Pioneer SPEC-2

Pioneer M-77

1 9 7 5 may 1975
1 9 7 7 1977
1 9 8 0 1980

Launched two years after the Exclusive M3 in Japan as a would-be Exclusive, the 1975 M-77 became for the export markets the famed SPEC-2 powerhouse in 1977.

If the circuits are partly similar, the execution isn't and Pioneer kept a fair distance between the M-77 and the Exclusive M3.
The M-77 cost 180,000¥, the Exclusive M3 315,000¥ so... smaller transformer (but toroidal !), a more standard layout and no luxurious wood enclosure either.

Circuit-wise, the SPEC-1 has an Class A pre-driver stage with current mirror circuit ; a 2-stage Darlington DC - OCL circuit is employed and a triple push-pull circuit for the output stage.

Relays act as protection circuit at the pre-driver and output stages, and also during power on/off, when the current surge reaches... 300 amperes !
The capacitors are 15,000µF each, for a total of 60,000µF ; a back switch allows to select speakers' 4 Ohm or 8 Ohm (nominal) impedance.

Added to the M-77 for its SPEC-2 export version is... nothing : they are the same.

The M-77 sold somewhat poorly in Japan and vanished rapidly, the SPEC-2 sold very well elsewhere, remaining available in Germany as late as 1980 with stocks lasting quite probably even longer than that.

Pioneer was then at the A-9 and the Communication Series but demand was still there for old-fashioned silver with big VU meters.

Pioneer SPEC-2, image 1 Pioneer SPEC-2, image 2 Pioneer SPEC-2, image 3
Pioneer SPEC-2 specifications
Title Value
Power : 2x 250W (20Hz...20Khz, 8 Ohm, 0,1% THD)
Frequency response : 5Hz...80Khz (+0/-1dB)
Power bandwidth : ??
S/N ratio : > 110dB (IHF-A ; input shorted)
Damping factor : 50 (20Hz...20Khz ; 8 Ohm)
THD : < 0,1% (rated power, 1Khz, 8 Ohm, DIN)
IMD : < 0,1% (rated power, 1Khz, 8 Ohm, DIN)
Input : 2,5V / 50kOhm
Semiconductors : 55 transistors
75 diodes
PC : 500W / 900VA nominal
Dimensions : 48 x 18,7 x 44,5cm
Weight : 24,3kg.
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page online since : october 2005
page updated : september 2010
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