Yet another Planar Magnetic Line Source, the SMAPPP

if I really need the loudspeakers to be so high.
Perhaps about 150 cm is enough, I can then make the mid membrane wider with
Thank Wrinex for the valuable (as always) input.
I haven't thought of the return paths yet, but I think your suggestion with aluminium traces is the best; the return path can be made very wide as they can be folded before gluing them down.

Do you think that such a membrane really needs to be corrugated?
It all depends on how low you want it top play i think, i only use corrugation so i can get away with no tension at all side ways. the distance that dictates the resonance. so with a tensioned foiled it works fine res will just be much higher
i got one foil here that only shows 20mm to the outside world (so the foil itself is wider) (it is single ended i must admit) , but that one can play from 350 hz on its own up to 18khz or more. its in the video for the last audio meeting i did. i would not say they where the best.... many things could be much better but it shows the idea why i corrugate
im sure you can make one without corrugation !! and since you plan on using a mid range all will be fine i guess ? maybe try a mini panel oif the same width before you make a huge one, just to see where that resonance will end up ? make sure the length is at least 4 times as long as the width so the vertical distance is far away from the sideways distance so you look at the resonance dictated by the width only since thats the thing you want to play with to get it as low as you can in resonance
ooooh i guess your fine then when using 1500Hz. well since corrugation makes it not resonate , normally what is giving the membrane stability is the tension (since a flat foil wont stay flat without tension). having corrugation spanning this width makes it possible to be not floppy and resonate (to an extend if the width becomes to big it will give problems) thats why it is pretty suitable for a foil that does not have to span a great width. having no tension can get the foil to have a resonance as low as 200-250 hz somethign not possible with a stretched foil for the same width
i dont know what the slope is but i think its 6 or 12, they are almost a apogee copy with some changes. 12 dB on the bass and 6 on the tweeter makes sence to me (did many panels like this) reason is , with the 12 db (LR) you can counter the raise in mid/top (and open baffle loss) and create a crossover at the same time this will end up in the region of 500-800Hz, you then use a tweeter that can play low at around 500-800 and it will fill in pretty nice and also adds up the best with the 12 db.. and not many parts needed. could be they used 12 db on the tweeter as well depend on how low they might be able to reach. they used on the bass panel the same method as the apogee or what you might be wanting to use.. a tensioner sidesways. on a corugated foil like hte apogee. i believe.
i must say there is still one BIG resonance though. depending on the tension.. so it wont be insane smooth. but will be smoother then lets say a panel without slanting , or a panel (like magnepan) without tuning knobs. Or tie downs as they call it.

In the end the idea is the same fill in some gaps in the 80-175 region. and lower the main res peak in dB's around main res (lets say 45 Hz)

By the end of this week i show an (prototype idea) alternative of doing it :) made possible by a friend of mine, so i cant take credit for that. it involves an active amp... but the result should be in theory lower distortion (still allot to test) and NO resonance peak at all ! witch can be nice.. since it wont hit magnets premature, and wont make it a one note bass. and if you got enough power and excursion room... you can even make it work 10-20 Hz lower then the resonance normally would allow. .. this feature i would not recommend though :) eats power.. but its fun it can... it makes less wide panels possible ( if the power handling allows it) ... to go as low as 50 Hz from a 20 cm wide panel... maybe even smaller.
well in the end ... i need to test all of this :) its just things that could be possible.... in theory :)
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Really, that was the factory's original narrative, too (Apogee). But - IMO - the distributed resonance can be presented by inaequal tensioning of rectangular shaped membrane.
yeah having that slant is nice. but some pieces will hit the magnets before others... so although the main res peak might be less it will still hit the magnets at its lowest resonance. although maybe on higher volume.. witch is a win for them :)
NO resonance peak at all ! witch can be nice.. since it wont hit magnets premature, and wont make it a one note bass. and if you got enough power and excursion room... you can even make it work 10-20 Hz lower then the resonance normally would allow. ..
If the damping (electrical and/or mechanical) is enough for necessary Q-reduction, the membrane movement will be constant velocity mode to the near of the resonance (12 dB/oct. slope decreasing farfield-output). Below resonance it will turn to 18 dB/oct. roll-of rate gradually, because the membrane compliance determined the constant amplitude mode. It needs a lot of electrical compensation, but the quality of sound can be a good reason for a lot of effort.
it will be electrically but with the use of MFB, so it measures the membrane movement. and there is a loop in the amplifier correcting what it sees. and most usefull i noticed in res park. :) so damping but without using felt etc. in the end i i need to test and play with it for a long time. i seen the prototype never used it !
Yes neodymum, i hope to make a video about it soon
by the way it is still a prototype :) and i like my speakers passive. to be fair, but its cool to play with and see what we can do. its a proven concept in normal drivers. he just made a way to make it possible on planars. now the question is.,... is it usefull :)