Pioneer A-09

1 9 9 2 july 1992
1 9 9 6

Last ultra 2-channel from Pioneer - a mini-Exclusive of sorts.

Really an Exclusive but Pioneer seemingly prefered to hook the A-09 with the PD-T09 (aka PD-95) and other high-end components which, however did not bear the "09" tag : D-07 DAT, T-1100S recorder and S-HE100 loudspeaker !
That would've been the role of the A-07 but it doesn't fit either - not only Sony makes strange moves :)

Anyway -
Borrowed from the earlier Exclusive M7 is the separation of... everything : two boxes in one, voltage and current stages remain fed by different transformer windings.

The transformer is a copper-shielded 400VA EI which feeds the control, phono, voltage and current sections separately.

The attenuator is real luxury : hand-made, it isn't a regular potentiometer but a 40-steps calibrated resistance array allowing a maximum of 0,5dB balance error. As in the Exclusive C7 and in fact, it is the same as in the C7 but there is only one for both channels ; the same attenuator was used in the Micro Seiki CL-M2DC ultra preamp ; it was actually built by Tokyo KO-ON Denpa under the Type C-3 reference.

Stereo separation up to 20Khz shoots high at 90dB.

The output transistors are bipolars from Toshiba (2SA 1265 and 2SC 3182) ; drivers also bipolars (2SC 4793 and 2SA 1837). The low-NFB, DC-Servo and current-mirror input stages start with two FETs.
Output stages have no NFB loop at all - a late return to the 1979 M-Z1a ?

The capacitor block holds two 15,000uF and two 30,000uF, all Pioneer-made. The preamp stages hold 22 bipolars and FETs (per channel) ; regulations everywhere.

Low internal impedance, non-magnetic almunium slabs, diecast and higly ribbed resin base, select custom caps, non-symmetrical and ribbed heatsinks, ultra-short signal paths (the power transistors are all set at the back of the heatsinks, too), realy-driven i/o and protection, an OFC AC cord which enters the enclosure by the underside to reach the transformer directly, and fully dual-mono structure (after the transformer) - all this copper-plated from top to bottom.

The A-09 is a full Class A design with low distortion, very high damping factor and no NFB loop in the final stage : up to 2x 140W on a 2 Ohm load !

Albeit fairly rare (it did cost 480,000¥), the A-09 is one of the best and most "musical" integrated amplifiers ever made.

Pioneer A-09, image 1 Pioneer A-09, image 2 Pioneer A-09, image 3
Pioneer A-09 specifications
Title Value
Power : 2x 35W (8 Ohm, 20Hz...20Khz, 0,05% THD)
2x 70W (4 Ohm, 20Hz...20Khz, 0,05% THD)
2x 140W (2 Ohm, ?...?, 0,05% THD)
2x 90W (4 Ohm, 1Khz)
2x 45W (8 Ohm, 1Khz)
THD : 0,05%
0,060% / 30W / 40Hz
0,055% / 30W / 1Khz
0,062% / 30W / 20Hz
Damping factor : 150 (20Hz...20Khz, 8 Ohm)
200 (1Khz, 8 Ohm)
Power bandwidth : ??
Frequency response : 20Hz...20Khz (RIAA, ±0,2dB)
1Hz...150Khz (+0 / -3dB)
Rise time : 1,4us (10Khz)
Inputs : Phono MM (2,5mV / 50kOhm)
Lines (150mV / 50kOhm)
Balanced (150mV / 600 Ohm)
Max. input level : 150mV (MM, 0,05% THD, 1Khz)
Outputs : 2x Tape rec. (150mV / 1kOhm)
2x speaker pairs (4...16 Ohm)
S/N ratio : 87dB (MM ; IHF-A)
73 / 69dB (MM ; DIN ; rated power / 50mW output)
109dB (lines ; IHF-A)
96 / 74dB (lines ; DIN ; rated power / 50mW output)
PC : 220W
Dimensions : 44 x 19,8 x 48cm
Weight : 28,8kg.
Pioneer A-09 : 0 topic
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page online since : february 2010
page updated : march 2010
page type : LGT / KNB
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