Why are woofers shaped like bowls?

ded · 26th February 2006, 08:03 AM

Does anyone know why almost all the woofers mounted in speakers are bowl-shaped?

Logically flat membranes would be more phase-aligned to the tweeters?
And the air molecules would all be pushed at the exact same time from the same plane.
(I know it is really splitting hairs but with everyone getting crazy about time-aligning in their favourite software, does the dispersion 'spread' from the different depths of a woofer cone, 'undo' all their hard work?). Smear?

A speaker is a piston agitating the air, is it something to do with the magnet behind and the best design for driving the membrane?

ded
www.dedart.com
strange photos, strange music, strange words.

Cojo · 26th February 2006, 10:57 AM

Quote:

Originally Posted by ded

Does anyone know why almost all the woofers mounted in speakers are bowl-shaped?

Logically flat membranes would be more phase-aligned to the tweeters?
And the air molecules would all be pushed at the exact same time from the same plane.
(I know it is really splitting hairs but with everyone getting crazy about time-aligning in their favourite software, does the dispersion 'spread' from the different depths of a woofer cone, 'undo' all their hard work?). Smear?

A speaker is a piston agitating the air, is it something to do with the magnet behind and the best design for driving the membrane?

ded
www.dedart.com
strange photos, strange music, strange words.

because it's easyer to make a sturdy construction. Try to get a flat piece of paper sturdy!

Ps. their is actually flat membran speakers on the market.

/Cojo

nosebleedaudio · 26th February 2006, 12:59 PM

Quote:

Originally Posted by Cojo

because it's easyer to make a sturdy construction. Try to get a flat piece of paper sturdy!

Ps. their is actually flat membran speakers on the market.

/Cojo

The cone is a strong design. PMC's IB1 uses a flat woof and if you tap on it you will notice its very ridged..

r0ck1r0ck2 · 26th February 2006, 01:11 PM

good thread!

Cojo · 26th February 2006, 01:38 PM

Just for information...

I asumed that when you said bowl shaped you ment cone shaped, right? Well, when I think about it there is actually bowl shaped speakers. For exapmle the Blue Sky Monitor One, the have aluminium bowl shaped wofers!

/Cojo

max cooper · 26th February 2006, 02:56 PM

You have to give those loooong waves a head start!

ded · 26th February 2006, 03:57 PM

I did mean "cone".

So is it easier to have rigidity with little mass by using a "cone"?
You could have a flat plane, but it would have to be thicker and therefore, heavier, right?

Then you have the problem of inertia, and the membrane overshooting in both directions, and you lose the ability to duplicate the original dynamics of the recorded signal.

Are there any "lay-man's" guide to why the majority of speakers are the way they are? Hopefully free of the "marketing" tech-talk that doesn't really explain what issues have and haven't been resolved.

For instance, another engineer told me that the 20-80HZ waveforms are impossible for the majority of small (under 12 inch) woofers to propagate.
True or False?
If true, do I imagine the bass frequencies I am hearing??

ded
www.dedart.com
strange images, strange music, strange words.

Cojo · 26th February 2006, 04:26 PM

Quote:

Originally Posted by ded

I did mean "cone".

So is it easier to have rigidity with little mass by using a "cone"?
You could have a flat plane, but it would have to be thicker and therefore, heavier, right?

Then you have the problem of inertia, and the membrane overshooting in both directions, and you lose the ability to duplicate the original dynamics of the recorded signal.

Are there any "lay-man's" guide to why the majority of speakers are the way they are? Hopefully free of the "marketing" tech-talk that doesn't really explain what issues have and haven't been resolved.

For instance, another engineer told me that the 20-80HZ waveforms are impossible for the majority of small (under 12 inch) woofers to propagate.
True or False?
If true, do I imagine the bass frequencies I am hearing??

ded
www.dedart.com
strange images, strange music, strange words.

Wow, this is real heavy questions man...

