One Audiophile: While Dynamat works, it is cost prohibitive to use in big quantities. Technically, while the Dynamat may work "better" in an all out effort as compared to the Asphalt or Vinyl based sheets i linked to above when used all by themselves, in all reality, there really isn't a noticeable difference in actual use. Combining the "Liquid Nails" and "generic" damping sheets approach that i listed above really does offer a HUGE bang for the buck.
As far as horns / horn bodies go, let's just say the differences between damped / undamped are pretty amazing : )
When using "foam insulation", did you use something along the lines of "Great Stuff" ( aka "foam in a can" ) or was it something different ? I've tried using that before but it was WAY too cumbersome to work with on drivers / horn bodies.
The one place that i did find it to work well was on the inside of folded bass horns in the corners. In order to minimize internal standing waves, i like to radius the corners in these designs. I do this by taking a sheet of paneling and bowing it out so that there is a gentle curve rather than a dead-end corner. Once you get the paneling tacked in place, you can fill in the gap between the cabinet and the radius created by the paneling with "Great Stuff", heavily packed fiberglass or something similar. The idea is to deaden the cabinet and offer some form of support for the paneling so that it does not contribute its' own resonance to the sound. This is another trick that can make a world of difference as it really cleans up upper bass / lower mids on such a design. Once again though, this is a very time consuming project that would kill a manufacturer if trying to mass produce a product. It can be done simpler than what i mentioned, but like anything else, the results are not quite as good using a "short-cut" approach either. Sean
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