Just ordered a roll just for the fun of it.
It might turn up as multi-layer membrane for a planar or even as an extra layer for an AMT. Or maybe it will be used as an ordinary double-sided tape.
I´ll wait a while with the carbon anyway.
But let's see what it can do when it arrives.
It might turn up as multi-layer membrane for a planar or even as an extra layer for an AMT. Or maybe it will be used as an ordinary double-sided tape.
I´ll wait a while with the carbon anyway.
But let's see what it can do when it arrives.
oh maybe really stupid, but yesterday night i found out the tape is not a tape 🙂 thought it whas some sort of double sided tape. but it is actually only the acrylate sticky stuff that you can find on tapes. i managed to get my hand on a pdf wich describes some acoustical transducers. without the missing pages.
I think the way you inplent the push pull and the size will determen how wel this might work. they say in the pdf that getting higher ac voltages imposed on the DC bias will increase distortion. when the ratio is low in a push pull the distortion can be as low as 1 % wich is still better then most loudspeakers.
i can send you the pdf if you like. its pretty interesting and has allot of other uses for EAP's as well
I think the way you inplent the push pull and the size will determen how wel this might work. they say in the pdf that getting higher ac voltages imposed on the DC bias will increase distortion. when the ratio is low in a push pull the distortion can be as low as 1 % wich is still better then most loudspeakers.
i can send you the pdf if you like. its pretty interesting and has allot of other uses for EAP's as well
Last edited:
So the input signal is biased in order to get a contraction of the VHB between the charged plates, some thousand of Volts or so.
That means that during the positive half cycle of the "ripple", the VHB is even more contracted by the increased force that results from the two plates being more attracted to each other but for the negative half cycle, it will be a relaxation of the VHB.
Not an active expansion as the bias isn't swapped.
(That could be done of course, having a total swing of +/- of the bias voltage.
But, AFAIK, the resulting contraction/expansion isn't linear of the total range)
Wouldn't the two half-cycles have skewed duty-cycles of the resulting forces (and thus the reproduced sound)?
That means that during the positive half cycle of the "ripple", the VHB is even more contracted by the increased force that results from the two plates being more attracted to each other but for the negative half cycle, it will be a relaxation of the VHB.
Not an active expansion as the bias isn't swapped.
(That could be done of course, having a total swing of +/- of the bias voltage.
But, AFAIK, the resulting contraction/expansion isn't linear of the total range)
Wouldn't the two half-cycles have skewed duty-cycles of the resulting forces (and thus the reproduced sound)?
well still because it contract along the film three is no sound reproduction. there are ways to get that ofcourse, either by a spring or air (like a small balloon) but better in my opninion is to use 2 menbrames each for one cycle one to actively pull and another to activly push. so for instance you ahve 2 menbrames on one round circular spacer . if you stick the middle part thats is not coated to eachother
say you got a total menbrame of a diameter of 10 cm you coat both menbrames except a circle in the middle with diameter of 6 cm, you then stick both menbrames to eacht other at the cicle that is not coated. if you wire the both mrenbrames out of phase. one should be pulling the other depending on the positive cycle or the negative.
i think the bias is used because the VHB is indeed non linear above a certain voltage it works great but below that, for lets say only a stepup tranformer will not result in the wanted movement.
so the above contraption would result in an active push pull system/ combined with the relaxsation of one of the menbrames.
here i posted it in the first page
http://202.114.89.42/resource/pdf/5366.pdf
i think its a rather nice idea. also because it could drive a large mebrame as well like honeycomb or foam or whatever. if you enlarge the eaps width, the stroke increases. i could imagine you could maybe even make some sort of longtrow panel this way... even the results in their measurement are not that bad
the panel thats generating sound is only 5 cm in diameter, another thing is in the last pdf i posted the metnioned that High AC voltages is not a good idea or at least the ratio has to be something around 0.1-0.2 or something. in this experiment they used 1000-AC 2000 dc. far off , so the distortion could be decreased further.
if you use the thicker VHB wich is perfectly capable of handling way higher voltages then 2000 bias. you could increase the ac as well.
