Guest atilsley Posted May 7, 2014 Posted May 7, 2014 I think the simple clean lines of this OB are very good....good pricing also. Here's some pics of OB's I found....quite nice.
Owen Y Posted May 8, 2014 Posted May 8, 2014 (edited) It strikes me that a lot of these open baffles are too small to support low bass. Plenty of width coupling to the floor, helps too in this regard. And central/symmetrical driver placement tends to reinforce/concentrate front/rear cancellations at specific freqs. Otherwise, very pretty designs! Cheers, Owen Dark Lantern blog - http://darklanternforowen.wordpress.com/ Edited May 8, 2014 by Owen Y 1
davewantsmoore Posted May 9, 2014 Posted May 9, 2014 Narrow OBs are fine, they just need a correctly designed crossover/EQ
henry218 Posted May 9, 2014 Posted May 9, 2014 Narrow OBs are fine, they just need a correctly designed crossover/EQ and high xmax woofers if qts less than 0.6
Guest atilsley Posted May 9, 2014 Posted May 9, 2014 Bert Doppenberg's OB....way cool. Uses x4 15-inch BD woofers/side. I've started to build the half version...thinking about using x2 Altec 416's/side. Project stalled. Frames built.
Owen Y Posted May 9, 2014 Posted May 9, 2014 This is heading off topic but, if you're going to use big woofs & room boundary reinf, then building-in is the ultimate option... Cheers, Owen Dark Lantern blog - http://darklanternforowen.wordpress.com/
Guest Posted May 9, 2014 Posted May 9, 2014 Bert Doppenberg's OB....way cool. Uses x4 15-inch BD woofers/side. I've started to build the half version...thinking about using x2 Altec 416's/side. Project stalled. Frames built. Any links for more info on this?
davewantsmoore Posted May 9, 2014 Posted May 9, 2014 and high xmax woofers if qts less than 0.6 Always more excursion or additional/larger drivers The Qts isn't relevant to xmax at all .... but a component of it, Qes can be relevant to power handling. In the case where you have a high Qes driver, and an amplifier with >> 0 output impedance. This produces extra efficiency at system resonance, which may help if Pe (power handling) is your limit. I posted a picture of this in another thread of your recently. Wings or H frames can be very effective at extending the baffle of a bass dipole speaker.... but they do detract from the style of a traditional 'OB'
henry218 Posted May 9, 2014 Posted May 9, 2014 Always more excursion or additional/larger drivers The Qts isn't relevant to xmax at all .... but a component of it, Qes can be relevant to power handling. In the case where you have a high Qes driver, and an amplifier with >> 0 output impedance. This produces extra efficiency at system resonance, which may help if Pe (power handling) is your limit. I posted a picture of this in another thread of your recently. Wings or H frames can be very effective at extending the baffle of a bass dipole speaker.... but they do detract from the style of a traditional 'OB' yeah sure, but we are discussing about flat baffle, no U, H nor W baffle was mentioned.
davewantsmoore Posted May 9, 2014 Posted May 9, 2014 yeah sure, but we are discussing about flat baffle, no U, H nor W baffle was mentioned. Sure... I know they weren't.... until I bought them up at the end of my post as a way to help excursion/power handling (because aside from EQ, or more drivers, it's about the only other option) The main point of my post, was that the Q of a driver has no bearing on how much Xmax you will need. If we had 3 drivers, same size, all with very different Q .... then they still need to move the same amount to make the same output. Thave all have identical excursion
Guest atilsley Posted May 9, 2014 Posted May 9, 2014 Marc On the Orelo, Check bert's forum... http://forum.bd-design.nl/index.php?mode=thread&id=17094
andyr Posted November 23, 2021 Posted November 23, 2021 Does "zero baffle" count? See the 'Kyron Gaia' Or my own 'Satoris': Andy 1
davewantsmoore Posted November 23, 2021 Posted November 23, 2021 20 minutes ago, andyr said: Does "zero baffle" count? Yes. I'm going to make a woofer like this (the bottom bit). For all open baffle speakers the baffle should be: Acoustically small Low diffraction Non resonant Resonances are the problem for woofers..... and arguably for the lot. Making the baffle accoustically small is also hard as it means tapering the width of the baffle for each driver. .... so you get the worst diffraction (which can be addressed somewhat), and fix the other bits..... so there's a lot to like about the concept. 2
davewantsmoore Posted November 24, 2021 Posted November 24, 2021 51 minutes ago, davewantsmoore said: Non resonant It's very hard to see in the pic, but those woofers are suspended on rubber straps / cradle... The woofers are bolted tightly to each other with metal rods..... but they don't touch the metal frame at all.
aertex Posted November 24, 2021 Posted November 24, 2021 Dave, how would you expect this woofer arrangement to sound as far as quality and quantity of low bass?
klm Posted November 24, 2021 Posted November 24, 2021 Almost identical to the Celestion 6000 subwoofers from 1996.
