Aurex SD-77
¥ 120,000 (around 1977)
Commentary
A channel divider that employs an arithmetic circuit method that creates high-pass and low-pass characteristics in a single circuit.
The calculation circuit is of the double integral and subtraction type. This method has been used in the field of measuring instruments. It is possible to produce both low-pass and high-pass characteristics simultaneously with one circuit. Moreover, the obtained change characteristic is symmetrical around the cross point. Even if the slope characteristic or Q characteristic is changed, this characteristic does not change. The sum of the voltages is always kept at 0 dB, and smooth connection with no phase shift is obtained.
A class A DC operational amplifier IC is used as the active element, so that a large bare gain can be obtained and the so-called bounce characteristics can be suppressed to a practically negligible level, resulting in ideal damping characteristics.
A discrete configuration is used for the mixer section and excellent characteristics are obtained.
The cutoff characteristics can be switched between 6dB/oct. and 12dB/oct.
In the SD-77, the operation section for determining the crossover frequency is independent. The frequency varies depending on the capacitance and gain. However, by setting the capacitance to a constant value, the frequency can be determined only by changing the resistance of the gain control. This allows the crossover to be continuously variable.
The volume uses a 22-contact detent type high-precision metal-coated volume with 22 points for switching between high and low frequencies.
By changing the damping characteristic (Q characteristic), it is possible to change the damping characteristic near the cutoff frequency.
It can also be used as a 2-channel Divider by using only one of the low and high crossover points.
Equipped with independent level control for each band of low, middle and high.
A buffer amplifier is provided at the output stage.
The protective resistor of 100 Ω becomes the output impedance as it is.
A reed relay with a high operating speed is used to prevent click noise when the power switch is turned ON/OFF.
By attaching the separately sold Carrying Handle TO-1, it can be mounted on a 480 mm width JIS standard rack.
Model Rating
Type | Channel divider |
Circuit system | Double integral and subtraction type arithmetic circuit system |
Gain | 0dB |
Maximum power output | 6V |
Harmonic distortion (20 Hz to 20 kHz) | 0.003%(1V) |
Crossover point (switch-over) | Low : 80, 100, 125, 150, 200, 250, 300, 400, 500, 600, 700, 800, 900 Hz 1.0, 1.25, 1.5, 2, 2.5, 3, 4, 5, 6 kHz High frequency : 300, 400, 500,600,700,800,900 Hz 1, 1.25, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15 kHz |
Slope characteristic | 6dB/oct, 12dB/oct (switch switching) |
Input impedance | 100k Ω |
Signal-to-noise ratio | 100 dB (20 Hz ~ 20 kHz, Output 2.0 V) |
Output impedance | Hi, mID, LO/ch : 600 Ω |
Change in Q | 1 to 0.7 |
Semiconductor used | IC : 8 FET : 8 Transistor : 52 Diode : 19 units |
Power supply voltage | 100 VAC, 50Hz/60Hz |
Power consumption | 8W |
External dimensions | Width 450x Height 93x Depth 375 mm |
Weight | 5.8kg |
Sold Separately | Carrying Handle TO-1 (¥ 3,000) |