Audio Research D-250 (1980s)
The best documentation of the Audio Research D-250 Mark II Servo is a December 1986 review in Audio magazine's AURICLE column. It called the amp the third generation of one of the most widely praised vacuum-tube power amplifiers ever built, and, at $6,900, one of the most expensive (Audio, December 1986, p.124). The review credited it with roughly 240 watts per channel into 4-, 8-, or 16-ohm loads. That was remarkable for a tube design, even if it was unexceptional for transistors. The amplifier measured 19 inches wide by 10½ inches high. The depth reading was lost to OCR noise in the surviving scan.
The D-250 also turns up in other Audio reviews of the mid- to late-1980s as a reference-class amplifier. A "best-buy breakthrough" review of a much cheaper amp noted it would not fare well head-to-head against the Audio Research D-250 or the Conrad Johnson Premier Fives (Audio, October 1985, p.235). That put the D-250 among the era's elite tube power amplifiers.
Little else is documented beyond these period mentions. No production years, full specifications, or circuit details are confirmed, and no service literature has surfaced.
- Type: vacuum-tube power amplifier (Mark II Servo)
- Power: about 240 W/ch into 4, 8, and 16 ohms (per Audio, December 1986, p.124)
- Price (new, 1986): $6,900
- Dimensions: 19" W × 10½" H (depth undocumented)
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