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ATI AT4000 Power Amplifier

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Signature 4000 Series 200wpc 8ohm – 300wpc 4ohm 2 to 7 channels £3249 – £6249

ATI amplifiers are only available through authorised ATI registered dealers


AT4000 Morris Kessler Signature Amplifiers


Montebello, CA  – Amplifier Technologies, Inc., the prolific manufacturer of many of the high end audio’s best amplifiers today 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%.

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% THD at 8 ohms with all channels driven and 300 Watts RMS at 4 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.

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.


Power Amplifier Specifications

Number of Channels – 2 to 7

EIA 1kHz Output Power at 8 Ohms* – 250 Watts

EIA 1kHz Output Power at 4 Ohms* – 375 Watts

FTC Full Bandwidth Power at 8 Ohms – 200 watts

FTC Full Bandwidth Power at 8 Ohms – 300 watts

Input Sensitivity for Full Rated Power – 1.95 Volts

Frequency Response at Rated Output – 20hz to 2o khz +/- 0.1db

Phase Response – +5 to -5 degrees from 20 hz to 20 khz at 1 watt

Signal-to-Noise Ratio “A-Weighted” – greater than 128 db 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 rated EIA Power at 1 khz

Intermodulation Distortion (IMD) – Less than 0.05% at full rated ftc power: less than 0.01% at full rated EIA Power at 1 khz

Load Impedance – Safe with all types of load. Safe for 4 – 16 ohms

Power Bandwidth – +0, -3db from 5 to 80 khz

FTC Damping Factor – greater than 400 from 10hz to 400 khz

Crosstalk – greater than -80db from 20hz to 20 khz

Gain – gain of 28dB ±0.2 db

Slew Rate – >60V/us

Input Impedance – Nominally 50k ohms

Remote Trigger Voltage – 3.3 to 24 Volts DC at 5 mA or greater

DC Output Offset – Less than ±5 mV

Power Requirements – 220/240 v

Net Weight (lbs/kg) Model Dependent – 51 to 93 / 23 to 43

Chassis Dimensions (H x W x D) mm – 203 x 438 x 429 (Without feet: H = 178)

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.



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