LMS 5400 Ultra xmax/xmech measurements and non-linearity - AVS Forum
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post #1 of 76 Old 03-23-2012, 10:01 AM - Thread Starter
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I decided to take some measurements on some of my LMS ultra drivers, as they did not seem to be reaching the advertised excursion levels.

With the driver free air, I was able to see that on the inward stroke, it would easily hit the spider support which is just over 1.5" from the cone. However, on the outward stroke, I was not seeing much more than 1.25" of excursion.

Is the stroke just non linear at this range?

My measurement system was crude, but fairly effective. I set a measuring tape on a fixed surface and aimed it towards the center of the driver. I then took a pencil with a soft eraser and marked it, so that I could see where on the measuring tape the pencil would touch the cone when the sub wasn't moving. I set it up so that it was at 3" on the tape. Next, I played a low frequency test tone so that I could hear the cone was tapping on the spider support. I slowly moved the pencil, eraser side first, towards the moving cone to see where it would impact. From these tests, I was unable to see outward excursion of over 1.25"

xmax on this driver is listed at 38mm with xmech being just slightly beyond that.

Thoughts?

Video of test here:

http://www.youtube.com/watch?v=aoFH0xz8b_g&hd=1

Measurement of inward xmax showing over 1.5" before xmech:



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post #2 of 76 Old 03-23-2012, 10:07 AM
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not,

Can't watch the vid right now.

Was this free-air?

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post #3 of 76 Old 03-23-2012, 10:11 AM - Thread Starter
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Quote:
Originally Posted by dbldare View Post

not,

Can't watch the vid right now.

Was this free-air?

dbl

That was in an enclosure with a second LMS 5400 ultra, which wasn't being powered at the time. You can hear it hitting the spider support, which is over 1.5" of inward travel, but not moving more than 1.25" outward.
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post #4 of 76 Old 03-23-2012, 10:12 AM
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So my next question would be, "Is this common across all your drivers?"


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post #5 of 76 Old 03-23-2012, 10:14 AM
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Would like to see what Kyle says about this one.

Nice vid, Not. I like your DIY-tastic measurement 'rig' too. At first I was expecting you to have bought some laser system or something.

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post #6 of 76 Old 03-23-2012, 10:17 AM - Thread Starter
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Quote:
Originally Posted by dbldare View Post

So my next question would be, "Is this common across all your drivers?"


dbl

yes, at least on 3 I tested.
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post #7 of 76 Old 03-23-2012, 10:22 AM
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I wonder if it could possibly be enclosure related.?.?.? Have you tried it free-air?


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post #8 of 76 Old 03-23-2012, 10:25 AM - Thread Starter
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Quote:
Originally Posted by dbldare View Post

I wonder if it could possibly be enclosure related.?.?.? Have you tried it free-air?


dbl

No, the driver moves around far too much to be able to test like this free air without blocking the pole vent.
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post #9 of 76 Old 03-23-2012, 10:26 AM
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Test baffle?

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post #10 of 76 Old 03-23-2012, 10:27 AM
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Yeah - I thought about that just after posting.


I'm with Scott here.

Let's see what Kyle says.



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post #11 of 76 Old 03-23-2012, 10:41 AM
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the second driver might be exascerbating the non-linear behavior. try shorting it and rerun the test.

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post #12 of 76 Old 03-23-2012, 10:45 AM - Thread Starter
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Quote:
Originally Posted by LTD02 View Post

the second driver might be exascerbating the non-linear behavior. try shorting it and rerun the test.

I ran it with both drivers hooked up as well. Same behavior.
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post #13 of 76 Old 03-23-2012, 01:36 PM
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I'm a bit confused... your first post says free air, but the subsequent posts say it is in the enclosure and that you aren't doing free air testing. Also, I see the vid but can't see the links of the two measurements. The vid shows how you get outward excursion, but how are you measuring inward excursion with that method?

I'm wondering if you have changed something to get more free air conditions that I'm missing. If not, since you have two drivers in a shared enclosure, you could either remove the other driver to leave a large open hole, or wire the other driver out of phase. Both conditions would approximate a free air test, the second perhaps a bit more so and easier to do.

