Description
Tube stereo power amplifier.
Introduced
1980
Discontinued
1985
Revisions
D90 Revised
D90B (1981)
Options

MSRP (US new retail)
D90: $2,195
D90B: $2,450. Later increased to $2,695.
Specifications
Power output  90 watts per cannel minimum continuous (both channels
operating) at 16 ohms from 25 Hz to 20 kHz with less than 1% total
harmonic distortion. Typically below .01% at 1 watt. Approximate
power available per channel at "clipping" (both CH. OP, 1kHz): 105
watts D90B: 80 watts per cannel minimum continuous (both channels operating) at 16 ohms from 25 Hz to 20 kHz with less than 0.5% total harmonic distortion. Typically below .005% at 1 watt. Approximate actual power available per channel at "clipping" (both CH. OP, 1kHz): 90 watts 

Power bandwidth  (3dB points) 12 Hz and 60kHz D90B: (3dB points) 12 Hz to 50kHz 
Frequency response  
Input sensitivity  1.2V RMS for rated output (adjustable) 
Input impedance  75 kOhms, nominal at maximum gain 
Output taps  
Output regulation  Approximately .8dB, 16 ohm load to open circuit D90B: Approximately .3dB, 16 ohm load to open circuit 
Overall negative feedback  17.5dB D90B: 21.5dB 
Damping factor  Approximately 12 D90B: Approximately 25 
Distortion  Intermodulation distortion: Less than .5% at 1 dB below rated
output (100V p to p, 16 ohms) (SMPTE method) D90B: Intermodulation distortion: Less than .3% at 1 dB below rated output (100V p to p, 16 ohms) (SMPTE method) 
Slew rate  20 V/µs D90B: 15V/µs 
Rise time  2.5 µs D90B: 5 µs 
Hum & noise  Wideband, unweighted, more than 90dB below rated output Line components, more than 80dB below rated output 
Power supply energy storage  240 joules total 
Power requirements  105125VAC 60 Hz (210250VAC 50 Hz) 800 watts maximum. 400 watts at "idle". 500 watts at rated power. 
Tube complement  D90: (4) 12AX7, (2) 6FQ7, (2) 12AT7 (4 matched pairs) 6550, (1) 6550 
D90 Revised: (4) 12AX7, (2) 6FQ7, (2) 12AT7, (4 matched pairs) 5881, (1) 6550  
D90B: (1) 12AX7, (5) 6922, (4 matched pairs) 5881, (1) 12BH7, (1) 12AT7  
Other  
Dimensions  19" (48 cm) W (standard rack panel) x 7" (18 cm) H x 16.5" (42 cm) D (front panel back). Handles extend 1 5/8" (4.1 cm) forward of front panel 
Weight  64 lbs. (29 kg) Net, 80 lbs. (36.3 kg) Shipping 
Reviews
Pictures
D90:
D90B: