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Supersteff

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  1. Hi Chris and Mark (Gnarly) This is a very interesting discussion, and also a bit complicated to discuss, depending on what trade-off´s are made/intended?! That would be one set af trade-off´s as, I see it. A two way horn-system with a set of woofers to do the 20-200 Hz duty. A. That requires bigger ports to go low. B. the "big 402 horn" does not provide optimal loading for the woofers in the lower octaves, meaning that the modulation distortion can go up!? These are my assumptions, they may not be correct. I have just begun to understand the implication and importance of (inter-)modulation-distortion in my own experience with two big basshorns in my listening-room years ago, due to knowledge conveyed by you (Chris), an the article called "The Mud Factor". I called it the effekt of invisible/weightless bass back then. Today I know/believe it is the absence of modulation-distortion I heard back then! I liked that invisible/weightless bass so very much, in fact I strive to have it in my future system. Therefor I have been thinking of an other set of trade-off´s, a three way system: A "big 402 horn" with Axi2050´s with smaller off-axis ports (and smaller woofers I guess) crossed at maybe 80Hz to some sort of horn-sub-bass that is more optimized for that region of bass, i.e. 20-100 Hz, length and flare-rate. Of course placed in a corner, and it will fill some more space!. With this set of trade-off´s I would still have full-range directivity with less disturbance from the off-axis ports and lover modulation-distortion in the bass. I do assume that the ports in a MEH do have to be "oversized"/made bigger, to be able to play down to 20 Hz without chuffing. This has been one of the things I have been thinking about for some time. And I guess it has to be remembered here, that the "original K402 MEH" was developed to be a center-speaker, and not for corner-placement! That must must have influenced the choice of woofers and porthole-dimensions? I have often wondered how a K402MEH, optimized to be supported by a Jubilee-bass-bin would have to be constructed? Also I have been wondering, if the woofer-section of the K402MEH is approaching direct radiating bass-reproduction due to less and less hornloading as frequency goes down? I know the K402 is a conical horn and hence has no cut-off as an exponential horn does. You, Chris, have shown illustrations about that before, but is there a point, where the woofers see no hornloading anymore? All that said. The "big 402 horn" as proposed by Chris might just be a very fine and balanced compromise! Regards Steffen
  2. Hi Mark Nice work! Thanks for trying my idea. I have been looking at the picture of your compromise, smiley with round hole. In a way it seems to me that it approaches my suggestion for at smiley (in average pulls the middle section of the port nearer to the apex/CD), constructed as an arc with the center in the apex. So it gets more 🙂 than 😊. That would for me be the geometrically most beautiful solution! Although I don´t know if that is a valid design-criteria!? I think it was good old Buckminster Fuller who said something like: "A good solution of a problem is often also a beautiful solution for the eye!" If you have the time, energy and motivation then here is a new proposal: What if you make a 🙂/smiley with an open mouth. An elliptically shaped port, eventually a "smiling" ellipse. Still following the idea of an arc relative to the apex, but just wider in the middle section of the port. This could somehow be "the beautiful version" of the smiley/hole-version. Maybe you will have to place the "smiling-ellipse-port" off-center relative to your woofer, to get it near enough to the CD? Just an other compromise/trade off!!!! Happy experimenting! Steffen
  3. Hi Mark I have been wondering about "time-smearing" (maybe the wrong word for that effect?) due to different distances to the apex of the "open area" of the ports (off- or on-axis). What defines the wave-front of the woofers response, i.e. acoustic center!? It apparently is no big issue with round holes! Chris wrote something about it some time ago. That the cancelation-notch is "spread" out due to differences in distance of the outer/middle/inner part of the port relative to the apex. I hope you do understand what I am trying to explain!? I would have expected a "happy face/🙂" to be best!? If I imagine the sound-wave-front to progress out through the conical horn as a segment of a sphere (like a soap-bubble), then the surface of the sound-bubble would "cut" the horn-wall as a "happy face" ( equal distance to the apex at all positions). You can se a bit of that in the big Jericho synergy´s with 6 times 18" drivers firing through holes that are arranged in an arc, following the intended sound-bubble! Could you try a happy face to? Following the sound-bubble. I think it would be an arc with the center in the apex. But I think you can figure it out. 🙂 Steffen PS: Thank you for experimenting and sharing!
  4. Hmm Wouldn't that be kind of the same as bass-reflex? Maybe you could tune lower with heavier passive radiators, but you still have all the "bad" things from the bass-reflex! I have contemplated making a big MEH with four 8" woofers (one each corner) covering maybe 100-300 Hz, supported by 4 times 15" woofers (one each corner) as kind of a build in sub with 1/4 wavelenght integration. In that way I could reduce the size of the off-axis ports near the compressiondriver, hoping that the extra bigger holes further out the horn for the 15's won't disturb the sound waves in the midrange so much, and gain more membrane-area in the sub! That would make a really big true point-source! We'll see, if I ever build it. But I would prefer that approach to a design with passive woofers. Steffen
  5. Maybe this answers your question? I believe there are many woofers out there that can be used in a MEH, especially considering that you need a DSP anyway to cross, boost and attenuate. Steffen
  6. @rickmcinnis Is that a similar idea as with Geddes foam-plug of reticulated foam in front of the throat in his Summas/OS high-frequency-horn? As I have understood it, Geddes foam-plug is there, to prevent "back-reflections" from the horn-mouth to re-enter the horn and be emitted out. Some sort of absorption of reflections? Maybe it´s something related to his HOM´s!? Well, I´m not sure my explanation is right. But an interesting thing to explore if it has "relaxing" effect, and could be an improvement!? Steffen
  7. Hi Gnarly. I'm just guessing here. Are FIR-filters always with the same delay? Maybe the lower the crossower-frequency the longer the needed delay, due to longer wavelenghts? My thought is, that the delay is given by the high-pass-crossower-frequency, in your case 100 Hz. You could check that hypotese, by creating high-pass-filters with say 200 Hz, and see if the deley gets shorter/lower or stays the same!? I think that for lower frequencies you need more taps, and more taps make more delay. Is that correct? Steffen
  8. Hi gnarly/Mark Well that was my best guess on the delay. Maybe Chris can shed some light on that phenomenon? And your FIR-filters are interesting! Have to go now. Steffen
  9. fantastic---you have the CAD drawings of the MEH K402 - in a rectangular cabinet , could you simulate what size drivers could fit ? Hi RandyH000 I think you mistake me for someone else, maybe StabMe, who has an other thread in this forum making a wooden K402-horn? I don´t have any drawings, unfortunately.
  10. Hi Gnarly Well I kind of thought of you, when I wrote "somebody" 😄. It seems you are pretty skilled in building horns. I hope to become skilled to, but have some issues preventing me from starting up my synergy-projects. Interesting to see what you come up with. I think it is important to think thoroughly about the design of the "experiment" to really know what you are looking for. As said, I´m most interested in Danley-style ports. On the other hand, I have contemplated to build a horn your stile (one woofer top/bottom in between the walls), but with two smaller woofer-ports instead of one, i.e. like a compromise between Danley-style and Gnarly-style. That way the port would not be in the center and the ports would be smaller!? Dunno if that is a good idea? Can this be caused by a phase-shift/delay caused by the acoustic low-pass-filter of the band-pass-enclosure that the woofers are playing through? I think Tom D hinted at something like that once. A lot to learn! I really appreciate this learning environment/forum and the people contributing with knowledge and experience. Well this thread has partly developed into some sort of learning/understanding thread for Big MEH´s, so I don´t know where else to put it? Most of the threads started by Chris tend to develop into educational threads going in all sorts of directions, answering all kind of questions in regard to MEH´s! Maybe start a new thread for "Experiments and explorations of the MEH-concept"? I think we are quite some people following this thread, that do not have access to K402-horns for different reasons (me living in Denmark, Europe), but are inspired by the K402 for some kind of DIY-solution like yours. Steffen
  11. Well the SH96 has a square cabinet, that does not fit in the corner! But the SH96 is an inspiration. I have been contemplating 4 woofers (16 ohms all in parallel) too, to be able to place the woofer centered over the off-axis ports. Steffen
  12. OK, thank you. Then the advantage of top/bottom woofers is mostly, that it is easier to build a "triangular" cabinet for the horn, making it fit the room-corner better and maybe picking the boundaries up better? Like the SH50 but 90x60. Steffen
  13. I have been wondering for some time, weather it makes a difference, where the off-axis-ports are located, i.e. on the sides or top/bottom? How does it affect the horizontal dispersion? In other words, would it be a good idea to place the woofers top/bottom, so that the off-axis-ports disturbances are moved from the horizontal to the vertical plane? Suggestion for an experiment: Someone builds a 60x60 horn of reasonable full-range MEH size, mount a CD and woofers on two opposing sides and then measure polar response vertical, horizontal (and maybe even diagonally?) with and without off-axis-ports drilled (like Gnarly did). There are of course at least two options for the placement of the off-axis-ports, Danley-style and Gnarly-style. I´d prefer to see the results for Danley-stile off-axis-ports. That experiment could potentially be very educational if carefully designed. Maybe there could be some group-funding per PayPal to pay for some sheets of plywood? I am not in a position to execute that experiment. Steffen
  14. Hi all Celestion has developed a piece of software to simulate horns for their compression-drivers, called HornWizard: https://celestion.com/our-news/celestions-hornwizard-app-makes-winter-namm-2021-debut/ I have downloaded it and did play with it a bit, some time ago. You can simulate horns with and without diffraction-slot and it will compute the frequency-plot (maybe also polar-plots, can´t remember). It also generates a nice picture of the simulated horn, and the one´s with diffraction-slot always seem to look like the big Celestion horn for the AXI2050, shown previously in this thread! What I did notice was that the frequency-plots for horns simulated with diffraction-slot have high-frequency-ripple, the one´s without do not! Play with it an see for your self. regards Steffen
  15. Thank you also from me for starting this thread 🙂. I decided to boy the book as a gift to my self! I have been looking for horn-knowledge all over the internet since my very first search-entry on the AltaVista-search-engine back in the 90´s, and the first homepage I found was Thomas Dunker´s Hornspeaker-homepage!!! I spend lots of time studying that Homepage. I even met Thomas at a triode-festival in the early 2000´s, where I also heard Peter Bahnsen´s three way cornerhorns with 108 dB/w/m sensitivity. Amazing. And now 20 years later we have this nice book. I have spent some time reading the first 8 chapters of the book, the historical part, and must say that I did enjoy it very much. It has been kind of a pleasant start of the learning curve for me, not too steep, providing some overview! Also I found it very interesting and enlightening to get to know why and when who invented what. It provided me with perspective and also some respect and awe of the capabilities of these early scientists moving forward on unproved ground. These guys did NOT have computers! And PWK did not have much driver-material to choose from for his constructions in the 40´s! Those were pioneers. I have just finished page 422. I have picked up quite some knowledge here and there in the historical part of the book, and have started to think : What do I want to get out of this book? What is of particular practical interest for me? It seems to me that I need to be very aware of what context some statements are made in, i.e. is a statement referring to an exponential horn or a conical horn!? Most horns up till recent times are some kind of exponential/curved wall horns, or horns combining exponential loading with partly straight walls to improve directivity! I am mostly interested in everything relating to big full-range MEH´s, like the K402 MEH, and some sort of a horn-subwoofer for that (maybe being a tapped horn of some sort?). And of course I am interested in, what I can fit into my living-room! Looking for good and reasonable compromises. I´ll continue reading................. Steffen
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