...and I have no idea! Only someone with more knowledge in this area can tell the aswer?

/Cojo

nosebleedaudio · 26th February 2006, 04:35 PM

For instance, another engineer told me that the 20-80HZ waveforms are impossible for the majority of small (under 12 inch) woofers to propagate.
True or False?
If true, do I imagine the bass frequencies I am hearing??

ded
www.dedart.com
strange images, strange music, strange words.[/quote]
I would disagree, the PMC I was referring to (IB1) has a 10", and blows most 15" woofs doors off. Clean and well defined bass..

covert · 26th February 2006, 04:53 PM

Quote:

Originally Posted by ded

For instance, another engineer told me that the 20-80HZ waveforms are impossible for the majority of small (under 12 inch) woofers to propagate.
True or False?
If true, do I imagine the bass frequencies I am hearing??

It's not true. Diameter of the cone is not a limiting factor, assuming that othe factors are equal.

On the other hand, one of the basic principles in psychacoustics is that the brain will fill in low end. If you hear say the second harmonic and up, your brain will supply the fundamental, to some degree.

26th February 2006, 04:58 PM

Some of those flat piston drivers are also passive radiators, such as those in the older Polk Audio and Mackie 824s. Sony had some ES series flat pistons that sounded pretty good, but they were pricey. They used a honeycomb sandwich. I have seen some cheese car audio speakers in triangle shapes as well, coned and flat. Freaky.

It isn't just the shape. It is the material as well.

There are flat speakers made of carboard, wood, plastic used for computers and guitar amplifiers.

ded · 26th February 2006, 05:32 PM

If the diameter does not play a role, why don't we have only tweeters?

At concerts where I do really "feel" the low fundamental frequencies there are large diameter woofers in arrays working together.

A low E is 41.20 Hz and a 27 foot long wave ( 8,359 metres) can a 10 inch cone vibrate that slowly and successfully reproduce it. Or are we only hearing the 2nd harmonic an octave higher?

I guess my question is why do larger diameters "seem" to be better at reproducing the very low end, if size doesn't matter.

The person who said the under 12" woofer is incapable of driving the very low end, has had a studio for years and.... has built his own speakers. I am still not convinced by the manufacturer's claims of small speakers reaching down to below 90hz.

But why can't they? ( if they can't).

ded
www.dedart.com
strange images, strange music, strange words.

Sounds Great · 26th February 2006, 06:26 PM

Quote:

Originally Posted by ded

The person who said the under 12" woofer is incapable of driving the very low end, has had a studio for years and.... has built his own speakers. I am still not convinced by the manufacturer's claims of small speakers reaching down to below 90hz.

And claims of headphones accurate down to 20 hz?

nathanvacha · 26th February 2006, 07:20 PM

Quote:

Originally Posted by ded

For instance, another engineer told me that the 20-80HZ waveforms are impossible for the majority of small (under 12 inch) woofers to propagate.
True or False?
If true, do I imagine the bass frequencies I am hearing??

OOh, i get to be scholarly and pitch in on this one. Yes, you do. Your brain actually replaces the low frequencies if the higher fundamental tones are present. As i understand, this works on the same principle as a subharmonic synthesizer. It all falls under "psycho-acoustics" -- how your brain interprets what your ears pick up. Also, as i understand, maxxbass works on this principle as well. If you find that there's not enough bass in your mix but if you crank the bass it gets boomy, you can e.q. out part of the low end leaving the harmonics of something like a bass guitar, and your brain will put it back into what your hearing and come out as huge, awesome bass that's not boomy. Screw around with it, it sounds amazing.

structuredloud · 26th February 2006, 08:15 PM

Quote:

Originally Posted by covert

It's not true. Diameter of the cone is not a limiting factor, assuming that othe factors are equal.

On the other hand, one of the basic principles in psychacoustics is that the brain will fill in low end. If you hear say the second harmonic and up, your brain will supply the fundamental, to some degree.

