MEgamer :
i dont get ur speaker and driver analogy. really if ur talking abuot thsi kind of topic then all u have to know is that surface area times excursion is proportional to the volume. know matter what size, assuming they weigh the same, its power thats dependent on volume.
there is no 'driver' and 'speaker' or its 'speaks'... wat kind of analogy is that???#
power is volume.. and that is power of the (coming from the) speaker.
doesnt matter how many watts you are feeding it.. it depends on how well the speaker performs when given the power it is designed for.
an abnormally strong magnet will boost a 100 watt speaker because the magnet is what drives the cone in and out when the voice coil is energized.
the spider can be stiff and resist the force of movement.
the magnet can be weak and provide little force of movement.
anyways..
when you tell me that there is no 'driver' or 'speaker' .. it makes me think you have simply read a book and dont have any hands on experience for yourself.
give me $25 and i will send you a speaker that has very little 'drive' and a whole lot of 'speak'
the speaker emits sound without moving very much.
generally based on the way the voice coil is wound.. but a magnet with a very thin focal point can also help provide the same end-result.
'drive' is the moving in and out without saying much.
'speak' is the exact opposite .. there is sound pouring out of the dustcap, but the speaker is barely moving.
if you have a speaker that can 'speak' a whole bunch.. then start adding 'drive' and the sound will start to move outwards from the dustcap.
a speaker cone has its own radiating pattern.
but the design of the motor also has its own radiating pattern.
zoom in on the speaker movement with me..
you can have a speaker that will play a single note and the cone will simply move in and out at the wavelength of the frequency.
OR
you can have a speaker that will play a single note and the cone will slowly move in and out (point to point xmax) while also moving in and out at the wavelength of the frequency being asked to play.
if you record the cone movement on a camera there will be a difference.
the first example, the cone moves in and out of the wavelength only.. and you will probably see the speaker cone ripple and bend.
but the second example, you will see the cone slowly moving in and out (within the linear xmax).
its like watching the cone move in and out of a total .75 inches .. but the wavelength only requires a few millimeters.
its safe to say that a speaker cone can move in and out more than what is required for the wavelength.
the results arent going to help you calculate your room very nicely.
a very very crude example:
i hand you a ball and i tell you to throw it.
it doesnt matter how far you draw your arm backwards (as long as it is drawn backwards more than 6 inches)
you draw your arm back and throw the ball.
if you draw your arm back 6 inches or less.. that is considered a toss, no matter how hard you move your hand forward.
and it really helps bring the situation to a close.
if i tell you to make the ball go through the air.. you have the choice of throwing it or tossing it.
how hard you throw or toss the ball is like changing the amplitude with the volume dial.
i know the throwing a ball example doesnt fit perfectly, perhaps because there is some confusion with 'drive' and 'speak' yet.
there are some speakers you can use for examples.
the kicker l5 or l7 both have lots of 'drive' with very little 'speak'
the cone moves in and out a great deal.. producing pressure inside the car.
an infinity subwoofer has lots of 'speak' with very little 'drive'
inside the car you hear the subwoofer, but you dont feel the bass as much as the kicker sub.
for a subwoofer, yeah.. you might want the cone to move in and out without 'speaking' so that you have nothing but loads of air to get the sound from.
this is the essence of muddy sound.. pure mud if you will.
but the only way to get subtle details from the load of air is if the air is sealed up and the air pressure has the ability to flow freely (unobstructed) to allow the subtle changes in wind move throughout the cabin space.
and it isnt necessarily possible until the air chamber is already pressurized.
that means.. to accomplish a quick change of the speaker cone.. a piece of string hanging from the rear view mirror MUST move at the exact same time the cone moves.
if the cone moves outwards (and stays there).. the string needs to be pushed forwards and stay there (gravity will draw the string through the air until it is settled and sucked on)
if the cone moves inwards (and stays there).. the string needs to move backwards towards the seats and stay there.
this is optimal.. but takes designing to accomplish.
if you just throw an amp and subwoofer into the trunk and the cone moves outwards and stays there.. its gonna take some time before the string moves.
since the cabin isnt already pressurized.. the string will only vibrate.
that means subtle details wont be as solid and pronounced.. which means you wont hear them at all.
i have seen a video before of the pattern emitted by speakers.. if the sound pressure is high enough, you can see it and record it with a camera.
obviously i am about at the end of what i know.. because i dont know how those patterns contribute to 'drive' and 'speak'
but i can make a logical guess.
if you have nothing but 'drive' .. the pattern seen will simply be LFO's and you will see exactly how the chamber is bouncing pressure and creating a pattern.
its a choice to use only specific polar patterns or the entire polar response.
specific polar patterns will show lines throughout the room as they combine to create the most pressure.
obviously you have to have enough pressure to break visual standstill.
but the chamber has lines going through it like spider waves when specific polar patterns are used.
when all of the polar patterns are used.. the entire chamber will stay completely solid and there wont be any 'liquid movements' unless they are purposefully induced.
