Here’s a pair of open baffle speakers that have become a long-term side project. They’re a Nelson Pass design according to “SLOB” (Slot-Loaded Open Baffle) principles. The 8” Lowther driver (on the main baffle) is gone, and I increased the size of the mounting hole to fit a Zenith 49CZ852 that was “EnABLed.” The 15” organ speaker (on the bottom-rear baffle) is gone, too—replaced by an Eminence Alpha-15A which was recycled from a Pure Audio Project speaker. I sometimes perch an ESS Great Heil AMT on top of these, but the Zenith driver is so capable and so outstanding that I’m not sure the gains of augmenting the frequency extremes outweigh the costs. Speaking of Pure Audio Project, I also have a pair of unused Trio frames waiting for me to get inspired to dive into another OB project. My dream was to have those support a wider baffle than the PAP standard ... and to use one of the 18” Acoustic Elegance woofers optimized for open baffle use. Those woofers might be slightly too big in diameter for the spacing between the PAP frame uprights, though, so that project is on pause. One day! Like most audio technologies, OB speakers excel in certain areas and fall short in others. How much you enjoy them is sure to depend a lot on personal preferences and priorities, which we’re all free to manage for ourselves, right? Although I greatly prefer horns (both the build challenge and the listening experience), I do enjoy OB speakers a lot, which is why I keep working at them. No doubt they’re easy to put together and then modify. There’s hardly a better person to teach OB and related principles than the late Siegfried Linkwitz. Here’s a link to the Loudspeakers section of his website. Good luck!
My Lii drivers showed up this afternoon and were promptly mounted in the waiting baffles. The first thing I did was bring my sub out to the middle of my listening area and turn the crossover value to it’s maximum (around 200hz). When I dropped the needle on my NM first pressing of The Wall, my default audition album, I immediately heard the space in the music. The sound is open and airy, maybe a touch shouty at first, but as I tweaked the placement that began to improve . I know these drivers will need some time to break in, and I will no doubt need to add a larger driver and increase the baffles size to accommodate that. I definitely see a bit of promise in the concept of these OB speakers though, the next step will be to get a pair of the Eminence Alpha 15a drivers on their way and CNC a couple of new baffles, but until then I think I will leave these little baffles hooked up and continue to tweak the setup.
Thanks, I think this will at least be a fun journey and a welcome learning experience. Those baffles look interesting, how’s the bass response with the slot loaded woofer?
I have to say that the disappearing act these little things can do is really quite impressive. My Rogers do a really good job of that, but these are definitely better. The tonality is very very natural as well, and the detail is just fantastic.
Where to start? How good and full range are they when you are already counting on using sub woofers? If they need reinforcement in the lows why won't they need it in the highs? There is not even guarantee the mids would be good. Theoretically it is nice to have something simple without crossovers. That is something you are already negating with the idea of adding the sub. I've only heard a pair of Tannoy with single drivers, everything else was DIY with a variety of speakers. Not one of those I've liked, to me they all sounded dull or muddy, two or three ways is what works for me. Since you've bought them already it'll be interesting to know what you think, there is nothing better than first hand impressions and what really counts is what you think.
Admittedly I have already diverged from the simple single driver concept, as soon as the first notes came from those little 8” drivers that idea was dead to me. What interest me now is the detail and spacious sound that these drivers DO deliver. Moving forward with an active crossover design I believe will result in a sound that should be much more complete in its delivery, but to me part of the fun of this is the experience. Since this is my first attempt at a diy loudspeaker I may be a bit overly optimistic, but for not much expense it should be an enjoyable journey.
It's my understanding that the barrel shaped baffles are designed to sit on the floor for bass reinforcement. That's how they are able to get away with such a small baffle. I understand if you want to do it your way, but you might be making your sub work harder than it needs to. You did a really nice job on your baffles, they're beautiful!
Correct, these were designed to be on the floor. If you want them raised as shown, I bet you could fill the sound in by covering up that open part of your stands which would somewhat extend the baffle to the floor.
