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Noob question about BAs vs Dynamics

post #1 of 19
Thread Starter 
Why do BAs typically have less bass than dynamics? I read part of the reason is because of the airspace and that Dynamics have more. If this is true why don't they make the BA bigger to get more airspace. Also if you have a multi-driver BA, why don't they use one dynamic for the bass and the rest for the mids and highs? There's probably a few BAs already like this, so why not make them all like like? Thanks!
post #2 of 19

Because not everyone wants overemphasized bass (?)

post #3 of 19
Thread Starter 
Quote:
Originally Posted by Syld View Post

Because not everyone wants overemphasized bass (?)

I picked up the Sony XBA-1 BA and have been giving myself some brain burn in with these. I've been listening to them for the past 4 days. A couple of the groups I have on lossless, I've seen in concert and when I listen to them through the XBA-1, it's like the whole bottom end of the spectrum fell out.
post #4 of 19
Quote:
Originally Posted by JonnyRocket View Post

Why do BAs typically have less bass than dynamics? I read part of the reason is because of the airspace and that Dynamics have more. If this is true why don't they make the BA bigger to get more airspace. Also if you have a multi-driver BA, why don't they use one dynamic for the bass and the rest for the mids and highs? There's probably a few BAs already like this, so why not make them all like like? Thanks!

 

Someone may correct me or have better answer but a BA driver tries to recreate the bass that's recorded whereas a dynamic driver actually creates bass due to the movement of the diaphram, and yes with this it makes the air move which adds to a more visceral feeling to the bass. Also there are some pretty bassy BA earphones especially multi driver customs but it is just a different type of bass.

post #5 of 19

I prefer multi-driver BA bass over a dynamic driver but that's just me.  Tighter and more articulate, never any distortion.

post #6 of 19

Because of how they are tuned.  There are BAs that have plenty of bass (majority of them are multi-BA though; that doesn't mean that it isn't possible to make a bass-heavy single-BA).  It all has to do with how they are tuned.  Dynamics can be tuend to sound like BAs, BAs can be tuned to sound like dynamics.  

 

As for the moving air remark, this has already been proven false.  We measure the air moved by the amount of pressure that is applied to the system.  Pascals are the standard way to measure pressure, however, in audio, we use a logarithmic scale for Pascals called Decibels.  BA IEMs can produce the same decibals in the bass region as many dynamics if tuned to do so.  So it has nothing to do with moving air as they both have the ability to move the same air.  They may not be tuned to do it though.


Edited by tinyman392 - 12/19/12 at 11:11am
post #7 of 19

Well said.

post #8 of 19

Obviously, the only way to make sound is to move air, no matter how much or little, and both BA and dynamic drivers move air. Tinyman is correct about the tuning aspect (shaping of the housing, size of internal airspace, many other things), but fundamentally, a dynamic driver moves air differently than BA driver, mostly due to the design: it moves a pushes a diaphragm.  Many BA driver units move a smaller amount of air, which means there is often less bass impact, but there can be plenty or even more bass extension (down to 15 Hz, 10 Hz, etc).

 

Think about a home stereo speaker with it's round dynamic driver, then watch this video from a Westone technician about how BA drivers work.  

post #9 of 19
Quote:
Originally Posted by kmhaynes View Post

Obviously, the only way to make sound is to move air, no matter how much or little, and both BA and dynamic drivers move air. Tinyman is correct about the tuning aspect (shaping of the housing, size of internal airspace, many other things), but fundamentally, a dynamic driver moves air differently than BA driver, mostly due to the design: it moves a pushes a diaphragm.  Many BA driver units move a smaller amount of air, which means there is often less bass impact, but there can be plenty or even more bass extension (down to 15 Hz, 10 Hz, etc).

 

Think about a home stereo speaker with it's round dynamic driver, then watch this video from a Westone technician about how BA drivers work.  

 

I need a source for this...  All my sources show BAs moving as much air as dynamics.  Remember, air moved = dB produced from the driver.  It's definition, no questioning that one.  Now, think of it this way, pressure = force / area.  Dynamic drivers tend to have a larger area, so they need more force.  BA's tend to have less area, but don't need to exhert as much force.  So they actually cancel each other out quite nicely.  

 

Let's take a deeper look this way and compare the Yamaha EPH-100 and the Heir Audio 3.Ai in terms of their ability to move air.  The 3.Ai tops out at around 102 dB @ 70 Hz while the EPH-100 tops out at 105 dB at 40 Hz.  The amount of air being moved here is actually very close and very similar.  

 

Why is this happening?  Well, let's put it this way, the dynamic drive is larger, so it puts out a larger force, but has more area to fill.  So we get a larger force, but a large area to pressurize.  However, the BA has a very small area to deal with, but can't create a very large force.  In general, a larger force, but bigger area will have the same output as a small force with small area.  There are many ways to think about this, but the pressure really equalizes itself out either way.  So to simplify, let a = small area, A = large area, f = small force, and F = large force (case sensitive), we get:

 

F/A = f/a

 

Since their ratios essentially cancel out.  

