Check out these other great forumsSoundSolutionsAudio.comAudioAddicts.netCarAudio-Forum.comCarAudioResources.comHomeAudioForum.net

Jump to content

nuff said.

Release your inner EVIL!



Photo
- - - - -

Linear Motor Technology - A Reference


  • Please log in to reply
234 replies to this topic

#1 SoundSplinter

SoundSplinter

    Regular Member

  • Vendors

  • 920 posts
  • Gender:Male

Posted 06 April 2005 - 03:23 AM

As many of you may have heard, we indeed have some exciting news about TC Sounds' Linear Motor technology. After years of development, and months of negociations, SoundSplinter has been granted exclusive rights to be the first distributor of Linear Motor technology enabled drivers! Posted Image

Few prototypes have been made thus far, but those that were have been given exceptionally high acclaim by those who have experienced them. My goal is to work with TC Sounds to continue this saga in appropriate fashion, bringing to market a truly awesome driver, capable of massive excursion, huge output, high power handling, all with incredibly low distortion and a beastliness that will amaze any onlooker (and of course every listener!).

So you might be asking yourself, "What is this Linear Motor technology all about? I've been hearing the term thrown around forever now but could never get my hands on it.. Is this a dream?" Posted Image

.. A dream come true maybe! Posted Image

__________________________________________________________________________

Variable Density Coil - White Paper
By Thilo Stompler
Property of TC Sounds, Inc.


__________________________________________________________________________

Principle

Electromechanical systems are made up of coupled electric and magnetic circuits. By a magnetic circuit, we mean a path for magnetic flux, just as an electric circuit provides path for the flow of electric current. In electromechanical devices, current-carrying conductors interact with magnetic fields (themselves arising from electric currents in conductors or from permanent magnets), resulting in electromechanical energy conversion.

Consider a conductor of length "L" placed between the poles of a permanent magnet producing a magnetic flux density B in the "air gap" between the poles N - S (ref. Image 1). Let the conductor carry a current "I" and be at right angles to the magnetic flux lines. The conductor experiences a force F, in the direction of which is perpendicular to both the conductor and to the magnetic filed lines, and the magnitude of which is given by F=(B)(I)(L). For N conductors (or turns), F becomes (N)(B)(I)(L).

A more general statement which holds for an arbitrary orientation of the conductor with respect to the flux lines is the cross product of the two vectors B and L, i.e. F=(I)(L) x B (Ampereís Law).

Note: If L is expressed in Meters, B in Tesla and I in Amperes, the Force is given in Newtons.

Posted Image


Standard voice coil implementation

Voice coil actuators are direct drive, limited motion devices that use a coil winding within a permanent magnet field to produce a force proportional to the current applied to the coil. These non-commutated electromagnetic devices are used in linear applications requiring linear force and high acceleration.

In its simplest form, a linear voice coil actuator is a tubular coil of wire situated within a radially oriented magnetic field, as shown in Image 2.

Posted Image


Based upon the required operating stroke of the actuator, the axial lengths of the coil and the magnet assemblies can be chosen so that the force versus stroke curve stays very flat. Since the coil density is uniform, this is somewhat possible if the magnetic field in the air gap of the permanent magnet circuit remains constant over the rated stroke.

In some cases the axial length of the coils exceeds that of the magnet by the amount of coil travel. In other cases the magnet is longer than the coil by the travel length. Compared to the short-coil configuration, the long-coil configuration provides a superior force-to-power ratio and dissipates heat better. The short-coil, however, has a lower electrical time constant, smaller mass, and produces less armature reaction. Neither arrangement provides a perfectly linear force-versus-travel characteristic. Most of the force acting on a bobbin is generated in the "air gap" of the magnetic circuit (as can be seen in Images 3, 4, & 5), where the magnetic field magnitude B is highest and fairly constant. However a long coil will also be subjected to the leaking fields above and below the gap region. Since such leakages are not symmetrical (ref. Image 5), they are an inherent cause for non-linearity when using a uniform density coil.

In some implementations, the magnetic steel return can be notched and/or the permanent magnet shaped in order to provide a more uniformed field. This operation is not always effective, especially when dealing with a long stroke device. Drivers utilizing this method are much more sensitive to a slightly offset coil, which will result in an undesirable manipulation of the BL curve. Furthermore, it is not very economical.

