Audio Database

The

Aurex SC-lambda 90F
230,000 yen(around the 1982 time)

Description
 
Stereo power amplifier developed as amplifier corresponding to the digital audio age based on the technology cultivated by SC-lambda 99 or SY-lambda 88II.

The newly developed complimentary power MOS FET is carried.
While this power MOS FET (2SK405, 2SJ115) that the Aurex developed has adopted the double diffusion type structure called pi-MOS and realizing high proof-pressure-ization, it is high gain, and also improvement in the speed is attained.
Furthermore, high power is realized by suppressing ON resistance low simultaneously, moreover, the conventional driver circuit can be used as it is, and it has the features, like parallel use can also be simplified.

Circuit composition carries out parallel connection of the newly developed power MOS FET, and in first rank dual FET cascode connection and a two-step dual transistor differential cascode connection current mirror voltage magnification stage, Darlington connection is made and it is driving.

The super lambda power source which 2SK270A which is low noise dual FET used by SY-lambda 88II and SC-lambda 99 was adopted as the input stage, and also crosses to a broadband and has established reputation in it by a low noise and low impedance is introduced, and the noise of the power-source part is stopped.
Furthermore, the signal to noise ratio which lowers internal resistance to a semiconductor device by fully sending current, is considering it as the driver circuit of a low noise, such as preventing thermal noise, and was excellent as a result is realized.

AC power source -> in order to promote the low noise between amplifier, and low impedance-ization, the super lambda power source is adopted as the power-source part to a pre-driver stage, and the polish is applied to sound quality.
The large-sized toroidal transformer of 410VA is adopted as a power transformer, and secondary winding wire has 3 power-source composition which divided each power source for the object for electric power magnification, the object for voltage magnification (driver circuit), a protection circuit, and indicators, and is reducing the mutual intervention.
In order to decrease impedance, while large-scale-izing a power switch, it is parallel and the commutator is used. While a commutator uses a high-speed type thing, the thorough design, such as giving a silver clad, is performed to the terminal.
Moreover, the mass large-sized electrolytic condenser of the high-quality sound type developed by SC-lambda 99 is used for the circuit for electric power magnification stages, and also it is in the super lambda power-source part for driver magnification stages,The newly developed electrolytic condenser is adopted, and also impedance[ low ]-izing, reduction of different-species metal-to- metal contact, and prevention of vibration are sharply improved by connecting parallel a u lambda-II type lambda capacitor, a Copper-foil styrene capacitor, V Cong, etc. to each electrolytic condenser.


In order to prevent sound quality degradation by direct-current servo circuit where the active device was includeded unlike common direct-current amplifier, it is considered as servoless direct-current amplifier.
The return circuit which affects sound quality is simple by this, and the music play which was excellent at the time of the Oide power is possible.

A basic signal circuit is considered as very simple composition, and the carbon resistance of high reliability called RM resistance is parallel used for resistance of a NFB loop or each signal system. While distributing and carrying out frequency of noise by using a different value from each resistance, coloring depended for resistance to cry is lost and the flatness on Hearing impression is taken into consideration.
Moreover, the capacitor which wound the butyl rubber of the vibration isolation around the Copper-foil styrene capacitor is used for the part which the non-linear ingredient of a transistor generates, and the resonance of the capacitor is held down.

The Copper-foil styrene capacitor which has established reputation in the solid capacitor of a signal system and a power supply system as well as lambda 99, a u lambda-II type lambda capacitor, GU capacitor, etc. are adopted, and, in addition to impedance[ low ]-izing, reduction of different-species metal-to- metal contact and a vibration isolation are promoted sharply.
Furthermore, by the special process, over a broadband, there is little resonance and it has realized the good characteristic of energy balance.

lambda resistance which uses as a resistance object the copper which uses lambda 99 for sauce resistance of the power MOS FET of an output stage is adopted. All the courses through which large current flows by this are unified with the element which uses copper, and are lambda loop circuits where different-species metal is not mixed.

The large-sized peak power meter is carried and it can monitor without a range change.
Brightness is changed into the lighting of meter in two steps.

Two variable input terminals are carried with it being direct.
The variable terminal can perform volume control with the volume control switch of a front, and a volume position can be checked by five-point LED on the front panel.
It does not pass along input volume etc. by a direct input terminal, but is soon connected with the first rank of amplifier.

The clean drive circuit original with an Aurex is carried.
The non-linear ingredient of back electromotive force detects the distorted ingredient generated owing to in 3rd cord tied to the minus terminal of the speaker, it feeds back in amplifier, and distortion is negated. Thereby, reduction can obtain higher-harmonic-wave distortion or less to 1/10, and the features, such as formation of impedance zero of reduction, a flat frequency response, and a speaker cord and dumping factor infinity, are sharply acquired in intermodulation distortion.
The clean drive terminal is designed connect with the minus terminal side of a speaker and demonstrate power, for in an emergency, carries the sparse high-speed protection circuit, and protects a set from incorrect connection.

When direct-current voltage leaked to the speaker output terminal, or when a speaker short-circuits, the unusual high temperature inside a set to a set other than the conventional protection circuit which protects amplifier is protected, and the temperature protection circuit which prevents thermal run-away is also carried.

Rear
Internal
Power MOS FET Commutator Commutator GU
Toroidal Electrolytic Electrolytic Copper-foil
Clean

Rating of a mode
Form Stereo power amplifier
<Amplifier part>
Output power (20Hz - 20kHz) 100W+100W (8ohms)
THD (20Hz - 20kHz) 0.007% (at the time of an Output power 8ohms)
Cross modulation distortion (50Hz:7kHz=4:1) 0.007% (at the time of an Output power)
Frequency response direct-current-100kHz+0 -1dB
Output bandwidth (distorted [ 0.05% ] 8 ohms) 5Hz - -100kHz three dB
Input sensitivity/impedance 1V/50kohm
Remains noise (input short-circuit) 70 microvolts (8ohms)
Signal to noise ratio (IHF, A network) - 126dB (input conversion)
Dumping factor 150
Speaker impedance A, B:4ohms - 16ohms
A+B: 8ohm-16ohm
<Meter part>
Meter indicating range 1mW-200W (8ohms)
- 50dB - +3dB
Directions accuracy - 50dB or more : 20Hz-20kHz±2dB
- 50dB or less : 20Hz-20kHz±3dB
<Synthesis>
Power supply voltage AC100V, 50Hz/60Hz
Power consumption 320W
Dimensions Width 420x height 158x depth of 385mm
Weight 15kg