the heat from the components to the heatsink. The heatsink, in turn, must dissipate this heat or become too hot for the internal components to operate properly. The heat can be transferred from the heatsink by three different processes: Conduction, Radiation, or Convection.
Conduction is defined as the process by which heat is transferred through matter, without transfer of the matter itself A practical example of this would be the cooling system in your car which circulates a liquid (matter) in order to transfer the heat away from your engine.
In the mobile environment, conduction is not the primary process of transferring heat from the heatsink. The use of a circulating liquid or gas is impractical, unless specific provisions were made in the design of a heatsink to accomodate this type of transfer.
There is nothing in the vehicle which could easily be used to heatsink the heatsink. Air is the only (practical) conductive (heat transfer) medium involved when you install an amplifier in your car. As we will discuss later, heat radiated by the heatsink is conducted out into the environment, triggering the process of convection.
Radiation is defined as the process of giving out light, heat, or other radiant energy. An example of this process would be the sun. It radiates heat, light, and other radiant energy.
Radiation is the primary process of heat transfer for a heatsink. As the conducted heat builds (from the internal components), it radiates from the surface out into the surrounding environment. The amount of heat radiated by the heatsink is determined by its surface area. The traditional way to add surface area is to use fins, expanding the radiating surface without increasing the overall dimensions of the amplifier.
So why doesn't the Art Series heatsink employ the traditional use of fins since it must adhere to the same rules of thermodynamics that all other heatsinks do? We must discuss the third process - convection before the answer will become clear.
Convection is defined as the transfer of heat from one place to another by the movement of heated particles of a gas or liquid. An example of this process would be warming your hand by holding it in the hot air rising from an oven.
When an amplifier's heatsink becomes warm, it conducts heat out into the surrounding environment, warming the air. The warm air begins to rise, creating air currents which draw heat away from the heatsink. With a traditional finned heatsink, this process is most effective when the amplifier is mounted on its vertical axis. As with chimney, the air circulates upward, over the fins, improving the heat transfer process.
Your ability to take advantage of convection is limited by the installation constraints imposed by the mobile environment. Mounting an amplifier on the vertical axis is not always possible and generally, not preferred (by the consumer). The amplifier's heatsink is left with only one primary process for heat transfer - radiation.
Engineers have recognized the importance of radiant surface area, but the constraints of the automotive environment have forced heatsink designs to remain compact. In order to improve radiating efficiency, designers have simply added more fins. With limited space, adding more fins means that they get closer together What PPI's engineers observed was that fins in close proximity radiate heat from fin to fin rather than into the environment. If convection is not available to draw the heat out from between the fins, the heat becomes trapped, causing a reduction in radiant heat transfer efficiency.
The Art Series heatsink addresses this problem and improves radiant heat transfer efficiency by providing more effective radiating surface area. Combined with our highly efficient (less wasted energy in the form of heat) PWM power supply, the result is an amplifier with improved thermal capabilities.
As with any amplifier, care must be taken when selecting a mounting location. There must be two inches of air space around the heatsink for proper heat dissipation to take place. If mounting in an enclosed area, a fan may be added to improve heat transfer. Refer to the Section on Installation for more information.
AM II Protection Circuitry | Watts |
| 100 |
All Art Series amplifiers utilize
ahighly-efficient, Pulse-Width Modulated power supply.
This means the amplifier | 50 | | | | | | | | | | | |
| | | | | | | | | | |
| | | | | | | | | | | |
will continue to operate within | | | | | | | | | | | | |
regulation until the battery | | | | | | | | | | | | |
voltage drops below 11 volts | 25 | | | | | | | | | | | |
or the heatsink temperature | | | | | | | | | | | | |
reaches 75 degrees Celsius. | | | | | | | | | | | | |
This new power supply also | | | | | | | | | | | Ohms |
| | | | | | | | |
incorporates the second | 8 | 4 | | 2 | 1 | | 0.5 | |
generation of PPI's Adaptive | | | Figure A: | AM II Protection | Circuitry | | | | |
MOSFET protection circuitry. | | | | | Output Power vs. Impedance | | | | |
| | | | | | | | | | | |
This advanced protection circuit was developed to prevent shut-off due to the fluctuating impedance loads presented by today's complex speaker systems. The adaptive circuit optimizes output power to maintain uninterrupted operation whenever the amplifier senses an impedance load of less than 2 Ohms. A low impedance indicator (Diagnostic L.E.D.) is provided to let you know when the amplifier is operating in this mode. It is important to note that there is no increase in output power below the 2 Ohm threshold. Maximum power is achieved at 2 Ohms. AM II provides you the satisfaction of knowing that your Art Series amplifier will continue to play when momentary impedance dips occur.( Refer to figure A )
In the case of a short circuit, AM II will engage to protect the shorted channel but will continue to play the unaffected channel. When this occurs, audible distortion will be heard. Turn off the system and repair the short. Once the problem has been repaired, the amplifier will return to normal operation.
