Audio Database

AU - α 707 mr

MR series pre-main amplifier with New Hyper α -X x balance circuit.

New Hyper α -X balanced circuit is adopted in order to reduce the generation of electrical noise generated inside the circuit to 0 for operation.
This circuit is composed of a Hyper α -X balanced circuit and an advanced Wilson current mirror type vertically symmetrical balanced constant current circuit developed by further developing the Wilson current mirror high CMRR type constant current circuit which realizes a theoretical improvement effect of 140 dB in CMRR.
As a result, we have succeeded in making the driver stage into a closed loop with separate windings, adjusting the current dispersion due to DC offset caused by the asymmetry of elements in the circuit, and improving the stability of the operation of the circuit itself.
In addition, the main power supply section of the output stage, in which transformers and electrolytic capacitors are concentrated, is also a closed loop with separate windings. Through the entire system from the sound inlet to the sound outlet, an optimum operating environment for a balanced amplifier is constructed.
In addition, it uses the NM-LAPT power device for audio.

In order to improve response to instantaneous signals, a new diamond differential circuit is adopted in the drive stage. Since - output can be taken out without phase inversion, current supply capability for input signals that change rapidly is high and excellent characteristics are realized.
In addition to the cascade connection of the first stage FET, the driver power supply section is vertically symmetric and balanced, making the circuit wide range and high speed, and making the operating characteristics of the New α -X balanced amplifier more excellent.
It is also effective in preventing sound quality degradation when connecting to external devices with different impedances.

New α -X balanced power supply is used for the power supply part.
The output stage is a balanced closed type and the driver stage is a vertically symmetric balanced constant current power supply. The closed loop configuration is completely independent from the earth. This prevents the adverse effect of unbalanced power supply current, which causes the deterioration of sound quality, on sound quality.
In addition, large power transformers, elliptic electrolytic capacitors, and fast recovery diodes are used.

Reinforced twin monaural construction is used to prevent vibration of power supply and signal systems.
Power supplies such as large transformers and electrolytic capacitors, which are the vibration sources of the power supply system, are installed in the center. Power units such as power transistors and radiators, which are the vibration sources of the signal system, are arranged symmetrically on both sides of the housing, independent of the power circuit board. This prevents interference between the left and right sides, ensures an optimal weight balance, and structurally controls the natural vibration of the amplifier.

In order to cut off the transmission path of vibration, we have adopted an integrated mechanical feedback system developed with our own know-how.
Isolation parts made of pure copper with high internal loss and excellent vibration absorption effect are used between the master volume and the chassis, between the power transistor and the radiator, and the mounting base of the electrolytic capacitor to control vibration.
In addition, Teflon tapes and sheets with stable molecular structures are used to isolate the space between the insulator and bottom plate and between the radiator and bonnet and chassis to prevent sound quality degradation due to vibration.

Uses high-quality parts such as oval insulator with special structure and gold-plated lead.

Power amplifier for direct input of Route 3 Equipped with a direct input, directly connected to the power amplifier section.

Equipped with a source power direct that transmits the input signal of all normal lines to the power amplifier section without passing through the accessory circuit.

A 6-row detent volume is used.

Model Rating
Type Integrated amplifier
Power Amplifier Unit
Effective output (10 Hz to 20 kHz
Simultaneous operation of both channels)
160W + 160W (6 Ω)
130W + 130W (8 Ω)
Total harmonic distortion factor (at effective output) 0.003% or Less (8 Ω)
Cross modulation distortion factor 0.003% or Less (8 Ω)
Damping factor 150 (8 Ω)
Frequency Response (1W) DC ~ 300 khz + 0 -3dB
Input Sensitivity / Impedance 1V/5k Ω (1 kHz)
Signal-to-noise ratio (A network) 120 dB or more
Dynamic Power 405W (2 Ω)
320W (4 Ω)
210W (6 Ω)
TIM Sawtooth Measurement limit value or less
Slew rate 200 V / μ sec
Rise time 0.5 μ sec
Preamplifier Section
Input Sensitivity / Impedance
Phono MM : 2.5mV/47k Ω
Phono MC : 300 μ V/100 Ω
CD, Tuner, Line, Tape/DAT1, 2 : 150mV/20k Ω
Phono maximum allowable input MM:210mV(THD 0.01%)
MC:21mV(THD 0.1%)
Frequency Response (1W) Phono MM : 20 Hz to 20 kHz ± 0.2 dB
CD, Tuner, Line, Tape/DAT1, 2 : DC ~ 200 khz + 0 -3dB
Signal-to-noise ratio (A network) Phono MM : 88 dB or more
Phono MC : 70 dB or more
CD, Tuner, Line, Tape/DAT1, 2 : 110 dB or more
Tone control Maximum variation of Bass : ± 6 dB (50 Hz)
Maximum variation of Treble : ± 6 dB (15 kHz)
Subsonic filter 16 Hz (-3dB), 6dB/oct.
Loudness + 6 dB (50 Hz), + 4 dB (10 kHz)
Rated power consumption 330W
External dimensions Width 471x Height 162x Depth 452 mm
Weight 23.5kg