Subs with XBl^2

[newtitan 10+ year member]

I have the XXX mid just to back up somewhat what Sk said

the xbl2 is really a ll its crapped up to be etremely clean!!!! and very low distortion levels

the funny thing is that I am so used to the older lp "dirty sound"

that the xbl2 "sounds " is almost too clean for my taste LOL

but the midrange is Niiiiiiice

Id love to a/b the extremis to teh XXX to compare

as soon as 4 ohm or dual vc comes out I will

 

[Warbleed 10+ year member]

I believe its because the midrange is a more natural sound than those low low bass notes, our ears are more acustom to how they are 'suppose' to sound. The midrange area is where things like human speech falls, and is easiest to detect anomolies. Set your EQ bumping some music until you think it sounds right, then change to talk radio and see how it sounds. most likely it'll be too bass heavy, but the midrange wil be close®. How much sub 50hz bass do we hear naturally? Very little. Most of that low bass we hear is generated, enhanced, distorted, etc by digital processors. Its hard to listen to it and relate it to a sound we hear in nature (other than man-made, through a speaker). I believe that's why sub systems seem to be so unbalanced with the rest of people's stereo systems, and why people seem to have more trouble deciding how bass 'should' sound.

Too many want to replicate concert-like bass levels without concert-like high frequency levels. They think the bass should "thump them in the chest."

I agree most people, in car audio especially, set very unrealistic bass levels. It's not uncommon to see people with a sub system playing 20dB+ louder than the front stage. Now to anyone who actually LIKES accurate reproduction, that sounds god awful. I won't even listen to a stereo that sounds like that. I have sat it countless cars and immediately tried to persuade them to disable any and all boost, and to reduce the subwoofer level to a more realistic setting.

There's nothing wrong with some slight emphasis in the bass range, but when you get the sub level too much higher, then you aren't even producing the recording accurately anymore.

No one has ever said that XBL^2 or other flat BL topologies are the ONLY way for a driver to sound good, but it is definitely true that flat BL = MUCH lower distortion vs. a traditional motor with a parabolic BL curve. That's just the unavoidable consequences of physics. Constant motor force is better than changing motor force, period, as far as accurate reproduction is concerned.

Stephen referred to Scanspeak and Seas. Scanspeak's Revelator, as well as Seas' Excel, both have very sophisticated, but still somewhat standard motors. They both have pretty parabolic BL curves, but they have fairly flat Cms curves, and a very low inductance. Those, unsuprisingly, are the three biggest contributors to distortion. Having a flat BL curve makes the largest difference, but if we are comparing drivers with the same topologies, the drivers with higher displacement coupled with low inductance and flat Cms curves are going to be the most accurate midranges. That's just the way it works out. If the Seas and Scanspeak drivers had flat BL curves, they'd be even better.

 

[SPL140.2 5,000+ posts]

what is the motor in shocker audios subs? I know earthquake sound is using the motor structure but is it the same as the XBl^2? Or is it just very similar?

 

[Warbleed 10+ year member]

what is the motor in shocker audios subs? I know earthquake sound is using the motor structure but is it the same as the XBl^2? Or is it just very similar?

Both of those are just overhung, they are not XBL^2, nor anything remotely similar to XBL^2.

 

[req 5,000+ posts]

basically they use a huge fecking top plate (if youve seen a shocker sig, you know what i mean) to focus the magnetic energy on a small 'ring like' structure that sticks out between the pole piece and the magnet. this is called overhung, because the ring is at the top of the pole and the top-plate. wheras, "normal" motors just use the whole top-plate edge to form the magnetic gap, versus using a smaller surface area as the gap.

lemme try and draw it cross-sectionally...

now, im not exactally POSATIVE on how the overhung\underhung motors work. thats my IMPRESSION on how they do it. basically that little 'lip' on the top plate there, and the pole vent is where the magnetic field is strongest. and this is where XBL2 does its work. by using the same 'magnetic force' but centering it on the top plate, and 'overlapping' fields by cutting out rings in the pole and the top plate, it creates a stronger motor force and keeps the voicecoil\cone moving more linear with a longer stroke.

its not "exactally" what the motors look like. but thats what my guess' are.

anyone have cross sections of diferent motors?

