open baffle loudspeakers and room size

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My cardboard baffles do shake like hell but it is just for testing. I wonder how they will sound on a proper pannel. I am thinking in acrylic glass, 12mm. I have to say that I really like the sound of these Beyma's and the limitations are on frequency extremes, so no XO on the mid range can be beneficial. It is just a matter of adding something below 100Hz and above 15Kz....
But I guess that I am not going back to my boxed speakers.

Miguel
 
I've found that resin bonded phenolic paper aka Tufnol is the bees knees for baffles. It is incredibly stiff and much less resonant than ply, MDF and glass. It also machines well with woodworking tools if you keep the tool speed down. Go for the most basic grade. You will not be disappointed!
 
Yeah, gotta love the ease with which OBs can be built to be good looking. Of course, this is from the guy whose raw MDF shelf baffles look better than any other speaker he's ever owned. Just something about an appropriately tall (instead of not quite tall enough), slender, neutral colored baffle with with attractive black and silver drivers mounted at the top. Even with the questionable Yamaha 8"ers in them, I've managed to eq them to a point where I'm getting an f3 of somewhere around 40Hz out of them which is adequate for me if not perfect. I'm still hunting for thoughts and opinions on replacement 8" drivers (preferably) or 10" drivers (should be able to blend with the tweeter highpassed either 1st order at 2500Hz or 2nd order at 2000Hz).

I've thought of having the woodshop that built our enormous entertainment center build and finish a pair of "shelves" to match it, kinda like when we needed more modular shelves for it (its some kind of cherry finished oak ply that the wife adores), and either hinge mount them to the sides or freestand them right next to it somehow to get an OB upgrade for the living room. Right now, the only speaks she approves of are large bookshelves, laid on their sides, sitting in the outer-bottom corner compartements of the center itself. They get a hella bass gain from their placement (only -6dB at 20Hz from an 8" woofer rated to 45Hz), but the cost is a collapsed sound stage and a bit of mud in the upper mids and treble (same speaks sound better overall with a fairly deep and tall, if not terribly wide sound stage and noticeably clearer upper mids and treble, but you can hear them starting to roll off the low end at 55Hz or so). Anyway, point is that OB give the DIYer another potent weapon in the war to obtain WAF.

Kensai
 
Nuuk, those are great but she wants minimum visual impact. And I guess that full acrylic baffles will cost not much more than wood/acrylic ones. I just need a good source (cheap) for it. Which tweeter are you using and how is the XO?

I have been thinkng about how are the reflections behind the baffle. In my case, as I want lower frequencies, I though of puting some driver in the bottom of the baffle, but with a NaO style approach. I just don´t know if this affects the sound of the full-ranger. Supravox uses a similar approach, but without the NaO style box for sub. And they also use a tweeter.

http://www.supravox.fr/Doc kits/panneauplan.pdf

Miguel
 
Hi Miguel,

The tweeters are cheapo items from CPC (Order code LS0025966). They are connected to the 201 terminals via a series 4.7 uF capacitor.

I am sure there are better tweeeters but at what cost? My ears tell me that these work very well and a female friend who listens to a lot of hi-fi, commented that the top end was clearer than anything else she has heard!

I take your point about the visual impact aspect but large pieces of acrylic sheet are nowhere near the cost of my baffles!

I am also looking to extend the bass response of my baffles. I have been considering single drivers on the main baffle, the NaO concept and the twin-driver W baffles! And I reckon an active crossover would be the way to go with any of these.

For me, it's a question of finding the right drivers at the right price! ;)
 
Hi Nuuk,

If you see Supravox's link they have a 0.47u for the tweeter and a 20mH choke on the sub. This gives some nice XO points around 90Hz and over 10KHz. Of course those drivers are on the expensive side but I wonder if we can´t use this approach. The Beyma's 8AG/n cover the region between these points quite well.
And that baffle is ONLY 31 cm wide! Like you say, need the rigth (=cheap) drivers. And then biamp the whole thing :devilr: .



Miguel
 
Open baffles have great possibilities

I'm in the middle of construction of a pair of hybrids that combine TL's for the bass with a line array OB for the mid/highs. This is my second version of a design I came up with over a year ago which I trademarked Ultor. Ultor with it's phased array of 24 drivers in each cabinet was an incredibly successful design for a full range, uncolored hi-efficiency speaker that throws just like a large horn, but is a complicated cabinet to build. I have had great revues from most who have heard them. I am trying to reduce the cost in this next version and if successful I have hopes of manufacturing it.

My proprietary design is not open for public discussion but I chimed in here to say that I am another who has discovered the magic in open baffle speakers. This coming from a seasoned Altec VOT horn owner who is used to highly efficient, highly dynamic, low distortion loudspeakers that can project. I went to great effort and expense to make a large set of 50Hz front horns (shown elsewhere on DIY Forums) and I really prefer the sound of my UltorTM speakers which I conceived of since. The OB part of the Ultors is one important key in the success of the design and the associated lack of cabinet coloration I enjoy so much and which makes them sound so real IMO.
 
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