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Author Topic: Plans for this 21" 18sound speaker?  (Read 9132 times)

Tim Weaver

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Re: Plans for this 21" 18sound speaker?
« Reply #10 on: February 23, 2014, 06:56:56 pm »

From my earlier design I figured that one 21LW1400 in a good box would be *almost* equal to an SRX728 in regards to efficiency and maximum CLEAN output. You can push the 728 quite a bit harder into the badlands of distortion, power compression, and voice coil burnage. But apples to apples the 18 sound driver would hold it's own just fine.

I'm not sure this driver would be worth it to put in a horn anyway. It would have to be a huge horn to do any good at all. The 21LW1400 will play nicely into the mid 30's in a reasonable sized box.
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Bullwinkle: This is the amplifier, which amplifies the sound. This is the Preamplifier which, of course, amplifies the pree's.

Onlin Barna

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Re: Plans for this 21" 18sound speaker?
« Reply #11 on: February 23, 2014, 08:23:57 pm »

Thanks for all the replies, its great that people can always learn here. :)

By the way,  I haven't bought the speaker yet. I am also considering 18LW1400. Its almost half price so I could get double pcs for the money. (First 1 or 2 then 4 or 8 pieces)

I have found only one plan for that speaker: http://wizardaudio.hu/hasznos/hangfal%20tervek/bass/bass%20reflex/pdf/18Sound%20Kit18%20B.pdf

But if you have or can make a horn plan for it, Im interested!
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Peter Morris

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Re: Plans for this 21" 18sound speaker?
« Reply #12 on: March 31, 2014, 01:11:30 am »

Thanks for all the replies, its great that people can always learn here. :)

By the way,  I haven't bought the speaker yet. I am also considering 18LW1400. Its almost half price so I could get double pcs for the money. (First 1 or 2 then 4 or 8 pieces)

I have found only one plan for that speaker: http://wizardaudio.hu/hasznos/hangfal%20tervek/bass/bass%20reflex/pdf/18Sound%20Kit18%20B.pdf

But if you have or can make a horn plan for it, Im interested!


FWIW I have a very similar box (220L @ 35Hz) load with the 21LW1400. Its sounds great, everyone thatís uses it just loves the sound.  I have also use the 18Lw1400 in that box - in comparison the 21 goes, as a guess, about 4dB harder with similar input and sounds a little better.  The extra output isnít apparent until you start to push the level up.
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Tim Weaver

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Re: Plans for this 21" 18sound speaker?
« Reply #13 on: March 31, 2014, 01:29:05 pm »

Thanks for all the replies, its great that people can always learn here. :)

By the way,  I haven't bought the speaker yet. I am also considering 18LW1400. Its almost half price so I could get double pcs for the money. (First 1 or 2 then 4 or 8 pieces)

I have found only one plan for that speaker: http://wizardaudio.hu/hasznos/hangfal%20tervek/bass/bass%20reflex/pdf/18Sound%20Kit18%20B.pdf

But if you have or can make a horn plan for it, Im interested!


OK, since you seem to be thinking that "Larger=Louder" I'll explain the problem to you in a pretty simple way. Horns put a LOT of stress on a cone driver. A bigger 18" or 21" cone simply can't resist the bending forces inside a horn's compression chamber as easily as a 12" or smaller cone can. That's why you see a bunch of horn sub designs with 12" drivers in them. As of today's technology the 12" sized driver has a strong enough cone, and is big enough to mount a strong motor to the frame which results in the best candidate for a horn driver.

In a horn, the speaker is like an engine in a car. There are many other factors that play into how loud the system gets. The size of the driver is just not that important when you factor in all of the other things.


In a bass reflex cabinet, the amount of air displaced by the driver is the biggest factor in how loud it can get. That's why we see 18"'s and 21"'s in standard BR cabinets. The huge cones sweep a lot of air. A 12" driver would have to move in and out about 4 times as much as an 18" to sweep the same volume of air.
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Peter Morris

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Re: Plans for this 21" 18sound speaker?
« Reply #14 on: April 01, 2014, 10:59:56 am »


OK, since you seem to be thinking that "Larger=Louder" I'll explain the problem to you in a pretty simple way. Horns put a LOT of stress on a cone driver. A bigger 18" or 21" cone simply can't resist the bending forces inside a horn's compression chamber as easily as a 12" or smaller cone can. That's why you see a bunch of horn sub designs with 12" drivers in them. As of today's technology the 12" sized driver has a strong enough cone, and is big enough to mount a strong motor to the frame which results in the best candidate for a horn driver.

In a horn, the speaker is like an engine in a car. There are many other factors that play into how loud the system gets. The size of the driver is just not that important when you factor in all of the other things.


In a bass reflex cabinet, the amount of air displaced by the driver is the biggest factor in how loud it can get. That's why we see 18"'s and 21"'s in standard BR cabinets. The huge cones sweep a lot of air. A 12" driver would have to move in and out about 4 times as much as an 18" to sweep the same volume of air.

Hi Tim,

I think that was certainly true of old driver designs, but there are lots of 18Ē even 21Ē drivers that are now suitable for horn loading.
Here's a new one from 18sound - http://www.eighteensound.com/PRODUCTS/Products/ProdID/63/CatID/8#.UzrTfWkbrq4

@ Onlin here is a horn design for an 18sound driver like the one you mentioned - http://www.eighteensound.com/Portals/0/EnclosuresKits/18sound_18%20horn%20loaded.pdf
« Last Edit: May 09, 2014, 10:07:24 am by Peter Morris »
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duane massey

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Re: Plans for this 21" 18sound speaker?
« Reply #15 on: April 01, 2014, 06:13:55 pm »

Interesting. In the full-size straight horns I have built over the years I found pretty much the opposite to be true as far as stress goes. In the biggest horns I've ever built (20hz horn w/ 5 15" woofers) one of the biggest surprises for most people who were brave (or foolish) enough to venture all the way into the horn was how little cone movement there was.
I can certainly see where smaller folded horns could be problematic, but I typically neither design or build these.
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Duane Massey
Technician, musician, stubborn old guy
Houston, Texas
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