Yamaha A-1000

October   1 9 8 4 october 1984
1 9 8 7 1987

Follower of the CA-1000 bestselling series - a bit cheaper and not fully in Class A anymore.

"Dual Class A amp with ZDR" means two amplifier sections (one in A, the other in AB) "circling" the loudspeaker terminals with an NFB loop to effectively damp the counter-reaction between amplifier output and bass cones - the schematic is below.

Two 47,000µF rectifying caps, two 22,000µF smoothing caps and a basic structure which is quite reminiscent of the old CA-1010.
Also present is a pre/main set of i/o terminals and big speaker terminals.

Besides ZDR (Zero Distortion Rule : watch distortion at the output and inject a reversed-phase equivalent at input), a nice touch was added : RICHNESS !

Richness isn't an elusive tonal quality but a three-position tone control to perfectly match the A-1000 to Yamaha's bestselling NS-1000 series and later two siblings.

Position 1
fits the NS-2000 by adding 7,5dB at 30Hz

Position 2
belongs to the NS-1000M and NS-1000x by adding 7,5dB at 40Hz

Position 3
is a freebie adding the same amount of dBs but higher at 50Hz.


The export A-1000 was fairly different and named A-950 in Japan.

Yamaha A-1000, image 1 Yamaha A-1000, image 2
Yamaha A-1000 specifications
Title Value
(japanese version) (japanese version)
Power : 2x 120W (6 Ohm, 20Hz...20Khz, 0,003% THD)
2x 140W (4 Ohm, 20Hz...20Khz, 0,003% THD)
2x 100W (8 Ohm, 20Hz...20Khz, 0,003% THD)
Damping factor : 100 (1Khz / 8 Ohm)
Inputs : 160µV / 220Ohm (MC)
2,5mV / 47kOhm (MM)
150mV / 47kOhm (lines)
THD : 0,005% THD (MC > rec)
0,003% THD (MM > rec)
0,003% THD (lines > SP out, 50W / 8 Ohm)
Frequency response : +0 / -0,5dB (20Hz...20Khz)
±0,2dB (MM)
±0,2dB (MC)
S/N ratios : 72dB (MC, 160µV input)
86dB (MM, 2,5mV input)
108dB (lines)
PC : 300W max.
Dimensions : 47,3 x 15,9 x 43,4cm
Weight : 16,5kg.
List price : 128,000¥
page online since : june 2009
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