Denon PRA-6000

1 9 8 2 june 1982
1 9 8 4 1984

Extremely rare preamplifier encased in Star Trek-ish looks.

The center of all circuits inside is the total absence of any NFB loops for "real-time audio technology".
This is done by "teaming" two FET transistors in cascode-bootstrap, one functioning in exact reverse mode. The "loop" is therefore as minimal and direct as can be - there is no loop.

And since, theoretically, FET has a square transmission characteristic for output current against input voltage, whatever distortion is left is 2nd harmonic only. Goody.

Doing away with NFB is something very 1979-1981, as done, for instance, by Pioneer with the 1980 Z1 mini-series : C-Z1, M-Z1, H-Z1.

Implemented differently by Denon (and others) however allowed separate patents to be issued - there always was more cash to be gotten from that path than from selling three hundred high-end audiophile preamplifiers !

After being chased out of the landscape, NFB loops nevertheless came back in the mid 1980s : as in the A-1000 bestseller, Yamaha with the Zero Distortion Rule (ZDR) did the same basic system but came back to comparing input and output and injecting a reversed-phase equivalent... but within an NFB loop !

On a more common plane, the PRA-6000 had a 100VA transformer within a huge power-supply, glass-epoxy boards, low internal impedance, OFC wiring and copper busses, dual-mono structure, and a 15mm thick glass front panel making this display of advanced technology a real... display.

Also a three phono inputs with dual-frequency subsonic filter (CD hadn't yet arrived from its imminent future), a high internal slew rate of 500V/µs to naturally cater to the upcoming digital sources (:), non-magnetic shielding of the toroidal, MC and EQ sections, DC Servo everywhere... and... then... some.

Denon was (is) Japan's most advertising-prone brand and the PRA-6000 / POA-8000 were proeminently seen in almost all magazines between 1982 and 1984.
That makes a lot of ads !

At 450,000¥, however, the PRA-6000 wasn't planned to be sold by the thousands - I believe the production run to be of about 500 (tops), worldwide.
I nevertheless sure wish I could hear this summum of engineering designed just before digital audio changed the scene alltogether.

Denon would sit the rest of the 1980s out of the stratospherically expensive market before producing one ultimate set of ultra high-end : the PRA-S1, POA-S1, DP-S1, DA-S1.

The later marriage to Marantz made D&M (2003-2008), but that is really an entirely different story - maybe better but certainly not as lavish.

Denon PRA-6000, image 1 Denon PRA-6000, image 2 Denon PRA-6000, image 3
Denon PRA-6000 specifications
Title Value
MC Input MC Input
Phono 1/2/3 : 0,125mV / 100Ohm
Max. input level : 19mV at 1Khz
THD : < 0,002% (20Hz...20Khz)
Frequency response : 10Hz...100Khz (± 0,02dB)
S/N ratio : 76dB (for -154dBv input)
MM Input MM Input
Phono 1/2 : 2,5mV / 50kOhm
Max. input level : 380mV at 1Khz
THD : < 0,002% (20Hz...20Khz for 2V output)
Frequency response : 10Hz...100Khz (± 0,02dB)
S/N ratio : 86dB (IHF-A)
Stereo separation : > 80dB (20Hz...1Khz)
> 70dB (20Khz)
Gain : 35,6dB at 1Khz
LINE level input LINE level input
tuner/aux/DAD/tape play : 150mV / 50kOhm
Nominal output : 1,5V
0,002% (20Hz...20Khz, at 5V output)
2Hz...300Khz (+0 / -3dB)
10Hz...100Khz (+0 / -0,2dB)
S/N ratio : 100dB (IHF-A)
Stereo separation : 100dB (vol. max ; 20Hz...1Khz)
75dB (vol. max. ; 20Khz)
100dB (vol. -20dB ; 20Hz...1Khz)
75dB (vol. -20dB ; 20Khz)
Tone controls Tone controls
Turnovers : 125Hz / 2Khz
125Hz / 8Khz
500Hz / 2Khz
500Hz / 8Khz
Range : ± 0,5 / 1 / 2 / 4 / 8dB
Subsonic filter : 12dB /octave at 16Hz
6dB /octave at 20Hz
General General
Componentry : 80 FETs
171 transistors
123 diodes
11 ICs
1 rectifier stack
8 lead relays
2 relays
AC outlets : 3 switched (210W max.)
2 unswitched (700W max.)
PC : 90W
Dimensions : 45,5 x 13,4 x 39,2cm
Weight : 14,3kg.
List price : 450,000¥
Denon PRA-6000 : 0 topic
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page online since : march 2007
page updated : july 2010
page type : LGT / KNB
page weight : 174.69 Kb / 0 b

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