Originally Posted by Jmmmmm
Does the thickness of the bluetac actually affect the change in sound? If it does, is it just due to the decrease in air volume inside the cup, or is there something else?
I don't think I'm familiar with this bluetac, but depending on the density the volume will either be increased or decreased. Light wool, like the synthetic, fluffy material used in pillows will make the driver perceive a larger volume. If the material is stuffed hard inside the enclosures the size might be perceived as reduced. If you use housing isolation material (don't know if you've got rockwool?), which is higly dense, the volume will definately be reduced.