I'm thinking about building a pretty big BLH into a bookcase. It would use a Fostex FE166. It would have a path length of 3.1meters (~ 10ft) and a fairly big moth area of 2100 sq cm. The mouth is at the top and is ceiling loaded. The horn would be built into a false back in the bookcase and the driver would look like it is in a small box sitting on one of the shelves (see attached sketches). The mouth flare pretty much relegates the top shelf to knickknacks and pictures but the lower shelves are deep enough for DVDs and moderate size books. It sims pretty well in hornresp (see attached picture) which shows it getting down to close to 40hz.
I realize there are going to be some pretty severe placement limitations: it's going to be against a wall and the separation is going to have a pretty small range. Toe-in is not an option but I could make angled baffles and get 10-12 degrees if it was important. These horns/bookcases would live in my family room so positioning options, even for smaller speakers, are pretty limited too.
Why am I doing this? I haven't built a speaker in a couple of years and really want to try designing and building a big horn. I also know that if I want to ever take it out of the basement it's going to have to not look like a big horn.
Has anyone seen something similar? I'm just starting on this so any thoughts, comments are welcome.
I realize there are going to be some pretty severe placement limitations: it's going to be against a wall and the separation is going to have a pretty small range. Toe-in is not an option but I could make angled baffles and get 10-12 degrees if it was important. These horns/bookcases would live in my family room so positioning options, even for smaller speakers, are pretty limited too.
Why am I doing this? I haven't built a speaker in a couple of years and really want to try designing and building a big horn. I also know that if I want to ever take it out of the basement it's going to have to not look like a big horn.
Has anyone seen something similar? I'm just starting on this so any thoughts, comments are welcome.
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that's an inspired packaging solution. one quick thought (w/o looking at your flare) is just rearranging s2-s6 to contain everything and then using s1 to s2 to play with small pieces to build as wedges or something to allow toe-in. if it's not too egregious, it'd be great to have every possible bit of flexibility to make sure TheCommitment is honored 
right away I was thinking that'd be a pretty sweet way to stash a bib too. nice.
right away I was thinking that'd be a pretty sweet way to stash a bib too. nice.
Thanks for the encouragement. I've got a bad summer cold so I probably won't start building until next week. While I'm feeling sorry for myself, I've played around some more with Hornresp. It looks like the basic design will work well with the Fostex FX120, with some minor changes to the throat and rear chamber volume. I've attached the FX120 sim below. Now I'm not sure which driver to use. I have both on hand.The FX120 seems to go a couple hertz lower than the FE166 and plays a few dB louder due to it's bigger xmax. The FX120 in this bookcase horn looks like it could go almost an octave lower than the same driver in my Pretty Big Horn from a couple years back. This is pretty exciting because the Pretty Big Horn, subjectively, had pretty good bass. I've attached a comparison of the FX120 in the Bookcase Horn (black line) and my Pretty Big Horn (light blue line).
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Drew up a similar project a couple of years ago - but SWMBO shot it down. The left side drawing shows how things would look in a OB configuration for the mid with a small Eminence horn - Eminence 6 for mids - Eminence 15 beta for bass in Uframe. The concept being that the speakers could "fold away" into the bookcase when not in use.
The right side shows the configuration for using the bookcase to camouflage a tapped horn woofer with a line array.
Of course you would need to use the same speaker array on each side - the drawing is simply to compare how things would look.
The second sketch up is a unit that was inspired by "Lord of the Rings" and I called them the Twin Towers
The right side shows the configuration for using the bookcase to camouflage a tapped horn woofer with a line array.
Of course you would need to use the same speaker array on each side - the drawing is simply to compare how things would look.
The second sketch up is a unit that was inspired by "Lord of the Rings" and I called them the Twin Towers
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Perhaps you can turn the opening so that the mouth fires from the upper shelf into the room rather than upwards? Otherwise a lot of the soundwaves will reflect back from the ceiling into the horn, possibly colouring the sound. Also, the top shelf can't really be used for storing anything anyomore.
Talearts - That's an interesting idea. I thought of something like that early in the design but was worried that exiting at the front shelf would put the mouth too far from the corner to get the full effect of the corner.
What I'm thinking about now is putting a 45 degree reflector in the top back corner and opening up half of the top. That way, half the sound would exit at the top while the other half would exit out the front shelf (which would be partially obstructed by whatever photos and nicknacks we place there). I'm still working out details but I'll try to post some updated sketches in the next day or so.
What I'm thinking about now is putting a 45 degree reflector in the top back corner and opening up half of the top. That way, half the sound would exit at the top while the other half would exit out the front shelf (which would be partially obstructed by whatever photos and nicknacks we place there). I'm still working out details but I'll try to post some updated sketches in the next day or so.
Here are some new sketches with a combined top/front mouth. I'm also showing some of the internal bends rounded off. I'm thinking of building it with square bends and then rounded bends and measuring the differences. I've also changed the width to 30" to improve the WAF a bit. I'm including another hornresp sim with the new dimension.
