Audio Database

DA-P7000
Commentary

A reference AV preamplifier with separate video and audio components.

The DA-P7000 uses an AV separate structure in which the video selector and audio circuits are housed in separate housings to eliminate interference such as noise.
The control signal is supplied from the audio section to the video section via a power line with an independent video winding transformer and a photocoupler. From this signal line, only the minimum required current and the signal for controlling the video selector are sent. Thus, the audio and video sections are completely isolated.

The video amplifier section uses a discrete configuration using a wide-band high-frequency transistor. Combined with the use of a video-only switch, it realizes a wide bandwidth of 20 MHz.

All selector circuits are equipped with a dedicated video bipolar switch IC. Since the bipolar switch consists of an emitter follower with low-output impedance and broadband characteristics, it provides excellent switching performance for video signals.

In order to prevent Y and C signals from interfering with each other, we have adopted a three dimensional board structure in which only the Y signal selector part of the signal processing circuit is composed of another board, and this board is made to stand upright on the C signal selector board so as to have the shortest wiring distance.
As a result, the Y signal and C signal are arranged at the shortest distance without crossing each other, and various characteristics are improved.

Y/C isolation circuit expert DCF is installed.
This circuit calculates the vertical and horizontal uncorrelated energy of video signals on a pixel-by-pixel basis and selects three types of optimal filters (BPF). It is an IC-based circuit that uses a horizontal band-pass filter (1-D) when the horizontal correlation is strong, a vertical band-pass filter (2-D) when the vertical correlation is strong, and an oblique band-pass filter (1-D + 2-D) when neither is strong.
This greatly reduces both horizontal and vertical dot interference and color fading compared to conventional products.

The video circuit has a two power supply configuration similar to the audio circuit. By separating the power supply circuit from the ground circuit, the inflow of unnecessary circuit current into the ground circuit is greatly reduced and high S/N is achieved.
In addition, the input-output coupling capacitor can be removed, resulting in higher picture quality.

Full digital audio signal processing is used in the audio section, so that analog input signals are converted into digital signals by an A/D converter and processed as digital signals until they are finally converted into analog signals and output.

The D/A converter uses a newly developed variable current discrete 1-bit DAC that brings out the original merits of the 1-bit type.
This DA converter drives an electronic switch at a constant current so that the circuit is not affected by power supply fluctuations. It also uses a constant current type PWM method to eliminate power supply voltage fluctuations by making the load current of the power supply constant. The differential amplifier and current / voltage conversion circuit use an audio OP amplifier (manufactured by PMI Inc. of the United States) with excellent power supply fluctuation rejection capability. DC servo is applied to eliminate coupling capacitors. This eliminates AM modulation distortion and maximizes linearity.

Digital volume is used for the volume circuit.
This volume has a structure in which the current value of the constant current source of the differential switch can be changed by the volume control circuit, and the rotation of the knob is detected by the rotary encoder linked to the volume knob, so that bit dropping does not occur at any volume value from 0 dB to -72dB.

To eliminate jitter and prevent degradation of sound quality, a jitter-free digital sound collector is used in the jitter elimination circuit.
This circuit has a dual PLL configuration consisting of two 1st and 2nd PLL circuits. The 2nd PLL uses a newly developed wide-band lithium tantalate oscillator with frequency accuracy and stability comparable to those of quartz crystal, and with a frequency variable width of more than three times that of conventional ones and ± 3,000 ppm or more.
The digital input signal is first demodulated by a clock generated by the 1st PLL, and the data is written into a memory buffer of three words by a dedicated IC. The 2nd PLL resynchronizes the clock of the 1st PLL to generate a high-precision clock with less jitter. This clock is used to read the data written into the buffer and eliminate jitter.
In addition, if the response of the PLL circuit is fast, the oscillator in the loop will follow the jitter and create a clock with a lot of jitter. Therefore, the slower the response of the 2nd PLL, the better the jitter removal effect. However, if the response is too slow, the lock will be released easily and the sound will be cut off. Therefore, by changing the response of the 2nd PLL to two speed automatic transmission and switching between fast and slow speed depending on the situation, stable lock is secured and the ultra-slow response of the PLL is achieved.
An independent shunt regulator is applied to the power supply of the PLL circuit for each block to suppress the generation of jitter caused by the inflow of power supply noise.