Quite right, and a sine wave (no additional partials above the fundamental) can be heard sounding at 40hz through a pair of iPod buds.

Drumsound · 26th February 2006, 08:36 PM

The cabinet design also figures in to the frequency response of a speaker.

ded · 26th February 2006, 08:48 PM

"If you find that there's not enough bass in your mix but if you crank the bass it gets boomy, you can e.q. out part of the low end leaving the harmonics of something like a bass guitar, and your brain will put it back into what your hearing and come out as huge, awesome bass that's not boomy. Screw around with it, it sounds amazing."

EQ out the deep, deep end and it re-appear thanks to your mind??
It would have to happen for everyone, to be useable.
You couldn't do this and then have someone come in and say "where's all the bottom end".

Are you sure?

And 40 Hz on ipod buds?? I am one of the few who doesn't have one.
Could someone generate a 40 Hz signal, bounce it to disk, MP3 it (Hmmmmmm, I am a bit wary already) and tell me they hear (feel) something.
A tickle. Is the ability to vibrate at low frequencies size dependent? (Sounds vaguely sexual?)

So why do we use all those huge monitors to "accurately listen to the bottom end of our recordings??

This is more confusing than I thought it would be.
And the recessed cones are a phase-dispersion problem for me to work out.
I'll leave that to later.

ded
www.dedart.com
strange images, strange music, strange words.

Sounds Great · 26th February 2006, 09:02 PM

Quote:

Originally Posted by ded

"If you find that there's not enough bass in your mix but if you crank the bass it gets boomy, you can e.q. out part of the low end leaving the harmonics of something like a bass guitar, and your brain will put it back into what your hearing and come out as huge, awesome bass that's not boomy. Screw around with it, it sounds amazing."

EQ out the deep, deep end and it re-appear thanks to your mind??
It would have to happen for everyone, to be useable.
You couldn't do this and then have someone come in and say "where's all the bottom end".

Are you sure?

And 40 Hz on ipod buds?? I am one of the few who doesn't have one.
Could someone generate a 40 Hz signal, bounce it to disk, MP3 it (Hmmmmmm, I am a bit wary already) and tell me they hear (feel) something.
A tickle. Is the ability to vibrate at low frequencies size dependent? (Sounds vaguely sexual?)

So why do we use all those huge monitors to "accurately listen to the bottom end of our recordings??

This is more confusing than I thought it would be.
And the recessed cones are a phase-dispersion problem for me to work out.
I'll leave that to later.

ded
www.dedart.com
strange images, strange music, strange words.

You don't "hear" 40 Hz. You could only feel it. You don't hear all that much below 100Hz.

warhead · 26th February 2006, 09:16 PM

My HR824's can move down to 25hz, you can "watch" it but you sure don't hear it.

War

Han · 26th February 2006, 11:23 PM

structuredloud · 27th February 2006, 01:57 AM

I was just guessing when I said 40hz on iPod earbuds. I just did a test, and I can catually hear down to 30hz very clearly in a noisy cafe on them. And no I'm not hearing the second partial.

<img src="http://www.structuredloud.com/gearslutz/30hz.jpg">

jerry123 · 27th February 2006, 02:56 AM

I believe that sound is audible down to 1Hz.
One cycle per second would be a tap.
Tap turns to a buzz at around 10-15Hz and then to a tone just over 20Hz.
Tap, buzz, tone and noise being the components of sound.
This is just my understanding of audible low freq.

Sounds Great · 27th February 2006, 04:53 AM

Quote:

Originally Posted by structuredloud

I was just guessing when I said 40hz on iPod earbuds. I just did a test, and I can catually hear down to 30hz very clearly in a noisy cafe on them. And no I'm not hearing the second partial.

<img src="http://www.structuredloud.com/gearslutz/30hz.jpg">

What sort of a test did you do to conclude that?

