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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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jetter
3,050 posts
 
This is a little off topic. But I’ve wondered if plugging the ports on speakers that do no come with plugs can damage them by causing excess woofer excursion than the speaker was designed?
erik_squires
16,345 posts
 
Hi Jetter, 

It actually works the other way. Below the port resonance, driver excursion increases dramatically faster than with a sealed cabinet. 

Below resonance, the tube acts as a simple vent, eliminating the air-spring (i.e. acoustic suspension) portion of the cabinet. By plugging the cabinet, the air-spring remains working at all frequencies, controlling excusrion but also, of course, reducing bass up to a point. 

At around -10 to -20 dB sealed and ported speakers have about the same output.

Best,

E
jetter
3,050 posts
 

Thanks Erik, so its the opposite of what I was thinking.  Maybe its time to go to the local craft store and purchase some of their foam cones. 

George

bdp24's avatar
bdp24
9,892 posts
 
One thing to consider is that the speaker designer chose the internal volume of the enclosure based on the fact that it is ported. He would have probably used a smaller enclosure if he was using the same woofer in a sealed application. With the port plugged, there will be unintended consequences---you will have changed the performance and behavior of the woofer.
prof
3,479 posts
 
Plugging the port of a speaker tends to reduce efficiency, does it not?
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