I’d like to build it but I fear that it would just be a big expensive experiment that would result in storage rather than regular use. There is only one living room layout (for us) that would accomodate their size but my wife hates it that way, so I have restrained myself. Plus we have nowhere to store such big speakers when not in use.
Absolutely!!
I’d build them for you just so I can play with them before handing them over. It’s a really simple construction. Would be perfect for a beginner!
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If they need to be say 3-8 feet out from the front wall, then I’d have to play down my sitting room, instead of across as I do now.
Major reorg, but worth it if they sound as good as I suspect they would.
Do you know of anyone in the UK who builds Gravesen kits for other people?
I would love to do this.
Might have a hire a van to get them home. 
A very interesting, if rather large design. The most complicated part looks to be the assembly of the crossover.
As I understand it, using ‘wings’ or a rear frame (doubles up as a support) has a similar effect to a larger baffle in terms of front to back wave cancellation. Drivers with a QTS of 0.7 or higher should be used as they have a more shallow LF roll-off in ‘free air’ applications. I wonder if a good quality car audio driver would work well in an OB as many of those are designed with high QTS as they can be placed in all manor of enclosures (doors/rear deck etc.) and thus need to be flexible.
An Interesting thread. IME, the best feature of an open baffle design is the sense of spaciousness that the rearward radiation provides.
The best single source of information on cone based open baffle designs must be Siegfried Linkwitz’ site linkwitzlab. I’m surprised no one mentioned his work on cone driver based OB speakers, since he was TTBOMK, responsible for the cone driver based (as opposed to ESLs) OB revival in the ‘90s. His commercial designs for Audio Artistry were well reviewed by Stereophile, getting Class A ratings. After he left AA he set up a web site for his DIY designs. The site is full of useful information on OB speakers and most of the information is not available elsewhere. His active DIY designs from the first, the Phoenix, to his last, the LX 521.4 are fairly popular with DIYers. Somewhere on his site he even gives details of a lower cost passive DIY alternative to his commercial OB designs for Audio Artistry. Anyone with basic DIY skills wishing to dip their toes in OB waters without spending a fortune should look at his OB prototype. There is a lot of support available for SL’s designs all over the world, see the oplug-support site. Now his speakers can even be bought fully assembled from a site called LXmagic.
My brother built a pair of LX 521.4s some years ago and has now sold on his Spendor SP 2/3s. Having heard both I can understand why. The 521.4 is a really good speaker and IMO can’t be beaten for sound quality even at several times it’s parts cost.
Besides SL, JohnK has published a very fine 4 way DIY OB design, then there is Troels Gravesen’s OB design, mentioned earlier in this thread.
So lots of scope, whether one wants to DIY an OB , or buy fully assembled ready to play.
Edit: For diy designs also have a look at the diyaudio and quarter-wave sites
Edit 2: I see John K has shut down his web site. He designs are now hosted on speakerdesign net. He can be contacted on diyaudio
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Yes, Danny Ritchie of GR Research, who also designs OB speaker kits uses various shapes of wings to improve front/back soundwave cancellation.
(The links to his videos have been removed from this thread but anyone can find them via Danny’s site or New Record Day. Some NRD YouTube videos have binaural sound clips).
Thanks - lots of useful OB info in your post.
Clayton Shaw of Spatial Audio often cites Linkwitz, whose work helped him as he began trying to make OB speakers.
In the 90’s we could often see glass speakers in nice apartments. Waterfall french speakers were a fashion in those days. I wonder if they are open baffled.
Glass speakers. ( open baffled?)
I’m baffled by those!
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Thanks Alex - this is an interesting UK based OB kit design.
Jim
These Monacor Katana M1s do look good, and are priced so that even if they are not keepers it would be an ok risk to take.
There’s a YouTube video (in German) with binaural sound clips for anyone who’s interested.
They say : “ Very stylish in your living room, these speakers consist of a sound generator at the base and a glass slide.
Each area of the window has the function of emitting a certain sound frequency. So the base of the speaker will produce the bass and the top will produce the treble.
It will cost you $ 3000 each for the speakers and $ 2000 for the SubWoofer.”
What frequency FR please?
Having just listened to a range of different OB speakers on YouTube, it is clear that not all of them sound great!
(This is even despite the obvious and major drawbacks of listening to speakers via YT…)
Hi JimDog, I’d personally be wary of judging much sound wise on YT tbh. As I said earlier their quality I believe lies within a relatively limited choice of music, maybe live Jazz trio and acoustic music per se. If you like to rock out to loud music, when the family is out, I would try and look elsewhere, unless you could build them yourself (could be an exciting project). That way you would not loose out too much financially, as they will also have limited appeal in the second hand market I should think due to their limited WAF. Sorry if I’m being boring here 
Best Peter
PS. I love listening to Guttenberg and get smitten with his almost childish excitability. But he does like a lot of things…
All the specs I could find
Connectivity:Wireless, 5.2GHz
**Sensitivity:98 DbSpeaker Power Output:**100 W
**Frequency Response:150 – 22k HzDimensions:**18.5 inch x 18.5 inch x 48.5 inch ( L x W x H )
Individual Unit Weight **:**68 lb.Power Input :100 – 240 VACAudio Control Via App **:**Full Volume Control Functionality With Built In Bluetooth 4.1 Music Streaming Via App
LED Light Control Via AppFlexible & Fully Customizable Light Control Featuring Music Asynchronous Lighting Mode
Here’s an example of a well designed OB, John K’s NaO Note:
Upper panel only, not including bass unit
Directivity control is outstanding.
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