Pioneer SX-680 receiver

Step Up to Stereo Excellence

Pioneer has an advantage few other stereo makers can offer; our investment in hi-fi technology is extensive and expensive.

Your benefit from such advanced electronic innovations as hybrid ICs in the power amplifier section. Pioneer-exclusive ICs in the FM/AM tuner section and high-efficiency circuit techniques throughout the sensibly-priced SX-680 stereo receiver. Power delivery is a continuous 30 watts per channel, both channels driven into 8 ohms from 20 to 20,000 Hz, with no more that 0,1% T.H.D.

High Circuit Stability in Power Amplifier

The hybrid ICs in the power amplifier of the SX-680 not only lower costs but ensure high circuit stability as well. Each contains the bias, driver and output stages required for its channel, and each forms as independent quasi-complementary circuit. Dual-type transistors are used in the first-stage differentials to contribute to better temperature characteristics. Two large 8,000 µF electrolytic capacitors prevent power "dry-up".

The Independent Power Meters:

We've given the trim, well-organized front panel of the SX-680 a new visual appeal by including functional, direct-readout power meters in the upper lefthand area. They are interesting to watch as they follow the level changes in your music, but they are practical, too, use them to make sure that your speaker systems are receiving just the right amount of power for maximum efficiency and best musicality. Their logarithmically-compressed scales indicate from 0,01 to 60 watts on easy-to-read calibrations.

 

First;Class Phono Equalizer for Dynamic Disc Reproduction

Real hi-fi "purist" insist on the most precise performance in phono equalizer circuitry so that the wide dynamic range of today's disc records is never compromised. Precision is what you get in the SX-680; RIAA equalization is flat ±0,3 dB, over the wide 30 to 15,000 Hz frequency range. Phono overload is 200 mV at 1 kHz, with only 0,1% or less T.H.D. so that you may use the cartridge of your choice. Three low-noise transistors and a powerful supply system are included.

Automatic FM Pilot Signal Canceller: You Can't Buy Better

This special device is so good we use it even on the most expensive Pioneer receivers and FM tuners. A Pioneer-exclusive IC is used in the stereo FM demodulator; it contains a PLL circuit to ensure wide stereo separation under any circumstances, but it also has an amazing Automatic Pilot Signal Canceller to ensure that the audio output is free of all non-audio content.

Dual-Gate MOS-FET in FM Front-End

Technicalities like these are what make Pioneer the stay-ahead leader in hi-fi. The dual-gate MOS FET in the FM front end of the SX-680 has very low feedback capacitance and a particularly high gain (two to three decibels over mono-type units). When teamed up with the three-gang variable capacitor, it helps to provide a usable FM sensitivity of 1,9 µV (10,8 dBf) on mono, which translates into superb FM reception in any locale.

 

Specifications

Amplifier Section

Continuous Power Output: 

30 watts per channel at 8 Ω 

37 watts per channel at 4 Ω

Total Harmonic Distortion no more than 0,1% (continuous rated power output)

Intermodulation Distortion:  no more than 0,1% (continuous rated power output)

Damping Factor: 25 input Sensitivity/Impedance:

Phono :  2,5 mV/50 k Ω

AUX: 150 mV/ 50 k Ω

Tape Play 1, 2 :  150 mV/50 k Ω

Phono Overload Level:  200 mV ( 1khz T.H.D. 0,1%)

Output Level/Impedance

Tape Rec 1, 2 :  150 mV

Speakers:  A, B, A +B

Headphones:  Low impedance

Frequency Response

Phono (RIAA EQ) :  30 to 15,000 Hz ±0,3 dB

AUX, Tape Play :  10 to 60,000 Hz +0,5 -1,5 dB

Tone Controls:

Bass :  ±8 dB at 100 Hz

Treble :  ±10 dB at 10 kHz

Loudness Contour:  +6 dB (at 100 Hz) +3 dB (at 10 kHz)

Hum and Noise (IHF, short-circuited A network, rated power)

Phono :  75 dB

AUX, Tape Play :  90 dB

FM Tuner Section

Usable Sensitivity: 

Mono : 10,8 dBf (1,9 µV)

50 dB Quieting Sensitivity: 

Mono :  16,7 dBf (3,8 µV)

Stereo :  37,0 dBf (3,8 µV)

Signal-to-Noise Ratio

Mono :  80 dB

Stereo :  70 dB

Distortion (at 65 dBf)

Mono :  0,07% (at 100 Hz ); 0,07% (at 1 kHz); 0,2% (at 6 kHz)

Stereo :  0,15% (at 100 Hz); 0,15% (at 1 kHz ); 0,25% (at 6 kHz)

Frequency Response:  30 to 15,000 Hz +0,2 dB -1,0 dB

Capture Ratio:  1,0 dB

Alternate Channel Selectivity:  60 dB

Spurious Response Ratio:  65 dB

Image Response Ratio:  65 dB

IF Response Ratio:  90 dB

AM Suppression Ratio:  50 dB

Muting Threshold:  19,2 dBf (5 µV)

Stereo Separation:  40 dB (1 kHz); 30 dB (30 Hz -15 kHz)

Subcarrier Production Ratio:  50 dB

SCA Rejection Ratio:  65 dB

Antenna Input:  300 Ω  (balanced); 75 Ω  (unbalanced)

AM Tuner Section

Sensitivity:  300 µV/m (IHF, ferrite antenna); 15 µV (IHF, ext. Antenna)

Selectivity:  26 dB

Signal-to-Noise Ratio:  50 dB

Image Response Ratio:  40 dB

IF Response Ratio:  40 Hz

Antenna:  Built-in ferrite loopstick antenna

Semiconductors:  3 FETs; 5 ICs; 21 Transistors; 29 Diodes

Power Requirements:  110/120/220/240 V 50/60 Hz

Power Consumption:  95 W (UL), 210 VA (CSA)

Dimensions (W x H x D):  435 x 144,5 x 314 mm (17-1/8" x 5-11/16" x 12-3/8")

Weight:  8,9 kg (19 lb 10 oz)