I'm giving my 4 way OB full range dipole design for free under the "do whatever you want with this" licence.
I wrote a bit more about the whole project for the orion pluto lx forum (Linkwitz support group) and done a lot of measurements, this is a copypaste here.
Hi all. My name is Ben. I was born on may 21st, so 521 name (it's date when SL designed the baffle) made me very happy 😀. I've built and enjoyed the lx521 for some years now, and have preached everywhere about how great that speaker is. However, after a long time, I've decided to undertake designing and building a second set of similar yet quite different speakers. There were a couple of goals to achieve:
1st - WAF. Lx521 is very beautiful, especially so if you understand what it represents. But most people think it looks at least weird, if not ugly. I also moved to a smaller space with my wife and needed something more practical and "normal" looking.
2nd - keep all the bass performance, no sacrifices in function to gain WAF and practicality.
3rd - audiophile pals at my place and some at audiophile shows comment how voices sound strange on lx521. I thought about it a bit and, they really don't... but I think I got the gist of the issue. LX521 is a dipole behavior all throughout, meaning it kills room interactions as much as possible, both by radiating 8 pattern (not illuminating sides) and by keeping spectrally very similar reflections to the front wave. But in doing so you disconnect voices from the room and put them in the phantom image alongside the rest of the music. They won't sound like they are actually in the room to some extent - and this can be observed. I didn't really want to admit it because I really like SL and 521, but there we go, it's how it is. In order to get the great soundstage and reflections, you sacrifice a bit of intimacy in vocals. I tried to design a speaker that keeps the dipole behavior through the whole spectrum but expands the vocal range of around 1-4 khz by a bit, by making it radiate somehting between a dipole and omni in that range in hope of adding back that "like in the room" vocals. If that makes any sense. I already have a true lx521 reference anyway.
So after a long time, here is the result of my work. The speaker is called waffle. For the waf. My wife finds them pleasing. It's also possible to add black audio transparent cloth to mask them into black blocks.
next to the lx521
The speakers are made with 16 SB acoustics drivers, from my research really only them and SEAS, mybe scanspeak (expensive) and some vifas made sense. You need very well designed and build drivers with specific traits, like vented spider and so on. The drivers are very nice indeed.
Me next to the speaker, I'm 180cm tall.
The speaker has full vibration cancelling and 8 bass drivers total. I should point out that I'm not objective, obviously, but the sheer power this speaker commands is ridiculous. Insane amount of highly controlled bass is possible, down to what, 10ish hz or so. It's funny feeling that big articulated power coming from such tiny things, and the inherent complete vibration cancelling is great, absolutelly no vibrations anywhere, together with that monstrously powerful bass. It's weird. The rest is a typical dipole goodness, vast articulated soundstage, but there is a bit more energy in vocals and they do sound like in the room instead of being more ethereal like. It would be relatively simple to undo this with an attachment to the baffle and some more eq, and make it more like the lx521, but where's the point, just get the lx521 then. The 1-4 khz range still behaves like a dipole, just a bit less so, as you can see in the directivity and spectral plots below.
Every single one of 16 drivers in this speaker has it's own amp, so levels of damping and control are really good.
The amp is a 16ch class d amp with 250w per channel. The psu for the amp is literally just 3 atx psu's unearthed and in series to produce 36 volts dirt cheap.
Some measurements:
2.88ms gated on axis FR
1/12 oct smoothed FR
bass enclosure response nearfield (front and 2 openings on rear)
Lower midrange response nearfield (front and rear)
Distortion above 300 Hz, white line is thd (for bass you need something else, which I can measure/plot, but just didn't have the time and it will be good anyway as there really are no issues)
RTA maximum around my room
Spectral energy - this 60 hz spike is a room mode. I can see no stored energy above Schroder f, but it is raw so it looks ribbed. For pleasure. There is a bit of "fattening" between 1 and 4 khz, as predicted/wanted, but the on axis FR remains neutral.
Raw waterfall plot. Again, ignore stuff below 300 Hz.
Nearfield waterfall for low midrange.
Nearfield waterfall for subs. There is some stored energy but it's way below anything that would be an enclosure resonance (it should appear at 120 Hz, and it does, you can see it on the far right), and I can hear no problems. I was originaly a bit worried, but now quite sure it's actually room modes because the same pattern apears on the low mid too which has nothing to do with the lower enclosure.
