Dual membrane high excursion planar magnetic bass driver Part 2 - 2 tunes 

well both should be done. i was indeed looking at seals/ rubber gaskets to be used. but i think the leaking is a smaller contribution then the resonance poo :)

@@joppepeelen In an isobaric configuration, the trapped airspace between the cones is the flexible "glue" that makes it work properly, and what you've done here is no different. If that airspace is not sealed, the cones don't couple together and distortion goes way up. I'd seal it it and run the measurements again, otherwise the felt will get all of the credit if you do both :)

tja dat kan natuurlijk ook , maar dat idee is al wat ouder :) en is met name op res heel zinvol. wel kleine bandbreedte :)

There is actually an old patent on it. Guess nobody could get it to work commercially.

@@andrejensen7837 well depends on what you mean, but membrane absorbers are... really old :) BBC used them back in the 60-70's etc

@joppepeelen No there is an old patent on it . Can't remember from who. Maybe magnepan.

yes shes so cute :) but i dont like her sitting on me while i sleep. i thought for 3 minutes it was cute but if this becomes a thing im screwed :)

im not sure, as you can see they are far from a real speaker. if i made one for sale they would be at least twice as long , i need to play with it before i could call a number. but a decent set would not be cheap. i mean not as cheap as a magnepan. i cant make that work since i am not a factory :)

well yes :) but far better right now then i ever achieved :) so i am a happy camper

problem would be i think finsing the same magnets :( i think one has to just look how its constructed and apply it to what suits there materiaal

well i hope so , since right now i had to use -10dB at resonance :) and i know the rest will look better if i can damp it instead of using a notch

verry low :) 82 give or take ? for 2 watt :) curently, since they are 4 ohm , just like the LRS are 4 ohm at 84-85dB. so efficientit is not :) but then againits not really a speaker :) just a test panel to see what it does :)

@joppe We expect to see a video of a wider version later today.

@@joppepeelen thanks. so, magnepan is big just because of the SPL problem I think. You have to find a way to rise up a sensitivity. Then all the markets are yours )

well yes, problem right now is by adding a 2e foil, res goes from 45 to 57Hz. so thats the lowest it can go.. so i need to make the panel slightly wider and we have some more bottom end and i might be able to bottom it out as well. so far i did not manage

​@@joppepeelenWhy does the res goes up by the second panel?

well then the middle is push pull.. bad name. and the others work like this. but still it would cost you twice as much on magnets.. so i am not to sure. most often size is king. so in this case this might work then go large. and it should work rather ok :)

@joppepeelen yeah probably beter to use the magnets for size. Then you migth could get the membrane a little closer to magnets that would give you much higher sensitivity.

It never slapped so far. The X max might be a bit high for such small panel

Yes if driven beyond the fs and excursion is not capable. All speakers have this problem at there limits of mechanical properties not handling the thermal electric .

well at resonance the panels go and have there own life... like all fullranges (most planar magnetics have a hump at res, these have as well but a bit biggger, less controll, but also free bass) the idea is use this but not to much :) distortion rises near resonance :( my idea would be making one wider lowering this res. since more distortion at 30 hz is less of a problem, we cant hear it that well. the lower it gets

@@joppepeelen yes you are right . I am hoping to some day get into building planners, cheers 🥂

i dont think so unless memory foam is open cell ? the thing is air needs to get trough, just slower then normal

​@@joppepeelenmemory foam is horrible, a buddy of mine experimented with memory foam for mid, bass and sub bass enclosures to use ad a comparison with Virginia wool , fiberglass, dacron batting , rockwool and other fibrous materials , the end result was not desirable to say the least. Some of the speakers back in the mid 1980s had tweeters with a open cell foam tweeter defuser on the faceplates , energy speakers from Canada had that design on a few of there models , I replaced the opencell foam with wool felt 2mm thick and the highs was so much more clear . Memory foam literally bounces the Soundwave to a great degree instead of absorbing the standing waves .

@@joppepeelen I use it any time I want to damp low frequencies. It is better than anything else that I have ever tried. Low frequencies do not need open cell. They even go through closed doors and walls.

@@jasontimothywells9895 Stories of "my buddy" is internet myths at their best. I actually use memory foam a lot myself. I understand how and why it works where. The claim about stuffing subwoofers is another situation and only applies to closed subwoofer boxes (been there, done that too!). With the closed box, it changes the speed of air and looks like a "bigger box". Memory foam actually reduces bass getting to the frame. This is why I recommended it here. I use it with 3 way speakers or FAST two way. It is really effective between 50 and 150 Hz.