however, if you are using inferior math to try and create a perfectly solid chamber.. you will see the artifacts because there will be liquid movements.
and let me just stop right here and tell people who dont know what i am talking about.
if you have ever been to the drag strip and watched funny cars race down the track.. you know that you can look across the track at the other bleechers and see them liquify as the car goes by.
its because the sound is loud enough to move the air with such strong pressure that the air distortion can be seen visually.
there are sound chambers with speakers that are powerful enough to make the same visual distortions.
sometimes you can actually pay to demo one of these.. i dont know if there are any available to the public or not.
what they do is take room LFO's and shrink them and shrink them until there is hardly anything left.
the reason why they are called LFO's is because 'usually' it takes low frequencies to produce enough pressure to consider a visual distortion.
there may be better words used to describe some things now that they have been teaching acoustics in college.
but the room fills up with soundwaves.
if you make the room easier to throw soundwaves first, you can manage experiments easier because the soundwaves have the air needed.
it IS physics.
there are physics in a speaker.. yes, a person of physics can create a speaker to fulfill their needs. (although not necessarily welcomed)
but its really about the physics of air.
completely about the physics of air as long as you have a speaker.
the speaker emits a pattern.. and that pattern is what is important if you want to take any speaker and make it sound the best it can in an environment.
i realize how far off i am about 'driver' and 'speaker'
what brought me to the conclusion was a 12 inch woofer i bought off of ebay.
the woofer was very stubborn and refused to play lower frequencies without a lot of amplifier power.
say from 30hz to 50hz .. the speaker didnt want to move in and out.
and that means there was sound pouring from the dustcap .. radiating to the outer edge of the cone because the cone was very stiff .. and the results are nothing short of what the cone could do to the air.
i did manage to get 30hz out of the woofers after using an equalizer.. but one of the voice coils became unwound.
what appears to be logical..
the actual voice coil and magnet where sensitive, which produced the sound.
but the suspension of the woofer was very stiff, which means the speaker cone didnt want to move in and out for any reasonable length of excursion that a woofer should be capable of.
it boils down to the fact of the voice coil 'willing' to move in and out.. but the speaker cone didnt want to.
its possible for the inside of a speaker.. where the voice coil is glued.. to move in and out a bit more than the outer edge of the cone.
this is one way a speaker can 'speak' without moving very much.
because you arent going to see the dustcap area move in and out more than the edge of the speaker cone.
also, this changes the pattern that is emitted from the cone significantly compared to a speaker cone that has a soft suspension (the stiffness of the spider and the stiffness of the surround).
to playback a frequency.. the speaker has to move in and out at the right interval, which is time dependant.
but the speaker can move in or out extra as long as the phase is flipped at the right interval.
flipping the phase is the amplifiers job.
moving in and out is the speakers job.
i am drawn back to sensitivity of the speaker again and again.
see.. if the spider, the surround, and the voice coil all have a desire to play a specific frequency.. playing a frequency far from the speakers desire can make the speaker become angry.
when this happens.. the speaker will move at the frequency it wants to move, with the frequency its being asked to play being mumbled.
OR
the exact opposite can happen.
the speaker will play the frequency it is being asked to play, but will mumble on about the frequency desired.
mumbling the frequency asked to play isnt going to provide lots of energy emitted for that frequency. (no 'speak')
instead.. the speaker says 'i am gonna play 30hz whether you like it or not'
and the 30hz added to the requested frequency makes the cone move in and out more. (the 'drive')
it can and should be seen as an artifact when all you want is the frequency you requested and nothing more.
BUT
you can use the 'desire' to your advantage.
if you ask a subwoofer to play 40hz and the subwoofer wants to play something else (usually a lower frequency) then you can get the benefit of emitting 40hz into the air.. and then use the lower 'desire' frequency to push outwards on the ripple, which is like the speaker playing a frequency and then shoving that frequency away saying 'get away from me'
its a bit easier if you think about it in steps.
to start..
you play four quick pulses (thats moving in and out eight times)
then you throw out a large (single) pulse.
it doesnt make sense because it looks like the speaker is playing 4hz at small amplitude, then 1hz at high amplitude.
but if you take those two seperate events and place them directly on top of eachother.. they will happen at the same time.
how and why does this make sense you ask?
because you get free amplitude without using the amplifier..!
now if the speaker plays 1hz and mumbles or struggles to play 4hz.. obviously you are asking for 4hz and you are getting it, but it isnt very loud = no (or little) 'speak' and all 'drive'
in practice, these setups dont always play each note with the same amplitude.
if there are severe timing problems.. usually the 'desire' frequency will win the battle and the 'requested' frequency will be forced to play 'affected'
that can cause a warm sound if the 'requested' frequency has timing problems that are found to be 'slow'
and it can cause a cool (or bright) sound if the 'requested' frequency has timing problems that are found to be 'too soon'
once you stop playing around with single frequencies and start playing some music.. you will see the cone moving in and out a whole bunch, but there isnt lots of volume coming from the speaker.