Directivity. You can see some really nice dipole behaviour up to 1 khz and above 4 khz. 1-4 khz still exhibits dipole like response but it's much less pronounced, as it radiates some energy to the sides, making vocals more "in room" like but the on axis FR remains flat. As I said, it could be modded to be like a dipole all the way, but you can just have lx521 for that, and it would introduce some other problems too actually.
I'm no Linkwitz, obviously, but at least I have a hobby.
I wrote a bit more about the whole project for the orion pluto lx forum (Linkwitz support group) and done a lot of measurements, this is a copypaste here.
Hi all. My name is Ben. I was born on may 21st, so 521 name (it's date when SL designed the baffle) made me very happy 😀. I've built and enjoyed the lx521 for some years now, and have preached everywhere about how great that speaker is. However, after a long time, I've decided to undertake designing and building a second set of similar yet quite different speakers. There were a couple of goals to achieve:
1st - WAF. Lx521 is very beautiful, especially so if you understand what it represents. But most people think it looks at least weird, if not ugly. I also moved to a smaller space with my wife and needed something more practical and "normal" looking.
2nd - keep all the bass performance, no sacrifices in function to gain WAF and practicality.
3rd - audiophile pals at my place and some at audiophile shows comment how voices sound strange on lx521. I thought about it a bit and, they really don't... but I think I got the gist of the issue. LX521 is a dipole behavior all throughout, meaning it kills room interactions as much as possible, both by radiating 8 pattern (not illuminating sides) and by keeping spectrally very similar reflections to the front wave. But in doing so you disconnect voices from the room and put them in the phantom image alongside the rest of the music. They won't sound like they are actually in the room to some extent - and this can be observed. I didn't really want to admit it because I really like SL and 521, but there we go, it's how it is. In order to get the great soundstage and reflections, you sacrifice a bit of intimacy in vocals. I tried to design a speaker that keeps the dipole behavior through the whole spectrum but expands the vocal range of around 1-4 khz by a bit, by making it radiate somehting between a dipole and omni in that range in hope of adding back that "like in the room" vocals. If that makes any sense. I already have a true lx521 reference anyway.
So after a long time, here is the result of my work. The speaker is called waffle. For the waf. My wife finds them pleasing. It's also possible to add black audio transparent cloth to mask them into black blocks.
next to the lx521
The speakers are made with 16 SB acoustics drivers, from my research really only them and SEAS, mybe scanspeak (expensive) and some vifas made sense. You need very well designed and build drivers with specific traits, like vented spider and so on. The drivers are very nice indeed.
Me next to the speaker, I'm 180cm tall.
The speaker has full vibration cancelling and 8 bass drivers total. I should point out that I'm not objective, obviously, but the sheer power this speaker commands is ridiculous. Insane amount of highly controlled bass is possible, down to what, 10ish hz or so. It's funny feeling that big articulated power coming from such tiny things, and the inherent complete vibration cancelling is great, absolutelly no vibrations anywhere, together with that monstrously powerful bass. It's weird. The rest is a typical dipole goodness, vast articulated soundstage, but there is a bit more energy in vocals and they do sound like in the room instead of being more ethereal like. It would be relatively simple to undo this with an attachment to the baffle and some more eq, and make it more like the lx521, but where's the point, just get the lx521 then. The 1-4 khz range still behaves like a dipole, just a bit less so, as you can see in the directivity and spectral plots below.
Every single one of 16 drivers in this speaker has it's own amp, so levels of damping and control are really good.
The amp is a 16ch class d amp with 250w per channel. The psu for the amp is literally just 3 atx psu's unearthed and in series to produce 36 volts dirt cheap.
Some measurements:
2.88ms gated on axis FR
1/12 oct smoothed FR
bass enclosure response nearfield (front and 2 openings on rear)
Lower midrange response nearfield (front and rear)
Distortion above 300 Hz, white line is thd (for bass you need something else, which I can measure/plot, but just didn't have the time and it will be good anyway as there really are no issues)
RTA maximum around my room
Spectral energy - this 60 hz spike is a room mode. I can see no stored energy above Schroder f, but it is raw so it looks ribbed. For pleasure. There is a bit of "fattening" between 1 and 4 khz, as predicted/wanted, but the on axis FR remains neutral.
Raw waterfall plot. Again, ignore stuff below 300 Hz.
Nearfield waterfall for low midrange.
Nearfield waterfall for subs. There is some stored energy but it's way below anything that would be an enclosure resonance (it should appear at 120 Hz, and it does, you can see it on the far right), and I can hear no problems. I was originaly a bit worried, but now quite sure it's actually room modes because the same pattern apears on the low mid too which has nothing to do with the lower enclosure.
