Thread: Car amp in boat
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Old 11-26-2012, 05:18 PM
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Originally Posted by dvsone79 View Post
I've got a Boss 4 channel "marine" sub running two tower speakers and a sub. It works well, but can get pretty hot. Anyone have any suggestions for fans? What/where to buy, how to power them, etc...

An amp getting hot to the touch, is not abnormal, especially with a Class-A/B. Even the more efficient Class-D amps get hot. The heat generated can be attributed to a few external factors and may be addressable. Is the amp getting hot enough to shut down for a period?

Cable gauge feeding amp: too small for current draw x distance can effect the amps efficiency, resulting in added heat and quicker thermal shutdown.
Speaker load per amp chnl. What speakers and how many total is the amp driving? As the amp's load, measured in speaker(s) impedance, will determine the amps output (on a typical amp but not all), so as the impedance drops, the amp works harder. This means more heat produced.
Tuning. Gains too high and cross-over points too low can cause the amp to work harder. Reducing the gains, setting all the full-range speakers to Hi-Pass and upping the cross-over point will lighten the work load of the amp.

When needed, external fans will work. The trick is to get the air flowing from the bottom as heat rises. Also orienting the amps vertically, will allow the heat off the heat-sinks to rise up and off the amp. When mounted horizontally the heat from the bottom heat-sink rolls across the upper heat-sink, reducing its effectiveness. If fans are used, you need to construct it so you have fresh air coming in via one fan and a means to pull the hot air out. Simply blowing hot air from locker across the amps does little.

There are lots of 12V fans out there. They can be easily wired up with a relay that triggered when the amps turn on, or with a manual switch. If you dig enough, there are some temp sensors out there that will turn the fan on at a calibrated point.
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