Audio Database


Technics SL-P720
79,800yen (around the 1987 time)

The compact disk player which enriched the functionality inheriting the technology of SL-P1200 and carrying technologies, such as classAA.

The classAA audio circuitry is adopted as a sample hold circuit and buffer amplifier.
In a sample hold circuit, it is transmitting to the subsequent stage, without opening voltage control amplifier wide and spoiling the amount of information of compact disk from capacitive heavy-load drive of charging the sampling signal of D/A to the capacitor for a hold.
Moreover, also in buffer amplifier, it was concerned with complicated load intensities put together, such as an input impedance of the preamplifier connected, and a capacitive load of a connecting cable, and there is nothing and the stable waveform transmission is realized.
Furthermore, classAA was adopted also as the I/V converter of a digital-analog-converter output, and the high-speed and highly precise L/R translation and the I/V translation are realized.

The super clean digital filter which combined the 96th newly developed digital filter and the 5th analog low pass filter with the audio circuitry unit is adopted.
An unnecessary noise component is removed and a phase response, a distorted property, the frequency characteristic, etc. are improved.

Also about the part which constitutes an audio circuitry, the study was repeated from double-sideds of a physical characteristic and an audition testing, and the high-definition tone quality has been obtained.
The Copper-foil styrene capacitor and the electrolytic capacitor for audios of fine-ceramics content are used in plenty for capacitors.
Moreover, the tone-quality checking is severely performed even into the material of the printed wiring on a ceramic board also with the low pass filter.

In order to prevent noise mixing to an audio circuitry from a digital circuit system or a servo circuitry system, the power source of an audio circuitry system was constituted independently of the digital circuit system / servo circuitry system, and the interference between circuitries is prevented.

The FF-1 laser pickup by 1 original beam scheme is adopted as the pickup part which reads the signal of a disk.
Compared with 3 conventional beam schemes, the use efficiency ratio of laser light is high, and the SN ratio of a regenerative signal is improved.
Furthermore, the signal reading capacity for adoption and the interval of a digital Accu servo system, a change-control-form lens system, etc. to be strong also against the crack and finger print of a disk and to have excelled has been acquired.

In order to suppress the oscillation which has an ill effect on the tone quality of a compact disk player, thorough oscillating measures are taken.
First, the two-layer compound weight base of a metal chassis and TNRC is adopted to the sound pressure oscillation from a speaker. It demonstrates the high vibration suppression effect while this was developed as a result of repeating a study repeatedly until it reached the location of through, a material, form, and a bolt in the vibration analysis by laser holography, and it obtains sufficient weight and an intensity.
Furthermore, in the cabinet upper portion, vibration proof is strengthened using the special vibration proof material determined by the computer simulation.
Moreover, to the floor oscillation which gets across to a setting stand, the oscillation which are four large-sized insulators first and gets across to the main unit of a player was intercepted, it was considered as the double insulator structure which carries out the floating of the optical deck from a main unit the whole loading mechanism on it, and the floor oscillation is shut out.
Besides it, the power transformer is also considering carrying out a floating with special dumping rubber etc. as thorough no vibrating and absent-resonance design.

2 speed search dial in which a detailed head search is possible is carried in right reverse bothways.
The refresh rate per rotation serves as 2 mode system for change-over for about 1 second (slow) and about 30 seconds (fast).
If it turns on the slow side, a precise access of a three-frame (1 / 25 seconds) unit of measure is also possible at the minimum.

The traverse delivery organization by the linear motor by microcomputer control was adopted, and the high-speed head search for an average of 0.9 second is realized.
Moreover, silence and an endurance are also improving.

The programmable music scan functionality to perform only the intro fraction of music one by one is carried.
Performance time can be set up freely till 1 to 99 seconds.

The operation by a hand is possible with attached ten key remote control.
Moreover, the digital attenuator functionality where a conditioningregulation can do a sound volume per 2dB from 0dB to -12dB is carried.

Rating of a mode
Form Compact disk player
<Audio part>
Output voltage 2.0V (0dB, EIAJ)
Frequency characteristic 4Hz-20000Hz±0.2dB (EIAJ)
Dynamic range 96dB or more (EIAJ)
SN ratio 101dB or more (EIAJ)
THD 0.003% or less (1kHz, 0dB, EIAJ)
THD 0.0015% or less (1kHz, 0dB)
Channel separation 105dB or more
Wow and flutter Below a limit of measurement (EIAJ)
<Signal format>
Sampling frequency 44.1kHz
Error correcting system Technics super decoding algorithm
Composite-izing 16-bit linear line
Scheme FF-1
Light source Semiconductor laser
Wavelength 780nm
Scheme High speed linear-access system
Scheme Brushless D.D.
Headphone-output level A maximum of 15mW/32 ohms (variable)
Power consumption 9W
Power source AC100V, 50/60Hz
Dimensions Width 430x height 97.5x depth of 260mm
Weight 5.2kg
Adjunct: Wireless remote control
Functionality 27 keys
The Battery used AA -- Battery 1.5Vx2
Dimensions Width 65x depth 155x18mm in thickness
Weight 140g (Battery included)