 

Let F = 3, A = 6

F/A = P

3 / 6 = 0.5

P = 0.5

 

Let f = .75 < F = 3, a = 1.5 < A = 6

F/A = P

.75 / 1.5 = 0.5

P = 0.5

 

Obviously these numbers are staged, but I'm just trying to make the point that the ratios really cancel each other out at the end of the day.  Now, obviously, we can play with this model to make the dynamic win out, we can also do the opposite to make the BA win out.  They thing is, playing with this model would be the equivalent of tuning a driver.  Driver size decisions, power, force outputs, etc, are all tuned into the driver.  It relies 100% on the tuning.  However, saying that because BAs push less area and therefore don't move as much air (pressure) is not strong statement.


Edited by tinyman392 - 12/19/12 at 2:12pm
post #10 of 19
Thread Starter 
In terms of car stereos is I like this?

Let's say I have an 18" sub and a 10" sub, each with a 300 watt amp. The amp is going to push the 10" louder (pressure?) because it has less force to move. For the sake of arguement, lets say it takes 600 watts to push the 18" sub. So if the 10" is a BA are you saying you could take two of these, hook up a 300 watt amp to each one and tune one to the high bass frequencies and take the other 10" with another 300 watt amp and tune it to the low bass frequencies in effect equalling the bass output of the 18" speaker (dynamic speaker) with a 600 watt amp.
post #11 of 19
Quote:
Originally Posted by JonnyRocket View Post

In terms of car stereos is I like this?
Let's say I have an 18" sub and a 10" sub, each with a 300 watt amp. The amp is going to push the 10" louder (pressure?) because it has less force to move. For the sake of arguement, lets say it takes 600 watts to push the 18" sub. So if the 10" is a BA are you saying you could take two of these, hook up a 300 watt amp to each one and tune one to the high bass frequencies and take the other 10" with another 300 watt amp and tune it to the low bass frequencies in effect equalling the bass output of the 18" speaker (dynamic speaker) with a 600 watt amp.

 

There's going to be more to it, but yes, similar effect.  Smaller speakers being easier to push, but need more power to push more force as they are limited by area.  Large speakers need more power to create more force as Newton's law of inertia states that it's harder for it to accelerate (and it weighs more as well), so it'll take more power to create a larger force.  

post #12 of 19
Thread Starter 
Quote:
Originally Posted by tinyman392 View Post

There's going to be more to it, but yes, similar effect.  Smaller speakers being easier to push, but need more power to push more force as they are limited by area.  Large speakers need more power to create more force as Newton's law of inertia states that it's harder for it to accelerate (and it weighs more as well), so it'll take more power to create a larger force.  

So the farther out the smaller speaker flexes the more force in needed to make it flex, limiting DB The bigger speaker needs more force because it is moving a bigger mass, limiting its DB, so in effect both of these negative forces cancel each other out?
post #13 of 19
Quote:
Originally Posted by JonnyRocket View Post


So the farther out the smaller speaker flexes the more force in needed to make it flex, limiting DB The bigger speaker needs more force because it is moving a bigger mass, limiting its DB, so in effect both of these negative forces cancel each other out?

 

Doesn't have to do with distance...  Your assertion is still right though.  Instead, if you are talking to create the dB through force, then it deals with mass and acceleration (Newton's second law; F=MA).  So the Force will be the equivalent of the objects mass times its acceleration.  Your second assumption regarding the bigger mass is true though.  Bigger mass is harder to accelerate, smaller mass is easier to accelerate.  How do we adjust this ratio again?  Tuning.  

 

__________

Mathematical break down:

Let F be the force, M be a large mass, m be a small mass, A be a large acceleration, a be a small acceleration

 

For the large driver:

F=Ma

 

For the small driver:

F=mA

 

The large mass cancels out the small acceleration while the small mass cancels out the large acceleration.  The forces are going to actually be very close to each other in general.  Again, you can play with this model more to make it one directional, but tuning will basically do the same stuff :p

post #14 of 19

Interesting, I was in the mobile audio business for almost 20 years - and all things being equal - the same high current amplifier is going to get more volume out of the 18" woofer than the 10" - if the impedance is the same and the sensitivity/efficiency of the speakers are equal - the 18's will be louder - they move more air. Now will they be as accurate? Hell. No. I used to build sealed boxes with 8" and 10" woofers and they didn't make as much noise as a ported 12" - but they hit hard - they were faster and more musical - and they took more power to drive. 

 

So now I'm really confused.

post #15 of 19
Thread Starter 
Quote:
Originally Posted by tinyman392 View Post

Doesn't have to do with distance...  Your assertion is still right though.  Instead, if you are talking to create the dB through force, then it deals with mass and acceleration (Newton's second law; F=MA).  So the Force will be the equivalent of the objects mass times its acceleration.  Your second assumption regarding the bigger mass is true though.  Bigger mass is harder to accelerate, smaller mass is easier to accelerate.  How do we adjust this ratio again?  Tuning.  

__________
Mathematical break down:
Let F be the force, M be a large mass, m be a small mass, A be a large acceleration, a be a small acceleration
For the large driver:
F=Ma

For the small driver:
F=mA

The large mass cancels out the small acceleration while the small mass cancels out the large acceleration.  The forces are going to actually be very close to each other in general.  Again, you can play with this model more to make it one directional, but tuning will basically do the same stuff tongue.gif

So in this instance the force is the electrical current being supplied and mA = Amature and Ma = Dynamic?
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