As the turns of the coil are located more remotely from the gap region, their contribution to the total force becomes lesser. The magnetic field seen by these turns decays quite rapidly, but is still significant (ref. Image 5).

When the coil travels along its stroke (ref. Image 4), a uniform density bobbin would be "missing" the contribution from the field located below the gap region since there are no turns interacting with such field. The same statement can be made for the case when the coil is at the opposite end of its stroke.

Posted Image

Posted Image


The uniform density bobbin is "missing" the contribution from the field located below the gap region since there are no turns interacting with such field. The result is a force-versus-displacement curve shaped as a bell as depicted in Image 6.

Posted Image

Posted Image


Variable coil density

An alternative to shaping the magnetic flux density is to shape the coil density in order to keep the product (N)(B)(L) constant. The variable density coil offers three bulges (ref. Images 7 & 8) at the center and at the extremities of the bobbin, in order to compensate for the lack of active turns when the coil travels near the end of its stroke.

Posted Image

Posted Image


Consequently the product (N)(B)(I)(L) remains nearly constant for the total stroke of the coil.

In theory, it is possible to shape the coil with many "steps" in order to get a perfectly flat response. Realistically, this might not be practical due to manufacturing issues as well as an economy. Based on the geometry (ratio of gap size to coil length mostly), five to seven segments are sufficient in order to provide linearity better than just a few percent (Image 9).

The shape of the coil is strongly linked to the magnetic structure hosting it. Such a shape is derived from a combination of Finite Element Analysis (FEA to compute the magnetic field) and self-consistent equations (solved within MathCAD) to represent the electro-mechanical behavior of the system.


Conclusion

Near perfect force linearity can be easily obtained by shaping the turn distribution of the coil of a voice coil actuator. The main drawback of such a concept is that the peak force obtained is less than that produced by a uniform winding. It is a trade-off between linearity and peak force. In a practical loudspeaker, this simply means that more magnet is required to obtain the same BL-product at rest, or small excursions. In an actual subwoofer system, the result is typically a threefold reduction in distortion, resulting in a significant easily audible subjective improvement in sound quality.

Posted Image


// End of document. Reproduced and edited by Michael Grynick with permission. April 6 2005.
  • -1
~mike

#2 SoundSplinter

SoundSplinter

    Regular Member

  • Vendors

  • 920 posts
  • Gender:Male

Posted 06 April 2005 - 03:30 AM

I would like to add that this driver is currently under development and as of the current date, we have no concrete specifications for the product that will come to market. To satisfy some curiousity, I would estimate that prototypes will be in hand within a few weeks, and I would hope that this driver will come to fruition within the next three months. These drivers will likely perform optimally with 1000wrms and above. Please realize that these are estimates only!

I would also like to welcome any and all comments about what YOU, the consumer and enthusiast, would like to see these drivers offer. Obviously we cannot satisfy everyone, and need to keep in mind the economics behind the development of this driver.. but seeing as we are in the prototype stage, it wouldn't hurt for you to express your own desires for our new LMT enabled drivers. Things to ponder might include the importance of excursion versus practicality, optimization for small or large boxes, and so on.

Make your voice heard! People are listening B)

As we get further into the development of this product, information will be posted in this forum - so feel free to visit often, we'd love to have you as a member!
  • -1
~mike

#3 idiot

idiot

    Junior Member

  • Members
  • 137 posts

Posted 06 April 2005 - 05:14 AM

I canít believe I understood nearly all of that. :blink: And the BL curve is seriously the closest to ideal Iíve ever seenÖ
  • 0

#4 repo_24

repo_24

    Newbie

  • New Members
  • 3 posts

Posted 06 April 2005 - 10:10 AM

What voice coil config(s) will be available? And you probably won't be able to answer this yet....but how about the cost? (I suppose it depends on how "big" you go with the sub :P )

If you could get something that flat-out outperforms the xxx/brahma/w7 for a price around those subs (or slightly more) I think you would have a DEFNINATE winner!

