Adding new DIY bass traps to my listening room. I'm considering building hollow, box type traps, faced on 4 sides with rockboard60 and sealed airtight, as in the ASC type tube traps, placed at the floor/wall junctions. Does anyone know, is there an advantage to this type trap, over a solid flat panel trap....I have both and both work, but I've no way to know or measure which is "better" for bass control. The hollow type will take up more floor space, in my family room, whereas the flat panel can be placed against the walls in the wall/floor interface. If both work equally well, I'd prefer the flat panels to save space........hope you followed this, I'm at work and in a hurry:)

The most important property of any bass trap is its size (surface area) and thickness. There's no particular advantage of a tube shape, except the part farther away from the corner has more of a gap than a panel would. So that helps a little. But tubes need to be pretty large to be as effective as panels. Like maybe 20 inches in diameter to work similarly to a 24-inch wide panel. The small DIY tubes I see that are 14 inches or even narrower are not as good as a 24-inch panel.

As for measuring, it's not difficult. This test tone "CD" you can download for free shows the raw room response at high resolution:

RealTraps Test Tone CD

The downside is it takes a long time to run the tones and plot them. Dedicate software is much better, but requires a computer be connected to your system. These are the programs I recommend:

ETF, Windows, $150
FuzzMeasure, Mac, $150
Room EQ Wizard, Windows and Linux, Freeware
This article explains how I use ETF, but the principles apply to all such programs.

This is related too:

Comparison of Ten Measuring Microphones

--Ethan

Thank you Ethan. Guess I'll go with the flat design. Easier to build, more conservative space wise and easier to get spouse approval:) A follow up question, if I may. Is there any point to placing bass traps behind furniture, i.e. an upholstered couch or would the furniture defeat the purpose??

Yeah, heavy furniture will block sound from getting to the traps. Of course, something like a lawn chair will have no effect at bass frequencies. So it's mainly a common sense sort of thing, where you can tell just by looking at the size and mass of the furniture.

--Ethan