Flush speaker placement and increasing bass

I have looked at all the dwgs of the rec placement of flush speakers. If the shelf they sit on is attached to an exterior wall and the interior wall is separate, how much will the bass be increased via this design? Would one have to roll of the bass at certain freq. I'm talking about the speaker response not the room response right now. Just seems like that hollow space between the walls would add to some of the low freq intensity. Is there any talk or consensus on this topic? Rocket

OK. I read the post by barefoot abt the +6db increase so I reckon my assumption was correct. His solution, add a -6db shelving attenuator circuit. Hmm!!??

Rocket - in thegood old days :) to measure a speakers performance they would bury the speaker in the ground so the front face was level with the ground. They'd then hang a mike over the speaker and measure the response. Now they stick it in an anocheic chamber. The reason to "flush mount" the speaker was because whilst the mid and high frequencies are directional the low frequencies aren't, a spaeker radiates low frquencies 360 degrees. The point of flush mounting (or soffit mounting if you prefer the term) is to do what the buried speaker did. It projects all the frequencies in the same direction. A free standing speaker suffers because the low frequencies are reflected from the walls behind and return in and out of phase with the original signal. Flush mounting eleiminates this probem and returns a more accurate low end response. Most speakers today have a built in low end rolloff to compensate for the increased response due to the lack of cancellations. here's Genelec's take on the subject http://www.genelecusa.com/learning-cent ... -mounting/ I hope this helps. cheers john