Any chance of doing a folded horn with 10'' depth? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 20 Old 05-29-2015, 04:16 PM - Thread Starter
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Any chance of doing a folded horn with 10'' depth?

Is there a way to do a folded horn sub with a 10'' depth? What is the software for modelling horn enclosures?

I'm thinking of doing a 70''x30''x10'' (WHD) folded horn sub to be placed behind my couch. Is it possible to get a 20Hz tuning with say a LAB 12 woofer under those dimension requirements?

Oops, I made a wrong measurement (measured the height of the arm rest instead of the height of the sofa...). The new height requirement has expanded from 20'' to 30''. The width requirement has gone up to 70'' from 50''.

Last edited by bcodemz; 05-30-2015 at 08:54 AM.
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post #2 of 20 Old 05-29-2015, 04:24 PM
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12" speaker in a 10" horn will have some problems.


Try: https://www.avsforum.com/forum/155-di...pped-horn.html
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post #3 of 20 Old 05-29-2015, 06:20 PM
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A depth of 10" is possible, but not a horn length of 50inches.

My HzHorn is like 27ft long (an order of magnitude longer), and but could be re-fitted for a depth 14inches no problem; and that is a BIG motor on an 18", a smaller cone and motor could fit in 10inches no problem.
The length would have to be 8 or 16ft at minimum I would think! (So an IB-wall.)
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post #4 of 20 Old 05-29-2015, 09:17 PM
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post #5 of 20 Old 05-29-2015, 09:23 PM
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Quote:
Originally Posted by bcodemz View Post
Is there a way to do a folded horn sub with a 10'' depth? What is the software for modelling horn enclosures?

I'm thinking of doing a 50''x20''x10'' (WHD) folded horn sub to be placed behind my couch. Is it possible to get a 20Hz tuning with say a LAB 12 woofer under those dimension requirements?
Picowrecker is ~ 45x23x13...and that is with a 10" driver.

Also only digs down to 25 Hz.

Hoffman's Iron Law still applies.
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post #6 of 20 Old 05-30-2015, 05:57 AM
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The TH spud is only 11" wide and that's with a pair of 8" drivers. I've seen some diy builds people sound pretty happy with.


I second the vote for the Anarchy TH. only goes down to 25Hz but for the size the output and impact are amazing. I've got a pair run in stereo in my front end, they are excellent. and don't take much power to really rock.

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post #7 of 20 Old 05-30-2015, 08:23 AM
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Quote:
Originally Posted by bcodemz View Post
Is there a way to do a folded horn sub with a 10'' depth? What is the software for modelling horn enclosures?

I'm thinking of doing a 50''x20''x10'' (WHD) folded horn sub to be placed behind my couch. Is it possible to get a 20Hz tuning with say a LAB 12 woofer under those dimension requirements?
Not with those dimension requirements, no -- there isn't enough space in there to get the path length or the volume.

The Anarchy that's been mentioned a time or two is close, but it won't get to 20 Hz, and I think it's more than 20" tall when you lay it on its back . . . but if you could accept that, you could get pretty close to having two of them behind the couch. The SPUD is the other good candidate that was mentioned, though it's also more than twice as tall as you want it to be.

But that's just the price of making low frequencies with horns. Bigness is mandatory.

If it's going right behind the couch and you're set on the Lab12 (because you have one already?) then you're probably better off with a ported box. You'd be close enough to it to get that visceral punch out of it, and boxes are a lot more dimensionally flexible than horn folds are. IMO, etc.
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post #8 of 20 Old 05-30-2015, 08:39 AM - Thread Starter
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Sorry guys, I made a stupid mistake in measuring. The height requirement is now 30'' instead of 20''. The width requirement is now 70'' instead of 50''. I think that'll make things a lot easier with double the box size.

Does anyone know what is the relationship between box size and a horn's low frequency knee, when everything else is the same? I.e. for ported enclosures a 4x increase in the length of the vent is required to reduce the tuning frequency by half. What is it for folded horns?

The Lab 12 is just a good 12'' horn suitable woofer that came up in my mind as I was typing. Realistically I was just wondering if I can build a 12'' folded horn sub that'll get me 20Hz under those box requirements. If not, 10''? 8''?

The TH Spud is interesting, but I'd prefer single drivers if possible, unless there are advantages with dual drivers.

