ati amplifier technologies inc
"ATI amplifiers are our specialty and the only products we carry"

ATI AT4005 Signature Series Amplifier

5 Channels - 200 Watts/Channel

Amplifier Technologies, Inc., the prolific manufacturer of many of the high end's best amplifiers has introduced a new series of amplifiers designed by their president and chief engineer, Morris Kessler. The ATI AT4005 amp and the entire AT4000 Signature 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.

The ATI AT 4005 amplifier and all the amplifiers in the AT4000 series are rated at 200 Watts RMS/channel into 8 ohms from 20Hz to 20kHz with no more than 0.03% THD with all channels driven and 300 Watts RMS at 4 ohms under the same conditions. The ATI AT 4005 amp has a signal-to-noise ratio that 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. The AT4000 is available in 2 to 7 channel configurations and is upgradeable by adding 200 Watt power modules. All ATI amplifiers are available in standard (17") and rack-mount (19") chassis and are covered by ATI's 7-year transferrable warranty.

ati at4005 front audio power amplifier

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 4000 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%.
  2. The design uses 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. Kessler used Thermaltrak output devices for the 4000 series. Unlike traditional designs where external diodes attached to the heat sinks track the amplifiers operating conditions and use the details to adjust bias, Thermaltrak devices have the diodes in the same package as the transistors. The results: bias is optimized in real-time.
  4. The 4000 series use dual DC servos to track and maintain DC offset. The result: DC in the amplifier's output is reduced to insignificant levels.
  5. All of the amplifiers in the series use dual toroidal transformers with independent secondary windings. Electrically, each amplifier channel has its own transformer.
ati at4005 rear audio power amplifier

See below for additional features common to all ATI AT4000 models:

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.
Thermaltrak Output Devices:
Thermaltrak devices have tracking diodes in the same package as the transistors so bias is optimized in real-time.
Power Cord:
Detachable, 3-wire cord.
7 Year Warranty:
Parts and labor against defects in parts or workmanship.
17.25"w X 7.875"h X 17"d (chassis). Handles protrude 1 3/4" (44.5 mm); add 1 1/4" (32 mm) for input/output jacks.
86 to 136 lbs (model dependent)


ATI AT4002 amp - 2 channel amplifier, 200 watts/channel
ATI AT4003 amp - 3 channel amplifier, 200 watts/channel
ATI AT4004 amp - 4 channel amplifier, 200 watts/channel
ATI AT4005 amp - 5 channel amplifier, 200 watts/channel
ATI AT4006 amp - 6 channel amplifier, 200 watts/channel
ATI AT4007 amp - 7 channel amplifier, 200 watts/channel

Models may be upgraded to a maximum of 7 channels, by having additional amplifier modules installed within the unit.

Made In The U.S.A.

The U.S. has always led the world in power amplifier technology, and still does. All ATI products are manufactured in Southern California in a modern 50,000 square-foot facility to exacting design specifications and rigid quality control. ATI manufactures all toroid transformers and assembles all circuit boards in-house. We use computerized Audio Precision test equipment to test each stand-alone amplifier module (DMC2) as well as the completed unit. This control and scrutiny of every phase of manufacturing guarantees unit-to-unit repeatability and a lifetime of accurate sound reproduction.