From: Dan Nelson <dprimary@e...>
Date: Wed Jan 19, 2000 8:01 am
Subject: honeycomb port absorber
I have the info from Brendan, I just haven't had the time to post it yet.
I wanted to work it into a new article. Do any of you guy's want to write about
resonators that I could edit into the section on bass absorbers?
> Stuffing broadens the Q (effective range) of the absorber .. if you are
> trying to address a single peak, a unstuffed resonator would be better. I
> wish someone would supply formulae for a "honeycomb" box as alluded to by a
> prior poster to the list ... as I recall he described a unit much like a
> speaker box with throated ports which could be tuned by port size and depth
> for very narrow Q's. An intriguing idea ... interesting to consider however
> that with a tight Q you will actually increase the reverb time of the target
> frequency (the box will store then reemit the captured frequency). This
> would be reduced by a stuffed box, but that would broaden the Q ... I guess
> you really can't buy a free lunch.
> > 3) What are the pros/cons to using a fiberglas (loose or ridgid)
> > product with a paper or foil backing ?
> The backing acts as an absorptive diaphragm which can be helpful if the
> resonant freq. of the backing is a target frequency ... if the resonant freq.
> of the backing is a hi-Q target freq. then turn the backing toward the room,
> if not then turn the backing away (or even better save money by buying
> un-backed batts and use the savings to buy thicker batts, or beer.
> > 4) Should the backing be installed adjacent to the wall or the
> > baffle ?
> depends ... see above ... the resonant frequency of paper backed R-11 was
> quoted in this list several weeks ago, but I'm not sure if I recall ... seems
> it was about 250 Hz, but don't rely on my memory.
> Scott R. Foster