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post #14 of 76 Old 03-23-2012, 01:54 PM
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Ricci has the geometric xmax at 33mm on Data Bass. That's roughly 1.3 inches. I thought I remember hearing the xmech was eerily close to the xmax on all TC LMS drivers.

http://www.data-bass.com/data?page=driver&id=4
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post #15 of 76 Old 03-23-2012, 02:18 PM - Thread Starter
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Quote:
Originally Posted by Bigus View Post

I'm a bit confused... your first post says free air, but the subsequent posts say it is in the enclosure and that you aren't doing free air testing. Also, I see the vid but can't see the links of the two measurements. The vid shows how you get outward excursion, but how are you measuring inward excursion with that method?

I'm wondering if you have changed something to get more free air conditions that I'm missing. If not, since you have two drivers in a shared enclosure, you could either remove the other driver to leave a large open hole, or wire the other driver out of phase. Both conditions would approximate a free air test, the second perhaps a bit more so and easier to do.

When it was open I measured the inward stroke, you can see its hitting the spider support. The video shows measuring while it was in the enclosure with the second driver disconnected. I tested with it connected as well.
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post #16 of 76 Old 03-23-2012, 02:19 PM - Thread Starter
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Quote:
Originally Posted by tgse3 View Post

Ricci has the geometric xmax at 33mm on Data Bass. That's roughly 1.3 inches. I thought I remember hearing the xmech was eerily close to the xmax on all TC LMS drivers.

http://www.data-bass.com/data?page=driver&id=4

He tested an older version.
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post #17 of 76 Old 03-23-2012, 02:23 PM
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Quote:
Originally Posted by tgse3 View Post

Ricci has the geometric xmax at 33mm on Data Bass. That's roughly 1.3 inches. I thought I remember hearing the xmech was eerily close to the xmax on all TC LMS drivers.

http://www.data-bass.com/data?page=driver&id=4

Not all of them. Just some. My Sound Splinter RLp18's are TCSounds manufactured and their Xmax is rated at 27.4mm while the Xmech is ~41mm.

Quote:
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He tested an older version.

Josh has tested both drivers, actually. The slightly older 5400 variant and the newer Ultra variant.

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post #18 of 76 Old 03-23-2012, 07:44 PM
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All of the ultras I have are the current version. I have not physically measured the clearance like Notnyt did in the pic above since they have all been in enclosures for a long time now. I haven't gotten the sealed test finished. I keep bumping other stuff with less of a track record ahead of it.
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post #19 of 76 Old 03-23-2012, 07:54 PM - Thread Starter
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I'd be interested to see what your tests yield for excursion.
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post #20 of 76 Old 03-23-2012, 08:11 PM
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Was your FP working at all to produce that free air sine wave in your YouTube video?
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post #21 of 76 Old 03-23-2012, 08:14 PM
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Truthfully...you have already established what the physical xmech limit is. The cone can't move any further. We know that the motor will get it there. All there is left is how much noise the motor and suspension make on its way there. As far as your pencil test I have a feeling that the excursion is equal on the inverse and outward strokes. You can't see the back of the woofer so it is difficult to say whether it is contacting the spider spacer for sure. It may just sound like it. Weird things happen sometimes so who knows. When I get a chance I will look at one of mine.
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post #22 of 76 Old 03-23-2012, 08:26 PM
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When I talked with Nathan over at Funk Audio a few weeks ago, he mentioned to me that the 5400 with 38mm of linear travel is hamstrung by 32mm mechanical travel, which is somewhat easy to bottom out/damage. He also told me that the LMS has a listed mechanical travel of 47mm but is simply not so. That number is the clearance in the motor, but the suspension limits at 32mm. The cone contacts the spider landing at 32mm. That's one of the reasons they started their own design/building of their TSAD drivers. Just to note, Nathan has quite a bit of experience with LMS subs. He's listened, tested and sold quite a few of them. So it looks like Notnyt tests/results are very close to Nathan's, no?
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post #23 of 76 Old 03-23-2012, 08:59 PM - Thread Starter
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Quote:
Originally Posted by Ricci View Post

Truthfully...you have already established what the physical xmech limit is. The cone can't move any further. We know that the motor will get it there. All there is left is how much noise the motor and suspension make on its way there. As far as your pencil test I have a feeling that the excursion is equal on the inverse and outward strokes. You can't see the back of the woofer so it is difficult to say whether it is contacting the spider spacer for sure. It may just sound like it. Weird things happen sometimes so who knows. When I get a chance I will look at one of mine.