Directivity. You can see some really nice dipole behaviour up to 1 khz and above 4 khz. 1-4 khz still exhibits dipole like response but it's much less pronounced, as it radiates some energy to the sides, making vocals more "in room" like but the on axis FR remains flat. As I said, it could be modded to be like a dipole all the way, but you can just have lx521 for that, and it would introduce some other problems too actually.
I'm no Linkwitz, obviously, but at least I have a hobby.
You would need:
SB23MFCL45-4 8x
SB12NMNRX2-25-4 2x
SB23NBACS45-4 2x
SB26STCN-C000-4 4x
This is quite expensive.
The designs are in cm.
Holes are optional. Pun intended.
Sorry about croatian, I can translate it into english if it's not self explanatory enough. Also, green are wooden square bars, I opted to use 2 on sides instead of one in the middle.
Attached are the cad files.
This of course needs 16 channel amps, or less if you decide to run tweeters and subs in some shared config. Ofc then you'd need to redo the eq part to fix that.
For eq, it's as follows:
stereo signal input (pre) : -18db
stereo signal input (pre, eq) : param. eq, 3.7 db, 3300 hz, q 1.8; lr4 high pass, 13 Hz
tweeters = lr4 high pass, 4500 hz
high mid = lr4 high pass, 500 hz; lr4 low pass, 4500 hz; parametric eq, -7.7 db, 1323 hz, q 2.1
low mid = lr4 high pass, 100 hz; lr4 low pass, 500 hz; parametric low shelf, +18db ,172 hz, q 0.7; param. eq, -10db ,837 hz ,q 4
sub = lr4 low pass,100 hz; param. low shelf, +18db, 49 hz, q 0.7; param. eq, -6db, 232 hz, q 1.5; param. eq, -10db, 115 hz, q 4; param. eq, -15 db, 135 hz, q 1.5; param. eq,-16 db, 145 hz, q 1.5
If you are a madlad and actually decide to build something like this, feel free to ask for help. If you want to donate something to me for my work, give it to some charity/humanitarians/animal shelter nearby instead.
Enjoy.
Oh and also do double check if everything makes sense. Don't hold me responsible if my drawings are flawed in some way. I hope they aren't and probably should be ok, but still.
This works best with full 2 Vrms (5.65 Vp-p) voltage capable EQ device.
My next project will be headphones. Lots of them.
SB23MFCL45-4 8x
SB12NMNRX2-25-4 2x
SB23NBACS45-4 2x
SB26STCN-C000-4 4x
This is quite expensive.
The designs are in cm.
Holes are optional. Pun intended.
Sorry about croatian, I can translate it into english if it's not self explanatory enough. Also, green are wooden square bars, I opted to use 2 on sides instead of one in the middle.
Attached are the cad files.
This of course needs 16 channel amps, or less if you decide to run tweeters and subs in some shared config. Ofc then you'd need to redo the eq part to fix that.
For eq, it's as follows:
stereo signal input (pre) : -18db
stereo signal input (pre, eq) : param. eq, 3.7 db, 3300 hz, q 1.8; lr4 high pass, 13 Hz
tweeters = lr4 high pass, 4500 hz
high mid = lr4 high pass, 500 hz; lr4 low pass, 4500 hz; parametric eq, -7.7 db, 1323 hz, q 2.1
low mid = lr4 high pass, 100 hz; lr4 low pass, 500 hz; parametric low shelf, +18db ,172 hz, q 0.7; param. eq, -10db ,837 hz ,q 4
sub = lr4 low pass,100 hz; param. low shelf, +18db, 49 hz, q 0.7; param. eq, -6db, 232 hz, q 1.5; param. eq, -10db, 115 hz, q 4; param. eq, -15 db, 135 hz, q 1.5; param. eq,-16 db, 145 hz, q 1.5
If you are a madlad and actually decide to build something like this, feel free to ask for help. If you want to donate something to me for my work, give it to some charity/humanitarians/animal shelter nearby instead.
Enjoy.
Oh and also do double check if everything makes sense. Don't hold me responsible if my drawings are flawed in some way. I hope they aren't and probably should be ok, but still.
This works best with full 2 Vrms (5.65 Vp-p) voltage capable EQ device.
My next project will be headphones. Lots of them.
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Forgot some of the most important things to say: other than Linkwitz, this is inspired (obviously) by JohnK and gainphile - so thank you both, a lot! 🙂
Thanks for posting the design and lots of detailed measurements! Looks nice, taking many cues from the successful LX521 design.
