SANSUI AU-666

Commentary

This pre-main amplifier was created not only with sound quality, function and expandability, but also with a design that is full of functional beauty and is closely related to the speaker system.

The main amplifier section uses a 2-stage differential-amplifier circuit and PNP and NPN for the output-transistor. It is a perfect direct connection positive and negative power supplies without an output-capacitor. It is a complete complimentary service Darlington circuit system.
For this reason, uniform NF is applied from the DC range to the entire audio range, the damping factor and output characteristics are constant up to the ultra-low frequency range, the speaker's exposure in the ultra-low frequency range is sharply reduced, and the intermodulation distortion in the amplifier and speaker is reduced.
Since the distortion component is canceled by the combination of PNP and NPN, the distortion of the amplifier itself is kept low.

A specially selected low-noise silicon transistor is used in the preamp section to minimize the noise.

In order to avoid using an electrolytic capacitor with poor transmission characteristics due to large phase distortion for the coupling capacitor, we use a direct-coupled circuit as much as possible, make the capacitor higher, and use a Mylar capacitor.
In addition, a Mylar type is used in parallel in areas where electrolysis is absolutely necessary to improve high-frequency characteristics.

Equipped with triple tone control that can adjust Bass, Treble, and Midrange.
Since the left and right can be adjusted separately, more accurate program and room acoustic compensation is possible.

It is also possible to separate the preamp section and main amplifier section.

Equipped with two types of speaker outputs, A and B.

A dedicated transistor is used for temperature guarantee, and a differential amplifier stabilizing circuit is used for the 2-stage differential amplifier to further stabilize the differential amplifier.
In addition, it uses 6 short-cut fuses for perfect protection in case of emergency.

Separate ripple filter circuits are attached to the main amplifier's positive and negative power supplies and to the preamplifier power supply to stabilize the power supply.

Equipped with an NF type low filter, high filter, loudness control, tape monitor circuit, headphone jack, muting switch, microphone input jack, etc.

Model Rating

Stereo pre-main amplifier
Main Amplifier Section
Rated output	Music Power (IHF) : 100W (4 Ω) 80W (8 Ω) Effective power : 45/45W (4 Ω) 35/35W (8 Ω)
Total harmonic distortion factor	0.5% or Less (Rated Output)
Intermodulation Distortion Factor (SMPTE, 60 hz : 7 khz = 4 : 1)	0.5% or Less (Rated Output)
Power Band With (IHF)	10 Hz ~ 40000 Hz (8 Ω)
Frequency characteristic	10 Hz to 70000 Hz, ± 1 dB
Channel separation	60 dB or More (1 kHz, Rated Output)
Hum and noise (IHF)	100 dB or more
Input Sensitivity / Impedance	1 V (Rated Output) / 50k Ω or More
Load impedance	4 Ω ~ 16 Ω
Damping factor	40 (8 Ω Load)
Preamplifier Section
Output voltage	Maximum power : 5 v Rated output : 1 V
Total harmonic distortion factor	0.1% or Less (Rated Output Voltage)
Frequency characteristic	20 Hz to 40000 Hz, ± 1 db
Channel separation	Phono1, 2 : 50 dB or more Tuner, AUX : 50 dB or higher
Hum and noise (IHF)	Phono1, 2 : 70 dB or more Tuner, AUX : 80 dB or higher
Input Sensitivity (1 kHz, Rated Output Voltage) / Impedance	Phono1, 2 : 2mV/50k Ω MIC : 3mV/50k Ω Tuner : 180mV/100k Ω AUX : 180mV/100k Ω Tape Play (Pin) : 180mV/100k Ω Tape Recorder (Din) : 180mV/100k Ω
Recorded output	Tape Rec(Pin):180mV Tape Recorder(Din):30mV
Equalizer	Phono : RIAA NF Type MIC : Flat NF Type
Controls	Bass : 30 Hz, ± 16 dB Midrange : 1500 Hz, ± 5 dB Treble : 15000 Hz, ± 15 dB
SWITCH	Low filter : 20 Hz, -10dB High filter : 20 kHz, -10dB
Muting	-20dB
<General>
Configuration	Transistor : 31 Diode : 5
Power supply voltage	100 V, 50Hz/60Hz
Power consumption	240W
External dimensions	Width 415x Height 127x Depth 278 mm
Weight	9.75kg