Audio Research D400 Mk2
Audio Research Corporation is without doubt one of the most important marques in the High End audio world. Simply a steadfast cornerstone manufacturer from the 1950s to the present day. Importantly, William Zane Johnson’s genius was responsible for keeping vacuum tube amplification alive and well during the (almost) all conquering transistor onslaught during the 1970s. Whilst tube amplification was the company’s mainstay, there was always solid state alternatives available. During the 1990s, the Audio Research D400 was the flagship solid state Power Amplifier.
The D400 is a class AB design which easily delivers 400watts per channel into a 4 ohm load. The power supply holds a mammoth 600 joules of energy storage in a dual mono configuration. This allows the amp to deliver 60amps of peak current per channel into difficult 1 ohm loads, that’s 3600 watts of instantaneous power per channel. To accomplish this task, the D400 uses 40 massive ‘multiple emitter transistors’ in a direct coupled output stage. These devices are more musical than conventional Bipolar transistors, yet more rugged and matched than mosfets. This gives the D400 advantages of both types with none of the drawbacks. The D400 will maintain its composure under the most demanding dynamic music conditions making it an ideal choice for any loudspeaker system currently available.
Despite its stunning output capability, the highly efficient D400 draws a mere 220 watts at idle. Other facets of the design also testify to the amplifiers serious high end prowess. Two separate power transformers are used to feed the input and output stages for maximum isolation and headroom. Special internal dampening techniques assure quiet operation of these transformers and other vibration sensitive components. The amp even rests on five specially designed polymer damping feet to further isolate the chassis. Massive heat sinking ensures very moderate operating temperature allowing for a variety of installation options. Inspection of the internals reveals an immaculate layout without a single crimp or press fit connection in sight. All connections inside this amplifiers are hand soldered for optimum signal transfer and reliability.
Input connection flexibility on the D400 is comprehensive with balanced XLR connections as well as normal and inverted single ended RCA connections. Output terminals are machined from solid special alloy and soldered to both sides if the circuit board for ultimate sonic purity and reliability. Internally the D400 is monitored by silent and sonically transparent protection circuits to prevent damage to both amplifier and speakers in the event of fault conditions at either input or output.
- High current 200watts into 8Ω and doubling to 400watts into 4Ω
- Balanced (XLR) Inputs
- Single ended inputs, both normal and inverted
- Power Output: 200watts into 8Ω, 400watts into 4Ω
- Power Bandwidth: 4Hz to 100kHz (full power)
- Peak Output Current: 60Amps
- Input Sensitivity: 2.0Vrms for rated output
- Gain: 26.0dB
- Input Impedance: 57kΩ RCA, 114kΩ balanced
- Input Polarity: Non inverting at normal inputs, Balanced pin 2+
- Output Regulation: 0.06dB 8ohm load
- Damping Factor: 150
- Slew Rate: 50V per μS
- Rise Time: 1.0 μS
- Noise: <150μV (106dB below rated output)
- Power Supply Capacitance: 270,000μF
- Power requirements: 210-250VAC
- Dimensions: 48 cm W x 23.4 cm H x 53 cm D. (includes handles and footers)
- Weight: 34.5Kg
Last but not Least
This pre owned Audio Research D400 Mark 2 is in very good cosmetic and working condition. The images in this listing are of the actual unit. We have no original inclusions, so no owners manual or original packaging. But we can and will pack it properly for an interstate trip if required.
For another pre owned Audio Research head over to ARC LS2
For a independent reviews on this amp go to Audio Review
For another independent review go to The Absolute Sound