LMS-5400 buy-in

**Ilkka** · **09-20-07, 05:33 PM**

Quote:

anidabi wrote:

You are kidding right? You must be talking about the avalance, because none of the LMS looks good on 650 liter enclosure.

He's probably using "heavy damping" and "minor leaks" options in Unibox. With those even the LMS looks pretty good in that kind of enclosure. But they don't correlate with real world measurements. One can't stuff a ported enclosure that much because then it wouldn't work as a ported subwoofer (Helmholtz resonator) anymore.

**SteveCallas** · **09-20-07, 08:51 PM**

Quote:

Ricci wrote:

Actually it looks pretty good in 650 liters tuned to 14hz with a 10" diameter port if you ask me. You could use an 8" port but its not going to be enough if you really crank it.

Well you wouldn't really want to use a 10" port because the length would be such that the port resonance would probably be audible. You could use a lower crossover, but then you are kind of wasting the upper frequency linear and output capabilities of this driver. I also wouldn't tune much higher than 13hz, as this driver is overflowing with capability - might as well shift some of it to the low end.

With the 8" port, you would be limiting how much output you'd be able to ask from the driver unless you don't mind chuffing. Sure, you'd be hitting reference levels before experiencing any problems, but it seems a lot of potential is wasted none the less. Also, the low end FR on such a design isn't damped enough - there is a resurgence in output belwo 20hz. On it's own it's not bad at all, maybe a db or two, but when combined with some room gain, you'd have a peaky low end.

A great driver, just not LLT friendly. It would be nice if they made one that was.

**SteveCallas** · **09-20-07, 08:59 PM**

Ilkka, perhaps a silly question, but could you hear any sonic differences between the drivers just from testing them in free air with a FR sweep? When it comes to real material, I wonder if the difference would even manifest itself, as the other two drivers stayed below 5% at the same levels in the audible range, which isn't shabby by any means except when compared to the LMS. Seeing as the distortion on the other drivers only starts rising in the subsonic range, and the subsonic range is mostly limited to movie sound effects, I wonder how much of a difference it would make.

Don't get me wrong though, this driver is clearly superior, and it definitely gets the nod.

**Klip** · **09-21-07, 07:45 AM**

Quote:

Ilkka wrote:

Regarding those passive radiators. Mine have only single 10" spider; someone over at AVS posted pics of his PRs, and they have dual spiders?

For ease of reference, I'll post the pictures here also:

**Ricci** · **09-21-07, 03:24 PM**

No I actually wasn't kidding. It doesn't look that bad. Yes it gets a little peaky around 13-15hz, but it's only 2db's. Whats wrong with using a little EQ? The 10inch vent would have a port resonance of 172hz, kind of low, yes, but i've seen worse. Of course this is not what it was intended for, and the response does look like crap compared to a nice 400L enclosure. 13-200hz response within 3.5dbs is far from terrible though.Maybe my parameters are off slightly. Of course this is all just simulation anyway, and not real world measurement.

NO I would not actually use an LMS like that.

**funky_waves** · **09-21-07, 07:58 PM**

Quote:

noah katz wrote:

"If you're using 2 PR's per active then it should never be a problem."

I stick with my contention that it doesn't matter for a PR no matter how hard you drive it.

YAH RIGHT, lok what i did to mine, and they where the oem10 passives with extra strong cones. dual passive enclosure with a single OEM10 both passives went. took very little figer presure to turn the cone out like that afterwords

**WillyD** · **09-21-07, 08:10 PM**

What were the circumstances of that, noah? Enclosure size, tuning, power...

**SteveCallas** · **09-21-07, 08:29 PM**

Quote:

Yes it gets a little peaky around 13-15hz, but it's only 2db's.

Now factor in room gain.

**Ilkka** · **09-21-07, 08:40 PM**

Quote:

Ricci wrote:

No I actually wasn't kidding. It doesn't look that bad. Yes it gets a little peaky around 13-15hz, but it's only 2db's.

2 dB? Unibox shows closer to 5-6 dB when compared to proper LLT.

Quote:

Whats wrong with using a little EQ?

Most EQs can't equalize frequencies below 20 Hz.

**Ilkka** · **09-21-07, 09:03 PM**

Quote:

SteveCallas wrote:

Ilkka, perhaps a silly question, but could you hear any sonic differences between the drivers just from testing them in free air with a FR sweep? When it comes to real material, I wonder if the difference would even manifest itself, as the other two drivers stayed below 5% at the same levels in the audible range, which isn't shabby by any means except when compared to the LMS. Seeing as the distortion on the other drivers only starts rising in the subsonic range, and the subsonic range is mostly limited to movie sound effects, I wonder how much of a difference it would make.

