Menu
Forum
What's new
New posts
Live Activity
Search forums
Members
Registered members
Classifieds Member Feedback
Car Audio Discussion
General Car Audio
Car Audio Build Logs
Car Audio Equipment
Subwoofers
Speakers
Amplifiers
Head Units
Car Audio Help
Wiring, Electrical and Installation
Enclosure Design & Construction
Car Audio Classifieds
Car Audio Classifieds
Car Audio Wanted
Classifieds Member Feedback
Gallery
New media
New comments
Search media
SHOP
Shop Head Units
Shop Amplifiers
Shop Speakers
Shop Subwoofers
Shop eBay Car Audio
Log in / Join
Test
Forum
Search
Search titles only
Search titles only
Log in / Join
Search
Search titles only
Search titles only
What's new
New posts
Live Activity
Search forums
Members
Registered members
Classifieds Member Feedback
Menu
Reply to thread
Forum
Car Audio Equipment
Subwoofers
Low xmax vs. high xmax??
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Message
<blockquote data-quote="T3mpest" data-source="post: 7778558" data-attributes="member: 560148"><p>Very good post.. Xmax is only important if the design you'll be using runs out of it.. Xmax in general is when a subs moves far enough that it loses 70% of it's BL value when vs when the coil is centered. Keeping within this range is important. First reason is ANY drop in BL is a loss of motor force, hence loss of effeciency. The further the coil can move without losing BL the more effecient the subwoofer is (not effeciency in the "rated" sense, but TRUE effeciency".. Also any loss of BL is a form of non-linear distortion and is generally the highest contributor to a subs distortion. If your going past xmax your making the sub have more distortion and putting more power to the coil for less actual speaker output, BL compression is very real and hardly EVER talked about</p><p></p><p>Secondly, SPL is ALWAYS about displacement.. The further a speaker canmove the louder it will be all things equal.. SPL subs may have smaller xmax ratings, but they have alot of motor force.. Xmax only says how far a coil can move before it loses BL.. If you don't have enough BL to move the cone that far without frying the coil in the first place then it's USELESS.. Most SPL subs have high BL for this reason. They can overcome the ports damping effect near tuning. A SQ sub with 35mm of xmax but very little BL can't do that in many cases, hence alot of people think SPL has nothing to do with xmax. However, since a high xmax limits BL compression, it's actually a good thing even for an SPL woofer. Once you can hit the supsension limits of a subwoofer near tuning, you've effectively maxed out how loud the box is. You can't generate any more air movement at that frequency by adding more power.. The less power you need to do this the better off you are.</p><p></p><p>Anyway some things said by certain people in this thread really isn't true.. A high xmax is good for a SQ woofer. The woofer can move further, meaning it can play lower, with less BL compression and do so with less distortion than a low xmax woofer... Xmax is king in a sealed design and many times SQ designs used sealed drivers (not a great idea in my opinion either, but it does happen). High xmax drivers are generally well controlled beyond xmax as well. At worst we can say, they are better behaved at any displacement before any driver with a lesser xmax, hence the lower xmax. Beyond xmax is when a speaker begins to lose composure, by definition it's 70% BL or 10% distortion, whichever comes first, with 70% being 10% thd in most cases... Some designs like XBL^2 for example actually are VERY linear in BL and VERY nicely behaved beyond it.. XBL^2 drivers BL drops like a rock after 70% BL, but exhibit almost no loss through 90% of their stroke. Meaning a woofer that can move 32mm would have basically NO TSP changes until 25mm or so.. Beyond 25 it slowly loses a bit of BL until 32.. Right at 32 it's nearly impossible to even get the driver to go beyond xmax as it's losing BL so fast it can't move any further.. That's why you never see any brahmas or XXX's with mechanical damage.. It's too hard to make them bottom or even go outside of their comfort zone.. They sound fine no matter how much power you put on them until you smoke the coil lol..</p></blockquote><p></p>
[QUOTE="T3mpest, post: 7778558, member: 560148"] Very good post.. Xmax is only important if the design you'll be using runs out of it.. Xmax in general is when a subs moves far enough that it loses 70% of it's BL value when vs when the coil is centered. Keeping within this range is important. First reason is ANY drop in BL is a loss of motor force, hence loss of effeciency. The further the coil can move without losing BL the more effecient the subwoofer is (not effeciency in the "rated" sense, but TRUE effeciency".. Also any loss of BL is a form of non-linear distortion and is generally the highest contributor to a subs distortion. If your going past xmax your making the sub have more distortion and putting more power to the coil for less actual speaker output, BL compression is very real and hardly EVER talked about Secondly, SPL is ALWAYS about displacement.. The further a speaker canmove the louder it will be all things equal.. SPL subs may have smaller xmax ratings, but they have alot of motor force.. Xmax only says how far a coil can move before it loses BL.. If you don't have enough BL to move the cone that far without frying the coil in the first place then it's USELESS.. Most SPL subs have high BL for this reason. They can overcome the ports damping effect near tuning. A SQ sub with 35mm of xmax but very little BL can't do that in many cases, hence alot of people think SPL has nothing to do with xmax. However, since a high xmax limits BL compression, it's actually a good thing even for an SPL woofer. Once you can hit the supsension limits of a subwoofer near tuning, you've effectively maxed out how loud the box is. You can't generate any more air movement at that frequency by adding more power.. The less power you need to do this the better off you are. Anyway some things said by certain people in this thread really isn't true.. A high xmax is good for a SQ woofer. The woofer can move further, meaning it can play lower, with less BL compression and do so with less distortion than a low xmax woofer... Xmax is king in a sealed design and many times SQ designs used sealed drivers (not a great idea in my opinion either, but it does happen). High xmax drivers are generally well controlled beyond xmax as well. At worst we can say, they are better behaved at any displacement before any driver with a lesser xmax, hence the lower xmax. Beyond xmax is when a speaker begins to lose composure, by definition it's 70% BL or 10% distortion, whichever comes first, with 70% being 10% thd in most cases... Some designs like XBL^2 for example actually are VERY linear in BL and VERY nicely behaved beyond it.. XBL^2 drivers BL drops like a rock after 70% BL, but exhibit almost no loss through 90% of their stroke. Meaning a woofer that can move 32mm would have basically NO TSP changes until 25mm or so.. Beyond 25 it slowly loses a bit of BL until 32.. Right at 32 it's nearly impossible to even get the driver to go beyond xmax as it's losing BL so fast it can't move any further.. That's why you never see any brahmas or XXX's with mechanical damage.. It's too hard to make them bottom or even go outside of their comfort zone.. They sound fine no matter how much power you put on them until you smoke the coil lol.. [/QUOTE]
Insert quotes…
Verification
Post reply
Forum
Car Audio Equipment
Subwoofers
Low xmax vs. high xmax??
Top
Menu
Home
Refresh