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Kal
Kal
open baffle speaker question
i see lots of designs for the diyer. i have never heard a pair of these [except magnepans] and need some advice if this is a project that would be worth attempting. the costs are minimal evidently but would like to hear from someone with experience about the sound quality of this design using quality drivers etc. are super tweeters needed? thanks
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Hi Hotmailjbc, you have two very good recommendations here, the Orion and several designs by GR Research. Nice thing about many of the GR designs is that they incorporate a 12" sub into the cabinet, but the separate sub is always an option. These may or may not be a challenging build depending on one's abilities. And there are simpler approaches if you just want to experiment. Or, another option is to contact one of the builders of these speakers and contract a pair. The open baffle designs can give you presentation close to the electrostatic/planar. They image very well, sometimes in circumstances that would destroy the presentation of most other designs. They can also have dynamics that approach that of horns. OB designs are usually pretty efficient also. Most speakers of this design don't give the "audiophile" presentation many folks get wobbly in the knees over, but that is a good thing IMO. Personally I would avoid single driver, full-range designs. (Except again for experimentation.) Unless one can afford really expensive FR drivers there will be response compromises. I know for myself that would just lead to my adding drivers and more xover parts to fill in the frequencies. I am very familiar with the OB-7 from GR Research since I can hear these from my neighbor's house, 100 yards away. ;-) I arranged the purchase of these speakers for this neighbor who was buying solely on my recommendation of Danny's work at GR. Long story short, my neighbor has been rocking the neighborhood for three years now, and still raves about the OB-7s every time I visit. He says he gets compliments all the time from people who stop what they are doing for a minute or so to listen. |
'Open baffle' usually refers to a cone speaker mounted on a baffle with an open back. Quite often this means there are no sides to be baffle either but that sort of depends on who you talk to. Technically speaking all planar speakers are open baffle by definition. However the term usually does not refer to them. Open baffle speakers can have multiple drivers. The old Carver Amazing is an example. But most open baffle setups you will see usually use a 'full range' driver of some sort, a Lowther, PHY or perhaps a Fostex. I saw a very convincing setup in Nelson Pass' room at RMAF about 3 years ago. He showed full-range driver that looked like a Lowther, and there was a second driver mounted on the baffle that was assisting with the bass. The speaker had very convincing bass and overall his system was quite musical. I seem to recall that he mentioned something about the dynamic range being limited in some way but don't quote me on that. |
I had David Lucas open baffles a while back. It took 4 12" woofers to generate good bass. The sound was very encompassing because it did radiate in virtually every direction. You can't call that good imaging...However, you have to be very careful about placement so the rear wave doesn't interfere with what you hear. Also, they tend to be fairly inefficient. A Lowther in an open baffle should waste a lot more energy than one in a properly designed cabinet. Keep in mind that tweeters aren't open baffle. So a design with a super tweeter is a compromise. I still have single driver speakers but in a cabinet that properly channels the bass and is much easier to place in a room. |
Hi Hotmailjbc, Atmasphere explained it ideally, even though most planars, ribbons & electrostatics are open back, they are usually refered to by their own terms. Open baffle normally refers to cone drivers mounted without a chamber. What design did you see specifically. I have built many speakers on my own. They place to start is the FRD Consortium. These are not tools for a beginner, but for standard designs will give you the information that you need to do designs that compete with some of the best. good luck, Tim |
thanks for all the advise/info. i have seen pictures and papers on lots of designs. what got me thinking about this is the wild burro site where he had some drivers called the betsy on sale and the speaker was a sheet of good grade plywood with some side wing type boards. i like to learn and experiment and keep it really affordable and figured 150 bucks to get my feet wet would be sort of fun. i just was interested in if this would be a good idea before i invested a day assembling this. thanks again john |