For anyone considering this: a good source of 16 channel amplification is a used Crestron CNAMPX-16X60. Only a small modification is needed to make the amp operate in standalone mode. A Behringer UMC1820 plus an ADA8200 will get you 16 (actually more) analog output channels to drive it, using computer audio DSP like Ecasound+LADSPA.
For anyone considering this: a good source of 16 channel amplification is a used Crestron CNAMPX-16X60. Only a small modification is needed to make the amp operate in standalone mode. A Behringer UMC1820 plus an ADA8200 will get you 16 (actually more) analog output channels to drive it, using computer audio DSP like Ecasound+LADSPA.
😱
Charlie Laub?
I'm using your LADSPA plugins myself for this speaker! 😀
You do realize this feels like talking to a legend to me, wow. Thanks for the reply my man, and for everything.
Charlie Laub?
I'm using your LADSPA plugins myself for this speaker! 😀
You do realize this feels like talking to a legend to me, wow. Thanks for the reply my man, and for everything.
I just came across this design, after reading about the shortcomings of the LX521 from
https://noaudiophile.com/RMAF_2015_Day_3/
https://hometheaterhifi.com/reviews...21-4mg-open-baffle-loudspeaker-system-review/
The difficulty really is making measurements that correlate to how we hear, and the effect in the room.
How do you like it, 2 years on?
https://noaudiophile.com/RMAF_2015_Day_3/
https://hometheaterhifi.com/reviews...21-4mg-open-baffle-loudspeaker-system-review/
The difficulty really is making measurements that correlate to how we hear, and the effect in the room.
How do you like it, 2 years on?
I'm obviously biased, but I like them very much, I prefer them over the lx521's. I think that the most likely culprit is actually absurdly powerful and tight bass coming seemingly out of nowhere. Just messes with your brain. 🙂
Well I missed this publication because I was in the Planar and Exotics sections. I wonder why you didn’t post in Multi-way.?
You solved the dipole bass dilemma within the use of extremely wide cabinets. And did vibration cancelling! Are you mech eng by training? Or did it come to you in a dream?
I bet the bass is amazing! What are you using for amps?
You solved the dipole bass dilemma within the use of extremely wide cabinets. And did vibration cancelling! Are you mech eng by training? Or did it come to you in a dream?
I bet the bass is amazing! What are you using for amps?
First, thanks 🙂
I wouldn't say I solved the dilemma, it's still very, very expensive, but this configuration does seem to be optimal in terms of compaction. You do get a resonance though that needs to be eq'ed out, but it's perfectly doable and sounds fine (with eq). I'm a doctor with more hobbies than sense :')
Bass really is something 🙂
Amps are 4 4way tpa3255 modules - these ones:
They work great, have balanced / se inputs, plenty of power, great specs and price.
I posted this in exotics because I considered fr dipoles as exotics. Sorry about that, thought they have to go here.
I wouldn't say I solved the dilemma, it's still very, very expensive, but this configuration does seem to be optimal in terms of compaction. You do get a resonance though that needs to be eq'ed out, but it's perfectly doable and sounds fine (with eq). I'm a doctor with more hobbies than sense :')
Bass really is something 🙂
Amps are 4 4way tpa3255 modules - these ones:
They work great, have balanced / se inputs, plenty of power, great specs and price.
I posted this in exotics because I considered fr dipoles as exotics. Sorry about that, thought they have to go here.
Also, the bass bins with such narrow side panels tend to vibrate anyway, so I just installed some extra vertical square beams inside them, that fixed the problem completely.
No, I haven't tried. But John K. has
https://musicanddesign.speakerdesign.net/u_frame.html
https://musicanddesign.speakerdesign.net/NaO-II-U-frame.html
The tunnel that radiates back must be quite long and damped (resistance). Still it will have standing wave resonances tht will limit upper end. Efficiency is rougly same as a dipole dropping towards lows. Kimmosto made woofers that has 2x18" drivers with cardioid pattern, he used similar side vents as D&D for midrange (covered with fabric in the pic)
https://www.audiosciencereview.com/...guides-for-constant-linear-directivity.58560/
Two opposing woofers, second with adjustable delay can be cardioid in certain rather narrow band https://www.genelec.com/w371a
I have briefly tested double dipole woofers in different arrangements, without dsp
https://musicanddesign.speakerdesign.net/u_frame.html
https://musicanddesign.speakerdesign.net/NaO-II-U-frame.html
The tunnel that radiates back must be quite long and damped (resistance). Still it will have standing wave resonances tht will limit upper end. Efficiency is rougly same as a dipole dropping towards lows. Kimmosto made woofers that has 2x18" drivers with cardioid pattern, he used similar side vents as D&D for midrange (covered with fabric in the pic)
https://www.audiosciencereview.com/...guides-for-constant-linear-directivity.58560/
Two opposing woofers, second with adjustable delay can be cardioid in certain rather narrow band https://www.genelec.com/w371a
I have briefly tested double dipole woofers in different arrangements, without dsp
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It's camilladsp now, driven from an asus xonar dx card.
