Three chassis tube stereo power amplifier.
This was a development model only but was too expensive to build and physically too large to make it a viable product. Instead of releasing the Dual 400, ARC used a lot of the design features from the Dual 400 and released the legendary D-150 amplifier instead.
There was a newsletter sent out with the following contents:
April 10, 1973 News letter Subject: Dual 400 Amplifier This newsletter is provided in advance of product availability to answer information requests. The Dual 400 amplifier will be the largest and most powerful in our series of high definition vacuum tube amplifiers. Construction will be again near military quality, featuring all anodized aluminum chassis, panels, cover, etc. Our normal extremely conservative component usage is again employed, as is our patented circuitry. Three chassis are used, with weight totaling 200 pounds. Rack panels with handles will be standard equipment, as will built in fans and meters. The power supply chassis is equipped with an eleven position switch allowing operation from 105 to 125 and 210 and 250 volts AC at either 50 or 60 hz. This chassis is also equipped with a meter so that line voltage (as well as proper operating voltage) may be monitored. Each of the two amplifier chassis is equipped with a pair of fans: one under each group of four (6550) output tubes. Additionally, a meter is provided to monitor power on 4, 8, and 16 ohms, as well as to allow individual output tube bias adjustment. This amplifier will be capable of providing approximately 400 watts RMS per channel at 4, 8, or 16 ohms into complex loads. If continuous commercial service full power sine wave operation applications are contemplated, an additional power chassis should be used. (One is adequate for music and speech applications.) A word of caution for any possibly home fidelity users: this unit idles at approximately 1000 watts of power input and heat output, so give due consideration to both power-line current requirements as well as anticipated environment temperature rise. The unit will also be available with only one amplifier chassis for monaural (single channel) operation, identified as the M-400. Prices are projected as follows: D-400 $2,950.00 M-400 $1,950.00 D-400C $3,950.00 (commercial version, extra power chassis)
April 10, 1973 Audio Research Corporation Preliminary Specifications Dual 400 Amplifier (and M400 amplifier) Power bandwidth: 15 Hz to 30 kHz Harmonic Distortion: Less than .1% at midband at rated power Less than .25% at 30 Hz at rated power (distortion also reduces as power decreases) IM Distortion: Less than .5% at rated power (60 Hz and 6kHz, 4:1) Less than .01% at 1 watt Sensitivity: 1.5 V RMS for rated power Output Impedances: 4, 8, 16 ohms Prices: D-400 $2,950.00 M-400 $1,950.00 D-400C $3,950.00 (commercial version) Availability: October 1973 All performance figures are based on continuous sine-wave and both channels operating. Shipments will start in October 1973.
The amplifier has been mentioned in the following magazines:
- Audio Amateur, 3/75 (USA)
- Radio&Television, Nr.3 1974 (Sweden)
MSRP (US new retail)
|Power output||400 watts per channel|
|Power bandwidth||15 Hz to 30 kHz|
|Input sensitivity||1.5 V RMS for rated power|
|Output taps||4, 8, 16 ohms|
|Overall negative feedback|
|Distortion||Harmonic Distortion: Less than .1% at midband at rated power. Less than
.25% at 30 Hz at rated power.
IM Distortion: Less than .5% at rated power (60 Hz and 6kHz, 4:1). Less than .01% at 1 watt
|Hum & noise|
|Power supply energy storage|
|Power requirements||105-125, 210-250 VAC 50-60 Hz|
|Tube complement||(4 matched pairs) 6550 per channel|