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Old 9th April 2015, 03:18 PM   #1
WrineX is offline WrineX  Netherlands
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Default sandwich esl ?Yummie

I mean literally , stator on stator on stator on stator :0

i made a small sandwich of a tiny panel for tweeter use, to see if this could work and to see what happens.

i costructed it so that all solder terminals are on the rim the high voltage terminals are tunrded 180 degree every stack so left is +HV right -Hv. etc



the panel is round and better would be a bit more oval, to get rid of some weird peaks and control vertical dispersion.


i measured first one solo panel (as you can see there are already some weird peaks, not sure what it is might be the fact its round) then i added one layer of insulation, a stator without copper but with all the holes as a normal stator. then a spacer with High voltage connection and another stator with spacer and menbrame.

since i dont swap stator polartity i switch polarity of the menbrame . i got one Hv + and one HV -, after each stacking i did a measurement to see what happens.


you can see that it almost ignores high frequencys, there is no gain. but the lower you go it does add up. and what is cool it composates for the roll off it had on the single panel.

second thing noticed clearly and we allready knew ofcourse, is resonance goes up.



Im looking forward to make a tiny bigger one with a little more room for the menbrame, with 0.5 mm spacing its pretty hard to keep the foil out of the stator. and lower the resonance. i would adopt the same design increase spacing a bit to 0.8 and add 2 more rings to it to lower res and play lower.


The high frequencys are pretty nice look at the dispersion, i think its rather ok. i cant hear any difference when i move my head. would be nice to make it a little bit higer then its wide, to not scatter high frequencies around the room where its not needed. vertical dispersion controll i measured all dispersion from approx 1 meter distance and smoothed 1/6th


i dont have a graph of the 4th stack, but its the same as the 2 and 3rd stack with some more SPL in the lower end and higher res freq. 1100hz.


the high frequency response of the 3rd stack is actually almost the same as second stack, dont know what i did wrong when i measured that. the opveral rolloff at 20k might be my class D amp, i will try to connect it to my main amplifier


i chose the size of the middle part based on a big tweeter, 1 inch +- 25 mm
Attached Images
File Type: png 1 2 or 3 stacked tweeter.png (26.6 KB, 287 views)
File Type: png off axis response 0 15 30.png (22.8 KB, 271 views)
File Type: png off axis response 45.png (20.8 KB, 270 views)
File Type: jpg IMG_2121.jpg (315.9 KB, 286 views)
File Type: jpg IMG_2122.jpg (317.7 KB, 284 views)

Last edited by WrineX; 9th April 2015 at 03:29 PM.
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Old 9th April 2015, 05:05 PM   #2
WrineX is offline WrineX  Netherlands
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im listening to them mates with a 12 inch OB, and im pretty impressed. crossed at 1450Hz bit higher then i would like, but still it sounds pretty good, and the dispersion is .... well i love to not be bound to one spot! , i sit in another room while i type this and i can hear everything clearly , also the highs. i ordered another batch of 0.5 mm pcb i have to play with this a bit more im affraid. i also tried my clas AB amp and the roll of at 18Khz is not my class D, maybe its the transformer, since the solo panel has the same roll off. either on class D or AB
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Old 9th April 2015, 05:19 PM   #3
tyu is online now tyu  United States
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Vary cool....good job.....keep up the good work.....an thanks for all the info an pic..lov to hear them.............
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Old 9th April 2015, 05:32 PM   #4
WrineX is offline WrineX  Netherlands
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welll believe it or not i have made the thing, where i usually think what does it add. a video. since my iphone sucks ofcourse. but it does give you a slight idea about dispersion. although i sometimes do watch these video's when im interested in some sort of design. but ofcourse you cant judge a speaker on it. also funny is i can hear my room (acoustics) really good on the phone its not dead thats for sure. pardon me for being wobbly, i might had a beer to much during listening


here is the monstrosity

https://www.youtube.com/watch?v=RBOjg3MTKa4



when i stand up you can really hear the room acoustics being twice as loud. funny because i did not notice this when i did it.



One thing to notice , The solo panel is almost 10 dB down in the lower frequency compared to the triple layered. compared to the 4 layer its even more like 12

Last edited by WrineX; 9th April 2015 at 05:37 PM.
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Old 9th April 2015, 07:58 PM   #5
tyu is online now tyu  United States
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Wow............that's just one speaker...........I like what I hear....phone is not bad at all...........I have heard a lot of speakers on youtube that I have owned an its a shock how close there sound is to my ears............to the sound in my room......I say your sound on ......1-10.......8....thanks
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Old 9th April 2015, 08:19 PM   #6
irribeo is online now irribeo  Netherlands
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cool
(my sony xperiaZ records quieter when I switch off wifi on mobile, the little ticking heard with iphone might also be some active circuit?)
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Old 9th April 2015, 08:51 PM   #7
WrineX is offline WrineX  Netherlands
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I Will make some decent pictures of THE components tomorow, instead of THE crappy foto.
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Old 10th April 2015, 06:08 AM   #8
Calvin is offline Calvin  Germany
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Hi,

stacking two is fine. It can give You up to +6dB of SPL at lower frequencies.
That may be just enough to cancel the acoustic phase cancellation, thereby lowering the demand for electronic EQ and drive power.
The effect lowers with rising frequency and from the upper midrange on there's no benefit anymore but phase issues begin, depending on the distance of the diaphragms.
With a design of n diaphragms and n+1 stators, phase issues up to total cancellation are inherent as it is impossible to achieve less than a few mm of membranes distance.

jauu
Calvin
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Old 10th April 2015, 07:39 AM   #9
WrineX is offline WrineX  Netherlands
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as you can see, it works at 1 khz still, also the phase cancelation should be visable in the higher frequency, even in this design. at least i expected it. but the graphs dont look verry different compared to only one stack. so im not sure whats going on.
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Old 10th April 2015, 08:52 AM   #10
WrineX is offline WrineX  Netherlands
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here are some pictures of the seperate parts. they are all sandwiched with 4 bolts. i added a white tiny dot as membrane support in the middle, not yet tested. might raise the res to high to be of any use. test will tell.

Pic 1 A spacer with Hv connection
Pic 2 3 stators with spacer and the membrane
Pic 3 Isolation stator, it is the same as a stator except without copper, to put on the copper side of a stator, so the actually copper to membrame distance is +-1 mm between every stator (0.5 air, 0.5 mm pcb material then the copper on that pcb)
Pic 4 other isolators.


as calvin mentioned and as i showed in the graph its usefullness is to counter eq in lower frequencies. i think thats verry interesting, when you want small size panels. th small sanwich here could even fit in a dustcap of a 15 inch to make a point source. it has a 87 mm in diameter in total (with the little ears) it wont fit into a coil former

in the graph you can see the gain starts to be usefull from 3 khz and down.
Attached Images
File Type: jpg P1030453.JPG (268.3 KB, 114 views)
File Type: jpg P1030454.JPG (345.4 KB, 113 views)
File Type: jpg P1030455.JPG (277.9 KB, 111 views)
File Type: jpg P1030456.JPG (260.0 KB, 87 views)

Last edited by WrineX; 10th April 2015 at 09:07 AM.
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