Don't get me wrong though, this driver is clearly superior, and it definitely gets the nod.

Not a silly question at all, Steve. Yes, I could hear a difference between the drivers with just a sine sweep. The LMS sounds cleaner/purer than the TC2k or the SDX15. Especially during the two highest sweeps.

But you shouldn't look at the absolute distortion ("stayed below 5%") because that's just a random value, so to speak. This kind of near field free-air testing doesn't really reflect any kind of real world situation (minus dipole subwoofers). It's only good for comparison purposes.

The LMS-5400 18" seems to have around 6 dB more output than the TC-2000 15" while keeping the same distortion level. Typically 18" will gain around 2-3 dB over 15", so the LMS seems to be at least 3-4 dB better than a typical 18" LGLC (and I would say XBL^2, too) subwoofer when it comes to harmonic distortion. Not quite the full 6 dB TC Sounds promised, but still quite a lot. Of course harmonic distortion isn't everything. The free-air frequency response looks really good due to total lack of typical inductance hump (actually looks like a small notch instead). That should work really well when put in an enclosure. I doubt much EQ will be needed to bring it nice and smooth. So quite different than the sealed Tumult or the TC-2000s I measured last time.

Then there is also power compression. The massive 4" VC with titanium former should perform really well when some real men power will be utilised. Then we will know more about the real difference to "weaker" drivers.

But naturally the LMS-5400 isn't really for those looking for the best bang for teh buck...but I guess that's pretty obvious.

**WillyD** · **09-21-07, 09:07 PM**

Quote:

o quite different than the Tumult or the TC-2000s I measured last time. Then there is also power compression. The massive 4" VC with titanium former should perform really well when some real men power will be utilized. Then we will know more about the real difference to "weaker" drivers.

for a GP session this fall.

**SteveCallas** · **09-21-07, 10:35 PM**

Ilkka, the free air measurements of the two TC2k drivers appear to be better behaved at the top end as compared to the measurements while in an enclosure. Why is that?

According to Dan Wiggins (who has kind of been taken down a notch in my mind after your testing), inductance was supposed to be a big problme for LMS motor technology, but clearly that doesn't seem to be the case. So it begs the question of whether or not this motor technology could be put to use to make an ultimate midrange/midwoofer. I'm still puzzled why the Tumult had such poor inductance when the coil should theoretically be pretty short. Also, Dan appears to be off the target on his commentary on dual spiders as well.

**Iggster1986** · **09-21-07, 10:52 PM**

Quote:

funky_waves wrote:

YAH RIGHT, lok what i did to mine, and they where the oem10 passives with extra strong cones. dual passive enclosure with a single OEM10 both passives went. took very little figer presure to turn the cone out like that afterwords

I guess those ti cones would help then

**Ilkka** · **09-22-07, 12:42 AM**

Quote:

SteveCallas wrote:

Ilkka, the free air measurements of the two TC2k drivers appear to be better behaved at the top end as compared to the measurements while in an enclosure. Why is that?

Does it really?

If you look at the THD graphs below, you can see that the upper one does have a dip at around 18-21 Hz (orange curve). That's the Fs of the driver (18 Hz by the spec). THD dips there because current varying inductance Le(i) (also known as flux modulation) dips there too. Impedance peak is at Fs, so the current through the VC will be low.

When put in an enclosure, Fb raises up. Now the impedance peak is at around 40 Hz. That's the Le(i) and THD minimum point now. Sealed enclosure also prevents back wave cancellation, unlike free-air "alignment". Combine these two and you'll realize that it only seems like the driver would behave better at the upper-end while measured in free-air. Also notice that the absolute sound pressure levels between these two measurements can not be compared.

Quote:

According to Dan Wiggins (who has kind of been taken down a notch in my mind after your testing), inductance was supposed to be a big problme for LMS motor technology, but clearly that doesn't seem to be the case. So it begs the question of whether or not this motor technology could be put to use to make an ultimate midrange/midwoofer. I'm still puzzled why the Tumult had such poor inductance when the coil should theoretically be pretty short.

It seems that inductance and its effects on performance are probably one of the hardest things to simulate properly. The most commonly used, Le at 1 kHz, value is totally useless with subwoofer drivers. The more accurate Ls, Lp, Rp triplet seems to work pretty well with more traditional motor topologies, but not with LMS (or else the figures given by the TC Sounds are wrong).