An ID interface is used to prevent the deterioration of sound quality caused by noise generated during transmission of digital audio signals that have undergone surround processing and other processing by DSP.
The ID interface is structured to transmit not the digital signal itself information contained in the signal, not the digital signal itself. It consists of two C-MOS FET analog switches, which are connected to the power supply when one is ON and to the ground when the other is ON. Both the power supply and the ground are kept clean with little noise. The digital audio signal is not directly input to the D/A converter, but when it is used as an open / close signal for two analog switches, the switch on the power supply side is ON when the signal is HIGH, and the switch on the ground side is ON when the signal is LOW. Thus, the high-low relationship of the newly created digital signal corresponds to the input signal, but the uncorrelated noise of the digital audio signal is shut out and clean D/A conversion is realized.

In addition to Dolby Pro Logic, MHT Logic and Mono Logic are available as surround modes.
MHT Logic is Mitsubishi's original surround mode that supports Dolby Surround encoded software. Sound field effects are fully digitally processed by DSP, and associated bit loss is handled by all-channel noise shaping to achieve high-quality surround playback.

The center mode can be selected from REAL mode and VIRTUAL mode.
The REAL mode is set when the center speaker is used. The entire band from low to high is output to the center speaker. The VIRTUAL mode is set when the center speaker is not used. The two LR2 speakers direct speech to the center using a directional enhancement circuit.
Furthermore, by adjusting the arrival time of the center channel signal with the C (CENTER) PRESENCE function, it is possible to improve the center orientation.

With the MULTI DELAY function, you can use two to four rear speakers to create a surround sound field similar to a room with six to twelve rear speakers. You can adjust the size of the sound field by switching between modes.

With REAR DELAY you can adjust the DELAY time of the rear speaker.
With the REAR FILTER you can adjust the cutoff characteristics of a low-pass filter that cuts out the high-frequency range of the rear-channel signal, usually set to 7 kHz, to 9 kHz for more sound, or to 4 kHz for a milder sound.

With the THEATER LPF, you can adjust recorded sources for movie theater playback with high-frequency enhancements.

With the AZIMUTH function, if the angle (azimuth) of the playback head is out of alignment with the recording head during the process of creating the software, you can adjust the offset of the azimuth of the software.

With the AUTO INPUT function, you can improve the situation in which speech sounds like dialogue from the center are heard through speakers other than the center channel.

Equipped with a subwoofer output. Digital processing of the low-pass filter enables three levels of switching between 40 Hz, 63 Hz and 80 Hz according to the characteristics. Cutoff characteristic is 24dB/oct.

In Mono Logic mode, you can add surround sound to monaural recorded video and LD software.

It is equipped with an on-screen function that enables you to adjust the surround sound mode and dub processing while checking the screen.
There are three types of displays : the main screen for selecting the input / output source and surround type, the sub screen for determining the volume of each speaker and whether the subwoofer is ON/OFF, and the REC monitor screen for checking the recording status.
In addition to superimposing, it can also be displayed on blueback Antilope cervicapra.

It is equipped with the ambisonic surround system licensed by Nimbus Records UK.
This surround system provides surround sound for normal stereo sources, but it is especially effective for four channel ambisonic-encoded software.

Comes with a wireless remote control with a lighting function that lights up when the button is pressed.
This remote control is equipped with an auto-function function that enables you to perform a series of operations with the touch of a button in a system composed of Mitsubishi AV devices that support auto-function. It is also equipped with a learning function that enables you to learn and operate the remote control functions of other AV devices.

Model Rating
Type Multichannel control amplifier
Digital input Optical : Line 5
Co-axial : 4 systems
Digital output Optical : 2 systems
Co-axial : 2 systems
Analog terminal Analog input : 10 systems
Analog outputs : Line 5
Preamp part output Front 2 ch, center 2 ch, sub-woofer 2 ch, rear 4 ch
Sound field control (digital) Dolby ProLogic
Ambisonic
MHT Logic
Mono Logic
Power consumption 72W
External dimensions Audio : W 425x H 132x D 464 mm
Video Part : W 425x H 87x D 393 mm
Weight 18kg
Attachment Wireless Remote Control