Open baffle speakers can work exceptionally well (I own a pair of Orions, and the latest versions are better than everything else I've heard provided you can live with the SPL limitations. Earl Geddess' waveguides crossed to large (10, 12, 15") mid-bass drivers where the dispersion matches are the only thing more than one or two Orion owners have preferred, but I've yet to hear those) but I wouldn't bother with any open-baffle design that didn't use multiple driver sizes and baffle widths scaled to fit the wavelengths involved and active cross-overs at least for the lowest frequency drivers. The issue is that below some frequency a dipole requires an additional doubling of displacement per octave. For a foot wide flat baffle this happens around 400Hz, 2 feet get you 200Hz, etc. People who throw too few drivers on a single baffle make it wide to compensate, which in turn produces a multi-lobed polar response that doesn't sound much like music (I say that after having heard the $42,000 a pair field-coil Feastrex drivers in such a configuration both with and with out sub-woofers). You need multiple drivers and baffle widths which get bigger at low frequencies. The same issue limits sensitivity at low frequencies. Put a 90dB bass driver in a 15" deep H-frame and it'll match a box speaker's output at 153Hz, 84.4dB at 80Hz, 78.4dB at 40Hz, and 72.4dB by 20Hz. You can use a pair of drivers and load them into half space to boost efficiency numbers to 99/93.4/87.4/81.4dB. If you don't want to limit low frequency extension, you need to either use an active cross-over (where the low sensitivity in the last octave doesn't matter, because there isn't much musical energy and you'd bottom the drivers anyways) or pad the rest of the speaker down to match which doesn't work. You can also rely on a high-Q resonance to get some low frequency output, but stored energy is never a good idea. Hotmailjbc writes: >the costs are minimal evidently but would like to hear from someone with experience about the sound quality of this design using quality drivers etc. Don't bother with a full range on a baffle even if you add a sub-woofer and/or super-tweeter. Done right the costs aren't minimal. Current Orion construction costs should be somewhere north of $2500 plus an extra 4-6 amplifier channels. The NaO Note is less expensive but is still a bi-amplified 4-way with 5 drivers a side ($1200 for just the drivers). |
Drew said and I quote[Don't bother with a full range on a baffle even if you add a sub-woofer and/or super-tweeter.] This is wrong info many experts use this design Including Nelson Pass. I think Nelson might have the edge in real world experience over Drew. Also the active crossover being necessary is again just opinion and not my experience at all. |
>03-04-11: Johnk Drew said and I quote[Don't bother with a full range on a baffle even if you add a sub-woofer and/or super-tweeter.] This is wrong info many experts use this design Including Nelson Pass. I think Nelson might have the edge in real world experience over Drew. Also the active crossover being necessary is again just opinion and not my experience at all. Nelson is an entertaining lecturer, does interesting things with analog electronics, and offers wonderful support to the DIY community but he's hardly an expert speaker designer. I heard Nelson's speakers back to back with Siegfried Linkwitz's Orion 4 at Burning Amp 2010. They did not compare. It was his BoB baffles on which I heard the Feastrex and Lowther field coil drivers at Burning Amp 2009. They didn't stack up to better designs at that DIY gathering either because the design concept is inherently flawed. |
Hi everyone Do any members have experiences, thoughts, opinions on JE Labs type Open Baffles? Did you find the soundstage to be low? Do you think OB set-ups primarily benefit from using quality tube gear or can budget solid state gear be used along with them? JE Labs OB The reason I ask all this is because I auditioned an OB set-up based off the designs in the above link and it had Audio Nirvana 12" Full Range Drivers. They were powered with a quality flea-watt tube integrated and the sound was heavenly. I bought the OB speakers thinking that wonderful sound could now be in my 2nd system. My 2nd system is all solid state budget gear. (re-built Hafler DH-220 amp, power cord speaker wire, Monster ICs, Pioneer receiver as a preamp, Sony SCD CE-595 as a source) When I listened to the OBs I found the soundstage to be low. When I auditioned them I set them up like how I would listening to them. Distance apart and sitting distance away. The only difference though is that in the audition room there was a wall behind me. I knew there would be some differences in sound because of the room and gear used but the differences I heard were drastic to me. I got lucky and the guy took them back. I still want to try an OB set-up but now amp wondering if I need to buy more expensive quality tube gear to get the best sound out of an OB set-up. I was looking at the Tekton OB4.5en and may be even the Tekton OB 6.5en speakers. Thanks in advance. |