Aurex SY-Λ 88

Commentary

A control amplifier based on the SY-88 to improve sound quality thoroughly.

The first stage of the MM equalizer amplifier circuit employs a differential circuit with a low noise dual FET developed by Aurex and a dual transistor 2SK-146 connected with a cascode bootstrap, and the second stage differential amplifier is also a 3-stage direct DC amplifier with a cascode bootstrap.
This circuit configuration has excellent thermal balance due to dual FET and dual transistor, and has succeeded in suppressing self-heat generation in the first stage and the second stage by cascode connection. As a result, DC drift can be reduced, and a DC amplifier with a simple configuration without a servomechanism is mounted on the vessel.
In addition, the linearity of the second stage with large amplitude is improved by the cascode bootstrap connection, and the distortion factor characteristic for the change of the input signal source impedance is also greatly improved.

The first stage of the flat amplifier section is a cascode bootstrap circuit using FET, and the second stage is also a cascode bootstrap circuit. Moreover, a servoless DC-amplifier is adopted as well as an equalizer amplifier, and a low-output impedance is realized by SEPP of class A operation on the servoless DC-amplifier. This realizes a design with less characteristic degradation due to connection code, etc.

Equipped with a head amplifier for MC cartridge.
In the first stage of this head amplifier, three Hi-gm FETs 2SK147, which were also used in the SY-99, are connected in parallel. This is a 3-stage direct connection DC amplifier configuration, which realizes high SN and low distortion factor.

The power supply unit is a separate power supply that separates the left and right channels from the transformer. The power supply circuit is also independent of L/R. Furthermore, by installing an independent constant-voltage power supply for each unit, mutual interference between each channel and each circuit is eliminated.
In addition to the low-noise Zener diode, the SY-Λ 88 uses a high-speed rectifying element with a small recovery time, which further reduces noise compared to the conventional Zener type constant current power supply.

High-quality sound condensers are used throughout the circuit in pursuit of sound quality.
The SY-Λ 88 is designed with carefully selected materials such as a Λ capacitor developed by Aurex and a high-quality electrolytic capacitor reflecting the concept of a Λ capacitor.

The newly developed high-quality volume is used.
The conventional volume contact has a structure in which the resistor and the center terminal slide into contact with each other, and the sound quality deteriorates because there are two points of contact. The newly developed volume and balanced volume used in the SY-Λ 88 improve the sound quality by improving the contact with the terminal.

It is designed to minimize the contact points of the signal path. When playing back records, the contact points of the signal path are limited to only two points of contact points of the phono input selector switch located at the front and rear of the equalizer amplifier connected with two contacts in parallel.
When other sources are input, only two points, the line input change-over switch and the phono input change-over switch, are used.

For ease of use, the phono function, line function and recording source selector switch are provided independently.
In addition, 2 systems of tape deck playback are equipped.

Model Rating

Type	Control amplifier
Equalizer Amplifier Section
Input Sensitivity / Impedance	Phono MM : 2.0mV/50k Ω, 100k Ω / 30 pF, 200 pF Phono MC : 0.1mV/100 Ω
Total harmonic distortion rate (1 kHz)	Phono MM : 0.002% (Rec out at 7.5 V output) Phono MC : 0.002% (Rec out at 7.5 V output)
Maximum allowable input (1 kHz, THD 0.002%)	Phono MM:450mV Phono MC:23mV
Signal-to-noise ratio (IHF A network, short circuit Pre-out)	Phono MM:88dB Phono MC:70dB
Equalizer deviation	20 Hz to 20 kHz ± 0.2 dB (Rec out)
Rated output	150mV(Rec out)
Subsonic filter	Phono MM/MC : 16 Hz, 6dB/oct.
Flat Amplifier Section
Input Sensitivity / Impedance	Tuner, Aux, Tape play : 150mV/50k Ω
Total harmonic distortion factor	0.002% at Aux, 1 khz, 3 v output
Cross modulation distortion factor	0.002% at Aux, 1 khz, 3 v output
Signal-to-noise ratio (IHF A network, short circuit)	Aux:110dB(1kHz)
Recorded output	Rec out:150mV
Rated output	Pre out1/2:1V
Maximum power output	Pre out1/2:15V
Frequency characteristic	10 Hz ~ 100 kHz + 0 -1dB (Aux)
<General>
Semiconductor used	Transistor : 65 Diode : 28 pcs FET : 18
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption	35W
External dimensions	Width 450x Height 93x Depth 386 mm
Weight	11kg