2005 Cabrio with Harman Kardon. I removed my rear interior to track down a short in the top and am considering replacing the rear speakers while everything is out. I know the H/K's rear speakers are 2 ohm dual voice coil and I would be replacing with 2 ohm single voice coil. Can I splice together the feed wires (pos to pos, neg to neg) and feed both to the replacement speaker? I've read posts that talk about using only one of the feeds and thus getting only half the power.

 

Combining different channels of an amp together for more powerful output is known as "bridging" an amp. Running an amp in bridged mode is possible if it is compatible with the internal circuit of the amp, otherwise it could burn out the amp. When an aftermarket amp is bridgeable, it would usually provide a switch for the customer to select between normal and bridged mode. Obviously the HK amp wasn't intended to be run in bridged mode, but that doesn't mean it can't. You decide on taking the risk.

The HK amp is designed for the HK speakers. The amp applies frequency response correction and crossover filters to compensate for the performance of each speaker. It can do this because it expects to be connected to specific HK speakers with known characteristics. If you use an aftermarket speaker, the quality will be unpredictable depending on its similarity to the speaker it is replacing.

 

Decided to abort the mission. I put some poly fill behind the stock speakers and called it a day.

 

Thanks RKW, super clear and concise explanation of how the HK amp and speakers communicate and why/how system is optimized for the OE HK speakers. Very helpful for anyone considering speaker changes.