Sansui Six (1972)

Sansui's SIX AM/FM Solid State Stereo Receiver incorporates the same fine tuner/amplifier characteristics as its more expesive counterparts, the legendary Eight and Seven. For this reason alone, the Six can take its place among the very finest of all medium powered stereo receivers, and it is, by anyone's audio standaeds, a sophisticated package of value. designed especially to reflect tonal quality, the Six offers a variety of advanced features incorporating the latest electronics circuitry and solid state achievements. Among them: a sensitive FM front end utilizing an MOS FET and a 4-gang tuning capacitor, a highly selective FM If amplifier with six ceramic filters and IC, an FM multiplex circuit with a switching circuit employing four choice diodes and LC type carrier leak filter, a signal strength meter, a two-stage Am AGC circuit, a three-stage direct-coupled low-noise equalizer, a completely direct-coupled OCL pure complementary ppower amplifier with a constant-current driver stage, and a newly designed relay-equipped protection circuit. For the utmost in versatility - a keynote of all Sansui stereo receivers - the Six offers provisions for connecting even new innovations such as a noise reduction adaptor - the latest Dolby, if you choose - and a 4-channel adaptor to upgrade your 2-channel system into a 4-channel unit at a later date.

Everything considered the Six just mightbe the stereo value of teh year. From stereo's company of teh moment - Sansui.

The Six's equalizer amplifier is a three-stage direct-coupled system employing three carefully selected low-noise silicon transistors in a unique PNP-NPN-PNP combination. This circuitry realizes excellent linearity and an almost identical facsimile of the RIAA equalizer curve. Other vitrues of this feature are a wide dynamic range, high stability, low distortion and a high signal-to-noise ratio.

Another innovation of the Six, one that is rarely found on other medium-priced and powered receivers, is the terminals for connecting a noise reduction adaptor - such as the latest Dolby System. This type of system, of course, eliminates annoying hiss and noise that has up until recently been considered unavoidable in tape recording and playback. Again, with the noise reduction adaptor terminal, you may bypass disconnecting your tape deck to use the adaptor.

The Six is complete with emitter-follower negative feedback high and low filter circuits utilizing transistors designed exclusively for this purpose. These filter circuits boast a sharp 12 dB/oct. cutoff characteristic.

In the FM frontend of teh Six is a solid combination ofsolid state sophistication. It utilizes a low-noise MOS FET (metal oxide semiconductor field effect transistor) combined with three expensive silicon transistors and a 4-gang tuning capacitor for its important FM RF amplifier and mixer stage. The result of all this capability is outstanding crossmodulation distortion and image ratio characteristics, as good as you'll find in a receiver in this price range. Outstanding sensitivity of 2,0 μV is another important characteristic of the Six's frontend and the reason why its tuner section can pull in distant, weak stations with an unmatched clarity.

The heart of the Six's tuner section, its IF amplifier, offers superb characteristics attained by the use of an IC embodying a 3-stage differential amplifier as well as six ceramic filters boasting excellent selectivity and cut-off characteristics. Quality specifications such as an IHF-rated selectivity of 60 dB and capture ratio of 2.0 dB are the result. You will also discover that distortion, separation and phase characteristics of the receiver are very near the top during FM stereo reception.

The Six's power amplifier adopts an all-stage direct-coupled OCL circuit equipped with two (plus and Minus) power supplies, and in the process does away with coupling capacitor and output capacitors. If you compare this circuit with the conventional power amplifier citcuit using coupling capacitors betwee amplifying stages, you find that the Six has distinct advantages in terms of reduced distortion and a wider power bandwidth. The absence of the output capacitors also prevents degredation of the amplifier damping factor and resultant deterioration of tone quality. The output stage of the power amplifier is apure complementary circuit using NPN and PNP silicon transistos to achieve ideal phase inversion and keep both harmonic distortion and intermodulation distortion minimal at all output levels.

The stability and safety of a direct-coupled amplifier depends upon the effectiveness of temperature compensation and the stable operation of the driver-stage differential amplifier. Included in the Six is a specialized transistor for temperature compensation and a stabilizing circuit used especially for the differential amplifier.In addition, four quick-acting fuses and a newly designed relay circuit are incorporated to protect abnormal current from flowing into your speakers in the event that the power transistor (s) are damaged. Once the abnormal condition is corrected, the relay circuit automatically restores itself. And then it also mutes the pop noise generated when the receiver is switched on or off.

