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Old Yesterday, 04:50 PM   #1
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Default Dual 18 Tapped Horn Design Concept

Hello all,

I've recently taken an interest in tapped horn subs and I wanted to pick the more experienced minds regarding this topic. Last fall I built two cabinets based on the Danley TH118 and now I would like to attempt a dual 18" tapped horn design where both drivers fire into a shared chamber.

I scratched out a doodle of the concept at work one day (please excuse the sloppiness). I am going to be making a more refined version in FreeCAD shortly. The flare rate with be optimized as well. So far my goal with this post is to explore the design concept and get your input on the design, primarily flaws and other important considerations.

I plan to use two 18 Sound 18LW1400 drivers (parallel)

Any comments/advice is always appreciated.

Thanks guys!
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Old Yesterday, 04:53 PM   #2
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Not sure if the attached file uploaded. Here it is again.

Click the image to open in full size.

http://imgur.com/u4sE0Wa
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Old Yesterday, 08:50 PM   #3
GM is offline GM  United States
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Well, due to its high Vas it wants to be up around 1300 L net for an Fs tuning, though with a bit of EQ it can get by with ~519 L net with a 3:1 CR. Still good for 130 dB/1 kW/m/2pi, so not too shabby.

GM
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Old Yesterday, 09:13 PM   #4
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Thanks GM,

My mind is still back in bass reflex land. How do you effectilytively calculate volume for a tapped horn? Throat to mouth volume?

The total box volume will be about 16' (4x2x2) or 453 liters. Hmmmm so the box should be bigger from what I'm gathering. I'd like to keep those outer dimensions so I can fit the box in my vehicle for transport.

Perhaps another driver with lower vas?

Thanks.
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Old Yesterday, 11:18 PM   #5
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Thanks GM,

My mind is still back in bass reflex land. How do you effectilytively calculate volume for a tapped horn? Throat to mouth volume?

The total box volume will be about 16' (4x2x2) or 453 liters. Hmmmm so the box should be bigger from what I'm gathering. I'd like to keep those outer dimensions so I can fit the box in my vehicle for transport.

Perhaps another driver with lower vas?

Thanks.
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Old Yesterday, 11:41 PM   #6
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Why not use the 2400 model 18?

It works well in smaller cabinets.
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Old Today, 12:16 AM   #7
GM is offline GM  United States
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Quote:
Originally Posted by SUBduction View Post
Thanks GM,

My mind is still back in bass reflex land. How do you effectilytively calculate volume for a tapped horn? Throat to mouth volume?

The total box volume will be about 16' (4x2x2) or 453 liters. Hmmmm so the box should be bigger from what I'm gathering. I'd like to keep those outer dimensions so I can fit the box in my vehicle for transport.

Perhaps another driver with lower vas?

Thanks.
You're welcome!

Correct for net Vb and + any losses through the bend[s], divider[s], bracing.

Correct.

Yes, a lot lower, like at least in half, i.e. the same driver specs except 1/2 Vas = ~346 L net, though of course efficiency/peak SPL drops too, HR predicts ~3.5 dB.

GM
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Last edited by GM; Today at 12:22 AM.
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Old Today, 03:24 AM   #8
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This is great! I really want to pick the best driver for the box. I'd love to find a balance of SPL and response.

So GM, I'm curious where a net vas of 1300 L is determined. I know I'm missing something here: 18LW1400 vas = 297 L x 2 drivers = 594 L + (?) = 1300 L. I did see the 18LW2400 has a vas that is 1/2 my cabinet size. Would this be more optimal? If not, why?

http://www.eighteensound.it/Portals/0/PDFs/18LW1400.PDF

http://www.eighteensound.it/Portals/0/PDFs/18LW2400.PDF
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Old Today, 03:34 AM   #9
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What extension are you after?

Your not going to be able to do dual 18 TH get it into a tiny cabinet and have any real spl near 40hz.

The TH18 is a single 18" cabinet and about 320 liters net design. Thats before you build it. So for dual 18's I would look at something like a pair of those cabinets in a singe cabinet. 650l design.

Or look for higher tuned TH's like the SS15 but in18 design.

Your other bet is to build a hybrid cabinet using the 18 LW1400 that you have. Did we establish you have these already?

If you do own these already then build a dual Cubo 18 in a single cabinet. Will be about 48" x 24" x 24" roughly.
https://freespeakerplans.com/plans/1...cab/11-cubo-18
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Old Today, 05:37 AM   #10
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Thanks chrapladm,

I like the cubo 15 ext so much I built 4 using the Dayton PA380. Great results for a $75 driver. The Cubo 15 ext has pretty good punch so I'm looking to add extension below 40 Hz, say about 30-40Hz. I'm not opposed to a single driver design If I can get solid performance from it. Cubo sub looks like it will extend into the 30-40 Hz range fairly well. I also know the 18LW1400 was used in the Cubo 18 by the designer... Hmmm, it may not be as original of a design but results are results.

I wonder what kind or extension and SPL I can get hypothetically from 350 L dual tapped horn. I would imagine much more SPL than extension.

Again, Thanks everyone.
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