Does Plugging Bass Port Affect Pace, Rhythm and Timing?


Hi, I recently purchased a used pair of Monitor Audio Silver S1 bookshelf speakers for, well, my bookshelf. :\  As expected, the presentation is a little muddy, and the highs not as extended as they might be otherwise on these speakers known for the quality of their tweeters.  I am about to try plugging the ports to see if any improvement could be had. I was wondering if there is any downside to plugging the ports on a bass reflex design as far as bass accuracy and speed. 
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I was given a pair of Advent indoor outdoor 2 ways from USA
stereo a few days ago...comments please..
Eric Squires...good one if they are standing high and the tweeters are recessed not dispersing the tops to your ears!
Any idea where i can procure the original main drivers for the advent indoor outdoor mini?
The one seems a bit burnt, want to replace both and compare to the jbl's.

Monitor Audio dual ports some of their speakers specifically for boundary tuning. My Silver 300 7G were a bit thick on certain vocals. Plugging both was too much, plugging the top port, too little, and plugging the bottom port, perfect, with no loss of extension or dynamics. Ported speakers roll off at 24 dB/Octave, sealed ones at 12dB/Octave. Porting at best gives another half octave of bass before rolling off. As for being below the tweeter axis, it's not the tweeter, rather you are in a phase cancellation lobe that's a function of driver spacing, crossover frequency and slope. Regardless, the fixes which you discovered are correct: the goal is getting more on axis with the tweeter. Actual tweeter dispersion is a function of driver diameter and wave guide (if any).  Remember those wave tank experiments in HS physics? The narrower the aperture the wider the dispersion, but the lower the output on the other side. Exactly the same with speakers. 

LOL@ people who would rather ask a forum something rather than just try a simple thing themselves.