Purchase the Rockford Fosgate Punch speakers P1675-S and P1675 for the H3 & H3T Hummer to get the best combination of an inexpensive price and improved sound quality. For the H3 Hummers with the Monsoon Sound System, purchase the Rockford Fosgate P3SD2-8 to replace the factory dual coil 8-inch subwoofer. Also, 2 packs of the Metra 72-4568 speaker harness adapters for GM vehicles are necessary to connect the door speakers without cutting the into the vehicle’s wires.
The pair of P1675-S Punch Speakers work the best upfront because it is a mid-range speaker with a separate tweeter for the highs. H3 & H3T Hummers have the front speakers working in combination with the OEM-equipped tweeters. To ensure that the proper frequency is being sent correctly to the speaker the speakers up front need to be mid-range. While the package does include the better quality tweeters, I have yet to install them.
In the rear of the Hummer, there are no tweeters associated with those speakers. This is why the full-range P1675 speakers should be installed in the rear doors. If Rockford Fosgate isn’t your brand, the front and rear door speakers are 6.75-inch in diameter. Make sure to grab one set of Midrange and one set of Fullrange for the best results.
The Rockford Fosgate P3SD2-8 8-inch dual coil subwoofer is a very specific choice because of the OEM speaker. While typical subwoofers have a single voice coil, dual voice coil (DVC) subwoofers use two separate voice coils, each with its own connections, mounted on one cylinder, connected to a common cone. Since the P3SD2-8 is a dual coil subwoofer this makes it very easy to swap into the factory location. I’m not aware of wiring harnesses out there, I decided to desolder the connections from the factory subwoofer and transfer the wire over to the new sub by resoldering those wires. This is the simplest solution I’ve figured out.
Overall, this is a quick upgrade to the sound system that will vastly improve the sound quality in an H3 and H3T Hummer.