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Discussion Starter · #1 ·
It is time. I have two of the 15" LMS-5400's. I have woodworking abilities. I have room behind the front wall of my theater. I have the need for high output at very low frequencies. What I don't have is any clue how to do much of anything in Hornresp. I have tried. I have done tutorials. It all spirals downward once I get very deep into it. I PM'ed max, and he gave me preliminary possibilities for success. So, I am asking for a collaborative effort here to design horns for these drivers that reach down to 10Hz with authority. I will have the higher bass frequencies covered, so I want to concentrate on VLF. The driver parameters as measured by Praxis:


Qts .341 .311

Qes .367 .335

Qms 4.786 4.223

Fs 22.951 21.323

Res 3.9 3.9

Ls 2.252 2.184

Lp 4.459 4.421

Rp 2.727 2.657

Sd 850 850

Vas 107.3 128.1

mms 460 446.5

cms 104.5 124.7

bl 26.55 26.38

n0 340 356.4

Splsens 87.31 87.52


If you horn gurus design it, I will build it. I will have it measured by a pro. Let's see what The Fatterhorn can do!
 

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I'll play along just cause of the name...



10 Hz = ~30 feet of horn. 2 15's = big horn regardless. This thing is not gonna be small.


Couple of things that will help:


Measurements and/or a sketch of the space you have to park this thing


Targets (efficiency, response, power handling....)
 

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I imagine the first set of numbers is spec, and the second set measured????


With Mike on board, I will guarantee you this: he will hit targets with a smaller box than I can. No question. A front loaded horn requires a rear chamber that takes away from horn path length and volume. A tapped horn does not suffer such space requiring problems, but has other compromises, again, it's a choice.....next stop, 10Hz horn!


Very interested to see what people come up with....


JSS
 

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Discussion Starter · #6 ·
I can do two enclosures, or just one if that is better. I have 10' x 8' x 32" to work with(the area in green on this pic). I will have to fire through the front wall.




I have CE4000's for each driver on 220V plugs, so I have 3600W available for each if needed. They roll off under 8Hz. So response from 8Hz to 30Hz would be fine. Anything above that is fine too, but I know how shifting response lower also shifts the uneven response area lower as well.
 

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OK, I have them averaged, and I am working with them in V8 of soho54s spreadsheet.


Specs I am using are:


Qts 0.326

Qes 0.351

Qms 4.5045

Fs 22.137

Res 3.9

Ls 2.218

Lp 4.44

Rp 2.692

Sd 850

Vas 117.7

mms 453.25

cms 114.6

bl 26.465

n0 348.2

Splsens 87.415
 

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oooh boy...
 

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Fatawan, are you replacing the DTS-10(s)?
 

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Discussion Starter · #15 ·
Quote:
Originally Posted by lilmike
OK - here's a tapped horn starting point.


Nothing special here, just threw the data into HornResp and made a tapped horn.
Mike:


It appears that setup has the driver over Xmax with anything above ~100W. With that amount of power, I get 107db at 10Hz, 117db at 17Hz, and 110 at 30Hz--sound right? Is that 17Hz peak(which is also peak driver displacement) typical?
 

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I can't find a 15" LMS 5400. I only see 18" version. Where did you get that from?


I'm excited to see what you guys come up with!!
 

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I hope you don't lose sight of the fact that just because you have the drivers it may make more sense to get ones more suited for horns.


One scenario is that you it takes 4X the power (making up the numbers) to do the same thing as with another driver.


But who knows, maybe you'll be able to use the xmax to advantage at the low end.
 

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Just as predicted, lilmike will generate a smaller box for the same output:


This sim is two horns of each type, corner loaded, 1W into each horn:




Same thing, quick 5 min in hornresp to se whatthe driver would like, OD/FLH-wise....


Very similar responses. For a first try, the Tapped horn doesn't have super-huge dips, which is a great plus, and hornresp exaggerates them anyway.


Excursion is essentially equal between the two boxes, the OD FLH peaks at 8Hz, the tapped horn may require some highpassing, as the driver unloads uncontrollably under 8Hz (according to hornresp). But with your signal chain, not a problem.


This driver doesn't really model that well in an OD FLH horn.....rear chamber size is very big. To tell the truth, a DTS-10 and a horn like this (tapped or OD) would be quite similar....the two 12"ers in the DTS-10 probably have about as much displacement as the LMS....make no mistake. In horns tuned this low with limited mouth area, displacement is still VERY important.


I agree that two horns would be best (one driver in each), to cancel some room modes.


I think it is a toss up. If you have the space, either box will serve VERY WELL, with ~120dB on tap from 8Hz on up (and over 125dB from 10Hz on up) with two of them corner loaded before room gain.... If you are space challenged, no question. TH wins.


JSS
 

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Hmmm - what is the xmax? (I have it on very good authority that it is 38 mm)


I confirmed that the LMS 5400 has linear excursion of 38 mm, and at 20 volts (100 W into 4R), I only get 10 mm of travel at 14 Hz. With a kilowatt, I get 33 mm, which is still within the xmax. Actual excursion may be lower than predicted. That is usually the case with my builds, but I typically don't tune mine to 10 Hz....cause I can't afford those drivers.



As I said - that is a starting-point simulation, certainly nothing to go cut plywood based on. I just wanted to get the parameters into the software so we all had a uniform starting point.


Someone else should probably check my entries - I coulda fat-fingered something.


Believe me - I can't properly design one of these in five minutes while multi-tasking at the office.....I'm not that good (or that lucky).

 

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Quote:
Originally Posted by lilmike
I can't properly design one of these in five minutes while multi-tasking at the office.....I'm not that good (or that lucky).

Ha! I am on vacation this week, and I should be building and hanging bass traps instead of screwing around on forums...


Oh yeah, if you highpass 2 of these and corner load, highpass to begin cutting below 10Hz, you can get over 130dB from them. But seriously, will you need that much? In my limited experience, I find that if a box can sim at 125dB corner loaded at Xmax, you have enough to do reference level cleanly (
 
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