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-   -   Big BLH in Bookcase? (http://www.diyaudio.com/forums/full-range/191033-big-blh-bookcase.html)

dhenryp 17th June 2011 04:23 PM

Big BLH in Bookcase?
 
2 Attachment(s)
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.

rjbond3rd 17th June 2011 06:47 PM

Whoa, definitely epic and really cool. Attaching to the wall presumably gives you some good bracing as well. I would love to hear the finished result!

blakkshepeaudio 18th June 2011 12:03 AM

Hah! What a great idea. DIY ingenuity at its best.

Nelson Pass 18th June 2011 04:49 AM

Highly original. Some books or LP's on the shelves will probably help too.

:cool:

grindstone 18th June 2011 06:04 AM

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.

picowallspeaker 18th June 2011 06:21 AM

I want to see it made right now !!!
Hear ...later :p
Hint : using many modular pieces you can make curves ,sort of tile work or...maze :)...I don't actually know if elbows may be good in such designs ( I fear so ).
Using more than a driver with the same chamber ?

saschagabor 18th June 2011 08:40 AM

If I didnīt have acceptance for larger speakers at home, this could turn out to be the perfect compromise. Donīt go patenting it, you hear! ;)

dhenryp 18th June 2011 07:52 PM

2 Attachment(s)
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).

c2cthomas 18th June 2011 08:43 PM

2 Attachment(s)
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

talaerts 19th June 2011 07:39 AM

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.


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