SANSUI AU-9500

Commentary

This is a top-of-the-line pre-main amplifier made by SANSUI using the best circuit technology based on selected parts.

By using well-vetted components and expertise, the OCL pure complimentary service circuit for all stages is stable, and by using a parallel push-pull circuit with high output and low distortion rate, the total harmonic distortion rate, intermodulation distortion rate, and power distortion are guaranteed to be less than 0.1% from 5 hz to 40 khz with sufficient margin from small output to large output.

The power supply section uses a large power transformer and a large capacitor of 4x4,700 μ F.
In addition to supplying power to the power stage independently for each channel, a + - 2 power supply system has been adopted to improve stability and enable the power transistor to be driven with allowance.
In addition, the power stage and pre-drive stage are provided with separate power supplies, and the pre-drive stage is driven at a higher voltage than the power stage, thus enabling stable driving without being affected by load fluctuations.

A parallel push circuit that can reduce the collector current of the power transistor to 1/2 of the conventional one. In this circuit, only the part with good current characteristics of the transistor can be selected. This circuit, combined with the all-stage direct connection OCL pure complimentary service circuit, can suppress distortion and obtain stable high output.
In addition, the differential amplifier, which influences the stability of all stages directly connected, is composed of two stages by a combination of low-noise transistors, and it is designed to perform ideal parallel push-pull operation by constant-current driving.

We place importance on the phase margin, which is considered as one means of measuring amplifier stability.
Reliability under all load conditions from the equalizer section to the main section is considered by taking not only the ultra-low section but also the ultra-high section as large enough.
As a result, it has a broad spectrum distribution for the fundamental wave, exhibits a characteristic response even to a pulsed music signal, and enables stable operation and high-quality sound.

The equalizer circuit is a 3-stage PNP-NPN-PNP direct-coupled equalizer circuit.
Moreover, the maximum allowable input is 300 mV due to the high voltage supplied from the stable constant voltage power supply.
In addition, the RIAA deviation, which affects sound quality, is guaranteed to be ± 0.5 dB at 30 Hz to 15 kHz by using a low-noise transistor, low-error resistor, and capacitor in the RIAA element.
Click noise generated during switch switching is solved by using - power supply and setting the base potential of the first stage to 0.

To protect the transistor, a current limiter circuit is built in to limit the collector current of the output stage and driver stage so that it does not flow more than a certain value when overloaded.
A relay combined with an electronic circuit and a short-cut fuse protects the power transistor and speaker in the event of an error.
The relay circuit also functions as an audio mute, so there is no unpleasant pop noise when the power is turned on.

Uses T. T. C. (Triple Tone Control) of only SANSUI that can obtain an ideal curve of ± 15 db in 3 db steps for low and high sound, and ± 5 db in 1 db steps for medium sound only.
The T. T. C. amplifier uses a low-noise FET to ensure high input impedance at the first stage, and is an NF type with 3-stage and 2-stage direct-coupled circuits.

With a tone selector circuit, the sound quality can be adjusted in a total of nine stages : low 150 Hz, 300 Hz and 600 Hz, high 6 kHz, 3.5 kHz and 2 kHz as rising and falling points, and middle 750 Hz, 1.5 kHz and 3 kHz as the center.
It is designed with a defeat switch so that each T. T. C. circuit can be defeated and flat characteristics can be obtained.

It adopts a 12dB/oct NF type dedicated active filter circuit system, and the cutoff frequency can be switched between 12 khz and 6 khz for the high filter and 25 hz and 50 hz for the low filter.
There is no variation in the frequency response in the middle range.

There are two tape monitoring circuits that allow recording and playback monitoring on either of two tape decks connected simultaneously.
The tape reprint switch allows you to freely reprint tapes from either tape deck and monitor them while they are being reprinted.
Moreover, you can enjoy recording and FM from the speaker as usual while reprinting.

A 4-channel stereo system can be configured by connecting a 4-channel adapter.
When a 4-ch adapter is not used, recording and playback monitoring can be performed by connecting a tape deck.
Tape reprints are also available from a tape deck connected to a tape monitor circuit.

