westend wrote:
The speaker mount is called a "baffle" in the audio world. There are not a lot of them made in the type pictured above. There are definitely better speakers in the size needed than came stock with your RV. I would suggest a "full-range" or "extended-range" speaker for this application. You will also want a speaker with a cone material that can withstand weather, polypropylene or kevlar are two.
A different solution for better sound may be to replace the baffle and crummy speakers with a jack and plug in a small pair of boxed speakers when at camp. They will sound better and you can locate them to fit your listening needs. If you want a subwoofer, start thinking about an additional amplifier or a subwoofer with internal amp that will also need power. IMO, it's a fool's errand for campground listening but some folks have to have big bass. It will either make you some friends or a lot of enemies in a hurry.
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A baffle is more of an enclosure, intended to go inside of a large cavity with a flush mounted speaker. The item displayed is a surface mount speaker adaptor. Look up a speaker RetroPod.