why does this piece of paper move so much?

[jmanpc 5,000+ posts]

the paper is trembling at his gayness //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

 

[Death By Bass 10+ year member]

That is air moving out of the port bud, look at how it oscillates to the change in pressure as the cone moves in and out. What else could it possibly be? The paper is moving, and is only moving at that point. The open end of the paper flutters as the air pushes it away and pulls it back. I don't know what else you're looking for.

its not AIR, it cant be AIR, because the woofer displaces about 1/10th as much air as what is needed to move the paper!!! thats the whole point, cant you work it out? //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif

 

[Death By Bass 10+ year member]

He has already shown that he doesn't know what he's doing.

as I have already said (seeing as your comprehension is clearly lacking) the front towers are only needed to play down to 50Hz, at which point, the subwoofers take over... get it? //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif

 

[Bluecamry 10+ year member]

It never ceases to amaze me how so many small speakers can move so much air. I would never look at a box that big for that speaker, but to each his own. As you have stated, its only for certain frequences.

Many people have already stated why, its just the way the box is designed.

 

[Death By Bass 10+ year member]

It never ceases to amaze me how so many small speakers can move so much air. I would never look at a box that big for that speaker, but to each his own. As you have stated, its only for certain frequences.
Many people have already stated why, its just the way the box is designed.

the box is meant for eight of the woofers, thats why its so big...

its clearly not AIR moving it, because, according to WINISD, I have about 4m/s port velocity (port noise cant be heard till about 20+m/s)

the only half logical explanation, is that its SPL moving it, and like I have thought from the start, its a 1/4 wave of 30Hz...

as the frequency decreases, the volume increases, till about 30Hz, after which is starts dropping off...

now, this isn't exactly how a 40Hz tuned enclosure is going to act, now is it...

 

[Bluecamry 10+ year member]

Eight would make more sense... I thought something was wrong. Its late...

Perhaps its just the waves were enough to escape the small hole between paper and box until... i dont even know what im saying anymore, that doesnt make anysense.

And its been said before, but who cares if it sounds good? Its interesting but not exactly worthy of a nobel prize for he whom figures out the great mystery of the vibrating piece of paper.

 

[PV Audio 5,000+ posts]

as I have already said (seeing as your comprehension is clearly lacking) the front towers are only needed to play down to 50Hz, at which point, the subwoofers take over... get it? //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif

You don't tune to 40hz in home theater for a tower bud. 40hz is subbass, and that's subwoofer territory. You want to tune in the midbass region where your subs are weak, 60-80hz, higher depending on size of speaker. It isn't just a big subwoofer box.
And it is air moving the piece of paper, there isn't anything else it could possibly or physically be.

 

[Immacomputer 10+ year member]

its not AIR, it cant be AIR, because the woofer displaces about 1/10th as much air as what is needed to move the paper!!! thats the whole point, cant you work it out? //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif

It IS air. As I have already said, the speaker is creating a resonance in the enclosure and that causes air flow (moreso air vibration). The paper is also reaching, or at, the point of resonance as well which will cause it to move like crazy.

Think of resonance as pushing somebody on a swing. If you push them at just the right time everytime, they're going to climb higher and higher as gravity helps them accelerate and you're adding to the driving force. Over time, you can get that person on the swing going extremely high, higher than you would be able to do with just one push. This is because you were pushing at just the right time to cause resonance in the system. If you decided to try to give your push when the swing was coming towards you, the swing would not go very far as this would not be the point to drive it into resonance.

The exact same thing is happening here. At the correct frequency, the enclosure is being put into resonance which causes the large amount of airflow and if the paper is also at resonance, it's going to move quite a bit as well. This IS what is going on here and it's perfectly normal.

