When should I bridge?

Frequently asked questions and the answers to them.

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Bill Fitzmaurice
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When should I bridge?

#1 Post by Bill Fitzmaurice » Tue Jan 29, 2013 4:53 pm

The answer is almost never. Forget about the silly power ratings that manufacturers post for bridged output, that's just advertising piffle aimed at the unwashed masses. Bridging isn't about power, it's about voltage swing. You use it when your amp doesn't have enough voltage swing to drive the speaker to its displacement limit. Nine times out of ten that's because the speaker has a high impedance, say 16 ohms. The tenth time is when your amp is rated at less than a quarter the power output that your speaker is.
If you do bridge when you don't need to the doubled voltage swing quadruples your chances of blowing drivers. Bridging into multiple cabs also can cause the amp to overheat, as bridging typically doubles the minimum load impedance, while using multiple cabs lowers the load impedance.