SANSUI AU-X1

Commentary

An amplifier designed to pursue the ideal that "an amplifier must be a single conductor with an amplification degree that faithfully transmits music signals" as far as possible.

Approximately half of the space is the power supply. All stages are independent on the left and right, power stage, pre-drive stage, flat amplifier / equalizer and MC head amplifier are all independent 8 power supply configurations.
It is a 2-transformer system consisting of a 600 VA large-capacity toroidal transformer and an 80 VI ・ EI transformer. Custom large-capacity electrolytic capacitor 10,000 μ Fx8 developed exclusively for audio is connected in parallel. A 1.2 mm thick copper plate is used in the ground circuit. Therefore, even if the speaker impedance changes with frequency, stable operation is achieved by the powerful power supply.

Equipped with a diamond differential circuit and newly developed linear high-speed output device NM-LAPT (Non Magnetic-Linear Amp. Power Transistor), we succeeded in reducing TIM distortion and envelope distortion, which are dynamic distortions that interfere with sound quality, to as close to 0 as possible.

From large die-cast heat sinker to high-efficiency triple-braided speaker cable wiring, each part is selected based on a reliable characteristic check and hearing.

The power amplifier operation switch on the front panel can be used to separate pre-power and power.

Power is supplied to the power stage using two windings with independent left and right channels and a large toroidal transformer (power supply capacity 600 va) with good regulation by two rectifier circuits. In addition, a custom large-capacity electrolytic capacitor 10,000 μ Fx8 developed exclusively for audio is connected in parallel, and a 1.2 mm thick copper plate is used for the ground circuit.
The pre-drive stage uses a large EI transformer (80 VA power supply capacity) with two independent power supplies for both left and right channels to powerfully drive the diamond differential circuit.
The equalizer amplifier and flat amplifier are supplied from independent constant-voltage circuits on the left and right sides, and the MC head amplifier is supplied from independent low-voltage circuits on the left and right sides with separate windings.

The newly developed NM-LAPT with high breakdown strength and cut-off frequency (ft100MHz) as a power transistor with high speed and excellent linearity is made into a triple push-pull connection, and is used at an operating point with excellent linearity.

The head amplifier section is a DC amplifier configuration that further advances symmetrical push-pull input / output using newly developed low-noise, high-gmP-ch and N-ch FET. The first stage is a direct-coupled push-pull input in which a large number of low-noise, high-gmP-ch and N-ch FETs are connected in parallel, realizing ideal input impedance and high S/N ratio.
The second stage is an MC amplifier circuit with excellent linearity and excellent open-loop characteristics due to a push-pull drive double-stage direct connection circuit using a combination of NPN-PNP transistors.
In addition, extremely stable operation is obtained by supplying power exclusively for MC and independently for the left and right.

The equalizer amplifier section consists of a direct-coupled DC amplifier with a diamond differential circuit. The first stage has good pair characteristics, low-noise, high-gm, differential input circuit using dual FET, and cascode bootstrap circuit which is not affected by input impedance.
In addition, the high-performance constant current circuit (PAT. PEND) composed of a 2-stage direct-coupled circuit composed of NPN-PNP transistor combination provides high CMRR (in-phase component suppression cost) at the summing point and excellent dynamic characteristics. The second and third stages are diamond differential circuit + current differential push-pull with excellent drive capability, and the output stage is SEPP circuit with Darlington connection, which has sufficient current margin. The low-output impedance and low-impedance NF circuit design provides sufficient dynamic range even against changes in load impedance, and S/N ratio is improved.

The flat amplifier adopts a push-pull drive DC amplifier configuration with a differential input circuit using newly developed 1 Tip (4 elements enclosed) FET in the first stage, and achieves excellent operation by independent power supply on the left and right.

The speaker wiring cord from the LAPT uses a high-efficiency 3-layer braided structure with ultra-low DC resistance and low inductance to obtain excellent transmission characteristics without deteriorating the slew rate.

Uses CP type (conductive plastic) master volume.