davewantsmoore Posted November 24, 2021 Posted November 24, 2021 1 hour ago, aertex said: Dave, how would you expect this woofer arrangement to sound as far as quality and quantity of low bass? I generally think that subwoofers sound idential when all else is equal.... and it often is. I have sealed, dipole, ripole, and (not anymore) horn subs all together that largely support this. If these are going to be used above ~200Hz .... then it becomes very complicated. Sources sum together, and create "coverage patterns" that can reduce reflections and cancellations in the room, and change the overall frequency response (especially, over multiple seats) ... but for that "quality" becomes more about "what are you doing with it" ... and less about dipoles or someting else being "better or worse". ... but when used << 100Hz, like the will be to begin with ... then none of that happens. "bass goes everywhere", and there's basically "no such thing as a dipole", per se. So why do it? ..... I think the distortion from rattles and buzzes will be lower, even when compared to a very small stiff cabinet like my sealed boxes (50cm cube), or ripoles. I'll be interested to see. The resonant frequency will be low. I'm expecting even lower than a ripole.... and more linear than a ripole (which has asymetric, and constrained airloading on the driver.... where this is "open"). I think with the Ultimax woofer (I'm thinking the 18") it should be perhaps even below 10Hz..... and so at sane frequencies (say >> 20Hz) the mechanical and electrical elements of the system resonance (ie. the Qms and Qes in TS parameter terms) aren't dominating the motion of the driver. Adding more mass to the cone isn't a big problem (as it's not power limited) ... so I can experiment with sticking things to the cones (like stiffeners, etc.) , or other silly stuff.... at the risk of wrecking expensive woofers, eeek. It looks real cool.... in a very ultilitarian, steampunk type of way .... and has the "omg wth is that thing" factor to it. Re: quantity of bass .... once the dipole response is corrected, then it will be flat response like any other speaker. So the bass will reach down to whatever frequency I want it to. At "loud but not crazy" (say like a bit over 100dB peak) I suspect it will be happy into the mid 20s.
Grant Slack Posted November 24, 2021 Posted November 24, 2021 (edited) 27 minutes ago, davewantsmoore said: I think the distortion from rattles and buzzes will be lower, even when compared to a very small stiff cabinet Hi Dave, I never seem to have any of that from the speaker, but plenty from the room, the furniture, the windows…. My conclusion is multiple ‘bread-and-butter’ subs are the way to go, even though they won’t have any ‘talking point factor’…. After all, like you say, the different ‘types’ don’t sound different per se. cheers Grant Edited November 24, 2021 by Grant Slack
davewantsmoore Posted November 24, 2021 Posted November 24, 2021 29 minutes ago, klm said: Almost identical to the Celestion 6000 subwoofers from 1996. Yes Quote Celestion's designer Graham Bank has therefore produced a subwoofer which operates as a boxless, minimum-baffle area, double dipole with a bass output beamed in its operating frequency range (25-100Hz). Fundamental questions must be raised, however, concerning the relationship of a dipole to room loading. Extensive computer-modeled tests on rooms and positions indicate that directional bass will be an advantage since the bass beam or lobe may be directed toward the listener, thereby giving a much higher proportion of direct sound. These days most experts agree this is wrong (ie. not an advantage), becuase the indirect sound arrives too soon. The different source directivity is also said to "stimulate less room modes" .... but it turns out that it just stimulates modes a bit differently, depending on where it's placed and pointed ... and compared to a sealed box or whatever, it's really a wash. I'd love it to be true, but very looks like not. 1
davewantsmoore Posted November 24, 2021 Posted November 24, 2021 5 minutes ago, Grant Slack said: My conclusion is multiple ‘bread-and-butter’ subs Yep, this is just another b+b sub.
aertex Posted November 24, 2021 Posted November 24, 2021 (edited) so you would expect these "zero baffle"/Baffleless" lower bass arrangements (say low 20's - 100-odd Hz) to produce "fast" (yes...I know what that term can conjure up!), low distortion, impactful bass that would blend seamlessly with upper horn loaded driver arrangements? If so, why do you think there aren't more of these applications used by horn speaker makers and horn speaker DIY'ers? Or, another way, what is the anticipated downside of this setup for low bass? I see the bigger, well recognised horn speaker producers (Avantgarde, Tune Audio, Aries Cerat, Magico Ultimate etc) go down much more complex, expensive lower bass options. Edited November 24, 2021 by aertex added words
davewantsmoore Posted November 24, 2021 Posted November 24, 2021 I should probably post more pictures. LOL 3 hours ago, aertex said: produce "fast" (yes...I know what that term can conjure up!), low distortion, impactful bass that would blend seamlessly with upper horn loaded driver arrangements? All subwoofers do that, as long as they have low distortion and flat frequency response. Getting the distortion low enough can be a big challenge. Dipoles (if anything) are worse in that regard. 3 hours ago, aertex said: If so, why do you think there aren't more of these applications used by horn speaker makers and horn speaker DIY'ers? I dunno... what do these people typically use? <shrug>. They all have their tradeoffs in (cabinet size vs. driver excursion / SPL vs. power input). They can all work. If you don't want a lot of subwoofers, then probably a horn sub is the go .... but that's a BIG box. 3 hours ago, aertex said: Or, another way, what is the anticipated downside of this setup for low bass? Relatively low SPL vs excursion..... although these will be 18"s (hence I say relative). This means that to keep the distortion low (enough) from the driver excursion, the SPL won't be able to be super high. ... but that's ok, this is one of 5 subwoofers. The others are 1 dipole (2x 2") and 3 sealed boxes (with 12 and 15" drivers). 3 hours ago, aertex said: I see the bigger, well recognised horn speaker producers (Avantgarde, Tune Audio, Aries Cerat, Magico Ultimate etc) go down much more complex, expensive lower bass options.
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