Originally Posted by
davef
Hi Kyle,
This is to be expected actually and basically means that plugs are working correctly for you. Since you have the center in a cabinet, it is more than likely that you have a bump in the response, typically somewhere in the 50-80Hz range. When you check levels with an SPL meter, it basically measures the average SPL over the entire frequency range being reproduced. By using the plugs and reducing the bump in the response, the average spl will measure lower.
Speaker sensitivity hasn't actually changed since sensitivity is typically calculated by using the output level of the midrange frequencies, of which the Q-Plugs will have no effect.
The benefit here is that the bump in the speaker's response has been reduced, the speaker will now measure flatter and setting center speaker levels will now be more accurate. Vocals should be more upfront, more prominent.