By connecting an N. R. (noise reduction) adapter, you can reduce tape hiss and record Hi-Fi on two connected tape decks simultaneously.
Playback can be performed on either tape deck by switching the tape monitor switch.

The speaker jacks are installed in the Route 3 of A, B and C. You can switch between A + B and A + C by using the speaker switch.

Two phono inputs are installed. Phono1 is designed to switch the input impedance between 50k Ω, and Phono2 is designed to switch the input impedance between 30k Ω, 50k Ω, and 100k Ω depending on the cartridge.

The preamplifier section and main amplifier section can be used independently by removing the connectors on the back panel.

It is equipped with a muting switch that can attenuate all of the range by 20 dB without using volume.

The Deck1, 2, and AUX have level adjusters that allow you to unify the input levels and eliminate the need to set the volume at each selector switch.

High impedance type microphones can be connected separately on the left and right.

Equipped with DIN connector for easy connection of tape deck.

Equipped with 5 position mode selectors : Stereo Reverse, Normal, Mono, L + R, L, R.

It is equipped with a loudness circuit.

It is equipped with 2 headphone jacks, and one of them is designed to turn off the speaker automatically when you plug in the headphone.

Equipped with 2 grounding terminals.

It has 4 AC outlets, Switchedx2 and Unswitchedx2.

All the knobs are made of pure aluminum.

Model Rating

Type	Pre-main amplifier
Rated output	Music Power (IHF) : 260W (4 Ω, 1 kHz) Effective output (single-channel operation) : 85W/85W (8 Ω, 1 kHz) Effective output (both channel operation) : 80W + 80W (8 Ω, 1 kHz) Continuous effective output (both channel operation, rated distortion factor 8 Ω, 20 Hz to 20 kHz) : 75W + 75W
Total harmonic distortion factor (rated output)	Not more than 0.1%
Cross modulation distortion factor	0.1% or Less (Rated Output, 70 Hz : 7 kHz = 4 : 1, SMPTE)
Power Band With (IHF)	5 Hz to 40 kHz
Frequency characteristic	3 Hz ~ 80 kHz, + 0 -1dB (Main Amplifier, 1W Output)
Damping factor	50 (8 Ω)
Input Sensitivity / Input Impedance (1kHz)	Phono1 : 2.5mV/50k Ω Phono2 : 2.5mV/30k Ω, 50k Ω, 100k Ω [Maximum allowable input 300 mV, total harmonic distortion rate 0.5% or less] MIC : 2.5mV/50k Ω Tuner, AUX (level adjustable) : 100mV/50k Ω Tape Monitor1, 2 (PIN) (level adjustable) : 100mV/50k Ω Tape Monitor2 (DIN) : 100mV/50k Ω 4 ch, N. R. Adaptor : 100mV/50k Ω
Output Voltage / Output Impedance	Tape Rec1, 2 (PIN) : 100mV/1.5k Ω Tape Rec2 (DIN) : 30mV/70k Ω 4 ch, N. R. Adaptor : 100mV/1.5k Ω Preamplifier (Rated Output) : 0.8V/1.5k Ω Maximum Output, Total Harmonic Distortion 0.5% or Less : 4.5 V
Crosstalk (rated output 1 kHz)	Phono1, 2 : 50 dB or more
Hum and noise (IHF)	Phono1, 2 : 75 dB or more Tuner, AUX : 85 dB or higher Main amplifier : 100 dB or more
Tone control	Bass (Defeat, 150 Hz, 300 Hz, 600 Hz) : / - 15 dB (20 Hz), 3 dB step Midrange (Defeat, 750 Hz, 1.5 kHz, 3 kHz) : ± 5 dB (1.5 kHz), 1 dB step Treble (Defeat, 6 kHz, 3.5 kHz, 2 kHz) : ± 15 dB (20 kHz), 3 dB step
Loudness (volume -30dB)	50Hz:+10dB 10kHz:+8dB
Low filter	25 Hz, 50 Hz : -3dB (12dB/oct.)
High filter	12 kHz, 6 kHz : -3dB (12dB/oct.)
Semiconductor used	Transistor : 58 FET:2 Diode : 37
Rated power consumption	205W (up to 550 VA)
External dimensions	Width 500x Height 140x Depth 347 mm
Weight	23.3kg