slat resonator wall

i'd like to clarify what the ideal specs are (if there are such a thing) on the slat resonator walls outlined in the SAE reference material. john's diagram shows diferent pieces of timber on the face of the wall of alternating widths (100mm, 50mm, and 25mm). i'm curious as to what pattern i should alternate them (i presume it would be 25, 50, 100, 50, 25, 50, 100, 50, 25 etc.) i'd also like to know in what pattern i should i place the gaps between the timber (the three sizes john has recommended are 10mm, 5mm, and 2.5mm). should i place the larger gaps next to the narrow pieces of timber, or next to the wider ones? finally, can anybody recommend a specific thickness of timber to use on a slat resonator wall? apologies if this has already been covered. i searched but could not find. thanks, max

There is some debate about whether or not the board width and the gaps have to be varied or not. Most times you see that they are, but in Rod Gervais' book he indicates that it isn't necessary. I don't know who is right here, just saying there are different opinions out there. There is a spreadsheet calculator to determine board width and spacing, it's in the stickies in the acoustics forum. Make sure you use the corrected one as there was a typo published in an acoustics book years ago that everyone copied, giving the wrong formula and also the wrong results. As far as board thickness, most people seem to just use standard 1x lumber (ie, 1x4s, 1x3s, 1x6s etc). At least that's how we refer to them in the states....

Well, there are two different goals with slot size and spacing. If you vary the slat and slot size, you will essentially be building a broadband helmholz resonator, if you build one with very specific slot spacing then you will essentially target a narrow band of frequencies... look over this thread. http://www.johnlsayers.com/phpBB2/viewt ... 6c48764325 kevin