corner loaded louspeakers

[Sjef]

I was wondering if anyonehere has ever build a loudspeakers wich is specially designed to work into the corner of the room and with that I don't mean big corner horns.

Reason for asking is because i would like to buil a bedroom system where there is no room for big loudspeakers but I still would like the benefit of big woofers because I hate the sound of minimonitors.
I was thinking of a very simple baffle mounted into the room corner as a triangular shaped enclosure, might be from the floor to the ceiling wich would make a nice TL enclosure. Anyone tried this? and if yes what where the results.

I know lot of people would argue that according to the 'book' it won't work but I would like to here from people who have actually tried it because I allready read a lot of comments from people who think that something does not work according to the 'book' of common design theories while most of the loudspeakers designs that excactly follow these rules where in fact the worst I have ever heard up to date. The best loudspeakers I have heard so far didn't give a damn about the common design theories so I want practical information not assumptions

[Brett]

Sure, why not make something designed to fit into the corners? Klipsch have done it for decades with the KHorn. Just take into account the extra boundary reinforcement and get some directivity from 1k or so up.

[Wayne Parham]

I've been doing that for decades. When loading the bass bin into the corners, you can force the radiation pattern to 90° all the way down to the Schroeder frequency. Add a 90° midhorn and tweeter with the appropriate crossover and you have constant directivity through nearly the entire audio band. I know of no other loudspeaker configuration that can do this.

• Imaging, placement and orientation

Add multi-subs to provide uniform coverage below the Schroeder frequency and you have room coverage that's about as uniform as I can expect can be accomplished.

• Posts about Multiple Subwoofers on AudioRoundTable.com
• Multiple Subs thread on DIYaudio.com

[Sjef]

Yes I am aware of cornerhorns and actualy have heard a few wich where very good in giving a "room filling" sense of reproduction. For my bedroom however this is way too big. Space is limited here but I do have two corners spaced about 3.5m apart. I was wondeing if someone else has ever tried something simple like a two-way design with a 6.5 inch driver and a tweeter, maybe with waveguide and mounting it plain simply on a baffle of say 8 to 12 " wide and place it directly in the corner to form a triangular shaped enclosure together with the walls. This could be from the floor up to the ceiling (2.55m) This is not a serious high end attempt, I just don't have any space and would like a "room filling" sound from them. That's something I'm trying to accomplish. I have tried al sorts of small speaker in there but they all sound....well, small so maybe the roomgain in the corner could give me some "bigger" sound. Maybe with the use of eq I can overcome the biggest problems from the corner loading.

I would like to try some corner horns in my living room but unfortunatly there are no two opposite corners there that I could use and my open baffle setup works just fine there.

[Wayne Parham]

I've designed many speakers for corner placement, in order to exploit the potential benefits of boundary loading and uniform directivity. The size of the bass bin doesn't matter too much in that the biggest feature of the loudspeaker is the expansion of the walls from the corner.

My six Pi and seven Pi loudspeakers use a 12" or 15" woofer driven at the room corner, a 90° midhorn and a 90° tweeter. This way, they all radiate a constant 90° pattern. However, I also make smaller two-way speakers that don't require corner placement. These crossover between midwoofer and tweeter where the directivity matches.

The woofers in these two-way speakers are large, a 12" woofer in the three Pi and a 15" woofer in the four Pi loudspeaker. In each case, the crossover is made where the direct radiating midwoofer directivity has collapsed to match the horizontal pattern of the tweeter horn. The vertical pattern is limited by the off-axis nulls, and I use horns that put as much sound as possible inside the nulls, limiting radiation at large vertical angles.

Most other manufacturers that make a DI-matched two-way do the same thing. The size of the midwoofer sets the crossover point, matching the directivities of the two subsystems. You run into competing priorities.