you think to yourself 'normally when the speaker is moving in and out like that its really loud and i have the amplifier turned up to 75%'
but you actually have the volume turned up only 50%
and maybe you dont realize this at all.. because lots and lots of the speakers that have flooded the market do the extra cone movement.
speakers from the 70's .. if you turned them up and the cone was moving in and out a whole bunch, you could point that speaker to your chest and feel all of the sounds being played.
and you could feel those sounds with very high detail.. what was requested to play is only what the speaker is playing.
nowadays.. if you want the same experience, you have to find some concert speakers.
not to be confused with DJ or band speakers.
actual concert speakers.
if you have the volume on those up.. you can stand by them and feel every little detail of the guitar string.
you can even feel the tip of the guitar pick.
those speakers are playing what is requested and nothing else.
DJ speakers have a hard time playing what is requested.. and they are also playing something extra that isnt requested.
that is why you can stand by a DJ speaker and feel vibrations.. but they dont match exactly with the audio you are hearing.
the feelings arent late or delayed.. what you feel is seriously loose and confusing with a bit of what you are hearing being felt.
speakers arent tight and precise when the cones are moving extra.. however, they are getting better and better.
the extra movement from the cone causes bloated air pressure and speakers sound like they are trying to fill a balloon.
some speakers dont have it as bad.. but they are dull with the details.
they dont sound plain dull anymore.. they sound dull and bloated.
bloated sounds like you have a fan blowing air between you and the speaker.
putting a fan in the room so that the air blows sideways directly in the line of sight between you and the speaker is not always the easiest thing to do because the fan might make too much noise and ruin your ability to listen to the speaker for a difference.
i have had the pleasure of listening to speakers that dont have excess cone movement.
it sounded like i was listening to paper speakers.
they didnt have lots of dynamics.. but all the main sounds were there and vibrated my body without any extra nonsense.
you might be able to find some old woofers that do the same thing.. but they are part of the same group of speakers that lack the extra details.
they sound dull and lifeless.. but they sound like they are running on enough watts to zap you.
if you start to use digital room correction to flatten your frequency response.. the programs you use should be able to listen for the extra cone movement while recording the sine sweep.
it would come across as the sine wave and something extra.
the digital room correction might think that there is a room resonance problem there and adjust for the room resonance.
it should make for an interesting end-result.
however, the digital room correction software might see the extra cone movement as extra amplitude for that frequency.
and that would simply raise the frequency response measurement for that frequency and be adjusted.
those old paper woofers had a job to do.. and that was to produce black sound, which is sound that is so detailed and not colored that you started to forget that there was a speaker in the room as your brain's imagination led you to believe the person is actually talking with his/her mouth and not through a speaker.
they have added fans to the sound regardless of the clarity.
and they have also made the timing too early which makes the speaker sound 'bright'
cant complain too much when the extra details are there.. because its a huge improvement of the speakers from the 60's and 70's
an important detail is how that extra sound pressure is affecting the room.
old speakers, you would actually hear some echo.
new speakers, you hear 'air' when you turn the speakers up and look for the echo.
i think the extra cone movement plays hell on trying to determine frequency phase.
i'm thinking the old voice coils had smooth and gradual phase changes.
the new ones have phase differences that are all over the place.
meaning.. the old ones had maybe two per octave.
the new ones have eight or twelve differences per octave.
OR
maybe the old ones didnt really have any phase differences at all.. and all you had to do was correct 30 degrees gradually across the frequency response.
i wouldnt know these specifics because i havent messed around with the old speakers.
but looking at frequency response measurements, the phase flips 180 degrees dozens of times.
my dynamic microphone didnt have phase problems since it was calibrated at an audio lab.
the amplitude correction eliminates varying phase of the microphone.. because any that did exist are now compensated for.
but since my microphone fell off my lap and broke.. i will be trying a phantom powered condensor design.
and since dynamic microphones are not as instantaneous as condensor microphones (unless the mic has small voltage applied)
the difference will be the speed of electricity compared to the speed of magnetic inductance.
anyways.. i am now depressed after having gone through the problem of extra cone movement.
i used to think one speaker was better than the other simply because of the way the voice coil was wrapped.
but i have grown to learn that there are other things like design effort put into the magnet and the movement characteristics of the spider.
my two twelves have a soft spider.. and the surround is almost soft enough that you can blow on it and watch it indent.
i know that the soft surround really helps the edge of the cone rather than being stiff and dissipating the vibration.
i am really bummed that i cant find any pictures or videos of high sound pressure that causes visual distortion.
although i did find this:
http/www.zainea.com/visual.htm
it shows the LFO's i was talking about.. but they call it 'sound propagation and scattering'
looks like the speaker is installed flush on the floor and they are having a look at all of the reflections, and not the initial energy emitted from the speaker.
this website shows a drawing.. its nothing photogenic though:
http/artsites.ucsc.edu/EMS/music/tech_background/te-01/teces_01.html
i am off to hunt down some real photos of sound being visual.