Well, he said "barely moves". It happens because of resonance which gives a mechanical advantage like a lever. The resonance works on both the driver and slave, reducing the motion of the driver which is being forced in by the signal, and pushes the slave out, since it's free to travel. Same thing applies to a tuned port.
Yes, ofcourse
Air mass ressonance tuning is lowered by mass/weight of passive/slave
Like air mass in a TL maybe ?
How about a TL with a passive slave ?
Or a "tapped horn" with passive slave ?
Air mass ressonance tuning is lowered by mass/weight of passive/slave
Like air mass in a TL maybe ?
How about a TL with a passive slave ?
Or a "tapped horn" with passive slave ?
A suggestion for the thread name...would be good for a band to adopt:
MJL21193 and the TL Tangents
MJL21193 and the TL Tangents
What's an "average" PR system?
Let me pick one out of the air. Let's say that the bass resonance is 30 Hz. That OK? Wavelength is about 36 feet. For an "average" box (I picked that one out of somewhere else), the longest dimension is probably under 3 feet, which means that the air is moving approximately as a plug.
Another way to look at the same thing: speed of sound is something like 1100 feet/s, so the pressures in the box are all equal in less than 3 milliseconds.
So I take it you see where I'm going with this? With the longest dimension shorter than the quarter wavelength, how can the air mass resonate? There are no reflections, correct? - they can't happen in such a confined space.
Inconsistencies and contradictions.
I need to bug out for a hour or so.
An impulse to the air mass will decay. I think the resonance you ask about will occur only if the air mass continues to be excited with energy...
right track?
right track?
A resonance requires the equivalent of a spring and a mass (at minimum!). If a mass has no spring, there's no resonance. If a spring has no mass, there's no resonance. You need both (at minimum!). A PR is actually a collection of masses and springs: the air and the PR each provide a mass and a spring constant, to first approximation.
The key is to understand what I wrote in my last post: if you drive an air mass slowly, the pressures are approximately equal everywhere in that mass. How slowly is slowly? I gave you some rough numbers to work from and where those numbers come from.
The key is to understand what I wrote in my last post: if you drive an air mass slowly, the pressures are approximately equal everywhere in that mass. How slowly is slowly? I gave you some rough numbers to work from and where those numbers come from.
Martin, It's easy to see why you have so many fans here.... which may be an unfortunate pun. 😛
This was something I tried to touch on earlier when I mentioned the speed of sound. I think many visualise the speaker moving... now we have compression in the end of the tube... now the wave is moving down the tube... what happens when it hits a corner?
Truth is, there's a wave expanding out of the end of the tube while the speaker is still starting to move backwards (postulating the given 20Hz wave and correct polarity). Putting things in the corners to maintain a constant cross-section is valid, imagining them as reflectors only applies to very high frequencies.
For low frequencies, rather than thinking of a wave traveling down a tube, it's more accurate to think of the air in the tube as a solid mass. Push on one end with the speaker, a wave is created in the room at the other. Now figure out the losses of the "solid" in the tube.
(And for those side-tracked on the bass reflex example, the closer you approach the resonance of the box, the more solid the air becomes. It's really all thermodynamics - at the resonant frequency of a box, the expansion of the air due to the heat generated by the compression of the air counters the force of compression, hence the air mass becomes more "solid". This is why adding insulation (stuffing) makes the box "bigger". As the air mass becomes more solid, it works more like a steel spring than limp spaghetti (as SY has stipulated is required for resonance).)
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So a sealed box does not resonate? News to me. The air is the spring and the mass at the same time.
Explain the inconsistency of the sidewalls of a pipe as opposed to a sealed box.
How can an air mass be driven to resonance at a low frequency if the wave can't reflect off the sides?
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The most effective debate is put forth by a person that truly believes or at least has YOU thinking that he truly believes.
Cards, close to vest...😀
MJL21193 said this...who agrees with it? Not I, red herring...not I
Tighten up your poker face, John...
Ricky said: "'Splain dis to me, Lucy"
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Explain exactly how you can excite the air mass to resonance.
Every kid does this: blows across the mouth of a pop bottle to make a tone. What is happening is the air mass within the bottle is resonating. You will notice the bottle is vibrating. Explain it so I might understand what is taking place inside that bottle Ed.
I have the ultimate poker face - no flesh! 😀
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Air mass ressonance of bottle is excited by a force
And force needs to be applied correctly to work, thats the trick
Only, I dont think its possible to make more than one tone, from the same bottle
It ressonates at its tuning, and only that, like a flute 😉
Actually, in a flute especially I think the applied force is more like a turbulence
And the trick may be that the small turbulence stays around the hole where its been applied
Yeah, I have been playing traverse flute
With the bottle it may be like a small ball of air, staying at the opening, and kept there by the opposing ressonant force in the bottle
And the trick is to not disturb that balance
Hmm, ressonance of a flute varies just slightly, only by applying small openings in different places, but tube length remains the same
But its at much higher frequency than we talk about here
Church Organ pipes ?
Vibrafone ?
Strange instrument with tubes/pipes below the sound "bricks", with a certain distance
Without the pipes it wouldnt sound good
😀 ROFL 😀
Of the many responses I could provoke, that will be cherished.
Thank You, So, so much. 😉
...don't forget that home work...
Glad I could amuse you. 🙂
Here's your opportunity chi..err Ed to showcase you superior understanding of the issue...you have the floor. Explain it, it shouldn't take long.
Better a chicken than a turkey.
I've met guys like you on many forums. I think your little game is dumb. You keep asking for explanations, but you're the little boy that cried "Wolf!". You want everything explained in your terms, but there's always a catch so you're never satisfied. It seems you're only happy when every thread ends up revolving around you, and your silly postulations.
Guys, don't feed the troll.
This thread has had enough name calling...
If you just want to antagonize please don't bother.
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