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I finally have a "final" design. I'm going with the Fostex FX120 and I've reduced the footprint again. It's now 12.75" d X 24" w X 78" h. This improves the WAF and only costs me a couple hertz on the low end and a fraction of a dB output at 1 watt compared to my previous 13.25" X 30" X 78" design.
I've included new sketches, including one view that shows the curved deflector right behind the throat opening to the speaker box. I've also included a larger scale detailed drawing of the bottom 42" high by 3.5" deep section of the horn. This drawing shows the detailed dimensions and shapes. The "teardrop" internal partition and deflectors will be made of 3.5" solid wood. This will be made of a sandwich of two pieces of 2" X 6" lumber (actual dimensions: 1.5" X 5.5") and one piece of 1/2" plywood or MDF. I've got a band saw so cutting the full 3.5" thickness won't be a problem. You could also use a jig saw but you would probably have to cut the three pieces first then glue them together.
Lastly, I'm attaching two new Hornresp sims: one for the FX120 and one for the FE166. The FX120 goes a couple hertz deeper and plays a couple dB louder (max SPL) so that's why I chose it. One note: the first horn segment has an exponential expansion while the other segments are straight conical expansions. The exponential flare was important for the first segment but made no difference for the others. It's no big deal as it's just as easy to cut the exponential curve as it is to cut a straight line.
I hope to start building this weekend.
I've included new sketches, including one view that shows the curved deflector right behind the throat opening to the speaker box. I've also included a larger scale detailed drawing of the bottom 42" high by 3.5" deep section of the horn. This drawing shows the detailed dimensions and shapes. The "teardrop" internal partition and deflectors will be made of 3.5" solid wood. This will be made of a sandwich of two pieces of 2" X 6" lumber (actual dimensions: 1.5" X 5.5") and one piece of 1/2" plywood or MDF. I've got a band saw so cutting the full 3.5" thickness won't be a problem. You could also use a jig saw but you would probably have to cut the three pieces first then glue them together.
Lastly, I'm attaching two new Hornresp sims: one for the FX120 and one for the FE166. The FX120 goes a couple hertz deeper and plays a couple dB louder (max SPL) so that's why I chose it. One note: the first horn segment has an exponential expansion while the other segments are straight conical expansions. The exponential flare was important for the first segment but made no difference for the others. It's no big deal as it's just as easy to cut the exponential curve as it is to cut a straight line.
I hope to start building this weekend.
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Progress Report
I've got the "bones" of one speaker built. In the attached interior picture, I've painted the curvy parts gray so they show up better. I've got a fair amount of work to do to complete one speaker, this is not including building a book case around it. It will probably be another week or two before I get a speaker done and some measurements made.
I've made a few detail changes but it's basically the design from my last post. I'll post updated drawings once I complete a speaker and do some measurements and I'm sure it won't change again.
I've got the "bones" of one speaker built. In the attached interior picture, I've painted the curvy parts gray so they show up better. I've got a fair amount of work to do to complete one speaker, this is not including building a book case around it. It will probably be another week or two before I get a speaker done and some measurements made.
I've made a few detail changes but it's basically the design from my last post. I'll post updated drawings once I complete a speaker and do some measurements and I'm sure it won't change again.
Attachments
This is a great idea. I think many of us are often looking for ways to hide horns or large TLs. If you have a normal 96" wall height I wonder if you have tried to model extending the sides to the ceiling and curving the back from its present 78"height to finish above the front panel, maybe with a decorative molding along the ceiling. This would make it look completely built in and would extend the length a small bit and maybe increase the mouth area slightly. This might reduce the ripple in the upper bass slightly. Could be done without altering the existing unit in anyway if modelling it shows any advantage. Great scheme anyway.
jamikl
jamikl
Thanks folks. This has turned out to take more time than I expected; it is a pretty big and heavy speaker, there are a lot of angle cuts, the two speakers are mirror images, and I'm having to plan a very specific order of assembly for the speaker and surrounding book case.
Jamikl - I have considered doing exactly what you said. My ceiling is 7.5 'high so the top of the horn will be just about a foot from the ceiling. I think I'm going to first experiment with an angled deflector at the ceiling to see if it makes a difference either in the frequency response or shape of the response.
Jamikl - I have considered doing exactly what you said. My ceiling is 7.5 'high so the top of the horn will be just about a foot from the ceiling. I think I'm going to first experiment with an angled deflector at the ceiling to see if it makes a difference either in the frequency response or shape of the response.
Almost a year ago, I built a giant OB woofer into the legs of a table kept almost against a wall. As a diversity woofer to my Klipschorn, results were excellent in terms of smooth and extended bass and diminution of room effects - in fact, too much output right at 20 Hz resonance.
My comments about it appear under my alias or "giant OB".
For example: post #411, http://www.diyaudio.com/forums/multi-way/123512-ultimate-ob-gallery-21.html#post2374499
Ben
My comments about it appear under my alias or "giant OB".
For example: post #411, http://www.diyaudio.com/forums/multi-way/123512-ultimate-ob-gallery-21.html#post2374499
Ben
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