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Carver A-400x AmplifierThe Carver A-400x stereo power amplifier carries the THX logo, signifying that it meets Lucas-film's stringent requirements for use in Home THX audio systems. The A-400x is otherwise conventionally styled and relatively compact and light for an amplifier rated to deliver, at less than 0.2 percent total harmonic distortion, 200 watts per channel into 8 ohms or 300 watts into 4 ohms (600 watts into 8 ohms in bridged mono operation).
The front panel of the all-black chassis contains only a power switch, a small green LED to indicate that it is on, and the THX logo. Optional handles, matching those for other Carver products, are available. The amplifier's heat sinks are located internally, along the sides; the ventilating holes are on the top, bottom, and sides of the case, close to the fins. Each output stage uses eight power transistors. The interior of the amplifier is sparsely occupied (not unusual for a basic power amplifier), with most of the components on a single circuit board and a large power transformer accounting for much of the 25-pound weight of the A-400x.
On the rear apron are two phono-type input jacks, two pairs of speaker outputs (insulated multiway binding posts), and an AC line-fuse holder. A small slide switch near the input jacks converts the amplifier to mono (bridged) operation, for which the speaker is connected to the two red (plus or "hot") binding posts. The A-400x is protected by a combination of relays, which disconnect the speakers if current flow through the output stage reaches levels that might damage the amplifier, and thermal sensors, which detect overheating and put the amplifier into a standby mode until the heat sinks cool to a safe temperature (operation is restored automatically when that occurs). There is also a DC-fault detector that prevents the amplifier from damaging the speakers in the event of an internal failure by instantly opening the output relays. Carver also suggests that if the loudspeakers are not rated to handle the amplifier's power (many are not), it is advisable to place in-line speaker fuses between the amplifier and the speakers, preferably using fuse ratings recommended by the speaker manufacturer.
In our tests, the Carver A-400x surpassed its power ratings by a comfortable margin, in both continuous and dynamic measurements, into loads of 4 or 8 ohms. The distortion ratings were equally conservative. Although the power output ratings are specified (and were easily met) at a 0.2-percent distortion level, the measured distortion was far lower than that, with typical readings in the range of 0.006 percent at 200 watts into 8 ohms and less than 0.015 percent at 300 watts into 4 ohms. Input sensitivity was exactly as rated, and the amplifier's noise level was 3 dB lower than rated.
In view of the amplifier's power capability, its moderate operating temperature was also noteworthy. It never became uncomfortable to the touch, even during extended high-power operation, and without requiring a potentially noisy fan.
In addition to being a fully THX-compatible amplifier, the Carver A-400x is equally suitable for any high-quality home audio system, delivering all the low-distortion power anyone is likely to need in a compact, affordable, and easily liftable package. ![]() |