#5 req

req

    Member

  • Members
  • 203 posts
  • Real Name:Andrew
  • Gender:Male
  • Location:Virginia Beach, VA
  • Vehicle:2003 Volkswagen GTi 1.8t

Posted 06 April 2005 - 10:14 AM

i dont even know what to ask :o

//edit

how bout a cross section picture of the actual LMT motor? because that tech paper didnt actually show me what it will look like.. just kinda like a mental picture and that 'bobbin' :unsure:
  • 0

Custom Built CarPC, Mosconi AS200.4 amplifiers, Helix P-DSP processing

Vifa XT25 tweeters, FatialPRO 4FE30 midrange, Exodus Anarchy midbass, Image Dynamics IDMax12 subwoofers

Team DIYMA 2012 5th place MECA modified street - disqualified and requalified


#6 Impious

Impious

    I Know The Pieces Fit

  • SSA Tech Team
  • 6,293 posts
  • Gender:Male
  • Location:Hollow Depths of Hell

Posted 06 April 2005 - 10:20 AM

I would like to see this sub be well suited for use Infinite Baffle; Low Q, low Fs, moderate Vas.

If you could get a very low distortion and linear motor, that performs well infinite baffle off ~500-700w (when IB) with a stroke of ~30-35mm (closer to 35mm) and really excels at the "low end"....that would be one insane "ultimate" SQ driver that could really hit the home audio market hard aswell.

Plus, I would pick up two myself :slayer: :slayer:
  • 0
I find that I can see a light at the end down beneath my self-indulgent pitiful hole.
Defeated I concede and move closer.
I may find comfort here. I may find peace within the emptiness.
How pitiful.

- TOOL, Reflection


I contend that we are both atheists. I just believe in one fewer god than you do. When you understand why you dismiss all of the other possible gods, you will understand why I dismiss yours. - Stephen Roberts






#7 80INCHES

80INCHES

    Regular Member

  • Members
  • 658 posts
  • Location:YONKERS NEW YORK
  • Interests:BASS..THATS MY ADDICTION AND THERES NO CURE

Posted 06 April 2005 - 10:21 AM

i'm speechless

80
  • 0
i blew 6 12's and 6 10's..in 2 different cars my next step is 15's in my new car...i just cant let go of that epicenter

<b><!--coloro:quot--><span style="color:quot"><!--/coloro--><div align='center'>Keep campaigning for this ass whoopin and you just might get elected</div><!--colorc--></span><!--/colorc--></b>
<a href="http://imageshack.us" target="_blank"><img src="http://img291.images...spankie2xx.gif" border="0" class="linked-sig-image" /></a>




AlphaDamp CLD Tiles - Get more Sound Deadening with less Sound Deadener[/CENTER]

#8 mrray13

mrray13

    5-27-20 to 7-20-08

  • Super Moderators
  • 16,020 posts
  • Location:southern Illinois

Posted 06 April 2005 - 10:24 AM

small/medium vented enclosure optimized...

power handling is perfect...

vc configuration..whichever...so mny amps available a specific impedence/number of coils isn't that big of an issue to me

cost in the $275-300 range for a 12

typical sexy soundsplinter looks

and myself getting a few!!





would midbasses/midranges be able to get this technology? something in the 6.5 to 8" size? powerhandling in the 200-500 range?





wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee :slayer:
  • 0

I'm not a big fan of ignorant, blanket statements that run rampant in DIY audio. That and my mommy didn't love me enough.


#9 Impious

Impious

    I Know The Pieces Fit

  • SSA Tech Team
  • 6,293 posts
  • Gender:Male
  • Location:Hollow Depths of Hell

Posted 06 April 2005 - 10:30 AM

cost in the $275-300 range for a 12

typical sexy soundsplinter looks


:stupid:

Annodized black cone would be teh sexy :D






would midbasses/midranges be able to get this technology? something in the 6.5 to 8" size? powerhandling in the 200-500 range?


HLCD!!!!!!

I want a horn that will fit in my car and realisticly(sp?) play down to 300hz with little to no equalization needed. Now, get to work and make it happen :hyper:

Seriously though, 5.25" - 8" mids (even mids like the Koda's that can double as subs) would absolutely rock!
  • 0
I find that I can see a light at the end down beneath my self-indulgent pitiful hole.
Defeated I concede and move closer.
I may find comfort here. I may find peace within the emptiness.
How pitiful.

