What is stereo?

There are now two system of high fidelity, monophonic (monaural) and stereophonic. Monophonic is a system that starts from one microphone and is fed through a single high fidelity set. Stereophonic is a double system. Two separate microphones are placed at different sides of the orchestra and two different systems are used to keep the two signals or channels separated. Two separate speakers are used, placed on different sides of you room. Stereo is much like 3-D photography, two slightly different sound reach your ears giving you a new dimension in sound.

H.H. Scott '59

Sansui AU-217

 Clean, Low-Distortion Power
The AU-217 delivers 30 watts per channel min. RMS, both channels driven, into 8 ohms from 20 to 20,000 Hz, with no more than 0,06% total harmonic distortion. 
Circuit configuration in the AU-217 is a differential input with constant current source, followed by a current differential push-pull driver and, finally, a Darlington-arranged power output.  In the driver circuit,  the AU-217, which  is a Sansui exclusive, the advantages include low open-loop distortion and stability against voltage and thermal changes. The Darlington-arranged power output used in both the AU-217 has a low output impedance and features low distortion.

Rated Watts Available on Demand
As mentioned, Sansui uses musical inputs not only steady-state test signals, to test the AU prototypes. Design refinements are made after repeate auditions to ensure musicality. While your own ears can cartainly tell the difference, you might like to know that we have improved the sound by lowering TIM (Transient Intermodulation) distortion, reducing crosstalk and giving the Aus excellent transient response.
As a result, the rated watts on  AU-217  - 30 watts  - are guaranteed to be fully available on demand. What all this means can be understood by the following illustration.
Suppose there's a competitive amp with 30 watts RMS power which has the same specifications as does the AU-217. set the volume controls on at both amps at maximum position, feed both amps with a clipping level signal. A connected oscilloscopewill show clipped waveforms from both amps. Yetwhen a heavily modulated musical signal is applied, the AU-217 still sounds clean and clear, while the rival amp sounds distorted and harsh.  The reasons lie in the fact that the former has far rediced transient intermodulation distortion than the latter.
 Versatile Preamp Section
Precision Phono Equalizer
One of the most critical tasks required of a phono equalizer is precision. If phono signals are "colored" in the equalizer, no tone controls or other devices can ever restore tham to proper "flat" response. This is why we've used only the finest available  parts to give the phono equalizers in the AU-217  the ability to stay within ±0,5 of the RIAA equalization curve over the entire 30 to 15,000 Hz spectrum.
This model use PNO transistor inputs followed by a low-noise NPN transistor direct-coupled amp.fed with dual voltages from the power supply. High overload of 180 mV for the AU-217,  together with accurate RIAA equalization, let you enjoy dynamic unclipped record reproduction even at full power operation.
Bass/Treble NF Controls
The tone control circuit inn the AU-217  is located in the NF (Negative Feedback) network of the elaborate low-distortion power amp. This configuration features low distortion and high signal to noise, because all inputs - Aux, Tuner and Tape  - are sent direct to the power amp, (Phono equalizer output also goes direct to the power amp)
The Bass/Treble controls themselves have click stops for smooth and accurate use. Bass has a range of ±12 dB at 50 Hz Treble is ±11 dB at 15 kHz.

Effective High and Subsonic Filters
Scratchy records, hiss noise from tapes and any other high frequency noise is eliminated effectively without harming musical content since the High Filter on all this new AU models feature a sharp cut-off response of -6 dB/oct with a 3 dB attenuation at 7 kHz. If your phono cartridge has a high "Q" factor or resonance in the low frequencies, or if you want to play warped records without causing subsonic intermodulation, use the Subsonic Filter on the AU-217.

Loudness Switch
The human hearing mechanism becomes insensitive to the high and low ends of the audible spectrum as the level or volume of a sound decreases.  When listening to music at low levels switch in the Loudness circuit on your AU it boosts the lows and highs just enough to restore flat reproduction across the entire frequency range
Rugged Power Supply
Large transformers and electrolytic capacitors form the newly-designed power supplies in both models. The capacitors in the AU-217 are each 6,800 µF. These powerful supplies are located as far as possible from the phono equalizers to avoid hum pickup and assure accurate reproduction of musical input.
Low Profile Design
 The smart new looks of the Sansui AUs are practical too. Each component is designed to fit neatly into a standard EIA equipment rack (such as the Sansui GX-5) along with your Sansui cassette deck, the AX-7 Mixing Amplifier or the matching TU-217 FM/AM Tuner.
Other Features:
Left/Right Balance with Center Clock
Tape Monitor Switch
Stereo Headphone Jack
Large One-Touch Speaker Treminals
AC Outlets - Switched and Unswitched 200 watts each maximum
Power Output
Min. RMS both channels driven 20 - 20,000 Hz, no more than 0,06% T.H.D.:
30 watts per channel into 8 Ω
Min. RMS both channels driven at 1,000 Hz, no more than 0,06% T.H.D.:
37 watts per channel into 4 Ω;
34 watts per channel into 8 Ω
Load Impedance:  8 ohms
Total Harmonic Distortion:  less than 0,06% at or below rated min. RMS poer output
Intermodulation Distortion (70 Hz : 7,000 Hz = 4:1 SmPTE method)
Less than 0,06% at or below rated min. RMS power output
Damping Factor:  80 into 8 Ω
Frequency Response (at 1 watts):
Overall (from AUX):  10 to 50,000 Hz +0,5 dB , -1,5 dB
RIAA  Curve Deviation (30 to 15,000 Hz):  +0,5 dB  -0,5 dB
Input Sensitivity/ Impedance:
Phono :  2,5 mV/ 47 k Ω
Aux :  150 mV/ 47 k Ω
Maximum Input Capability:
Phono :  180 mV RMS
Output Voltage / Impedance:
Tape Rec (PIN):  150 mV into 47 k Ω load/ 300 Ω
Hum and Noise:
Phono :  76 dB
Aux :  94 dB
Channel Separation:
Phono :  65 dB
AUX :  68 dB
Bass :  +12 dB -12 dB at 50 Hz
Treble :  +11 dB -11 dB at 15 kHz
Subsonic :  -3 dB at 13 Hz (6 dB/oct)
High :  -3 dB at 7 kHz  (+6 dB /oct)
Loudness (volume control at -30 dB position):
=8 dB at 50 Hz
+6 dB at 10 kHz
AC Outlets:
Switched :  200 watts max
Unswitched :  200 watts total
Power requirement:
Power Voltage :  100, 120,  220, 240 V;  50/60 Hz
Power Consumption:  145 watts
Semiconductors:  30 transistors; 21 Diodes
Dimensions (W x H x D):  430 z 110 x 340 mm
Weight:  8,4 kg (18,5 ) NET

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