I just mean't that in terms of bandwidth, an 18" doesn't need to move as much to reproduce low frequencies. An 8" driver must move much quicker to accerelate much quicker (more SPL) to reach that same frequency.
So the 8" driver must move much quicker and do a lot more work than the 18" driver.
But then, hypothetically speaking, what if we had a 60" driver ? Would that work given a sizable motor structure ? So then a 60" driver would need the least amount of work, would be the "fastest", and would be the lowest.
The it's true what Dan Wiggins said. The fastest driver is the driver that can move the lowest, the loudest.
--Sincerely,
So the 8" driver must move much quicker and do a lot more work than the 18" driver.
But then, hypothetically speaking, what if we had a 60" driver ? Would that work given a sizable motor structure ? So then a 60" driver would need the least amount of work, would be the "fastest", and would be the lowest.
The it's true what Dan Wiggins said. The fastest driver is the driver that can move the lowest, the loudest.
--Sincerely,
Andrew, would I be incorrect in saying that acceleration is the same thing as velocity, or is it correct to say that it's a function of acceleration, or is it proportional to accerelation ?
If I am incorrect, please explain the difference. Thanks.
--Sincerely,
If I am incorrect, please explain the difference. Thanks.
--Sincerely,
Velocity is a product of acceleration times time.
Given a certain acceleration, a particular velocity will be reached in a calculable time.
Umm..... Velocity is speed. Acceleration is a change in speed, and can be positive or negative in value.
Yep, that's good enough.
Given a certain acceleration, a particular velocity will be reached in a calculable time.
Umm..... Velocity is speed. Acceleration is a change in speed, and can be positive or negative in value.
Yep, that's good enough.
Not quite, but for diaphragm movement, close enough.Andy Westcott said:
Vaughan, when you say work, do you mean force * distance?
Hi,
acceleration, speed and distance are all related.
See attached graph of constant acceleration changing to constant velocity.
The slope of the varying velocity is a measure of the acceleration.
The flat section is the time during which the speed does not change.
The distance is time * velocity which just happens to be the area under the graph.
Fortunately the area under the sloping part of the graph also follows the same rule:- area under the graph is distance, even when the acceleration is not constant the rule still holds.
A speaker following a single tone (frequency) is following a simple harmonic motion. If you could plot the speed time graph for this it would look like a sinewave. But again the rules still follow. It's just a bit more complicated working out the slope (which is ALWAYS varying) and calculating the velocity (always varying).
Hope this helps!
acceleration, speed and distance are all related.
See attached graph of constant acceleration changing to constant velocity.
The slope of the varying velocity is a measure of the acceleration.
The flat section is the time during which the speed does not change.
The distance is time * velocity which just happens to be the area under the graph.
Fortunately the area under the sloping part of the graph also follows the same rule:- area under the graph is distance, even when the acceleration is not constant the rule still holds.
A speaker following a single tone (frequency) is following a simple harmonic motion. If you could plot the speed time graph for this it would look like a sinewave. But again the rules still follow. It's just a bit more complicated working out the slope (which is ALWAYS varying) and calculating the velocity (always varying).
Hope this helps!
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Notax said:
LOL, what's with the retarded naming scheme? "Magnat Aggressor 5000 Deathmatch"? Did some 14 year old think of that....?
Magnat Aggressor 5000 Death Match:
Regarding the "Copper plated magnet system to reduce eddy current losses and better heat abstraction"
Typical car speaker advertising, and complete rubbish.
Why do they assume buyers of in-car entertainment are idiots??
The speaker might well be a good performer, but why advertise it in this silly manner?
Sorry - rant over. 😀
Regarding the "Copper plated magnet system to reduce eddy current losses and better heat abstraction"
Typical car speaker advertising, and complete rubbish.
Why do they assume buyers of in-car entertainment are idiots??
The speaker might well be a good performer, but why advertise it in this silly manner?
Sorry - rant over. 😀
So am I correct in my assessments on this issue (last page) ? Please, someone more knowledgeable in this area please correct me if I'm wrong.
Thank you.
--Sincerely,
Thank you.
--Sincerely,
Vaughan said:
The first statement is true, assuming the motor constants stay the same. Think of a car. If you reduce its mass (holding engine power constant), you'll increase the acceleration.
There is no such thing as "instantaneous" acceleration. The term you're looking for is "bandwidth." A sub does not need a high bandwidth nor "speed"- the signals sent to it are, by definition, bandwidth-limited. A good woofer does need low distortion and reasonable damping.
Acceleration is the time derivative of velocity, i.e., just as velocity is the rate of change of position, acceleration is the rate of change of velocity. (5 point bonus question: what do we call the rate of change of acceleration?)
8 versus 18 is a much broader and fuzzier question, but it is certainly true that for the same excusion, the 18 will move more air and give higher SPL. Note that an 8" can produce a frequency just as low as the 18, but just not as loudly (all other things being equal).
I am now using a pair of modified XXX 18" drivers now for my home stereo system, I used to have Tumults, but I kept ruining them. They sound really good, give massive bottom end output and do not sound "slow in slightest. With 18Hz tuning and 2600 wrms each, they aren't real efficent, but they still can belt out the bottom end...