Sounds Great · 27th February 2006, 04:58 AM

Quote:

Originally Posted by jerry123

I believe that sound is audible down to 1Hz.
One cycle per second would be a tap.
Tap turns to a buzz at around 10-15Hz and then to a tone just over 20Hz.
Tap, buzz, tone and noise being the components of sound.
This is just my understanding of audible low freq.

I don't think that is correct. Even a 60 cycle hum, you are actually hearing harmonics, not the fundamental.

A tap would require a complex waveform to create, an attack, a decay, etc. Nothing to do with frequency. Same with a buzz, a sine wave with some extra action, or perhaps a saw wave. Still not frequency dependent.

jerry123 · 27th February 2006, 05:16 AM

Good answer. I didn't think about that whole sine wave thing.

Sounds Great · 27th February 2006, 05:39 AM

Quote:

Originally Posted by jerry123

Good answer. I didn't think about that whole sine wave thing.

This is a subject that I find very interesting. I like to use headphones sometimes, but the frequency response ratings are absurd. You don't hear or feel 20 HZ out of a headphone.

I have for many years wanted to build a (contact) subwoofer that you could wear on your body while listening to phones. With a bit of tweaking this could be an awesome experience with the phones being able to concentrate on a full range of audio while the sub frequencies would be transmitted directly to your body via the "sub vest". One of these days when I have some money, I am going to get some patents and build this thing.

ded · 27th February 2006, 05:59 AM

"Tweeters can't move that much air. The size of a woofer is directly related to how much are you need to move, not freq response. Loud bass requires a lot of air to be moved, and is something you can feel if you stand in front of a loud sub, or sit in a loud car. Your hair blows around, nose hairs tingle, this is from air moving. Tweeters can't move that much air.

Cone shapes are also highly attribuatable (sp?) to the movement of air. It's easier to move lots of air with a cone shape, than with a flat shape."

Now we are getting somewhere!!

This is what I need, simple logical answers.

Hans posted a picture of a woofer with a flat face, where is that from?

Because, to be logical and "split hairs" again, doesn't a "deep" cone scoop up air and push it around, out of time alignement with the tweeter?

I have seen designs with the tweeter recessed to compensate for this.
Does it work?
Is it really necessary?

Next question?
How do sound waves from a cone disperse?
Does the the air from the back center get a more directional push than the leading edge near the "rubber" ring that is attached to the support.
Isn't there some sort of turblence like a smoker doing smoke rings as the moving air hits the static air?
I am trying to imagine what it would look like.
Then there are the edges of the cabinet.
Do we hear these "defraction" patterns?
What does it sound like?
Sound that curls????

Any sources for articles on this? Once again not manufacturer's "hype". Real experiments by people in lab coats without sponsors breathing down their necks for the "right" results.

I will be buying the book that was mentioned.

Master Handbook of Acoustics (Paperback)
by F. Alton Everest

Thanks for the info.

ded
www.dedart.com
strange images, strange music, strange words.

ncjames · 27th February 2006, 05:43 PM

OK, I've always read a typical hear HEARS down to 20hz, of course everyone's a little different, but somebody said you feel but don't hear below 100hz, I have to question that. In high volume situations it's the low frequencies you feel, but that doesn't mean you don't also hear them. Of course the ipod earbud test sortof prooves that too, since he certainly wasn't "feeling" sound from his earbuds.

I've read that psycoacoustically we hear increases in higher frequencies more acutely than increases in bass. Just a little factoid.

As far as not needing monitors that go low, you'd better have a keen ear for identifying those harmonics, because if there's an strong subbass signal you're not hearing (and you can't "look") you can produce some results that will really suprise you when they get in a bassy playback situation like a car with subs.

seriousfun · 27th February 2006, 10:00 PM

rufus13 and djui5 have it right. Read the Everest book. Nika Aldrich's book on digital audio has a great explaination of acoustics that starts the book.

