ATI AT4002

Morris Kessler Signature Amplifiers 200watt x 2ch

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Amplifier Technologies, Inc., the prolific manufacturer of many of the high end’s best amplifiers today introduced a new series of amplifiers designed by their president and chief engineer, Morris Kessler. The 6000 series amplifiers, available with 2 to 7 channels, are the company’s first new amplifiers in over a decade. Furthermore, their “signature series” designation with a facsimile of Kessler’s signature on the main panel acknowledges the special nature of these designs.

Beyond Kessler’s personal identification, these amplifiers are new in more significant ways.


  1.     As in Kessler’s previous top-of-the-line designs, these amplifiers are fully balanced, differential amps, but unlike his earlier balanced designs which were essentially balanced bridged amplifiers, the 6000 series uses only a single input stage with dual-differential output stages. The reason: the advantages of balanced designs are retained and noise is reduced by 50%.


  1.     The design uses current feedback instead of the more common voltage feedback. The reason: current feedback amplifiers are faster with virtually unlimited slew rate and are better able to reproduce today’s best music and film sound.


  1.     Kessler used Thermaltrak output devices for the 6000 series. Unlike traditional designs where external diodes or transistors attached to the heat sinks track the amplifiers operating conditions and use the details to adjust bias, Thermaltrak devices have the temperature sensing device in the same package as the output transistor. The results: bias is optimized in real-time.


  1.     The 6000 series use dual DC servos to track and maintain DC offset. The result: DC in the amplifier’s output is reduced to insignificant levels.


  1.     These amplifiers use a revised PCB layout. They are still modular with the complete amplifier including the power supply parts on a single card, but now the AC components are on one edge of the board and away from the signal input. The result: improved signal-to-noise performance.


  1.     All of the amplifiers in the series use dual toroidal transformers, dual power switches and dual line cords. The results: the AT6002 is now a complete dual-mono design and the amplifiers with many channels, as in the 7-channel AT6007, can be hooked-up to two independent 20 amp circuits for greater sustained output power than is possible from a single AC circuit.


All the amplifiers in the 6000 series are rated at 300 Watts RMS from 20 Hz to 20 kHz with no more that 0.03% THD at 8 ohms with all channels driven and 450 Watts RMS at 4 ohms under the same conditions. Signal-to-noise ratio is typically 128 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.


All ATI amplifiers are available in standard (17”) and rack-mount (19”) chassis with domestic (117V) of Export (220 to 240V) chassis and are covered by ATI’s 7-year transferrable warranty.


About Amplifier Technologies


Amplifier Technologies owns the ATI, Audioaccess, B&K, BGW and Theta Digital brands and designs and manufactures state-of-the-art audio components for its own and other brands in its facility in Montebello, CA. Guided by legendary amplifier designer Morris Kessler, ATI offers both performance and value in audio components.


Technical Data




Number of Channels 

EIA 1kHz Output Power at 8 Ohms* 

250 Watts

EIA 1kHz Output Power at 4 Ohms* 

375 Watts

FTC Full Bandwidth Output Power at 8 Ohms** 

200 Watts

FTC Full Bandwidth Output Power at 4 Ohms** 

300 Watts

Input Sensitivity for Full Rated Power 

1.95 Volts

Frequency Response at Rated Output 

20Hz to 20kHz ±0.1dB 

Phase Response 

+5 to -15 degrees from 20Hz to 20kHz at 1 watt 

Signal-to-Noise Ratio “A-Weighted” 

Greater than 128dB below rated FTC Full Bandwidth Output 

Total Harmonic Distortion (THD) Less than 0.05% at full rated FTC power; Less than 0.01% at full EIA power at 1kHz 
Intermodulation Distortion (IMD) Less than 0.05% at full rated FTC power; Less than 0.01% at full EIA power at 1kHz 
Load Impedance Safe with all types of loads. Rated for 4 to 16 ohms 
Power Bandwidth FTC +0, -3 db from 5 Hz to 80 kHz 
Damping Factor Greater than 400 from 10 Hz to 400 Hz 
Crosstalk Greater than –80 dB from 20 Hz to 20 kHz 
Gain Voltage gain of 28dB ±0.2 dB 
Slew Rate >60 V/μs 
Input Impedance Nominally 50 kΩ 
Remote Trigger Voltage 3.3 to 24 Volts DC at 5 mA or greater 
DC Output Offset Less than ±5 mV, Typically less than ±0.5mV
Power Requirements 120 VAC (other voltages available on export models) 
Chassis Dimensions (H x W x D) Inches 8 x 17 3/8 x 16 7/8 (Without feet: H = 7)
Chassis Dimensions (H x W x D) mm

203 x 438 x 429 (Without feet: H = 178)

Handles protrude 1.8” (45.7 mm); Add 1¼” (32 mm) for input/output jacks
Net Weight (lbs/kg) Model Dependent 51 / 23
Shipping Weight (lbs/kg) Model Dependent 62 to 105 / 28.2 to 47.7


 *EIA 1kHz Power refers to maximum average power in watts at 1 kHz with 0.01% THD and noise.
**FTC Full Bandwidth Power refers to maximum average power in watts from 20Hz to 20 kHz with 0.05% THD and noise.



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