Model Rating

Type	Stereo pre-main amplifier
Power Amplifier Unit
Effective output (5 hz to 20 khz, THD 0.007%)	160W + 160W (8 Ω) 220W + 220W (4 Ω)
Effective output (1 kHz, THD 0.003%)	160W + 160W (8 Ω) 220W + 220W (4 Ω)
Total harmonic distortion factor (5 Hz to 20 kHz)	0.007% or Less (8 Ω) 0.008% or Less (4 Ω)
Intermodulation distortion factor (70 hz : 7 khz = 4 : 1)	0.007% or Less (8 Ω) 0.008% or Less (4 Ω)
Output Bandwidth (IHF, THD 0.02%)	5 Hz ~ 70 kHz (8 Ω)
Frequency Response (1W)	DC ~ 500 kHz (+ 0 dB, -3dB)
Input Sensitivity / Impedance (1 kHz)	1V/33k Ω
S/N ratio (IHF, A-network)	125 dB or more
Channel Separation (IHF, 1 kHz)	95 dB or more
Rise Time / Fall Time	0.5 μ sec
Slew rate	± 260 V / μ sec
Headphone jack output	150 mW (8 Ω)
Speaker used	4 ~ 16 Ω (A, B) 8 Ω or more (A + B)
Preamplifier Section
Input Sensitivity / Impedance (1 kHz)	Phono1, 2 (MM) : 2.5 mV (47k Ω) Phono1, 2 (MC) : 0.1 mV (0.2k Ω or less) AUX, Tuner : 200 mv (33k Ω) Tape, Play1, 2 (PIN) : 200 mv (33k Ω)
Maximum Allowable Input (1 kHz, 0.01% THD)	Phono1, 2 (MM) : 330 mV Phono1, 2 (MC) : 40 mV
Output Voltage (1 kHz)	Tape, Rec1, 2 (PIN) : 200 mV (at 47k Ω) Pre Out1, 2 : 1 V at 47k Ω Max Pre Out (THD 0.05%) : 10 v (at 47k Ω)
Output Impedance (1 kHz)	Tape Rec1, 2 (PIN) : 600 Ω or less Pre Out1, 2 : 600 Ω or less
Total harmonic distortion factor	MC (1 kHz, Rec Out) : 0.005% or less MM (20 Hz to 20 kHz, Rec Out) : 0.005% or less Aux, Tuner, Tape Play1, 2 : 0.005% or less
Intermodulation distortion factor (70 hz : 7 khz = 4 : 1)	Aux, Tuner, Tape Play1, 2 (at 1 v) : 0.005% or less
Frequency characteristic	Phono1, 2 (MC, RIAA deviation, 20 Hz to 20 kHz) + / - 0.2 dB Phono1, 2 (MM, RIAA deviation, 20 Hz to 20 kHz) + / - 0.2 dB
Signal-to-noise ratio (IHF, A-network Short circuit)	Phono1, 2 (MC) : 76 dB or more Phono1, 2 (MM) : 91 dB or more Aux, Tuner, Tape Play1, 2 : 100 dB or more
Input reduced noise (A network, short circuit)	Phono1, 2 (MC) : -156dBV Phono1, 2 (MM) : -143dBV
Channel separation (IHF, 1 kHz)	Phono1, 2 (MC) : 70 dB or more Phono1, 2 (MM) : 75 dB or more Aux, Tuner, Tape Play1, 2 : 80 dB or more
Input-to-input separation (1 kHz, short circuit)	Tuner-Phono1, 2 (MM) : 90 dB or more Tape Play1, 2-Phono1, 2 (MM) : 90 dB or more Tuner-Tape Play1, 2 : 100 dB or higher Tape Play1-Tape Play2 : 100 dB or higher
Subsonic filter	16 Hz (-3dB, 6dB/oct.)
<General>
Power consumption	400W (Electrical Appliance and Material Control Law)
External dimensions	Width 480x Height 195x Depth 450 mm
Weight	27.7kg