 

[jmanpc 5,000+ posts]

it's not air or sound or anything.

the paper is trembling at teh gayness, just like I said earlier

 

[Death By Bass 10+ year member]

You don't tune to 40hz in home theater for a tower bud. 40hz is subbass, and that's subwoofer territory. You want to tune in the midbass region where your subs are weak, 60-80hz, higher depending on size of speaker. It isn't just a big subwoofer box.

there's nothing wrong with tuning to 40Hz. whats wrong with tuning to 40Hz? lol, why do you seem to think that tuning the front speakers to 40Hz is such a no no? //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif

 

[PV Audio 5,000+ posts]

there's nothing wrong with tuning to 40Hz. whats wrong with tuning to 40Hz? lol, why do you seem to think that tuning the front speakers to 40Hz is such a no no? //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif

//content.invisioncic.com/y282845/emoticons/uhoh.gif.c07307dd22ee7e63e22fc8e9c614d1fd.gif Oh, I don't know, maybe because I've built about 20-30 different types of home speakers and know a little bit about it? Again, as I've said, there is no information at 40hz that your front speakers should even be reproducing. The reason you port a speaker is to gain output at a certain frequency range. Mains are not made to reproduce subbass, and by tuning them to do such is useless. You want to accentuate your bass octaves, NOT subbass as that is for subwoofers. Again, a home speaker is not just an enclosure with drivers in it, it is a system that is made to reproduce music down to a certain area. Do you ever wonder why many towers have subwoofers built in, but are seperate? The actual mains themselves are not made to reproduce subbass notes, which is what 40hz is. A home audio system is about blending various components into a SYSTEM. The parts need to work together to create something that sounds as one. You don't want 8 "subwoofers" and a few tweeters in a box. You build the speaker to cover what it is made to cover, and mains are not made to reproduce subbass. And besides, you already proved your knowledge of home audio by placing a speaker on top of the enclosure just because you wanted 8 and it wouldn't fit.

 

[300watts]

the box is meant for eight of the woofers, thats why its so big...
its clearly not AIR moving it, because, according to WINISD, I have about 4m/s port velocity (port noise cant be heard till about 20+m/s)

the only half logical explanation, is that its SPL moving it, and like I have thought from the start, its a 1/4 wave of 30Hz...

as the frequency decreases, the volume increases, till about 30Hz, after which is starts dropping off...

now, this isn't exactly how a 40Hz tuned enclosure is going to act, now is it...

But the air is moving. The speaker is exciting the the air inside the enclosure. The air inside the enclosure acts as a spring to move the "piston" of air in the port back and forth. I think somehow you are confusing the fact that a port can never have more displacement than the speaker exciting it.

Its just a ported box. As for the tuning, I think the enclosure is tuned lower than you think. What I'm saying is that 3 sides of the port are significantly longer than the other. IE the port is longer than you have determined. An easy way to find out tuning is to plot the impedance of the actual enclosure and find where its miniumum occurs.

As for 30hz quarter wave, no way. 1/4 wavelength of 30 hz = ~10ft depending in the speed of sound.

You are saying SPL is moving the paper? SPL IS PARTICLE VELOCITY. These particles are what constitute air.

-chris

 

[Death By Bass 10+ year member]

As for 30hz quarter wave, no way. 1/4 wavelength of 30 hz = ~10ft depending in the speed of sound.

the enclosure is 4 foot, 7 inches tall... idiot...

the signal path, from the back of the woofer, to the bottom of the box, and back out the port, is around 2.9 meters, which is a 1/4 wave of 30Hz...

the enclosure IS acting as a TL...

plain and simple...

also, as I've said dozens of times already, there is nothing wrong with tuning the front speakers in a home audio system to 40Hz //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif

 

[Bluecamry 10+ year member]

The speaker is exciting the the air inside the enclosure.

Wrong, the air was already excited from seeing paris hilton on tv.

 

[Death By Bass 10+ year member]

P.S. 10Hz = "sub bass" 40Hz does not = "sub bass"

is 50Hz "sub bass" then? if I'm wanting the speakers to play flat down to 50Hz, I'm not going to tune to 50Hz now am I?