I actually ran it until it was hitting the spider, at about 42mm. I could tell because I put the little tab of cardboard there and I could feel it. There is just over 1.5" (42mm) between the spider and the cone. Actually the last roll of the spider is all hard from glue, and that is what hits the cone.

It seems like the way they're built that the roll surround limits the outward excursion to about 32mm. The inward stroke is limited to 42mm, which is the published xmax.

If my measurements are correct, it would have at least been nice to have accurate published specs to work off of when designing the enclosures. Granted, I can't really complain, these drivers are rarely pushed that hard, but for the price the specs could at least be accurate

Quote:
Originally Posted by spanish68 View Post

When I talked with Nathan over at Funk Audio a few weeks ago, he mentioned to me that the 5400 with 38mm of linear travel is hamstrung by 32mm mechanical travel, which is somewhat easy to bottom out/damage. He also told me that the LMS has a listed mechanical travel of 47mm but is simply not so. That number is the clearance in the motor, but the suspension limits at 32mm. The cone contacts the spider landing at 32mm. That's one of the reasons they started their own design/building of their TSAD drivers. Just to note, Nathan has quite a bit of experience with LMS subs. He's listened, tested and sold quite a few of them. So it looks like Notnyt tests/results are very close to Nathan's, no?

Apparently the newer LMS drivers shrunk the spider support so they have more clearance. I still don't see how that helps outward excursion which I think may be limited by the surround at around 32mm.
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post #24 of 76 Old 03-23-2012, 09:12 PM
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After my LMS-R 12" suspension completely detached and I was told to super glue it back to the frame or pay to ship the top assembly back for them to glue, even within the warranty period, I'm out of TC world.

I'll put a Zv3 18" up against an LMS-U any time for half the price.

 

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post #25 of 76 Old 03-23-2012, 09:17 PM - Thread Starter
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Quote:
Originally Posted by WiSounds View Post

After my LMS-R 12" suspension completely detached and I was told to super glue it back to the frame or pay to ship the top assembly back for them to glue, even within the warranty period, I'm out of TC world.

I'll put a Zv3 18" up against an LMS-R any time for half the price.

Are there specs on that driver anywhere?
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post #26 of 76 Old 03-23-2012, 09:21 PM
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Ricci is in the midst of testing one as we speak, I wanted him to have it to compare to the other drivers he has worked with because it is badass:

http://www.sundownaudio.com/index.ph...?category_id=2

Z v.3 18 D1/D2

Fs: 31.8Hz /31.9Hz
Re: 1.7 /4.0ohm
Qms: 5.5 /5.0
Qes: 0.5 /0.6
Qts: 0.5 /0.5
Cms: 49.5/45.8uM/N
Mms: 503.8g /541.4g
BL: 17.8N/A /25.6N/A
Vas: 104.2L /96.5L
Sens: 89.6 /88.5 1W/1m
Le: 2.0 /3.5mH
RMS: 1500 watts

Linear x-max by 70% BL is ~25mm one-way, the motor bottom is 47.5mm -- the suspension can handle a bit over 40mm one-way.


The 15 also models badass in quite tiny sealed enclosures. I have a frame for the 15 getting some chrome as we speak

 

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post #27 of 76 Old 03-23-2012, 09:35 PM
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Quote:
Originally Posted by notnyt View Post

If my measurements are correct, it would have at least been nice to have accurate published specs to work off of when designing the enclosures. Granted, I can't really complain, these drivers are rarely pushed that hard, but for the price the specs could at least be accurate

Damn...Agreed.

JSS
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post #28 of 76 Old 03-23-2012, 09:59 PM
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Yeah that does suck Not! Would you run these without a xover if they wouldnt bottom out? I guess a smaller box would have been nice but you didnt change much of the box design from the mal build anyway did you? I remember you having to cut some bracing that was making contact.
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post #29 of 76 Old 03-23-2012, 10:11 PM - Thread Starter
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They're the same boxes from my mal build with bracing adjustments. I don't know if I would change the enclosures much, or just go with a different driver like a 21" or something. Either way, it's just kind of disheartening.
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post #30 of 76 Old 03-23-2012, 10:38 PM
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if the case is that they will only 32mm outward travel, it would seem that there are a few other drivers that equal that. Mark had his UXL on the scope and I'm pretty sure it measured 3" P to P.

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