I've been trying to find the complete specifications for the Harmon Kardon Amp and Speaker system but have been so far unable to find them. Specifically I'm looking for the RMS wattage of the amp per channel, and the wattage and efficiency of the speakers and tweeters in the Convertible. (6.5s all the way around)

The reason I'm looking is because I'm looking to replace them all with Alpine Type X speakers, specifically Alpine SPX-17MB Mid-bass speakers in the rear, and Alpine SPX-177R components for the front.

If I replace the speakers with these without replacing the amp will the amp be powerful enough for these speakers without losing volume?

 

First, I wish you godspeed in finding the official specs. For some reason they are no where to be found. There is a lot of speculation that it's roughly a 40 watt per speaker system with 2 ohm speakers. Others have said 6 ohms. Peak RMS is speculated at 80-100 watts. However, this is all speculation because there is no spec-sheet anywhere.

Second, I hate to say this, but if you wanted to upgrade your system, you should have shyed away from the H/K because it, in the end, will more then likely cost you more money.

The H/K system is just that, a system. It's really hard to take pieces of that system away and replace them with others and have it maintain the quality of the system to begin with. The only thing I've found possible is adding an additional amp to the system (which I did here).

Some have complained that the system is not loud enough (which I can understand in the convertible), but replacing just the speakers isn't going to do very much for you. (curious, why just replace the speakers? the H/Ks are actually pretty decent quality for being paper cone)

Here is a good write up from veteran GBMINI about the H/K which may help in some ways (he's got a ton of other awesome info about upgrades on his site too)

If you're looking to upgrade your speakers I can almost guarantee that you'll need to either A) replace the entire system or B) add an aftermarket amp and run speaker lines from there.

Best of luck!

 

In the hardtop, the speakers are 2 ohm. I'd bet the same in the convertible but I've never seen inside.
Aftermarket 4 ohm speakers will instantly reduce your power level by a factor of 4!

Also, the H/K has external crossover for the low/high frequencies - instead it's built into the amp with separate signals to each speaker. Aftermarket has it's own crossover and it won't work with the H/K.

Finally on the hardtop the rear speakers are dual voice coil. Again not sure if that's true for the convertible - but if it is, putting one 4 ohm coil instead of two 2 ohm coils will lose loads of power.

Why would you want to replace speakers - what do you expect to gain from them? The H/K speakers/amp system is already tuned optimally

 

Well, this answers my question right there.

Guess I'll just continue with my plan of just putting a sub and amp in the trunk.