SB23MFCL45-4 is an absolute beast of a driver. I perfer 15 or even 18's for subs due to large efficiency boost, but this driver is really great, specs are amazing, build quality too.
Please take a look at my open-wing headphone stereo-sound experiment, thanks. https://www.diyaudio.com/community/threads/open-wing-headphone-crossfeed-stereo-sound.391630/
I'm excited to read this, and will ponder whether that's what I hear -- more "intimacy" or perhaps "immediacy" -- from my minimalist-XO/XO-less series of omni/LX experiments (many in the Fullrange Photo Gallery past two years).
Couldn't leave well enough alone... I inserted the Eve 5.25" nude driver above the 6.5" forming a 3-way LX -- Naturelle perched precariously above; their acoustic centers all lined up. Simplified the first-order XO (0.15mH->6ohm 6.5" up-firing; 0.47mH->5.25" frontal; 23.4ohm->2.7uF->8ohm Naturelle) but only had a few spare minutes to tweak. Anyway tone-sweep sounded pretty flat. If I had any sense this ought to be the end of diy.... Quite shocking how much more of musicians' intent and performance nuance came through.
Up-firing widebands alone or with frontal high-frequency sound, create a floating image above and well-beyond the speakers -- a phenonmenon I'm trying to understand.
Happy to meet you Ben. --Wm
Moved to Multi-WayJust found this thread. Very interesting design!
Aren't the bass cabs narrow and deep, rather than wide? Or am I misreading something?
apologies- it was supposed to say-
without the use of extremely wide bass cabinets...
One of the challenges in any OB or dipole design is getting enough bass.
Usually that means a big drivers on big baffles.
Or to reduce the baffle size by using a H frame, W frame U frame, and use two drivers per speaker eg. Orion, LX521, NaO
Cramming a quad of 10" SLS 830668 in a baffle 10" wide would work. As long as it only needed to play to 300Hz, the 10" SLS can manage this...
without the use of extremely wide bass cabinets...
One of the challenges in any OB or dipole design is getting enough bass.
Usually that means a big drivers on big baffles.
Or to reduce the baffle size by using a H frame, W frame U frame, and use two drivers per speaker eg. Orion, LX521, NaO
Cramming a quad of 10" SLS 830668 in a baffle 10" wide would work. As long as it only needed to play to 300Hz, the 10" SLS can manage this...
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Ah, now I see. 🤣
I actually have 8 of the tymphany 10" XLS waiting to be used. I've been scratching my head thinking about how to make an Orion/LX521 style woofer box that uses 4 per side without getting too large.
@Ardacer How do you find the cavity resonance behaviour with the depth you have there - about 48cm I think?
I actually have 8 of the tymphany 10" XLS waiting to be used. I've been scratching my head thinking about how to make an Orion/LX521 style woofer box that uses 4 per side without getting too large.
@Ardacer How do you find the cavity resonance behaviour with the depth you have there - about 48cm I think?
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There's only one at 120 Hz that needs to be notched out. The rest are taken care of by the steep crossover.
It's not perfect, but it works fine. 🙂
Also the SB23MFCL45-4 has 24mm linear excursion and 27 Hz resonant f. It's an absolute beast.
@wchang
Will do! Thanks.
I'm interested in making a HRTF tracking and real time EQ device at this moment, I believe your approach is a pretty good overall fix (have to read a bit more into it, I expect sub bass issues) but not a permanent one with regards to headphone inferiority compared to speakers. There's not much interest in this I gather, unfortunatelly.
It's not perfect, but it works fine. 🙂
Also the SB23MFCL45-4 has 24mm linear excursion and 27 Hz resonant f. It's an absolute beast.
@wchang
Will do! Thanks.
I'm interested in making a HRTF tracking and real time EQ device at this moment, I believe your approach is a pretty good overall fix (have to read a bit more into it, I expect sub bass issues) but not a permanent one with regards to headphone inferiority compared to speakers. There's not much interest in this I gather, unfortunatelly.
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