[jcx]

I am describing how the principle/definition is used by designers, manufactures of motors when communicating with other engineers - it is assumed the constant total conductor cross section, swapping wire size for turns/length with ideal transformer relations can be applied to get "the same" motor that works at differing I,V ratio that the user may want
 
this just is the industry standard engineering assumption - and if you want to talk with motor designers you need to learn it, not start arguing that you have a personal interpretation of "thinner wire" that means less mass, lower efficiency
 
wire size, resulting headphone Z is a "free variable" because you can design the voice coil motor with voice coil conductor material, cross section area and mass - and set all electro-acoustic parameters to the design goals
 
then you can select wire size, number of turns that fits the geometry for any electrical Z within a range, limited by packing factor/coil dimensions/layers/fraction of area wasted in minimum practical insulation thickness
 
this can be seen in practice with dual voice coil loudspeaker drivers, and that some loudspeaker drivers are offered with the same model #, same response with different Z; commonly 4, 8, sometimes 16 Ohms 
 
 
if you want to talk differences in motor designs that give different efficiency, damping, bass resonance frequency, other electro-acoustic properties then it is worth learning what motor design engineers use as design factors
 
for dynamic drivers with voice coil motors Thiele-Small parameters are widely accepted, used - even by thousands of amateur/hobbyist speaker builders
 
 
googling BL product gets the Wikipedia Thiele-Small article as 1st hit - I do try to provide enough info that interested people can get to the background material
 
 
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magfor.html is the fundamental
 
then you move to the practical implementation - say you can fit one length L of some wire into a voice coil in the magnet gap - then calculate the force/A
or you could use 1/2 diameter wire, which fits 4x L into the same voice coil cross section - now you have 4x force/A - but your wire can only carry 1/4 of the current at the same loss from resistance
so the net result looks just like you included an ideal electrical step-up transformer in series with the 1st 1 L design's electrical terminals

 

[Chromako]

Thanks for taking the time to help us out, JCX. I know it takes lots of time to write it up. 
 
Hmm... I can indeed tell why my specifying "thinner wire" ended up seeming wonky, given the assumptions the engineers put along with it... So I think I should have said something like "thinner cross section wire while keeping the same number of turns" or something like that...  
 
Reading your link right now... Quite educational indeed...
 
 

 

[Chris J]

I am describing how the principle/definition is used by designers, manufactures of motors when communicating with other engineers - it is assumed the constant total conductor cross section, swapping wire size for turns/length with ideal transformer relations can be applied to get "the same" motor that works at differing I,V ratio that the user may want

this just is the industry standard engineering assumption - and if you want to talk with motor designers you need to learn it, not start arguing that you have a personal interpretation of "thinner wire" that means less mass, lower efficiency

wire size, resulting headphone Z is a "free variable" because you can design the voice coil motor with voice coil conductor material, cross section area and mass - and set all electro-acoustic parameters to the design goals

then you can select wire size, number of turns that fits the geometry for any electrical Z within a range, limited by packing factor/coil dimensions/layers/fraction of area wasted in minimum practical insulation thickness

this can be seen in practice with dual voice coil loudspeaker drivers, and that some loudspeaker drivers are offered with the same model #, same response with different Z; commonly 4, 8, sometimes 16 Ohms 


if you want to talk differences in motor designs that give different efficiency, damping, bass resonance frequency, other electro-acoustic properties then it is worth learning what motor design engineers use as design factors

for dynamic drivers with voice coil motors Thiele-Small parameters are widely accepted, used - even by thousands of amateur/hobbyist speaker builders


googling BL product gets the Wikipedia Thiele-Small article as 1st hit - I do try to provide enough info that interested people can get to the background material


http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magfor.html is the fundamental

then you move to the practical implementation - say you can fit one length L of some wire into a voice coil in the magnet gap - then calculate the force/A
or you could use 1/2 diameter wire, which fits 4x L into the same voice coil cross section - now you have 4x force/A - but your wire can only carry 1/4 of the current at the same loss from resistance
so the net result looks just like you included an ideal electrical step-up transformer in series with the 1st 1 L design's electrical terminals

Nice!
I learned something!