Yes, I am actually working on a file to CNC new baffles that are full height with room for my 15” drivers too. I did have them on the floor at one point this weekend, and the sound was fuller, but the staging was a little to close to the floor.
that is a beautiful job on the baffle build. The Decware forums have a ton of great info on builds with the Lii Audio drivers. Good luck on dialing it in! I had been using single driver Super Alnico monitors with my 2 watt Deware SET amp. Paired with a matching Omega sub, these did really well. However, this Summer I caught the open baffle bug and built my own speakers using Lii Audio drivers. I went with the Crystal 10 drivers supplemented by the LiiAudio W15 bass drivers in the same baffle. The W15s are designed to work with OB speakers and can be crossed over fairly high. the final setup required me to power the W15s separately with a Crown amplifier. They are crossed over at 180 and blend beautifully. These speakers are fantastic IMO. After hearing OB bass, I am not going back to a subwoofer in a box. I couldn’t be happier. As a point of reference, my speaker journey over the last 8 years included The Omegas, Fritz Rev7s, and Harbeth P3ESRs. (only the Omegas were powered with the SET amp)
Glad to hear this, as it is precisely what I intend to do. I have a pair of Parasound amps that I plan to use with Alpha 15a drivers and the Lii’s will be driven by the MC 60s. If you don’t mind sharing details, do you have any wings on the bass sections of your baffles, and what shape did you use for the baffles. Also curious if your crossover is active or passive? I was thinking of using the miniDSP 2x4 for mine. I also thought that aligning the voice coils of the two drivers within the baffles might be beneficial.
There are wings on the sides. The shape is about 20 inches wide by 36 inches high using doubled up Baltic birch plywood to make them 1.5 inches thick. The crossover is passive so that the Crystal 10s run full range. I should play with the crossover more but my crude measurements show that I have a fairly flat response between 150 and 250hz. The bass is pretty great - I suspect that the wings play a role in helping. if you google Liionidas Open Baffle speaker, there is a Dutch site called AudioDandy with an article there that I used for inspiration.
The thing with active crossovers is the ease of changing parameters, as long as you don't spend too much money it is great to experiment with different set ups. Enjoy!!
Moving on with my experimentation I have a couple of larger baffles waiting for a pair of 15” drivers to show up. I plan to keep the design somewhat modular similar to Pure Audio Project baffles
After some recommendations to look at a better driver than the Alpha 15 I have the Audience Bianco 15s from Madisound installed in my baffles. I have these bi amped with the Lii Audio Fast 8s running off the McIntosh MC60s and the SBs each have their own Parasound 2125 v2. I set up the miniDSP to crossover at 300hz for now, but will start to fine tune this as I go.
I have to say I am very happy with the way these are sounding so far. The coming weeks will be telling as the drivers begin to break in though. I have my sub set to 60hz and am still getting very good bass, much better than I anticipated.
I’m curious as to how much the material you use to hold the speakers affects the sound (say, maple vs. pine, or wood vs. plastic, or whatever). I’d guess resonant frequencies come in to play?
I’m certain that it plays a part, how much I don’t know. I suppose some of that could be measured and would probably be something interesting to do in the future. For now I have actually been thinking that I should probably isolate between all of my connections with something like sorbothane to try and limit unwanted vibrations.
If you're looking at Sorbathane, take a look at Herbies GrungeBuster material too. I think it would work well in that application. It's available in sheet form, in different thicknesses. It's nice to work with, and doesn't stain other materials. Damping Sheet
Excellent suggestion, I have a Herbies mat on my TT and couldn’t be happier. I will definitely be ordering a couple of these.
I’ve been playing with crossover setup and placement for a few days now. Right now I am pretty settled on a crossover point at 400hz with Linkwitz-Riley 48 dB/octave slope. The bass is surprisingly good, and I’ve had no issues blending my SVS sub with these speakers. I keep adjusting the toe in to almost nothing at this point all the while maintaining a strong center image and nice tonality. These speakers are bringing a large lifelike sound and from what I can hear a very even frequency response, but I will measure that when time allows.
Things have evolved as I listen to these speakers. I have to say that with careful adjustments they got scary good for such a small investment. I did eventually change the base and tilt them back with spikes. This setup completely disappeared in the room, and the bass was good but I still crossed my subs in at 55hz. After the successful initial attempt I today brought in an additional pair of the 15” drivers, and I am hopeful that with more careful adjustments I will soon have these singing as well.
I started messing with the angle of the baffles individually as I was finding that the sound was less focused then my previous baffles. Based on the Pure Audio Trio design I had initially kept them on the same plane and tilted the entire speaker back by roughly 5 degrees. I wound up preferring the top drivers pointing more towards the listening position and the lower baffles slightly angled up. I am sure that a more technically mind person could explain about possible time alignment issues or any number of other reasons this sounds better, but I am not that guy. I also felt I was missing some transparency the original speaker had, which I attribute to the larger wings on my new speakers, I decided to narrow to portion of the wings behind the FR drivers similar to a GT Research solution. Here’s what I ended up doing.
At the rate you’re churning out new models, you’ll soon have to change your profile name to Tekton Jr.