Sound starts as compressions and rarefactions of the air - our atmosphere pushed from zero to infinite times per second. We can perceive approximately 20 times a second to 20 thousand times a second, and we call this sound. Atmospheric events can happen slower than 20 times a second (barometric pressure changes, for example) but we don't hear these.

So, even earbuds in an ear canal can move air 20 times a second, as well as 20 thousand times a second, so iPod earbuds can possibly play 20 Hz. Since the air is being pushed fewer times a second, it takes a lot more power per push to make these low sounds as loud to our ears as the higher sounds, hence the need for bigger pistons and engines (cones and coils in a speaker) to do bass.

Time alignment is simply getting the edge of the voice coils aligned, so the front of each wavform starts at the same time. All sounds, whether 20 Hz or 20k Hz, travel at the same speed - the speed of sound. There is diffraction distortion - smear - from speaker cones (and cabinet baffles), but it's generally audible at higher frequencies.

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26th February 2006, 08:03 AM	#1
ded Gear interested Join Date: Sep 2005 Posts: 28	Why are woofers shaped like bowls? Does anyone know why almost all the woofers mounted in speakers are bowl-shaped? Logically flat membranes would be more phase-aligned to the tweeters? And the air molecules would all be pushed at the exact same time from the same plane. (I know it is really splitting hairs but with everyone getting crazy about time-aligning in their favourite software, does the dispersion 'spread' from the different depths of a woofer cone, 'undo' all their hard work?). Smear? A speaker is a piston agitating the air, is it something to do with the magnet behind and the best design for driving the membrane? ded www.dedart.com strange photos, strange music, strange words.

26th February 2006, 08:36 PM	#16
Drumsound Lives for gear Join Date: Jun 2002 Location: Bloomington Il Posts: 3,644	The cabinet design also figures in to the frequency response of a speaker. __________________ Tony Oxide Lounge Recording See the Oxide Lounge! WWJMD? Come see me on the Tape Op boards! "If I have to flip flop more than three times in an A/B test to figure out what the difference is, I lose interest in that difference.'--Tchad Blake

26th February 2006, 09:16 PM	#19
warhead Jai guru deva om Join Date: Feb 2003 Location: South Carolina Posts: 8,474	My HR824's can move down to 25hz, you can "watch" it but you sure don't hear it. War __________________ Warren Dent (has moved on in business...) The gear website I'm building now, launches soon: www.ZenProAudio.com

27th February 2006, 05:43 PM	#28
ncjames Gear nut Join Date: Feb 2006 Location: Nevada City, CA Posts: 78	my two cents OK, I've always read a typical hear HEARS down to 20hz, of course everyone's a little different, but somebody said you feel but don't hear below 100hz, I have to question that. In high volume situations it's the low frequencies you feel, but that doesn't mean you don't also hear them. Of course the ipod earbud test sortof prooves that too, since he certainly wasn't "feeling" sound from his earbuds. I've read that psycoacoustically we hear increases in higher frequencies more acutely than increases in bass. Just a little factoid. As far as not needing monitors that go low, you'd better have a keen ear for identifying those harmonics, because if there's an strong subbass signal you're not hearing (and you can't "look") you can produce some results that will really suprise you when they get in a bassy playback situation like a car with subs. __________________ "...and knowing is half the battle." - GI Joe

26th February 2006, 01:11 PM	#4
r0ck1r0ck2 Lives for gear Join Date: Jul 2005 Location: Barcelona!! Posts: 1,456	good thread!

26th February 2006, 01:38 PM	#5
Cojo Lives for gear Join Date: Dec 2005 Location: Gothenburg, Sweden! Posts: 1,466	Just for information... I asumed that when you said bowl shaped you ment cone shaped, right? Well, when I think about it there is actually bowl shaped speakers. For exapmle the Blue Sky Monitor One, the have aluminium bowl shaped wofers! /Cojo

26th February 2006, 02:56 PM	#6
max cooper Lives for gear Join Date: Aug 2004 Location: tx Posts: 8,819	You have to give those loooong waves a head start!