It is also important to notice that the inductance varies with both excursion (Le(x)) and current/frequency (Le(i)). Here's an inductance simulation done on the AA Tumult 15D2 MK2. It was on AA's website while it was still up. Notice how the inductance raises really high during the backstroke, especially at low frequencies. That is normal behaviour since during the backstroke there is more iron inside the coil.

Below is a Klippel analyzer measurement on an Eclipse LMT SW8200 (by npdang at Diy Mobile Audio). It shows that the inductance variation with the excursion is really small. Maybe this is one of the reasons why the LMS seems to have such a good upper-end performance?

edit: These two inductance measurements are NOT comparable.

Quote:

Also, Dan appears to be off the target on his commentary on dual spiders as well.

Could you refresh my memory?

**SteveCallas** · **09-22-07, 01:04 AM**

Ilkka, I should have been more specific. I wasn't referring to the higher frequency distortion, but the actual FR. In the free air measurements, the dropoff at 100hz is less than it is when the driver is in an enclosure.

**WillyD** · **09-22-07, 01:13 AM**

Quote:

Ilkka wrote:

Could you refresh my memory?

I saw this the other day: http://forums.audioholics.com/forums...ad.php?t=21421

You posted in that thread.

Anyways, about half the way down, a post by ssabripo (from Wiggins) talks about dual spiders.

**Ilkka** · **09-22-07, 01:13 AM**

Quote:

SteveCallas wrote:

Ilkka, I should have been more specific. I wasn't referring to the higher frequency distortion, but the actual FR. In the free air measurements, the dropoff at 100hz is less than it is when the driver is in an enclosure.

Yes, that's the Qtc in effect. In free-air/IB the Qtc will be close to Qts, meaning very low (~0.3), but in an 70 liter enclosure (my own dual subwoofer), the Qtc will be around 0.7. That is what makes the frequency response to change its shape.

**Ilkka** · **09-22-07, 01:30 AM**

Quote:

WillyD wrote:

I saw this the other day: http://forums.audioholics.com/forums...ad.php?t=21421

You posted in that thread.

Anyways, about half the way down, a post by ssabripo (from Wiggins) talks about dual spiders.

Oh yeah, I remember that.

Well, even though I greatly respect Mr. Wiggins (and Hyre too), I have to say that the XBL^2 has been a slight letdown. So therefore I would take his "other" info with some reserve.

**ssabripo** · **09-22-07, 08:08 AM**

Quote:

Ilkka wrote:

Oh yeah, I remember that.

Well, even though I greatly respect Mr. Wiggins (and Hyre too), I have to say that the XBL^2 has been a slight letdown. So therefore I would take his "other" info with some reserve.

i wouldn't necessarily call it a "letdown" per se, but I hear ya.... In its defense though, I have to say the XBL^2 drivers I've played with (Avalanche, tumult) have had some of the cleanest, most accurate bass I've heard, including the older LMT15 (pre-cursor to the LMS 5400).

But yeah, some of the hoopla on the XBL^2 in that paper by Dan has been proven to not be exactly the case.

ps- just to clarify, not all those comments are straight from Dan. Some of it came comments from Deon Bearden and Tom Nousaine

**Ilkka** · **09-22-07, 01:11 PM**

Quote:

ssabripo wrote:

i wouldn't necessarily call it a "letdown" per se, but I hear ya....

I started to feel a little bit bad about that sentence so I edited it.

Quote:

In its defense though, I have to say the XBL^2 drivers I've played with (Avalanche, tumult) have had some of the cleanest, most accurate bass I've heard, including the older LMT15 (pre-cursor to the LMS 5400).

Exactly. And that leads us to the real million dollar question: Is slightly higher upper-end (say above 40-50 Hz) distortion actually preferred by many? Does it make the driver sound more accurate and punchy because there is more high frequency content in the mix?

**SteveCallas** · **09-22-07, 03:50 PM**

Quote:

I have to say the XBL^2 drivers I've played with (Avalanche, tumult) have had some of the cleanest, most accurate bass I've heard

Quote:

Is slightly higher upper-end (say above 40-50 Hz) distortion actually preferred by many? Does it make the driver sound more accurate and punchy because there is more high frequency content in the mix?

It would be nice to see an Avalanche 18 measured because some owners are saying there isn't enough punch in the higher frequencies. I have to think that be because it is clean near the top, and they want that synthetic punch. The Tumult that was measured IS a letdown to me - Dan could go on for pages about how everything he did was the right choice, but the measurements say something else. I dare say it measures poorly for the price - they were going for ~$600. I wouldn't be suprised to see the Avalanche at half the cost best the Tumult in just about every regard....except maybe for power hadling capability.

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