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SY, I'm a bit confused with the statement you made about an 8" being able to reproduce any frequency compared to an 18".
Perhaps you could elaborate ?
But it is true that because an 18" driver can move more air, it will accelerate quicker (according to Dan Wiggins), and therefore would be able to reproduce any given low frequency signal (like, for instance, 20 hz), better than the 8" driver (all things being equal, of course).
Also, is it not true that if a driver can reproduce a given frequency that it is moving as quick as it has to to reproduce that frequency ?
Please correct me if I'm wrong. Your help would be appreciated. BTW, I hope I'm not coming across as stupid, but could you perhaps use an analogy to explain the whole acceleration, velocity, speed thing because I see conflicting opinions everywhere and I could use your input.
Thank you !
--Sincerely,
Perhaps you could elaborate ?
But it is true that because an 18" driver can move more air, it will accelerate quicker (according to Dan Wiggins), and therefore would be able to reproduce any given low frequency signal (like, for instance, 20 hz), better than the 8" driver (all things being equal, of course).
Also, is it not true that if a driver can reproduce a given frequency that it is moving as quick as it has to to reproduce that frequency ?
Please correct me if I'm wrong. Your help would be appreciated. BTW, I hope I'm not coming across as stupid, but could you perhaps use an analogy to explain the whole acceleration, velocity, speed thing because I see conflicting opinions everywhere and I could use your input.
Thank you !
--Sincerely,
I don't really understand what's clouding the issue for you. If given enough travel and a capable motor, an 8" driver can reproduce very low frequencies, as an 8" driver moving say 3" is the equivalent of an 18" driver moving some smaller distance - equations have already been given. Both drivers will have to move their allotted distance in the same amount of time, so the 8" driver will have to move faster. If the motors on the 8" and 18" drivers are proportionally capable, the drivers will have the same acceleration capabilities - at a given frequency at a given output level though, the 18" driver just won't have to move as far, and thus, it won't have to move as fast.
Excursion capabilities of the 8" driver becomes a limiting factor in being able to reproduce low frequencies at some point, and there are some negative effects associated with the use of very large excursion drivers - thus, larger drivers are used for lower frequencies. When trying to reproduce those very low frequencies, the 18" driver is more efficient, will have to move much less distance, and should produce much less distortion in the process.
You're making it too difficult
Excursion capabilities of the 8" driver becomes a limiting factor in being able to reproduce low frequencies at some point, and there are some negative effects associated with the use of very large excursion drivers - thus, larger drivers are used for lower frequencies. When trying to reproduce those very low frequencies, the 18" driver is more efficient, will have to move much less distance, and should produce much less distortion in the process.
You're making it too difficult
What Steve said. It's easier than you're making it out to be.
Look, what's the size of the diaphragm of headphones? A centimeter or two? Yet they can have very deep bass. It just can't be played loud enough to hear unless you get your ears very close.
The relationship between position, velocity, and acceleration is one of the most fundamental aspects of physics. Check out the explanation in any elementary calculus or Newtonian mechanics book. Velocity is rate of change of position (e.g., 60 miles per hour). Acceleration is rate of change of velocity (e.g., 32 feet per second per second).
Take an easy example. The Earth's gravity imparts a constant acceleration to all objects (Galileo). That acceleration in British units is 32 feet per second per second. What does that mean? If I drop a weight off the Leaning Tower of Pisa, it starts at an initial velocity of zero, and as I let it go, it begins to accelerate at 32 ft/s/s. After one second (I neglect air resistance), its velocity is 32ft/sec. It continues to accelerate at 32ft/s/s. So after the second second, its velocity is 64ft/sec. After the third second, its velocity is 96ft/sec. Each second, under the constant acceleration of gravity, the velocity increases by another 32ft/sec. And continues to do so until it hits the ground.
(pedantic alert: yes, yes, I'm using the term "velocity" to really mean "speed," so mentally insert the term "toward the earth" at each usage to make it into an Official Velocity, approved by the American Vector Council)
Look, what's the size of the diaphragm of headphones? A centimeter or two? Yet they can have very deep bass. It just can't be played loud enough to hear unless you get your ears very close.
The relationship between position, velocity, and acceleration is one of the most fundamental aspects of physics. Check out the explanation in any elementary calculus or Newtonian mechanics book. Velocity is rate of change of position (e.g., 60 miles per hour). Acceleration is rate of change of velocity (e.g., 32 feet per second per second).
Take an easy example. The Earth's gravity imparts a constant acceleration to all objects (Galileo). That acceleration in British units is 32 feet per second per second. What does that mean? If I drop a weight off the Leaning Tower of Pisa, it starts at an initial velocity of zero, and as I let it go, it begins to accelerate at 32 ft/s/s. After one second (I neglect air resistance), its velocity is 32ft/sec. It continues to accelerate at 32ft/s/s. So after the second second, its velocity is 64ft/sec. After the third second, its velocity is 96ft/sec. Each second, under the constant acceleration of gravity, the velocity increases by another 32ft/sec. And continues to do so until it hits the ground.
(pedantic alert: yes, yes, I'm using the term "velocity" to really mean "speed," so mentally insert the term "toward the earth" at each usage to make it into an Official Velocity, approved by the American Vector Council)
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