well i give it another shot tomorrow, i also looked at some magnet structures in femm. my magnets are not ideal of course since i dont use the complete 20mm deep gap. i better should use 10x10 or something. a return path at the back should help the field even more. but it might be in the way and give weird resonances so wont be trying this soon 
Ok i tried the W so 4 folds. different sizes result is a bit sad loads of distortion and low ouput. i then tried te amt way with the same magnets just flipped them 90 degrees. made a 10 fold version instead of the 6 and 4 of the normal ribbon style magnet arrangement. SPL rocketed 12 db above the others. for the same given load. im not 100 convinced yet, but it looks this a more effective way. but it also decreases the low end conditions. i will try some different materials now to see if i can extend it a bit.
loads of distortion and low ouput. i then tried te amt way with the same magnets just flipped them 90 degrees. made a 10 fold version instead of the 6 and 4 of the normal ribbon style magnet arrangement. SPL rocketed 12 db above the others. for the same given load. im not 100 convinced yet, but it looks this a more effective way. but it also decreases the low end conditions. i will try some different materials now to see if i can extend it a bit.Ok i tried the W so 4 folds. different sizes result is a bit sad
Can you post measurements, so I can compare
Ok i tried the W so 4 folds. different sizes result is a bit sad
Maybe like this
i used it as this
N\/\/\/\/\/\/N
- .............. -
S...............S
Ofcourse my current did not go one direction but every pleat/fold it switched from down to up
i used 4 x 40x20x5 mm magnets, not the biggest
your design is
N|S/\/\/\N|S like a normal ribbon
this first one has side ways movement. i did measure all failures be it not well documented. but the amt was by far the most efficient. (be it verry low resistance, but the others had that to)
i will upload some
N\/\/\/\/\/\/N
- .............. -
S...............S
Ofcourse my current did not go one direction but every pleat/fold it switched from down to up
i used 4 x 40x20x5 mm magnets, not the biggest
your design is
N|S/\/\/\N|S like a normal ribbon
this first one has side ways movement. i did measure all failures be it not well documented. but the amt was by far the most efficient. (be it verry low resistance, but the others had that to
)i will upload some
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Here's a measurement. with a 16 folds membrane. but thats it the limit for the 30 mm gap, or have to find some reinforcement without Upping the resonance freq.
BLUE AMT STYLE
RED W style in normal ribbon magnet structure.
both measured at same distance around 25 cm, and resistance is almost the same. 2 Ohms so very low but good enough for testing. both there distortion is a tad to high for my taste but i think there is a margin to gain lower distortion. for instance my magnets also influence the pieces where the tracks go sideways, this will result in upward movement. not something you want but since this one is so small 2 cm of the total 10 cm high has these sideways tracks. so have to make a bigger membranous and dont drive it the full length. (at least thats my theory)
and i have some hearable resonances left, witch i should be hunting down so i know what to do with it next time
i am very pleased the thing extends to 20khz. something i was afraid of with the deep folds
BLUE AMT STYLE
RED W style in normal ribbon magnet structure.
both measured at same distance around 25 cm, and resistance is almost the same. 2 Ohms so very low but good enough for testing. both there distortion is a tad to high for my taste but i think there is a margin to gain lower distortion. for instance my magnets also influence the pieces where the tracks go sideways, this will result in upward movement. not something you want
but since this one is so small 2 cm of the total 10 cm high has these sideways tracks. so have to make a bigger membranous and dont drive it the full length. (at least thats my theory)and i have some hearable resonances left, witch i should be hunting down so i know what to do with it next time
i am very pleased the thing extends to 20khz. something i was afraid of with the deep folds
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