One very minor little nit pick:
96 dB @ 1 mW is efficiency rating
106 dB @ 1 Volt is sensitivity rating

 

[jcx]

dB SPL re 1 mW is called sensitivity too - and it could be argued that fully proper "efficiency" would be (power out)/(power in) and SPL isn't really a power unit- converting it to power requires several added assumptions: of some reference acoustic load, radiation condition, integration region

 

[Chris J]

it could be argued that a number like 1 mW @ 96 dB SPL expresses the efficiency of the conversion of electrical energy into acoustic energy.

assume we are using pink noise:
if speaker system A was 90 dB SPL @ 1 W @ 1 m, and speaker B was 100 dB SPL @1W @1 m then we would conclude that speaker B was more efficient than speaker A

let the endless discussion of semantics continue!

 

[xnor]

But, but, efficiency is usually dimensionless and specified as 0.0 to 1.0 or in percent!

 

[ab initio]

Quote:

assume we are using pink noise:
if speaker system A was 90 dB SPL @ 1 W @ 1 m, and speaker B was 100 dB SPL @1W @1 m then we would conclude that speaker B was more efficient than speaker A

 
Unfortunately, this is not true. You are only measuring the sound pressure level at a single location. If speaker A was a tiny, spherical transducer and speaker B was a very very large speaker (or better yet, an array of speakers) in an infinite baffle, then speaker A would radiate sound equally in all directions, with the SPL falling off like 1/distance^2 whereas speaker system B could focus its sonic energy at the location where you were measuring SPL. I that case, it's entirely possible that speaker A is actually converting more electricity into sound energy, even though the loudness at the location you are measuring is lower than B.
 
Here's a link on directional sound
 

let the endless discussion of semantics continue!

how did I do?

 
Cheers!

 

[Chris J]

Unfortunately, this is not true. You are only measuring the sound pressure level at a single location. If speaker A was a tiny, spherical transducer and speaker B was a very very large speaker (or better yet, an array of speakers) in an infinite baffle, then speaker A would radiate sound equally in all directions, with the SPL falling off like 1/distance^2 whereas speaker system B could focus its sonic energy at the location where you were measuring SPL. I that case, it's entirely possible that speaker A is actually converting more electricity into sound energy, even though the loudness at the location you are measuring is lower than B.

Here's a link on directional sound

let the endless discussion of semantics continue!

how did I do?

Cheers!

Well played!
You'll fit right in with the rest of us pedantic idiots on the Science Fiction Forum!

In this case, I add another assumption!
Assume both loudspeakers have the same radiation pattern!

 

[ab initio]

Quote:

Well played!

You'll fit right in with the rest of us pedantic idiots on the Science Fiction Forum!
 

Thanks

 
Quote:

In this case, I add another assumption!
Assume both loudspeakers have the same radiation pattern!

Quote:

assume we are using pink noise:
if speaker system A was 90 dB SPL @ 1 W @ 1 m, and speaker B was 100 dB SPL @1W @1 m then we would conclude that speaker B was more efficient than speaker A

 
Assuming we know the radiation pattern, I think we now have enough information to define a proper efficiency as the ratio of one power to another power. And now, yes, I think that comparing the SPL levels would be equivalent to efficiency!
 
Cheers!

 

[Chris J]

Thanks


Assuming we know the radiation pattern, I think we now have enough information to define a proper efficiency as the ratio of one power to another power. And now, yes, I think that comparing the SPL levels would be equivalent to efficiency!

Cheers!

efficiency = Watts / Watts !

No stinking units for us! or is it :mad: ?

 

[ab initio]

Quote:

efficiency = Watts / Watts !

No stinking units for us!

or is it

?

 
Personally, I find working without units a

.  Whenever somebody tries to discuss a problem in dimensional form it makes me

 
Besides, what the heck is a Jiggawatt anyways?

 
Cheers!

 

[Chris J]

 
Personally, I find working without units a

.  Whenever somebody tries to discuss a problem in dimensional form it makes me

 
Besides, what the heck is a Jiggawatt anyways?

 
Cheers!

 
At this point I recommend that we pick apart each other's grammar, spelling and sentence structure! Also critique each other's literary style! A JiggaWatt is a measurement used to quanify ONE BURST of phasor fire!

 

[xnor]

Or let's just get real again and acknowledge that sensitivity does not equal efficiency.

 

[Chris J]

Quote:

dB SPL re 1 mW is called sensitivity too - and it could be argued that fully proper "efficiency" would be (power out)/(power in) and SPL isn't really a power unit- converting it to power requires several added assumptions: of some reference acoustic load, radiation condition, integration region

Or use the same anechoic chamber when comparing two loudspeakers..........................which have the same, or similar radiation patterns.

 

[penmarker]

I'm confused because you guys are correct, yet you guys are correcting each other.