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AK Design Collaborative - Insubnia

My plan was to unveil a tapped horn serving as a stand for my MBOW1s for the fest but life seems to get in the way.
 
OK folks, as promised, the first iteration of the Insubnia...

Goal: to get as much extension (30Hz and possibly below) and output in a small(ish), economical package....

Here's the hornresp input window for a front-loaded horn using the TB WS1139SI, using the manufacturers T/S params:

Insubnia%20Input%20window.png.jpg


2V response, 1/2 (2Pi) space:

Insubnia%202V%202Pi%20Resp.png.jpg


The great thing about horns...move them inside and stick them in a corner:

Insubnia%202V%20half%20Pi%20Resp.png.jpg


Now, put some juice in....without a high-pass filter, the design can take 15V in before exceeding Xmax at 25Hz:

Insubnia%2015V%20half%20pi%20resp.png.jpg


Here's the excursion graph for 15V in:

Insubnia%2015V%20half%20pi%20excursion.png.jpg


I decided on an 85dB sensitivity to match the Indignias, and to get a smaller package. Volvotreter's tapped horn is also a great option, and is a more efficient design sensitivity-wise; I just prefer front loaded horns...

So, how big is it? Using 3/8" MDF, 20"x20"x8.75".

Here's what it looks like:

Insubnia%20overview.jpg


Insubnia%203D.jpg


Insubnia%20Measurements.jpg


To get 85dB sensitivity at 25Hz, you need 2x the size. Using the TB W8740P, you can get a few more dB for only ~10 more liters in size...but the response is not as flat from 30-70Hz, it rises a tad bit more...but you can get more overall output....

Make the TB W8-740P a 20Hz horn, and you double the size. I thought the WS1139SI was a good compromise in size vs output...

JSS
 
It's mighty amazing to be getting 115 dB out of just one these little drivers down there.... :yes:

Danley DTS-10:

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Hm. Wonder what I could do with a roughly 3 foot by 2 foot by 2 foot space, and an 18" woofer? :D

Regards,
Gordon.
 
ArtD said:
I read VT's site a while ago and imagined the long version of the tapped horn lying on its side with speakers sitting on top of it at either end with books, etc. in-between them. It could be quite unobtrusive used that way (providing you have an empty wall to lie it against) and gets your floor speakers up to a better height for listening.
Click to expand...

I've always thought that building a sub into TV stand/media cabinet would be a good way to make a large box disappear. Shelves or drawers up front and the sub compartment in the rear or bottom. The suggested 20 x 20 x 9 size certainly is in the range of a component cabinet...rack-mount subwoofer anyone? Good luck, it looks like a fun design-build project.

I'll stick with my 8 ft^3 sub for now.
 
GordonW said:
Hm. Wonder what I could do with a roughly 3 foot by 2 foot by 2 foot space, and an 18" woofer? :D

Regards,
Gordon.
Click to expand...

Lots....12 cu ft can get you into 20Hz territory at decent volumes (still not reference, but close though). Hoffman's still applies for horns... Small, loud, low. Pick two. I chose small and low for this one.

With that space, a double W8-740P horn can get you far...for only $100 in drivers....

There is a hornresp tutorial over at AVS for simple front loaded horns:

http://www.avsforum.com/avs-vb/showthread.php?t=1211856

and for tapped horns:

http://www.avsforum.com/avs-vb/showthread.php?p=17835074#post17835074

This horn will be the subject of my design, fold and build your own bass horn tutorial....

JSS
 
The point would be, would it be remotely practical to build a tapped horn around an 18" woofer.

I might be able to persuade the powers that be to go as tall as 4 feet... 2 feet wide, 2 feet deep...

The entire purpose would be to be so loud, as to never have to turn it up remotely close to full volume. Ever. :D

Regards,
Gordon.
 
GordonW said:
The point would be, would it be remotely practical to build a tapped horn around an 18" woofer.

I might be able to persuade the powers that be to go as tall as 4 feet... 2 feet wide, 2 feet deep...

The entire purpose would be to be so loud, as to never have to turn it up remotely close to full volume. Ever. :D

Regards,
Gordon.
Click to expand...

I am working with someone on a horn for the 18" Maelstrom. 17Hz horn, over 50 cuft. He is putting them in the ceiling...

JSS
 
I'm not sure I understand the idea of giant horn subs. By the time they are playing typical sub frequencies, the horn is no longer working like a horn. You do get some room gain down low, I suppose.
 
The big Mael horns will be horn loaded to around 17Hz. They will rock above 40Hz. The person wanted 140dB at 1m....I'm just trying to oblige...

As far as not being horn loaded at typical bass freqs, they act more like quarter-wave resonators near the corner freq, but the gains are for real...

Here's the Insubnia, next to the same driver in a 20 liter box, same 2V in, 1/2 space:

Insubnia%20vs%20sealed.png.jpg


JSS
 
Hmmm, I wonder how my Elemental Designs 3.6 6.5" subs would do in this TH. I have a pair loaded into a chambered TH (for lack of a better explanation right now) in my car. Would love to maybe do a pair of these and use them as the base for my mains.
 
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maxmercy said:
The great thing about horns...move them inside and stick them in a corner:

Insubnia%202V%20half%20Pi%20Resp.png.jpg


JSS
Click to expand...

All subs see similar boundary reinforcement when put in a corner. True horns have their LF cutoff extended in the corner but this does not being more like a TL bandpass.
 
dnewma04 said:
I'm not sure I understand the idea of giant horn subs. By the time they are playing typical sub frequencies, the horn is no longer working like a horn. You do get some room gain down low, I suppose.
Click to expand...


I had been been reading everything I could find regarding LF horns when I started my all horn speaker project some time ago now . If I remember correctly, a horn loaded woofer would act as a horn down to it's resonant frequency and anything lower than that, a direct radiator. Do I have that right, Dave?


During that period, I spent quite a bit of time on the Volvotreter site. Although I wasn't following a lot of it, I found it to be fascinating stuff. I'm looking forward to following this thread to see where it takes everyone :yes:

RC
 
It will act like a horn to the rooms corner frequency. Once the wavelengths start to overwhelm the dimensions of the room, it does act like a direct radiator.
 
doucanoe said:
I had been been reading everything I could find regarding LF horns when I started my all horn speaker project some time ago now . If I remember correctly, a horn loaded woofer would act as a horn down to it's resonant frequency and anything lower than that, a direct radiator. Do I have that right, Dave?


During that period, I spent quite a bit of time on the Volvotreter site. Although I wasn't following a lot of it, I found it to be fascinating stuff. I'm looking forward to following this thread to see where it takes everyone :yes:

RC
Click to expand...

It is the flare rate and mouth area that determine the LF cutoff of the horn - it has little to do with the driver.
Consider that if it flares out fast you are making a midrange horn, the flare has to be gradual in proportion to
the wavelengths.

If the mouth sees an impedance mismatch to the air then the energy put in is reflected back down the line
rather than radiated, the mouth has to be large as compared to the wavelengths for a good impedance match.

The "horn" under consideration here is acting like a horn above 100 Hz where you see numerous peaks and
dips due to reflections.
 
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