Steve,
> how does that figure support your "thickness = distance" theory? <
This is not "my theory" - it's explained well by that very graph. The explanation is simple, and has been in my Acoustics FAQ for two years now. From my FAQ:
For a given thickness of absorbent material, the ideal air gap is equal to that thickness because it avoids a hole in the range of frequencies absorbed. For example, if you install fiberglass that is four inches thick with a four-inch gap, higher frequencies whose 1/4 wavelength falls within the four-inch material thickness are absorbed regardless of the gap. And for those frequencies whose 1/4 wavelength is between four and eight inches, the fiberglass is also at the proper distance from the wall or ceiling. This is shown below in Figure 6.
Have a look at that entire section in my FAQ, "Optimizing the air gap," for further explanations and additional charts.
> As to spacing from the wall, I would use more for lower frequency effect, whether I could only afford 1" stuff or 6" <
Sure, but that's when the "holes" in the absorption become more of a problem. The graph I posted from Everest's book is an extreme example, but it makes the point well.
> As to your innocence in the "feud", I never referred to posts just on this board <
Look, Steve, I'm here to help people and nothing more. I never start anything with Eric, though I have defended myself a few times when his attacks were blatant. Look at
any bad exchange between us in the last year on
any web site or newsgroup. In
every case Eric has taken pot shots at me,
never the other way around. For example, look at the last exchange at RO you just referred to. Here's a direct link:
www.recording.org/postx20156-0-0.html
Someone asked about rigid fiberglass density versus low frequency performance, and I replied by giving my direct experience based on tests I paid for in an acoustics lab. The
very next post in that thread is Eric attacking me and insulting my company's products. I replied politely and answered Eric's accusations. Eric replied with a huge diatribe, again attacking me personally and attacking my company's products. I think my reply was no less polite than could be expected by any reasonable person, and that was the last of my involvement. Eric and some of his friends continued to attack me and I ignored them. To this day Eric and his friends in StudioTips continue referring to that thread, and others they started, daily pointing out to all who will listen that I'm an asshole.
If you want a dozen more examples of Eric butting in and insulting me unprovoked, I'll be glad to post the links. Kurt Foster at RO told me he and Chris asked Eric to leave and stop posting there. Someone else who runs another acoustics forum - someone you know very well - told me he too is "sick of Eric's bullshit" (his words) and wishes Eric would go away.
I didn't see what Eric wrote in the two posts in this thread that he since edited, but I can only assume it's more of the same insults. No?
How can you possibly lump me together with Eric and accuse me of "it takes two to fight?"
--Ethan
