ATI's new 4000 Series amplifier lineup includes six models, ranging from the two-channel AT4002 ($2,995) up to the seven-channel AT4007 ($5,995). All models are rated at 200 watts RMS per channel at eight ohms and 300 watts RMS at four ohms, and all models have a fully balanced, differential design with two output stages per channel and a single input stage. Each 4000 Series amp can be configured in a standard (17-inch) or rack-mount (19-inch) chassis.
Amplifier Technologies, Inc. has added a new series of amplifiers designed by their president and chief engineer, Morris Kessler. The 4000 series amplifiers, available with 2 to 7 channels, share the design philosophy and circuit sophistication of ATI's award-winning 6000 Series amps with power output reduced to 200W RMS per channel at 8 ohms and 300 W RMS at 4 ohms. Furthermore, their "signature series" designation with a facsimile of Kessler's signature on the main panel attests the special nature of these amplifiers.
Beyond Kessler's personal identification, these amplifiers share these key features with the 6000 Series Signature amps.
1. Fully balanced, differential amplifier design with two output stages per channel but with only a single input stage. The advantages of balanced designs are retained and noise is further reduced by 50 percent.
2. Current feedback instead of the more common voltage feedback. The reason: current feedback amplifiers are faster with virtually unlmited slew rate and are better able to reproduce today's best music and film.
3.Thermaltrak output devices: Unlike traditional designs where external diodes attached to the heat sink track the amplifiers operating conditions to adjust bias, Thermaltrak devices have the diodes in the same package as the transistors so bias is optimized in real-time.
4. Dual DC servos per channel to control DC offset.
5. Dual toroidal transformers with independent secondary windings. Electrically, each amplifier channel has its own transformer.
All the amplifiers in the 4000 series are rated at 200 Watts RMS from 20 Hz to 20 kHz with no more that 0.03 percent THD at eight ohms with all channels driven and 300 Watts RMS at four ohms under the same conditions. Signal-to-noise ratio is typically 126 dB referenced to full output, so each amplifier in the series is capable of playing back the full dynamic range available on today's lossless recordings.
AT4002 Stereo Signature Amplifier $2,995
AT4003 3-channel Signature Amplifier $3,595
AT4004 4-channel Signature Amplifier $4,195
AT4005 5-channel Signature Amplifier $4,795
AT4006 6-channel Signature Amplifier $5,395
AT4007 7-channel Signature Amplifier $5,995
All ATI amplifiers are available in standard (17") and rack-mount (19") chassis with domestic (117V) or Export (220 to 240V) chassis and are covered by ATI's seven-year transferrable warranty.
• ATI AT6002 Stereo Power Amplifier Reviewed at HomeTheaterReview.com.
• Amplifier Technologies Debuts Morris Kessler Signature Amplifiers at HomeTheaterReview.com.