El Pipe-O

[Nelson Pass]

El Pipe-O is available now at www.passdiy.com

This is the first of a series of speaker projects we plan.

Merry Xmas.

[paulb]

Thank you, Nelson. Merry Christmas to you as well.

[fcel]

Did not expect to have this much to read over the holidays. Thanks NP and Merry Christmas to you and your family.

[Jimmy154]

Your second design looks better (after you blew those 2 focals). No folds or box to mess up the sound, like you where saying folds are bad. No wonder they sound better. Drunks also like to break my speakers, sometimes me also though.

[FrankDIY]

After a one week break on the forum, I am surprised to see that Mr Pass has give us a nice christmas gift. Very interesting and funny article. Thank you.

I can not resist to build something similar with my left over sub. Unfortunatelly I do not have a 14' ceiling (nor an X1000) but I really want to get my parties a little less boring so I will find a solution

[yup]

Can you effectively create a soundwave in a room which is smaller than the wavelength in question?

Just wondering....

Jeff

[pinkmouse]

Can you effectively create a soundwave in a room which is smaller than the wavelength in question?

Yes

It can be confusing, because at school we are all taught that sound waves all look like nice wobbly sine waves and have a nice neat wavelength.

This is true, but only part of the answer. Sound waves are actually waves of compression and rarefraction transmitted though a medium, and as such can travel in any size space at all. As long as you have a volume where the individual particles/molecules have free movement, they will respond to any stimulation of any wavelength.

If it was not so, we would be unable to hear anything lower in frequency than the wavelength of the human ear canal, so assuming this is 2cm long, we would be unable to hear below 16.5KHz

[phase_accurate]

You don't need to have a soundWAVE in order to hear sound.
Our ears are basically pressure receivers (this is not 100% correct, but close enough) so it is sufficient to have soundPRESSURE.
Any form of mechanical wave that propagates through a medium is consisting of motion and force. In the case of a soundwave this is sound pressure and velocity.

I think almost everybody has experienced the following once in a while: Somebody turns a car window down a little while driving, turning the car into a large Helmhotz resonator. At a certain speed it's resonance may be excited, resulting in a very annoying subsonic noise. This is usually below 10 Hz, if not even below 5 Hz. You can imagine how "loud" this must actually be, given the facts that it is clearly below our ear's "lower cutoff frequency" and how loud it is perceived.
One interesing phenomenon is that the "culprit" rarely notices what he's done while the other passengers complain: The one closest to the window is mainly exposed to the VELOCITY of the oscillation while the others are exposed to the sound PRESSURE.

Regards

Charles