- TOOL, Reflection


I contend that we are both atheists. I just believe in one fewer god than you do. When you understand why you dismiss all of the other possible gods, you will understand why I dismiss yours. - Stephen Roberts






#10 repo_24

repo_24

    Newbie

  • New Members
  • 3 posts

Posted 06 April 2005 - 10:52 AM

i dont even know what to ask  :o

//edit

how bout a cross section picture of the actual LMT motor? because that tech paper didnt actually show me what it will look like.. just kinda like a mental picture and that 'bobbin'  :unsure:

<{POST_SNAPBACK}>

http://www.tcsounds....ges/LM_news.pdf

have you seen that?

#11 ANeonRider

ANeonRider

    ANissanRider

  • SSA Regular
  • 4,499 posts
  • Location:Saskatoon, SK, CAN

Posted 06 April 2005 - 11:01 AM

Awww man, I want one.
  • 0
Scott
Posted Image
2003 Nissan Sentra SE-R Spec V: Stock Rockford Fosgate Premium CD Receiver w/ Balanced 6V output - Alpine PXA-H701/C701 combo - Peerless SLS 8" IB doors - Aurasound NS3 kicks - Vifa XT19 pillars - Alpine PDX-4.100 - Alpine PDX-1.600 - Sony XM250 - Exodus Audio XJ-15 IB
350 sq. ft. B-Quiet Extreme, Knukonceptz Wiring

MY CAR PROJECT LOG

MY HOME PROJECT LOG

#12 JimJ

JimJ

    Banned

  • BANNED
  • 18,490 posts
  • Gender:Male
  • Location:Blacksburg, VA

Posted 06 April 2005 - 11:32 AM

I'd be happy with two :) I don't have the amplifier power on tap to make three happy...two would be getting 750wrms a piece, and port them in the biggest box I could fit.

Wall?

:D
  • 0

#13 eric77

eric77

    Member

  • New Members
  • 467 posts
  • Location:newport beach, ca

Posted 06 April 2005 - 12:10 PM

My hopes
power handling- 1kw +
VC config- SVC 1.5 ohm no more than 2 ohm
Excursion-35mm or more :D
Price- under 400 for a 15
box- medium sized box would be fine. Im as happy as long as a 15 doesnt need 4.5 cu ft net ported. that would be just ridiculous.
sizes- 12" and 15"
looks- similar to the current rl-p

Mike, have you guys decided which motor you are going to use? *crosses fingers and hopes for a 3hp lmt driver*
Posted Image
audio- gone :(

#14 psycho72

psycho72

    Member

  • Members
  • 354 posts
  • Location:Los Angeles
  • Interests:My son, God, women, cars, audio &amp; music

Posted 06 April 2005 - 12:12 PM

Just had a flash


Team Sound Splinter


Ohhhhhhhhh!!!!!!!!!!!!!!!!!!!!!!!



On a more serious note, how much can you improve on the already impressive prototypes. You have first hand experience with them (btw can I come over and play with your toys Mike??) so what is the current goal. Improve low end? Cut costs? Improve SQ? Maybe poll us on what we would rather give up.

Jerry
  • 0
George Bush, Dick Cheney and Donald Rumsfeld are flying on Air Force One. The President looks at the Vice President, chuckles, and says, "You know, I could throw a $1,000 bill out the window right now and make somebody very happy."

The Vice President shrugs and says, "Well, I could throw 10 $100 bills out the window and make 10 people very happy."

Not to be outdone, the Secretary of Defense says, "Of course, then, I could throw 100 $10 bills out the window and make a hundred people very happy."

The pilot rolls his eyes and says to his co-pilot, "Such arrogant asses back there. Hell, I could throw the three of them out the window and make 56 million people really happy."

#15 ImReady77

ImReady77

    Junior Member

  • Members
  • 106 posts

Posted 06 April 2005 - 12:21 PM

will these have the tall surround like some of the prototypes? please keep the same cone as the rl-p.
  • 0




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

#1 Car Audio Forum Since 2001!