 

[Warbleed 10+ year member]

basically they use a huge fecking top plate (if youve seen a shocker sig, you know what i mean) to focus the magnetic energy on a small 'ring like' structure that sticks out between the pole piece and the magnet. this is called overhung, because the ring is at the top of the pole and the top-plate. wheras, "normal" motors just use the whole top-plate edge to form the magnetic gap, versus using a smaller surface area as the gap.
lemme try and draw it cross-sectionally...

now, im not exactally POSATIVE on how the overhung\underhung motors work. thats my IMPRESSION on how they do it. basically that little 'lip' on the top plate there, and the pole vent is where the magnetic field is strongest. and this is where XBL2 does its work. by using the same 'magnetic force' but centering it on the top plate, and 'overlapping' fields by cutting out rings in the pole and the top plate, it creates a stronger motor force and keeps the voicecoil\cone moving more linear with a longer stroke.

its not "exactally" what the motors look like. but thats what my guess' are.

anyone have cross sections of diferent motors?

Overhung is when the coil is longer than the top plate. Underhung is when the coil is shorter than the the top plate.

 

[SPL140.2 5,000+ posts]

Just curious on how the earthquakes zubzero line 12" has a linear of 4" of excursion and the subs with XBl^2 doesnt have that much. Does the earthquake have new motor technologies? This is all new to me, i never really cared before on this type of info.

 

[Warbleed 10+ year member]

Just curious on how the earthquakes zubzero line 12" has a linear of 4" of excursion and the subs with XBl^2 doesnt have that much. Does the earthquake have new motor technologies? This is all new to me, i never really cared before on this type of info.

No it doesn't. Just because it claims 4" of p2p EXCURSION does NOT make that linear excursion. I guarantee to you it doesn't even APPROACH 4" of p2p linear excursion.

The Earthquake drivers are mostly hype. Totally standard topology, just plain old overhung. Earthquake is pretty well known for misleading marketing info...looks like you were duped.

 

[RandyJ 10+ year member]

Question, if more excursion is desired, couldn’t the coil and motor just be elongated leading to a larger magnetic field for the coil to be in?

 

[Warbleed 10+ year member]

Question, if more excursion is desired, couldn’t the coil and motor just be elongated leading to a larger magnetic field for the coil to be in?

Well, not without compromises. You can only make the top plate so tall for a given motor design before you start losing flux. As the gap gets bigger, BL will go up, but xmax will go down, and BL linearity worsens.

If you make the coil longer, Re goes up, BL goes down, Mms goes up, BL linearity improves, and Le also increases.

 

[req 5,000+ posts]

this is why speaker design isnt so easy //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

its like box tuning, change one thing, and you gotta change everything.

and like i said warbleed, i wasnt POSATIVE on how overhung\underhung worked out... thats what i was THINKING it was.

but basically, all the motor strength is between the gap of the top plate and the pole piece. dual gap technologies, have - you guessed it, two motor\plate gaps, for a 'stronger motor force'... but i cant see this working very well unless there is a bigger coil and stuff. so i dunno if its actually that much better or not (as far as linerarity is concerned).

and is there a cross section of these motors? ive seen standard and overhung cross sections done before. but how about XBL2, TCx, or other ones?

 

[squeak9798 5,000+ posts]

Just curious on how the earthquakes zubzero line 12" has a linear of 4" of excursion and the subs with XBl^2 doesnt have that much. Does the earthquake have new motor technologies? This is all new to me, i never really cared before on this type of info.

As Warbleed said; that 4" figure is not Xmax (linear excursion), and it is also a peak to peak # (whereas Xmax is one way linear excursion). If you read their tech article/box recommendation page for the Subzero 12 (http://www.earthquakesound.com/subzero_12.htm) you can see they list "Electrical Xmax" (what I assume to be Xmag) as being 50.8mm p2p, which would translate into the sub having 25.4mm of supposedly "true" Xmax......which, while nice, is nothing overly "impressive". They also list "Mechanical Xmax", which I assume to be Xsus.....but Xmax would be the lesser of the two (Xmag and Xsus), which in this case would be Xsus.

 

[req 5,000+ posts]

squeak. where was that link that you sent me\posted that one time with all the cross sections of the drivers and descriptions of how they work.

it was some speaker theory page. lots of fun reading for me. i learned quite a bit, but i cant remmeber how exactally they drew over\underhung motors. what i drew up there was from memory, and i dont believe its 'correct'

 

[squeak9798 5,000+ posts]

I presume you are referring to this one:

http://ldsg.snippets.org/motors.php3

 

[req 5,000+ posts]

I presume you are referring to this one:
http://ldsg.snippets.org/motors.php3

yes! thats the one.

i was right on the overhung, but i didntremember what the underhung was. and its just that the coil is mad tiny and the gap is huge..

i stand corrected. i thought it was wrong, but i couldnt pinpoint\remember why. and remember kids, the "gap" is between the top plate and the pole piece! ;D

very VERY good reading material. if you like speakers, i really suggest you read that link