26th February 2006, 03:57 PM	#7
ded Gear interested Join Date: Sep 2005 Posts: 28	I did mean "cone". So is it easier to have rigidity with little mass by using a "cone"? You could have a flat plane, but it would have to be thicker and therefore, heavier, right? Then you have the problem of inertia, and the membrane overshooting in both directions, and you lose the ability to duplicate the original dynamics of the recorded signal. Are there any "lay-man's" guide to why the majority of speakers are the way they are? Hopefully free of the "marketing" tech-talk that doesn't really explain what issues have and haven't been resolved. For instance, another engineer told me that the 20-80HZ waveforms are impossible for the majority of small (under 12 inch) woofers to propagate. True or False? If true, do I imagine the bass frequencies I am hearing?? ded www.dedart.com strange images, strange music, strange words.

26th February 2006, 04:35 PM	#9
nosebleedaudio Lives for gear Join Date: Jun 2005 Location: Birmingham, AL Posts: 1,621	For instance, another engineer told me that the 20-80HZ waveforms are impossible for the majority of small (under 12 inch) woofers to propagate. True or False? If true, do I imagine the bass frequencies I am hearing?? ded www.dedart.com strange images, strange music, strange words.[/quote] I would disagree, the PMC I was referring to (IB1) has a 10", and blows most 15" woofs doors off. Clean and well defined bass..

26th February 2006, 04:58 PM	#11
Lowdbrent Guest Posts: n/a	Some of those flat piston drivers are also passive radiators, such as those in the older Polk Audio and Mackie 824s. Sony had some ES series flat pistons that sounded pretty good, but they were pricey. They used a honeycomb sandwich. I have seen some cheese car audio speakers in triangle shapes as well, coned and flat. Freaky. It isn't just the shape. It is the material as well. There are flat speakers made of carboard, wood, plastic used for computers and guitar amplifiers.

26th February 2006, 05:32 PM	#12
ded Gear interested Join Date: Sep 2005 Posts: 28	If the diameter does not play a role, why don't we have only tweeters? At concerts where I do really "feel" the low fundamental frequencies there are large diameter woofers in arrays working together. A low E is 41.20 Hz and a 27 foot long wave ( 8,359 metres) can a 10 inch cone vibrate that slowly and successfully reproduce it. Or are we only hearing the 2nd harmonic an octave higher? I guess my question is why do larger diameters "seem" to be better at reproducing the very low end, if size doesn't matter. The person who said the under 12" woofer is incapable of driving the very low end, has had a studio for years and.... has built his own speakers. I am still not convinced by the manufacturer's claims of small speakers reaching down to below 90hz. But why can't they? ( if they can't). ded www.dedart.com strange images, strange music, strange words.

26th February 2006, 08:48 PM	#17
ded Gear interested Join Date: Sep 2005 Posts: 28	"If you find that there's not enough bass in your mix but if you crank the bass it gets boomy, you can e.q. out part of the low end leaving the harmonics of something like a bass guitar, and your brain will put it back into what your hearing and come out as huge, awesome bass that's not boomy. Screw around with it, it sounds amazing." EQ out the deep, deep end and it re-appear thanks to your mind?? It would have to happen for everyone, to be useable. You couldn't do this and then have someone come in and say "where's all the bottom end". Are you sure? And 40 Hz on ipod buds?? I am one of the few who doesn't have one. Could someone generate a 40 Hz signal, bounce it to disk, MP3 it (Hmmmmmm, I am a bit wary already) and tell me they hear (feel) something. A tickle. Is the ability to vibrate at low frequencies size dependent? (Sounds vaguely sexual?) So why do we use all those huge monitors to "accurately listen to the bottom end of our recordings?? This is more confusing than I thought it would be. And the recessed cones are a phase-dispersion problem for me to work out. I'll leave that to later. ded www.dedart.com strange images, strange music, strange words.

