Aurex SY - Λ 88 II

Commentary

A control amplifier announced as an improved version of SY-Λ 88.

The newly developed stabilized super Λ power supply is used for the power supply to reduce the impedance between the AC power supply and the amplifier. This realizes an ultra-low impedance of only 0.5m Ω from DC to 100 kHz and low noise.
The Super Λ power supply employs a two stage differential feedback type power supply with high gain, high stability, excellent response, and wide range reproduction. In addition, the MC head amplifier is directly driven by the use of a low-noise transistor.

The AC power cord is 15A, the power transformer is 80 VA large-capacity toroidal transformer with double the wire thickness of the conventional transformer, and the PC board is 280 micron, reducing the resistance in details.

Large capacity power switches are used to reduce impedance, and low impedance is achieved by parallel use of rectifiers, newly developed electrolytic capacitors, and various film capacitors.
In addition, we use copper foil parts such as newly developed u Λ - II type capacitors, copper foil styrene capacitors and copper foil film capacitors to reduce resonance over a wide band by a special manufacturing method and obtain characteristics with good energy balance. Electrolytic capacitors also have excellent energy balance with less distortion by a special manufacturing method based on consideration of film capacitors.

To prevent deterioration of sound quality due to DC servo with active elements, all MC head amplifier, flat amplifier and equalizer amplifier are servoless DC amplifiers, and feedback circuit which affects sound quality is simple structure.

In the RIAA device, large-capacity Styrofoam copper (82,000 μ F, 28,300 μ F) capacitors, which have been said to be difficult to achieve, are manufactured by a special method and are used.

In the first stage of the flat amplifier, a single-chip dual FET2SK270 with stable temperature characteristics is adopted. Since the feedback resistance can be doubled with less noise, a high S / N ratio can be obtained while reducing the load of the feedback circuit.
In addition, dynamic range of 140 dB is achieved by high power supply voltage operation.

A newly designed switch-type balance adjustment mechanism has been adopted to reduce the contact points of the signal path.
In this circuit, the balance before the volume is set after the flat amplifier, and the level is changed by 5 steps combining a switch and a resistance. This method uses the output resistance of the flat amplifier. A resistance is inserted between the signal line and ground. The resistance value is changed by a high-quality contact switch to change the signal level. Therefore, when the balance knob is in the center position, there is no contact in the signal line and no resistance is incorporated.
With this structure, there are three contact points when playing a record : two points connected in parallel and one point with improved contact volume.

In order to bring out the performance of the MC cartridge, it is possible to switch the load impedance in two stages. Also, by installing a 100 Ω load on the MM terminal, it is possible to use the high-output MC cartridge without passing through the head amplifier.

Since the recording selector switch is configured independently, the recording source can be selected regardless of the source being played.
In addition, two tape decks can be connected for simultaneous recording and dubbing. In the OFF position, the deck connected to the REC terminal is disconnected, preventing sound quality degradation due to the nonlinear component of input impedance that occurs when the power supply of the deck is turned off.

When the input selector is set to the Phono Sub position, the subsonic filter operates.

The muting circuit operates in conjunction with the power switch in order to prevent abnormal sound during power ON / OFF.
The operation status can be checked by the indicator, which turns red when the switch is turned ON, and turns green when the muting is released. This muting works for Pre out and Rec out.

Model Rating

Type	Control amplifier
Input Sensitivity / Impedance	Phono MM : 2.0mV/100 Ω, 47k Ω Phono MC : 0.1mV/10 Ω, 100 Ω Tuner, Aux, Tape : 150mV/47k 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) Aux : 0.002% (3 v output, Pre out)
Cross modulation distortion factor	Aux : 0.002% (1 kHz, 3 v output, Pre out)
Signal-to-noise ratio (IHF-A Short circuit)	Phono MM:88dB Phono MC:70dB Aux:110dB
Frequency characteristic	Phono : RIAA deviation ± 0.2 dB (20 Hz to 20 kHz, Rec out) Aux : 10 Hz to 100 kHz + 0 -1dB
Maximum allowable input (1 kHz, THD 0.002%)	Phono MM:450mV Phono MC:23mV
Rated Output / Impedance	Rec out : 150mV/180 Ω (1 kHz) Pre out : 1V/100 Ω
Maximum power output	Pre out:30V
Subsonic filter	MM, MC : 16 Hz, 6dB/oct.
Semiconductor used	Transistor : 60 Diode : 15 pcs FET : 11
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption	30W
External dimensions	Width 450x Height 93x Depth 386 mm
Weight	9kg