Bass traps?

[simpleacoustic]

I once saw a site explaining the use of bass traps in speaker enclosures and I can't seem to find it anymore.Can anybody send me a link?I'm interested in it's uses like this but hardly ever saw them applied .

[weltersys]

Originally Posted by simpleacoustic

I once saw a site explaining the use of bass traps in speaker enclosures and I can't seem to find it anymore.Can anybody send me a link?I'm interested in it's uses like this but hardly ever saw them applied .

Bass traps are normally external to treat room problems, throwing away bass inside of a cabinet is, well, stupid :^).

Helmholtz resonators can be used to reduce a narrow peak, you may have read about that in some of the Danley tapped horns, IIRC, the DTS-20 "Tower of Power" may use some ducting to re-arrange some peaks.

[j.michael droke]

Hi there SA: I googled-up: atlantictechnology.com section drawing showing their bass trap. They call it "H-PAS". There is a animation included to show how the system works. This should be enough information for you to experimentally include a bass trap in your inclosure (leave back srrewed on so you can experiment with the sizes of the trap components) Hope you try the bass trap and document your work, listining experiences and possibly measurements. (*read the description paragraph for their explanation).... regards, Michael

[revboden]

unless the enclosure is massive you won't have the room for a bass trap. Hint: a 30Hz tube bass trap is ~20"/ 50cm in diameter.

[revboden]

Originally Posted by j.michael droke

Hi there SA: I googled-up: atlantictechnology.com section drawing showing their bass trap. They call it "H-PAS". There is a animation included to show how the system works. This should be enough information for you to experimentally include a bass trap in your inclosure (leave back srrewed on so you can experiment with the sizes of the trap components) Hope you try the bass trap and document your work, listining experiences and possibly measurements. regards, Michael

That's a Helmholtz bass trap. They can be used to lower a peak in resonance in a long port / transmission line.

[simpleacoustic]

(Helmholtz resonators can be used to reduce a narrow peak, you may have read about that in some of the Danley tapped horns, IIRC, the DTS-20 "Tower of Power" may use some ducting to re-arrange some peaks.)

Yes,it did mention Helmholtz resonators.I'm assuming these peaks cannot be corrected by a simple eq.
@ Michael,I did look at the H-PAS ,very interesting but I am wondering if its really worth the trouble especially in Pro audio.

[revboden]

Originally Posted by simpleacoustic

(Helmholtz resonators can be used to reduce a narrow peak, you may have read about that in some of the Danley tapped horns, IIRC, the DTS-20 "Tower of Power" may use some ducting to re-arrange some peaks.)

Yes,it did mention Helmholtz resonators.I'm assuming these peaks cannot be corrected by a simple eq.
@ Michael,I did look at the H-PAS ,very interesting but I am wondering if its really worth the trouble especially in Pro audio.

You could use a notch filter to keep the pipe resonance from occurring at all. But then again if pro audio is your thing you won't have a port or TL long enough to worry.


How they work is actually simple, Think about a really long port tube say 60", that would give a pipe resonance at ~112Hz. So you build a Helmholtz resonator tuned to 112hz and tap the port so the resonator sucks off energy when resonance is excited. The tap point position depends on how much energy you want to drain off.

[j.michael droke]

Hi there SA: Also look at Wikipedia under "acoustic bass traps", wherein they state:
Resonating bass traps absorbe sound at their fundimental frequency. Range can be broadened by using traps tuned to either side of the fubdimental frequency, size of traps in arrays will limit their usefullness.

One of the limiting factors for otherwise excelent performance of TH's for home or proaudio is excruciating peak in the 100 to 200 hz range, you may wish to investigate using bass trap(s) to cancil these peaks, to increase the BW. ...regards, Michael