Product Review (November 2008)
Active Thermal Management
Cool It II Equipment Cooler

By Kevin Nakano

The power density of components found in today's electronics keeps temperatures high, especially among those stored in tight quarters. For example, our Denon AVR-5308CI has seven 150-watt THX-certified power amplifiers in a single chassis. The challenge is to keep these components cool enough to be reliable for years to come. Ignoring this can drasticallly shorten the life of the internal electrical components due to thermal stress. To address this, a company called Active Thermal Management (ATM) has introduced several products that offer solutions for both cabinets (Enclosure Coolers) as well as for individual components (Equipment Coolers). We will cover the Cool-it II product, which is designed to keep a component cool by blowing air into the top of the chassis. This cooling system sits on top of the component and requires that there be some ventilation around the unit. It is ideal for components that have limited ventilation and localized heat buildup. This particular model will not be effective in a sealed enclosure simply because the hot air will just circulate as opposed to bringing in cooler air into the chassis.

The Cool-it II runs very quietly thanks to the design that limits the voltage to the dual 120mm brushless DC fans. These fans are rated at 12VDC, but only run at a mere 6.5VDC due to the 22 ohm power resistor installed in series with the voltage from the power adapter. The result is a very low noise level of only 19dBA. The Cool-it II only has an ON and OFF mode and does not throttle the fans at different speeds. The transformer-based power adapter is rated for 9VDC at 0.5 amps. The Cool-it II has an inline power connector that makes it easy to disconnect from the bulky power adapter. The unit measures only 15.75" wide x 6.75" deep x 2 1/8” high.

We installed the Cool-it II on the top of our Denon AVR-5308CI THX receiver inside of our StudioTech Ultra U-22T cabinet. Normally this receiver has pretty good ventilation thanks to the large vents on the chassis. However, due to the lower impedance of our M&K speakers connected to the receiver, the unit runs hotter than normal. This is where the cooling system helps keep our electronics in check. The fans on the Cool-it II have 1-inch stand-offs that provide an air gap between the fans and the top housing plate. This allows air to move in from the sides and down into the unit. The fans sit flush on top of the unit it is cooling. The design works well and moves a good amount of air into the chassis. Since the design uses a thermal sensor to turn the fans on, there is no need to switch power to the cooling system. It can stay plugged in and runs only when needed.

Thermal Sensor
We placed the thermal sensor on the hottest part of the receiver near the amplifier heatsinks using the high strength cube magnet provided with the system . For test purposes, we placed a digital thermometer probe next to the temperature sensor to measure when the Cool-it II turned on. At 89 degrees Fahrenheit, the fans began to run and air quickly circulated through the large chassis. Fan noise was minimal near the unit and inaudible when placed in the cabinet where we use the receiver.

Need More Air Flow?
Users must do this at their own risk as Active Thermal Management does not authorize any modifications to the Cool-it II and it may very well void the warranty. If users want to have more air flow, it is possible to change the power resistor on the terminal strip to a different value to change the fan speed. The fans can run at full speed by shorting the resistor completely, but the fan noise may become an issue. The trade-off in changing the resistor value is air flow versus fan noise. Both the fans and the power adapter are well within the design limits to handle this. However, the power resistor must be properly selected to handle the power dissapation, so we recommend contacting Active Thermal Management if a change is required.

The Cool-it II is a simple yet effective product to keep your expensive electronics reliable for years to come. Active Thermal Management has many solutions for a variety of applications for both cabinets as well as individual components. Larger cooling systems are also available if needed. We recommend checking out their website for more information. The system is very quiet and only adds about 2-inches to the height of the component. In addition, power consumption is very low (we measured less than 5 watts). The Cool-it II is an affordable ($139.95) cooling system and is the perfect addition to our expensive ($5500) Denon A/V receiver that we cannot afford to have fail on us.

- Kevin Nakano

OPPO BDP-103 Blu-ray Player

Review System

Projector: Mitsubishi HC5500 1080p LCD Projector
Screen: Stewart Filmscreen 100" FireHawk Screen on a Luxus Deluxe ScreenWall
A/V Receiver: Denon AVR-5308CI THX-Ultra 7.1 Channel Receiver
Amplification: Parasound HCA-2205AT THX-Ultra Five Channel Amplifier

Video Processor/Scaler: Anchor Bay Technologies DVDO iScan HD+ A/V Processor
Bass Management: Miller & Kreisel BMC Mini 5.1 Bass Management Controller
Front Speakers: Miller & Kreisel S-150THX (L+R) and S-150AC (Center) Speakers
Rear Speakers: Miller & Kreisel SS-250 Tripole® Surround Speakers
Subwoofer: Two Miller & Kreisel MX-350THX MkII THX-Ultra Push-pull Subwoofers
Room Treatments: Echo Buster panels and Bass Buster towers
Set-top Box: Dish Network ViP622 HDTV Satellite and Terrestrial Receiver with HDMI
Blu-ray DVD Player: Sony PlayStation3 with HDMI 1.3
HD-DVD Player: Toshiba HD-A1 HD-DVD Player with HDMI
DVD/CD/SACD Player: Sony DVP-NS900V DVD/CD/SACD Player
DVD Audio/Video Player: Kenwood Sovereign DV-5900M 400-Disc DVD Changer
DVD Player: OPPO Digital OPDV971H DVD Player with DVI Output
D-VHS VCR: JVC HM-DH30000U D-VHS High-Definition D-Theater VCR
Media Server: Kenwood Sovereign MRH1 Entre
Remote Control: Remote Technologies Inc. T4 Controller
HDMI Video Switcher: Octava 4 Port HDMI/Toslink Audio Switcher
DVI Cable: AudioQuest DV-1 20m DVI-D Cable
HDMI Cables: VizionWare Hi-Wirez 20-meter, Accell 45-meter UltraRun HDMI Cable
A/V Cables: Ultralink Platinum and Advanced Performance Series Cables

Review at a glance

Active Thermal Management - Cool-It II Equipment Cooler


  • Extremely quiet
  • Simple installation
  • Very low power consumption
  • Rated for continuous operation
  • Add only 2” – 2 ½” to equipment height
  • Package Contents

  • 2 - 120mm fans mounted on panel
  • 1 - Thermal switch with leads
  • 1 - AC Power Supply
  • 1 - Instruction Manual

    Product Data Sheet

    Company Information
    Active Thermal Management
    25570 Rye Canyon Road
    Valencia, CA. 91355
    Phone: 661-294-7999
    Fax: 661-294-1115

    Source: Manufacture Supplied
    Part number: 01-002-02
    MSRP: Cool-it II™ $134.95


  • Any comments or questions regarding the LAAF Web Site should be forwarded to

    Copyright © 1985-2008 L.A. Audio File