DIY Tube Traps

arthurs · « **on:** 12 Feb 2006, 11:00 pm »

I'm going to give these a try, any advice on what circumference to go for?

bpape · « **Reply #1 on:** 13 Feb 2006, 12:39 pm »

How deep to you want them to absorb? If you want them to be reasonably effective in the bottom end, plan on at least 16" diameter.

arthurs · « **Reply #2 on:** 13 Feb 2006, 01:53 pm »

I guess I'm looking for them to be reasonable effective around 55Hz so it would seem 16" would be the ticket....do you guys do anything like this? If not, do you recommend the Guilford for covering or something different? Thanks!

bpape · « **Reply #3 on:** 13 Feb 2006, 02:42 pm »

If you're looking for pure bass absorbtion, the cloth covering is not as critical.

My personal opinion is that unless the tubes are desirable from an aesthetic point of view, you'll get better performance down deeper for about the same money by straddling the corner at 45 degrees with 4" of 705 or 4-6" of 703.

You'll also find if you draw it out that it takes less floorspace.

arthurs · « **Reply #4 on:** 13 Feb 2006, 02:48 pm »

Can you drop me an e-mail off line? Thnaks

ctviggen · « **Reply #5 on:** 13 Feb 2006, 02:50 pm »

I think a Helmholtz radiator will "beat" any 4-6 inches of any insulation, depending on your measure. A Helmholtz radiator operates to have a much more specific Q (the Q of insulation likely isn't even definable). So, if you know you have one specific peak, a Helmholtz radiator will be much more beneficial than insulation. If you're looking for more general absorption, a Helmholtz radiator will not give you that. As for which is best depends on your criteria. Also, if you're making a cylinder of insulation without paying attention to resonant criteria (as you would when designing a Helmholtz radiator), then insulation straddling a corner will likely be just as good if not better.

arthurs · « **Reply #6 on:** 13 Feb 2006, 02:57 pm »

......and just like that I'm in over my head.....

Ethan Winer · « **Reply #7 on:** 13 Feb 2006, 06:18 pm »

Arthurs,

I agree with Bryan that what matters most is having big thick panels across as many corners as you can manage. ctviggen is also correct that a Helmholtz trap can target 55 Hz very well. But most rooms need absorption between around 80 and 300 Hz more than at lower frequencies, regardless of what you calculate or measure. So what you need most is broadband low frequency absorption. A Helmholtz trap targets a narrow range and to solve a specific problem, and is most useful after you have enough broadband absorption in place.

--Ethan

arthurs · « **Reply #8 on:** 13 Feb 2006, 07:12 pm »

so if I understand you guys, for a broadband absorption in the lower frequencies, just run something 4" thick 45 degerees across the corners and up the wall? Any rule of thumb on width and height? I guess I'd go 12" wide? My walls run around 8 to 9 feet and the ceiling bevels up at an angle until it flattens out. Speakers are 6' tall.... Thanks.

bpape · « **Reply #9 on:** 13 Feb 2006, 07:27 pm »

Generally you use 2' wide material to straddle the corners. The deepest part of the absorber will then have approximately 16" from the front to the corner.

The Helmholz absorbers can do a very nice job for specific issues that need to be addressed. In most rooms, initially, broadband absorbtion is needed which these will not provide. A Helmholz will work at best over about 1 octave. Also, they're more expensive and time consuming to build, easy to mis-tune if you're not very exacting when building, and also aren't as efficient per square foot as a broadband velocity absorber.

I'm not saying don't use them - just know specifically what you need and be ready to only target what they're tuned to.