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Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ.

An alternative approach

Ethan's right about the narrowness of the 9" trap as a treatment. That's the reason I said "They're only 9" wide traps so placement will need to be spot on."

A standard 2' wide panel of the sort often used for treatment of first reflections will cover a wider angle of the sound wave emitted from the speaker than a 9" trap at the same distance. Place the absorption device closer to the speaker and it covers a wider angle. You can get the same angle of coverage from the 9" trap by moving it much closer to the speaker. You still need to keep it on the line between the first reflection point on the wall and the tweeter (or inner edge of the front baffle for the front wall first reflection).

I can remember reading a review of the ASC tube traps by Jonathan Scull in Stereophile many years ago. What he did as one of his trap setup experiments was to create a wall of traps placed close to the outer edge of the speaker but aligned roughly along that first reflection path. Instead of placing half of the traps along each wall as Ethan suggests, try placing the 9" trap you're currently using on each side very close to the speaker but along the line of that first reflection path. That will ensure the trap "captures" sound from a wider angle of the speaker's radiation pattern than it will if placed close to the wall, giving you a similar kind of benefit to what you would get using a wider trap closer to the wall.

You may need to fiddle with the trap position a little in order to get maximum effect because of the narrowness of the trap but you should get absorption of a wider angle on either side of the first reflection path with the trap close to the speaker. Unfortunately by placing it that far from the wall you'll probably lose some of its effectiveness at lower frequencies but they're less critical when you're dealing with first reflections so you may still get good results.

Otherwise, if you need wider coverage close to the wall, panels are a more effective and economical approach than cylindrical traps.

You would probably get better results dealing with the side wall first reflections using Ethan's approach but then you lose the benefit of corner placement for your big traps. If you don't want to buy more traps or panels, placing the traps for the first reflections closer to the speakers may be more effective than a single trap on the wall while retaining the benefits of some corner bass trapping. What you're going to have to do if you run with the traps you have is balance the advantages of traps in the corner vs the advantages of wider coverage at the first reflection points and it's your call on which you prefer overall. There are advantages and disadvantages to both approaches.






David Aiken


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