The WAF Dipole. The Waff-ole. Waffle.

Discussion in 'DIY' started by Ardacer, Sep 22, 2020.

  1. Ardacer

    Ardacer Friend

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    I appreciate the input! Nao note series looks similar to lx521 too, and it was actually JohnK's work that preceded Linkwitz by a bit if I remember correctly. All such speakers will have to look similar. Linkwitz uses w frame configuration for his lx521, 2 drivers that are spaced 45 degrees apart from vertical axis each (meaning only 50% cancellation, mine is 90x2 so full cancellation). It's more like a tall square. I use 4 drivers in a quite a bit different configuration and design, that's more similar to some of his earlier designs and to some of gainphile's. This is indeed a very specific mix of the three inspirations, JohnK's, Linkwitz and Gainphile's work - actually least of it is Linkwitz. His baffle looks a lot different to mine (and he uses his tweeters in pseudo dipole fashion, while I use them in both true dipole behaviour as well as pseudo, there are technical differences, arguably large enough, he uses upper midrange as pseudo dipole as well, something I do not at all) .
    It's as thin as it's possible to get it to be at this time, so it is deeper. It should take less space in a normal room. However, as I said, you could put this on wheels and move around at will. Can't do that with Linkwitz or Nao's.
    I'm not dead set on selling anything to anyone just yet. This design is my own work, I didn't steal anything, all the plans, drivers and calculations are new. The fact does remain that full range OB speakers using H or W or M or such frames for the low end will all look very, very similar. My sub bass frame is actually 3 U frames stacked on top of each other, creating a W-like behaviour with no problems in phase shift, just the resonance which can be eq'ed and/or avoided with proper xo.

    There is a huge gap between this and a product of any kind, I know, be it plans or the speaker. That's why I'm not so sure about it. We'll see.

    First I have to actually see if the bloody thing even works, lol.
    I'd never compare myself to Linkwitz. The guy is an immortal legend.
     
    Last edited: Oct 7, 2020
  2. Hrodulf

    Hrodulf Prohibited from acting as an MOT until year 2050

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    I'm not implying that you did steal anything. Just saying how it will look to people. Unless you've got people in a listening session, 95% of them will judge your work by looks only. If you can grab their attention in the first 5 seconds, then they might want to delve deeper. If not, tough luck.
     
  3. Ardacer

    Ardacer Friend

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    Absolutely true. People accused JohnK of being a Linkwitz copycat, when the man actually designed his thing first. This will be called a rip-off, for sure.
    I don't really care much, it's not my livelihood, just a hobby.

    I'll contact the folks from Germany that keep Linkwitz'es business alive, perhaps they'd be interested. I have 0 interest in a war between myself and Linkwitz fans, cause I'm his no1 fan anyway.
     
  4. Priidik

    Priidik MOT: Estelon

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    Are the bass drivers SB23MFCL45?
    I am a bit interested on how this would do in a dsp raped 3 way compact monitor box.
    Anyhow, I am looking forward to your assessment of bass performance.

    I think you could have gotten away with using a 15'' woofer in something like this arrangement:
    upload_2020-10-7_16-2-37.png
     
    Last edited: Oct 7, 2020
  5. Ardacer

    Ardacer Friend

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    I think they are, yes.
    Thought about that, but it turns out the speaker wouldn't be slimmer than lx521 and you have 0 vibration cancelling.
     
  6. Thad E Ginathom

    Thad E Ginathom Friend

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    Cat been inside the speakers yet?
     
  7. spwath

    spwath Hijinks master cum laudle

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    I am wondering, how do you design something like this? So much going on, a lot more than something like a simple ported or sealed box where you just use the T/S parameters with a simple equation. I am going into the field of acoustics, and this thing is pretty crazy.
     
  8. Ardacer

    Ardacer Friend

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    It is a great start to read and fully understand JohnK's and Linkwitz'es website. Musicanddesign is down, but it can be accessed through wayback machine. If you want to get more technical, JohnK has a nice list of reading literature (books, articles) on the subject.

    Not yet, the little bastard. I'll move them to our flat when amps arrive, no doubt he'll be all over and in them
     
  9. Ardacer

    Ardacer Friend

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    [​IMG]

    [​IMG]

    [​IMG]

    finally done after all this time
     
    Last edited: Jun 3, 2022
  10. Ardacer

    Ardacer Friend

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    The splotch of energy at 60 hz is irrelevant, only data over 300 hz is believable. This is gated to 2.88ms to eliminate reflections, and is raw without any smoothing.
    I'll do distortion measurements and proper bass dipole measurements, and directivity plots next.
     
  11. Ardacer

    Ardacer Friend

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    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, every single 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.
    I have prepared plans, schematics, cad files for the speaker. Not sure what I'll do with them yet.
     
  12. Ardacer

    Ardacer Friend

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    Ok, so I wrote a bit more about the whole project for the orion pluto lx forum (Linkwitz support group) and done a lot of measurements.

    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 :D. 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.

    [​IMG]

    next to the lx521

    [​IMG]

    [​IMG]

    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.

    [​IMG]

    [​IMG]

    [​IMG]

    Me next to the speaker, I'm 180cm tall.

    [​IMG]

    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.

    [​IMG]

    Some measurements:

    2.88ms gated on axis FR
    [​IMG]

    1/12 oct smoothed FR
    [​IMG]

    bass enclosure response nearfield (front and 2 openings on rear)
    [​IMG]

    Lower midrange response nearfield (front and rear)
    [​IMG]

    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)
    [​IMG]

    RTA maximum around my room
    [​IMG]

    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.
    [​IMG]

    Raw waterfall plot. Again, ignore stuff below 300 Hz.
    [​IMG]

    Nearfield waterfall for low midrange.
    [​IMG]

    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. Not really sure what's going on. Probably room modes.
    [​IMG]

    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.
    [​IMG]


    I'm no Linkwitz, obviously, but at least I have a hobby.

    Have a nice day, discussion/comments/telling me I suck all welcome. :)
     
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    Last edited: Jun 5, 2022

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