Last edited by bcodemz; 05-30-2015 at 08:54 AM.
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post #9 of 20 Old 05-30-2015, 09:01 AM
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Look up the Lab12 tapped horn on diyaudio -- 20 Hz with a Lab12 in a 30x60 enclosure. But I think it's 14" deep, not ten.
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post #10 of 20 Old 05-30-2015, 09:05 AM
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You may also want to ask over on the sub forum at diyAudio. There are some really good designers over there but you need to be really specific with what are asking for as they tend towards pro audio.

As for programs Hornresp is the easiest to model horns.

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post #11 of 20 Old 05-30-2015, 09:19 AM
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An advantage of dual drivers is more SD for a given width.

IMO this might be a better case for typical sealed or ported. If it's right behind the couch having multiple drivers firing directly into the back of each seat might provide a better experience than a horn.

Is there a budget? Do you have an amp already?
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post #12 of 20 Old 05-30-2015, 09:49 AM
 
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Quote:
Originally Posted by bcodemz View Post
Does anyone know what is the relationship between box size and a horn's low frequency knee, when everything else is the same?
There is none. The low frequency knee is primarily determined by the horn length, the sensitivity at the horn knee primarily by the mouth area. But as for box size there are many other variables. For instance, the smaller the driver the smaller the rear chamber and throat size, which can result in a smaller box without affecting Fc and/or sensitivity. There's no substitute for experience where designing folded horns is concerned. If designing a ported box is a game of checkers then a folded horn is 3D chess.
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As for programs Hornresp is the easiest to model horns.
+1, but the calcs are only about 20% of the overall process.
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post #13 of 20 Old 05-30-2015, 11:33 AM
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+1, but the calcs are only about 20% of the overall process.
No doubt...sims only get you so far!

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post #14 of 20 Old 05-31-2015, 05:30 AM - Thread Starter
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Originally Posted by Bill Fitzmaurice View Post
There is none. The low frequency knee is primarily determined by the horn length, the sensitivity at the horn knee primarily by the mouth area. But as for box size there are many other variables. For instance, the smaller the driver the smaller the rear chamber and throat size, which can result in a smaller box without affecting Fc and/or sensitivity. There's no substitute for experience where designing folded horns is concerned. If designing a ported box is a game of checkers then a folded horn is 3D chess.
+1, but the calcs are only about 20% of the overall process.
How much longer does the horn has to be to lower the low frequency knee by an octave?

Where can I read and learn more about horn design?
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post #15 of 20 Old 05-31-2015, 06:27 AM
 
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Originally Posted by bcodemz View Post
How much longer does the horn has to be to lower the low frequency knee by an octave?
Twice as long.
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Where can I read and learn more about horn design?
A HornResp tutorial would be best. There are examples on-line. Most horn theory dates to the 1930s and 40s, and that's pretty much what you'll find as far as books are concerned. But those texts all pre-date T/S by decades, so they're of only limited use where modeling is concerned. Main stream horn research was pretty much abandoned with the advent of high power SS amplification in the 1970s, especially with respect to bass horns, so little printed material exists that ties together classic horn theory and T/S.
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post #16 of 20 Old 05-31-2015, 01:31 PM - Thread Starter
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Decided to go with a ported sub instead of a horn. I can put 2 woofers in the same sized cab and achieve almost the same output as a single woofer horn, and the time needed to learn about horns well is not worth it.

Now on the search for a good driver <7'' deep.
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post #17 of 20 Old 05-31-2015, 02:08 PM
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Originally Posted by bcodemz View Post
Decided to go with a ported sub instead of a horn. I can put 2 woofers in the same sized cab and achieve almost the same output as a single woofer horn, and the time needed to learn about horns well is not worth it.

Now on the search for a good driver <7'' deep.
You can always angle the driver if you can't find one to fit your maximum depth requirements.

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post #18 of 20 Old 05-31-2015, 02:24 PM - Thread Starter
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You can always angle the driver if you can't find one to fit your maximum depth requirements.
What do you mean by angle the driver?
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post #19 of 20 Old 05-31-2015, 02:31 PM
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Originally Posted by bcodemz View Post
What do you mean by angle the driver?
Something like what @carp did with his nearfield sub.
http://s232.photobucket.com/user/car...dur3f.jpg.html

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post #20 of 20 Old 05-31-2015, 03:28 PM
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Something like what @carp did with his nearfield sub.
http://s232.photobucket.com/user/car...dur3f.jpg.html

I love it, being able to still fully recline while keeping the driver as close as possible was a must. Doug (d_c) built it for me and it turned out great.
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