Specifications Audio Section

Power Output

IHF Music Power: 130 watts 4Ω at 1,000 Hz; 105 watts 8Ω at 1,000 Hz

Continuous RMS Power:

each channel driven: 48/48 watts 4Ω at 1,000 Hz: 39/39 watts 8Ω at 1,000 Hz

both channels driven: 34 + 34 watts 8Ω at 1,000 Hz

Both channels driven at 20 to 20,000 Hz: 28 + 28 watts 8Ω load

Total Harmonic Distortion:

Power Amplifier Only: less than 0,3% at rated output

Preamp Only: less than 0,2% at rated output (Phono);

less than 0,1% at rated output (Aux)

Overall (Aux to Power output): less than 0,3% at rated output

Intermodulation Distortion (70 Hz: 7,000 Hz = 4:1 SMPTE method):

Overal (Aux to Power output): less than 0,3% at rated output

Power Amplifier Only: less than 0,3% at rated output

Power Bandwidth (IHF): 10 to 50,000 Hz at 8Ω load

Frequency Response:

Power Amplifier Only: 15 to 40,000 Hz ±1 dB

Overall (Aux to Power output): 20 to 40,000 Hz +1 dB, -1,5 dB

Equalization RIAA Curve: +1 dB, -1 dB, (30 to 15,000 Hz)

Load Impedance: 4 to 16 Ω

Damping Factor: approx. 40 at 8Ω load

Channel Separation (at rated output 1,000 Hz):

Power Amplifier Only: better than 60 dB

Overall (from Phono): better than 50 dB

(from Aux): better than 50 dB

Hum and Noise (IHF):

Power Amplifier Only: better than 90 dB

Overall (from Phono): better than 70 dB

(from Aux): better than 80 dB

Input Sensitivity anf Impedance (at rated output 1,000 Hz):

Phono: 2,5 mV (50 kΩ)

Aux, Tape Monitor, N.R. Adaptor, 4-CH Adaptor: 150 mV (50 kΩ)

Power Amplifier Input: 800 mV (50 kΩ)

Output level:

Tape Monitor: 30 mV (DIN); 150 mV (PIN)

Preamplifier; 800 mV; Max output: 4,000 mV at 0,5% distortion

Tone Controls

Bass: +15 dB, -15 dB at 50 Hz (3 dB step)

Treble: +15 dB, -15 dB at 15,000 Hz (s dB step)

Filters:

Low: -10 dB at 50 Hz (12 dB/oct.)

High: -10 dB at 10,000 Hz (12 dB/oct.)

Loudness: +10 dB at 50 Hz, +8 dB at 10,000 Hz

Specifications Tuner Section

FM

Tuning Range: 88 to 108 MHz

Sensitivity (IHF): 2μV

Signal to Noise Ratio: better than 63 dB

Image Frequency Rejection: better than 75 dB at 98 MHz

Spurious Response Rejection: better than 85 dB at 98 MHz

Selectivity: better than 60 dB

IF Rejection: better than 85 dB at 98 MHz

Capture Ratio (IHF): 2 dB

Spurious Radiation: less than 34 dB

Total Harmonic Distortion

Mono: less than 0,3%

Stereo: less than 0,5%

Stereo Separation: better than 35 dB at 400 Hz

Frequency Response: 30 to 12,000 Hz +1 dB, -2 dB

Antenna Input Impedance: 300Ω balanced, 75Ω unbalanced

AM

Tuning Range: 535 to 1605 kHz

Sensitivity (bar antenna): 50 dB/m

Selectivity: better than 25 dB

Image Frequency Rejection: better than 80 dB/m at 1,000 kHz

IF Rejection: better than 80 dB/m at 1,000 kHz

General Specifications

Switches and Selector

Tape Monitor 1 and 2: Out, In

N.R. Adaptor: Out, In

4-CH Adaptor: Out, In

Loudness: Off, On

Filters High and Low: Off, On

Mode: Stereo, Mono

Fm Muting: On , Off

Speakers: Off, A, B, C, A+B, A+C

Selector: Phono-2, Phono-1, FM Auto, AM, Aux

Semiconductors: 72 transistors, 1 FET, 41 diodes,4 Zener diodes, 1 IC

Power Requirements: 100, 117, 220, 240 V, 50/60 Hz

Power Consumption: Max. 280 VA; Rated 100 watts

Dimensions: 424 x 140 x 315 mm (W x H x D)

Weight: 13,2 kg