Aluminum lid for a Radioshack Project Enclosure as a heatsink for an LM3886?

[haziz]

I want to use the 8x6x3 inch plastic Radio Shack project enclosures (Radio Shack Parts # 270-1809) that come with an aluminum lid as an alternative lid, for my monoblock LM3886 amp. Does the lid (basically an 8x6 inch aluminum sheet) used as the sole heatsink for a single LM3886 (monoblock) provide enough heat dissipation for an LM3886? I will likely be driving an 8 Ohm speaker.

BTW does the enclosure have enough volume to have the torroid (one of the Avel Lindberg 2 X 25V @ 2 Amps 100Va torroids from ApexJR), PSU and LM3886 boards in a monoblock setup without interfrence from the PSU/torroid into the audio circuit? I will place them as far apart as possible in the corners. There is enough volume easily for all three items but will I notice any audible interference?

Thanks.

Sincerely,

Hany.

[jackinnj]

The amount of heat that the an amplifier has to dissipate is a function of the rail voltages and load impedance -- there's a calculator on National's website which will give you the required thermal impedance at a specific set of voltages -- or you can calculate it by hand, and there is a chart in the product folder.

One way in which you can tell how much the heatsink (or chassis top) is capable of dissipating (its thermal impedance) is by attaching a power resistor to the lid and cooking it at 20 watts or so -- measure the temperature at the start and 30 minutes later --