26th February 2006, 11:23 PM	#20
Han Lives for gear Join Date: Jul 2002 Location: Netherlands Posts: 857

27th February 2006, 01:57 AM	#21
structuredloud Lives for gear Join Date: Feb 2006 Location: Oakland, CA Posts: 573	I was just guessing when I said 40hz on iPod earbuds. I just did a test, and I can catually hear down to 30hz very clearly in a noisy cafe on them. And no I'm not hearing the second partial. <img src="http://www.structuredloud.com/gearslutz/30hz.jpg">

27th February 2006, 02:56 AM	#22
jerry123 Gear nut Join Date: Nov 2005 Posts: 85	I believe that sound is audible down to 1Hz. One cycle per second would be a tap. Tap turns to a buzz at around 10-15Hz and then to a tone just over 20Hz. Tap, buzz, tone and noise being the components of sound. This is just my understanding of audible low freq.

27th February 2006, 05:16 AM	#25
jerry123 Gear nut Join Date: Nov 2005 Posts: 85	Good answer. I didn't think about that whole sine wave thing.

27th February 2006, 05:59 AM	#27
ded Gear interested Join Date: Sep 2005 Posts: 28	"Tweeters can't move that much air. The size of a woofer is directly related to how much are you need to move, not freq response. Loud bass requires a lot of air to be moved, and is something you can feel if you stand in front of a loud sub, or sit in a loud car. Your hair blows around, nose hairs tingle, this is from air moving. Tweeters can't move that much air. Cone shapes are also highly attribuatable (sp?) to the movement of air. It's easier to move lots of air with a cone shape, than with a flat shape." Now we are getting somewhere!! This is what I need, simple logical answers. Hans posted a picture of a woofer with a flat face, where is that from? Because, to be logical and "split hairs" again, doesn't a "deep" cone scoop up air and push it around, out of time alignement with the tweeter? I have seen designs with the tweeter recessed to compensate for this. Does it work? Is it really necessary? Next question? How do sound waves from a cone disperse? Does the the air from the back center get a more directional push than the leading edge near the "rubber" ring that is attached to the support. Isn't there some sort of turblence like a smoker doing smoke rings as the moving air hits the static air? I am trying to imagine what it would look like. Then there are the edges of the cabinet. Do we hear these "defraction" patterns? What does it sound like? Sound that curls???? Any sources for articles on this? Once again not manufacturer's "hype". Real experiments by people in lab coats without sponsors breathing down their necks for the "right" results. I will be buying the book that was mentioned. Master Handbook of Acoustics (Paperback) by F. Alton Everest Thanks for the info. ded www.dedart.com strange images, strange music, strange words.

27th February 2006, 10:00 PM	#29
seriousfun Gear addict Join Date: Sep 2002 Location: SoCal Posts: 439	rufus13 and djui5 have it right. Read the Everest book. Nika Aldrich's book on digital audio has a great explaination of acoustics that starts the book. Sound starts as compressions and rarefactions of the air - our atmosphere pushed from zero to infinite times per second. We can perceive approximately 20 times a second to 20 thousand times a second, and we call this sound. Atmospheric events can happen slower than 20 times a second (barometric pressure changes, for example) but we don't hear these. So, even earbuds in an ear canal can move air 20 times a second, as well as 20 thousand times a second, so iPod earbuds can possibly play 20 Hz. Since the air is being pushed fewer times a second, it takes a lot more power per push to make these low sounds as loud to our ears as the higher sounds, hence the need for bigger pistons and engines (cones and coils in a speaker) to do bass. Time alignment is simply getting the edge of the voice coils aligned, so the front of each wavform starts at the same time. All sounds, whether 20 Hz or 20k Hz, travel at the same speed - the speed of sound. There is diffraction distortion - smear - from speaker cones (and cabinet baffles), but it's generally audible at higher frequencies. __________________ doug osborne \| my day job \| Flying Faders II - Just Mix...Just Got Better!