Pioneer SX-1280

1 9 7 8 february 1978
1 9 8 0 1980

If the SX-1250 retains the "original monster receiver flavor", the SX-1280 has "end of an era" written inside it : some savings on build-quality and some parts nowadays difficult to find.

What it makes up with is a much welcome visual lifting and rarity : while SX-1250 s abound, 1280s were and still are rare - end of an era indeed.

Inside, despite less shielding, smaller caps (4x 22,000µF vs. 4x 15,000µF) is a 3-stage Darlington p-p output stage with Star Quad wiring (which oppose magnetic flux to cancel each other out), a bigga toroidal transformer, pure copper busses, Pioneer ICs (PA3004 for protection, PA1001A, PA1002A & PA3001A for the IF, muting and PLL & demod tuning sections), twin logarithmic power meters, FET drain follower/buffer amp for the MOS-Fet RF stage, junction FET in the mixing buffer, low-noise 3-stage DC SEPP phono stage with 4-step capacitance load setting and twin tone controls for 3000 possible tonal changes.
Also, crucial, a proper 32-step precision attenuator.

The enclosure is based on the same slant : wood front, sides and top cut to show the large heatsinks making the back - if the term existed, one could call that "muscular class". The rest is all chrome and shiny aluminium, shining all by itself.

The SX-1280 is very similar to the original SX-1250 and even if its build-quality is a slight step down... it IS the most desirable of the two !

The 1280 coexisted with the later and over-the-top SX-1980 for a while before being withdrawn along with the latter.
As for 95% of the receivers produced by japanese brands (G-33000, SX-1980, CR-3020, CR-2020, CR-1020, STR-V7, Model 2500 etc), the SX series was entirely export-only.

Pioneer SX-1280, image 1 Pioneer SX-1280, image 2 Pioneer SX-1280, image 3 Pioneer SX-1280, image 4
Pioneer SX-1280 specifications
Title Value
POWER AMP section POWER AMP section
Power output : 2x 185W (continuous, 8 Ohm, 20Hz...20Khz, 0,03% THD)
THD : 0,03% (rated output)
0,01% (2x 90W output, 8 Ohm)
0,01% (2x 1W, 8 Ohm)
IMD : 0,01% (rated output)
0,006% (2x 90W output, 8 Ohm)
0,005% (2x 1W, 8 Ohm)
Frequency response : 5Hz...100Khz (+0 / -1dB)
Damping factor : 30 (20Hz...20Khz, 8 Ohm)
S/N ratio : 105dB (IHF, input shorted)
Input : 1V / 50kOhm
PRE AMP section PRE AMP section
Inputs : 2,5mV / 50kOhm (phono 1)
2,5mV / 50kOhm (phono 2)
150mV / 50kOhm (aux, tape 1 & 2)
7,5mV / 50kOhm (MIC)
Phono 1 load settings : 100 / 200 / 300 / 400pF
Maximum phono inputs level : 300mV (1Khz, 0,03% THD)
Outputs : 150mV (tape rec 1 & 2)
1V / 1kOhm (pre out)
THD : 0,01% (1V output, 20Hz...20Khz)
Frequency response : 20Hz...20Khz (RIAA ± 0,2dB)
5Hz...80Khz (lines ; +0 / -1dB)
Bass control : ± 10dB at 100Hz (main)
± 5dB at 50Hz (sub)
Treble control : ± 10dB at 10Khz (main)
± 5dB at 20Khz (sub)
Low filter : 12dB/octave below 15Hz
High filter : 12dB/octave above 8Khz
Loudness contour : +6db @ 100hz / +3dB @ 10Khz
S/N ratio : 80dB (phono, IHF-A, input shorted, rated output)
95dB (lines ; IHF-A, input shorted, rated output)
Muting switch : -20dB
FM section FM section
Mono usable sensitivity : 9,8dBf (1,7µV)
50dB quieting sensitivity : 14,2dBf (2,8µV ; mono)
36dBf (34µV ; stereo)
S/N ratio : 80dB (mono, at 65dBf)
71dB (stereo, at 65dBf)
74dB (stereo, at 75dBf)
THD : 0,1% (100Hz, mono, 65dBf)
0,2% (100Hz, stereo, 65dBf)
0,1% (1Khz, mono, 65dBf)
0,15% (1Khz, stereo, 65dBf)
0,1% (6Hz, mono, 65dBf)
0,2% (6Khz, stereo, 65dBf)
Frequency response : 30Hz...15Khz (+0,2 / -0,5dB)
Capture ratio : 1dB
Alternate channel selectivity : 80dB
Spurious response ratio : 100dB
Image response ratio : 90dB
IF response ratio : 110dB
AM suppression ratio : 55dB
Muting threshold : 19,2dBf (5µV)
Stereo separation : 50dB (1Khz)
35dB (30Hz...15Khz)
Subcarrier product ratio : 65dB
SCA rejection ratio : 65dB
Input : 300 Ohm balanced
75 Ohm unbalanced
AM section AM section
Sensitivity : 300µV/m (IHF, ferrite antenna)
15µV (IHF, external antenna)
Selectivity : 26dB
S/N ratio : 55dB
Image response ratio : 40dB
IF response ratio : 40dB
Antenna : built-in ferrite loopstick
General General
Semiconductors : 5x FETs
6x ICs
67x transistors
50x diodes
Voltage : 120V / 60Hz (US & CA)
110/120/220/240V / 50-60Hz
PC : 430W (UL)
1000VA (CSA)
Dimensions : 55,6 x 18,6 x 46,1cm
Weight : 28,7kg.
List price : 900...950$
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page online since : september 1967
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