes into an analog signal by a MMB (Multiple Multi-Bit) system D/A converter, and cuts and outputs with the 4th analog filter.

The digital volume by special noise shaper processing technology is developed and carried in the volume control portion.
With the special noise shaper processing technology which uses DSP, the noise level in an audio frequency band can be lowered to theoretical full limits. For this reason, by being buried in a noise and carrying out the digital time sharing return of the data which carries out bit omission, it is raising to the resolving power more than a D/A converter.

The digital volume control which gave a feeling of operation of the analog is carried.
The disc in which the slit was cut radiately is attached to the shaft of a large-sized knob, when a disc passes a phase detector, a pulse is generated, this pulse is inputted into a microcomputer, and volume is adjusted.
This is developed further, the feeling of a rotating speed, matching of sound quality change, etc. are pursued thoroughly, and quality volume is made.

The tone control by DSP and a Compensation are carried, and since it is possible to change only frequency, control without sound quality change is enabled.

The MMB system D/A converter is adopted as a D/A converter.
The parallel drive of many (direct-current-300 8 per channel) 20 bitD/A converters selected carefully is carried out, and a MMB system inputs into all the converters, and after D/A conversion is carried out, it is adding the high-speed output of an 8 time oversampling digital filter.
A phase is coincided on high frequency by this, and the engine performance is improved with all the frequency and all the signal levels.

In order to make it synchronize with a DAI signal and to operate a D/A converter, the master clock which serves as a standard of a system by an ultra Jitter free PLL (Phase Locked Loop) circuit is extracted.
The crystal oscillator is adopted as an ultra Jitter free PLL circuit at a preamble signal (marker in which head of LR signal is shown) detector circuit, and VCO (Voltage Controlled Oscillator),The master clock extracted in this circuit is not influenced by a Jitter or pulse transmission distortion.

In order to carry out rise conversion of the sampling frequency to high frequency and to once carry out a resample on the frequency (48kHz, a level I) to wish, SFC (Sampling Frequency Converter) is carried.

20 bits of oversampling digital filters are carried in the oversampling digital filter 8 times.

The 4th Butterworth filter is adopted as an analog filter. This filter circuit suppresses rotation of the phase in a pass band to the minimum by optimization of cutoff frequency, and the element and interval which were selected carefully are aiming at the sound quality improvement.

The high-speed optocouplerr with the throughput of 40MBPS is adopted, and the digital part and the analog part are separated completely. By the high-speed transmission characteristic, the digital signal is transmitted to the analog part, without being accompanied by noise.

It is possible to change into the name which can change the display of an input position and has been registered beforehand, or to make an original name combining eight characters out of 96 kinds of a character and signs.

The analog output consists of full balance circuits by which floating was carried out from the ground.
Moreover, the output terminal carries the balance XLR connector and the disequilibrium RCA connector.


The option board slot is carried and analog-related input and output as well as the conventional preamplifier can be operated by the option board corresponding to an ADB standard.
An analog input is changed into a digital signal by the A/D converter in a board, and is changed into an analog signal by the D/A converter in a board.
Moreover, the line-in board is preinstalled.


Rear Option
An
A DSP assembly, a DAI assembly, a MMB D/A converter assembly mother board
Ultra DSP The
High Digital
High-speed

Rating of a mode
Form Digital preamplifier
Entry format
(EIA standard format)
The number of quantization: 16 bits - a 24-bit straight line
Sampling frequency: 32kHz, 44.1kHz, 48kHz (automatic detection)
Digital input format level
(EIAJ CP-1201)
Format: Digital Audio Interface
Optical: Optical input -27dBm - -15dBm
Coaxial: 0.5 Vp-p/75ohms
Digital output format level
(EIAJ CP-1201)
Format: Digital Audio Interface
Optical: Optical power -21dBm - -15dBm, luminescence wavelength 660nm
Coaxial: 0.5 Vp-p/75ohms
Frequency response 4.0Hz-20kHz±0.3dB
D/A converter A MMB system, 20 bits
Digital filter 20 bits, 8 time oversampling
THD 0.002% (20Hz - 20kHz)
S/N 122dB
Dynamic range 112dB (a 24-bit input, LPF:off)
Channel Separation 112dB (20Hz - 20kHz)
An Output voltage/impedance Balanced: 5V/50 ohm, a balanced XLR type
Unbalanced: 5V/50 ohm, a RCA phono jack
Volume control (DSP) Speed perception rotary system
0 - step variable between -95dB (0.1-5dB step), -infinity
Balance control (DSP) Speed perception rotary system
A difference on either side: 0--95dB A step variable (0.1-5dB step), -infinity
Tone control (DSP)
Low-pitched sound (Low) 200Hz : ±6dB (40Hz), a 0.5dB step
500Hz : ±6dB (100Hz), a 0.5dB step
Loud sound (High) 2kHz : ±6dB (10kHz), a 0.5dB step
7kHz : ±6dB (20kHz), a 0.5dB step
Compensation (DSP) +6dB(100Hz)
Attenuator (DSP) -20dB
Power source AC100V, 50Hz/60Hz
Power consumption 25W
The maximum Dimensions Width 475x height 150x depth of 406mm
Weight 21.5kg
Attachment Line-in board A.I. Artificial Intelligence-U1
Remote commander RC-19
Option: Option board
Digital relations
The HPC core キシャル input board DI-BNC1 (30,000yen)
A 75-ohm coaxial cable with a BNC connector is connectable.
Digital input: 0.5 Vp-p/75ohms

* 1 slot use

The Digital-input/output board DIO-OC1 (40,000yen)
The option board which carries the input-and-output terminal of the same axle and an optical fiber.

* 1 slot use
The HPC optical input board DI-ST1 (40,000yen)
The option board which carries an optical ST type link input connector.
The terminal is using the ultra high-speed link with the throughput of 150Mbps.
An optical input: -30dBm - -10dBm

* 1 slot use

The AES/EBU input-and-output board DIO-PRO1 (60,000yen)
The option board which carries the input-and-output XLR connector corresponding to AES/EBU (business-use digital standard).

* 2 slot use

Analog relations
An analog input is changed into a digital signal by the A/D converter in a board.
An output is changed into an analog signal by the D/A converter in a board.
The Line-in board A.I. Artificial Intelligence-U1 (50,000yen)
The high level (analog signal) input terminal for imbalanced connection is carried.
20 bits, 64 time oversampling, and 5th 冱igma system A/D converter are built in.

* Preinstall in the slot of Option1.
* 1 slot use

The Balance input board A.I. Artificial Intelligence-B1 (60,000yen)
The high level (analog signal) input terminal for balance connection is carried.
20 bits, 64 time oversampling, and 5th 冱igma system A/D converter are built in.

* 2 slot use

The Line-out board AO-U1 (70,000yen)
The output terminal for analog recording by imbalanced connection.
D/A converter: 20bit 4MMB system
Digital filter: 20bit 8 time oversampling

* 1 slot use

The Balance output board AO-B1 (\80,000)
The output terminal for analog recording by balance connection.
D/A converter: 20bit 4MMB system
Digital filter: 20bit 8 time oversampling

* 2 slot use

The Analog disc input board A.I. Artificial Intelligence-AD1 (100,000yen)
The high gain equalizer for analog record playback, and the carried option board.
MM/MC correspondence (gain: MM30dB, MC60dB)
Sampling frequency: 48kHz

* 2 slot use
The Line input-and-output board AIO-U1 (60,000yen)
The analog recording and the playback terminal for imbalanced connection.
Sampling frequency: 48kHz

* 1 slot use