Audio Database

L-570
Commentary

This is a pre-main amplifier developed by combining the know-how for ultra-low frequency expression obtained with the M-07 and techniques for processing very small signals obtained with the C-06 and E-06.

The power amplifier section uses a pure class A operation method. In this method, a constant bias current is always supplied up to the maximum output, so that there is no fluctuation in the operation point due to the signal, and the high-quality power characteristic of class A operation is achieved.

The power supply uses a large-capacity power transformer that is 30% larger than a normal same class amplifier.
In addition, the constant voltage power supply section of each stage independent winding has been thoroughly designed to have low impedance to improve instantaneous response capability. In particular, the current capacity to the power stage has a margin of 1.5 times that of the normal one to achieve ultra-low impedance.

The signal path from the input terminal to the speaker terminal is structured to completely eliminate complicated routing and unnecessary small objects.
For input switching, the wiring is shortened by remotely switching only the selected terminal including the ground terminal at the optimum position near the input terminal. For switching, a nitrogen gas sealed contact relay is used to improve sound quality.
In addition, the speaker terminal is dedicated without A/B switching, and the headphone terminal is also eliminated so that it is directly connected to the power stage without any extra circuit.

PC-OCC for sound quality control is used at important points for internal wiring.

A non-resonant bottom chassis has been adopted for the bottom chassis. Together with the construction with symmetric weight balance on the left and right, we are promoting non-resonance.

The amplifier for MC cartridge and the amplifier for MM cartridge are composed independently, and each of them is installed separately.
The MC amplifier uses a super-low-noise, high-Gm FET in parallel, and a low-noise reference voltage power supply combining constant current and constant voltage for the power supply part to realize an extremely low-noise power supply with low-impedance output.
The equalizer amplifier also operates in class A mode to enable high-quality analog disk playback.

The volume part uses an Ultimate attenuator.
The conventional continuously variable volume has a limit in sound quality due to the stray current of the sliding part and the material of the contact because metal slides on the carbon film. The Ultimate Attenuator used in the L-570 is a 32-contact rotary switch type attenuator that is based on a newly developed slide rotary switch and consists of a glass-epoxy gold-plated substrate with non-magnetic resistors mounted one by one, and a shield case made of die-cast extruded material. This reduces sound quality degradation in volume.

In order to ensure stable operation, we have newly developed and adopted a high efficiency radiator using pure copper fins with high heat radiation effect.

The sound quality is further improved by using the same material as the power amplifier M-07 in various parts such as the resistance of the gold plated cap. The L-570 uses parts for sound quality such as high-performance Styrol condenser and pure focus electrolytic condenser.

A tone compensator is used as the tone correction controller.

When the Recording Selector is in the OFF position, the recording output is disconnected from the signal system to prevent deterioration of sound quality.

Line phase sensor is used and the power supply polarity (direction of plug insertion) can be adjusted correctly.

Model Rating
Type Integrated amplifier
Effective power 50W + 50W (8 Ω, Class A Operation, Simultaneous Operation for both channels)
Total harmonic distortion factor 0.01% or Less (8 Ω, Rated Output, 20 Hz to 20 kHz)
Cross modulation distortion factor 0.01% or Less (8 Ω, 60 hz : 7 khz = 4 : 1, Direct)
Input Sensitivity / Impedance Phono MM : 2.5mV/50k Ω
Phono MC : 100 μ V/100 Ω
CD, Tuner, Line1, 2, DAT/Tape1, Tape2, 3, Processor : 150mV/50k Ω
Balance/Line : 150mV/50k Ω
Signal-to-noise ratio (IHF-A corrected)
Input short)
Phono MM : 86 dB or more
Phono MC : 74 dB or more
CD, Tuner, Line1, 2, DAT/Tape1, Tape2, 3 : 108 dB or more
Frequency characteristic Phono MM/MC : 20 Hz to 20 kHz ± 0.3 dB or less
CD, Tuner, Line, Tape : 10 Hz to 100 kHz - within 1 dB
Tone compensator Maximum variation : ± 4.5 dB
Pwer 100 VAC, 50Hz/60Hz
Power consumption 270W (according to the Electrical Appliance and Material Control Law)
AC outlet Switched : 2 lines
Unswitched : 1 line
External dimensions Width 438x Height 176x Depth 467 mm
Weight 30kg