A small direct radiating midwoofer will have a fairly wide pattern well up past the midrange, but when it is positioned in the apex of a room corner, the radiating angle is limited to 90°. This gives you some options that you wouldn't otherwise have. You must choose a crossover point below that where the pattern collapses, but it can be just about anywhere below that point. So you can make a small two-way speaker with an 8" midwoofer, for example, and crossover to a 90° horn anywhere below about 2kHz. Without the corner setting the pattern, you would need to crossover where the collapsing directivity matched the horn.

The thing you must be careful of when doing this approach is the transition from speaker cabinet to wall angle. If the crossover frequency is low, like in my six and seven Pi models, then the features of the speaker are acoustically small and the transition doesn't matter much. But as frequency goes up, the transition matters more because it becomes acoustically large. It's like the granularity of pixels on a screen. Far away, they can't be seen but close up, each one is apparent.

When you crossover higher, you'll want to blend the baffle with the apex expansion in some way so that the wavefront launch expands properly. Otherwise, a discontinuity is formed that makes reflections. One way to do this is with a curved baffle. Another way is with a rear-firing driver, like in my speakers. The rear-firing approach works better with lower crossovers, the curved baffle works better if you're crossing over higher.

Here is a list of more posts with information. I hope you'll find these useful.

• Pi horn design philosophies
• Pi Cornerhorns - a brief history
• Cornerhorn implementations
• Making speakers "disappear"
• 7pi and listening room considerations
• Positioning and subs
• Corner Horn positioning "Sweet Spot" for listening
• Recommended toe in
• Phase angles, crossovers and baffle spacing
• Baffle spacing, phase angles and time alignment, revisited
• Matching directivity in the vertical and the horizontal planes
• Baffle spacing, null angles, etc...
• K-Horn/ Pi-Horn Differences
• Klipschorn vs seven Pi cornerhorn
• Midrange Horn
• higher cut-off for 7pi (comments on cone drivers verses compression driver for mids)
• Pi Midrange Horn (more comments on cones for midhorns)

[Godzilla]

BIBs are designed to go into corners. Have a look at this website.

http://www.zillaspeak.com/bib.asp

These are tall, slim speakers designed for corner placement but it is not necessary for them to be in corners. They sound best that way. They are like back loaded horns but with the opening on top.

Godzilla

[phase_accurate]

There was once an article on a DIY corner TML in one of the two German DIY speaker mags. It was even a two-way TML wit a 12" and a 15".

Regards

Charles

Edit: Found the drawings on the net, but in "Krautish" only unfortunately.

http://www.visaton.de/de/bauvorschla...anleitung.html

[sreten]

http://www.visaton.com/en/bauvorschl...b30/index.html
http://www.visaton.de/de/bauvorschla...anleitung.html

Hi, English text, /sreten.

[Tubamark]

Aren't those links for a SUB? The original poster is wanting a small full-spectrum corner system . . . different animal.

Roy Allison certainly made it "work", and without horns. One just needs to figure out how to keep the driver distances as close as possible to zero to the adjacent surfaces, and choose crossover points for each driver that will prevent frequency notching (boundary null cancellation). Driver depth is usually what gets us in trouble; magnet hits the corner before driver frame touches the wall. using an actual enclosure compounds the problem.

If one can poke the corners out, or build the room around the speakers, the possibilities are endless.

I had some White Papers by renown engineer Roy Allison on his years of tests and designs; produced successful corner speakers for many years but the company went out of business in December 2008. . . The link I got the papers from is now gone.

Basically, a given driver center needs to be less than 1/4 wavelength from boundaries within its operating range OR greater than 3/4 wavelength from adjacent boundaries (often the case for tweeter) in order to prevent significant frequency notching. Similar rules apply for driver spacing.
In the real world some time/imaging smear is inevitable, but when done right, these systems are great for casual listening-- very nice, full sound over very broad listening area.

Definately not for the point-source, holographic, mini-monitor crowd, But probably perfect for what Sjef seems to be looking for.

Read for a couple general nuggets here: http://www.stereophile.com/interview...ur/index3.html
Also Google for Allison model three speaker, Allison effect, Roy Allison etc. His AES studies are available, but hard to get for free.
Good luck!

--Mark