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ATI Amplifier Technologies - AT 4000 - Multi-Channel Stereo Amplifier

ATI Amplifier Technologies Inc.

ATI Amplifier Technologies - AT 4000 Series - Multi-Channel Stereo Amplifier 


Amplifier Technologies, Inc., the prolific manufacturer of many of the high-end audio’s best amplifiersis known for their 4000 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 unlimited 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.

AC Power Connector
The AC input connector provides power to the unit with the supplied power cord. The 120VAC version of the 4000 series amplifiers is supplied with a15 Amp power cord with a standard NEMA-5-15P plug on one end. The 230VAC versions are supplied with Schuko IEC 60320 with C19 plug. Some 230VAC versions are supplied with a different plug. Please check with your dealer for details.

The power cord for your AT4000 series amplifiers may be plugged into a single 15 Amp circuit (120VAC) OR 8 Amp (230VAC).

Note: We can only ship to addresses within the USA. Visit for a list of International Dealers.

ATI Amplifier Technologies Inc.


Remote Trigger
         Activated from 3.3VDC to 24 VDC via a heavy-duty relay

Protection Circuits
         Optically - coupled with full automatic reset.

Toroid Transformers
         40% more efficient than EI type. Separate bi-filar windings for each channel guaranty lower noise and crosstalk.

Circuit Boards
         Double-sided, FR-4 glass-epoxy, computer-grade boards are assembled in-house.

Soft Start Circuitry
         Ultra soft turn on reduces in-rush current to a minimum. Multiple units can be turned on without tripping circuit breakers eliminating the need for sequencing.

Power Transistors
          High-current, bi-polar output transistors with active bias circuits result in effortless operation.

Power Supply Capacitance
         46,200 mfd per channel.

Power Cord
         Dual detachable, 3-wire cord.

7-Year Warranty
         Parts and labor against defects in parts or workmanship.

         17 3/8"W X 8"H X 16 7/8"D (without feet: H=7")

         62 to 105 lbs (model dependent)



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 Output Power at 8 Ohms**
         200 Watts

FTC Full Bandwidth Output Power at 4 Ohms**
         300 Watts

Input Sensitivity for Full Rated Power
         1.9 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

        Greater than –80 dB from 20 Hz to 20 kHz

        Voltage gain of 28dB ±0.2 dB

Slew Rate
        >60 V/µs

Input Impedance
        Nominally 28 k

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

DC Output Offset
        Less than ±5 mV

Power Requirements
         120 VAC (other voltages available on export models)

Chassis Dimensions (W x H x D) Inches
         17 3/8 x 8 x 16 7/8 (Without feet: H = 7)

Net Weight (lbs/kg) Model Dependent
         60 to 105 / 23 - 43

Shipping Weight (lbs/kg) Model Dependent
         96 to 146.4 / 43.6 to 65.5

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