say you got a total menbrame of a diameter of 10 cm you coat both menbrames except a circle in the middle with diameter of 6 cm, you then stick both menbrames to eacht other at the cicle that is not coated. if you wire the both mrenbrames out of phase. one should be pulling the other depending on the positive cycle or the negative.
i think the bias is used because the VHB is indeed non linear above a certain voltage it works great but below that, for lets say only a stepup tranformer will not result in the wanted movement.
so the above contraption would result in an active push pull system/ combined with the relaxsation of one of the menbrames.
here i posted it in the first page
http://202.114.89.42/resource/pdf/5366.pdf
i think its a rather nice idea. also because it could drive a large mebrame as well like honeycomb or foam or whatever. if you enlarge the eaps width, the stroke increases. i could imagine you could maybe even make some sort of longtrow panel this way... even the results in their measurement are not that bad
the panel thats generating sound is only 5 cm in diameter, another thing is in the last pdf i posted the metnioned that High AC voltages is not a good idea or at least the ratio has to be something around 0.1-0.2 or something. in this experiment they used 1000-AC 2000 dc. far off , so the distortion could be decreased further.
if you use the thicker VHB wich is perfectly capable of handling way higher voltages then 2000 bias. you could increase the ac as well.
Last edited:
could even make a square like the way they did and stick a piece of foam or hony comb in between, adjust the spacer distance and you have a loudspeaker. im particulair interested in scaling it up by a factor of 10 or so. see how low it goes. i guess low... since my thoughts where that it could not keep up with high fequency's but it reaches 30Khz. we all have seen in all youtube videos's that an eap can handle low frequency movements easy. you want more excursion? make the eap's wider.
No store in Sweden. Ordered the 20th at 8:55 and got it at 11:47 today the 22th.
Customs fee and VAT payed over the phone via the Swedish UPS office (got a text/SMS with the invoice).
Customs fee and VAT payed over the phone via the Swedish UPS office (got a text/SMS with the invoice).
nice , i paid by bank tranfer. i did not pay any VAT as of yet. i hope i did it right. or i just payed them randomly some money 🙁
5 minutes later
oh i did get my invoice 4 hours after i payed. it stated the same amount of money so i guess im save
looks like i am gone play this weekend or else next week 🙂
5 minutes later
oh i did get my invoice 4 hours after i payed. it stated the same amount of money so i guess im save
looks like i am gone play this weekend or else next week 🙂
Last edited:
you tried stretching a menbrame yet? i've seen this video that makes it look pretty eassy
https://www.youtube.com/watch?v=7CJpSPf24DQ
and
https://www.youtube.com/watch?v=dKPt9yzmw98
at least for a small menbrame
https://www.youtube.com/watch?v=7CJpSPf24DQ
and
https://www.youtube.com/watch?v=dKPt9yzmw98
at least for a small menbrame
Haven´t tried yet but yes, that will be the way I do it.
If a frame is 400x150 mm, 300x100 mm tape can be applied to one short-side end and a rod that can slide across the frame.
Slide the rod towards the other end and thus expanding the tape to 400 mm.
Of course can the rod actually be the other short-side of the frame.
Then it should be easy to extend the free 300 mm sides of the tape to the long-sides of the frame.
If a frame is 400x150 mm, 300x100 mm tape can be applied to one short-side end and a rod that can slide across the frame.
Slide the rod towards the other end and thus expanding the tape to 400 mm.
Of course can the rod actually be the other short-side of the frame.
Then it should be easy to extend the free 300 mm sides of the tape to the long-sides of the frame.
Just tried the above.
The backing will not come off more then 50 mm, then the bare tape cannot pull any more from the backing.
Anyway, with those 50 mm of bare tape, I didn't manage to expand the 100 mm wide tape to 150 mm width in one step without ripping the tape.
Perhaps with smaller steps and a little practice...
The backing will not come off more then 50 mm, then the bare tape cannot pull any more from the backing.
Anyway, with those 50 mm of bare tape, I didn't manage to expand the 100 mm wide tape to 150 mm width in one step without ripping the tape.
Perhaps with smaller steps and a little practice...
what do you mean with The backing will not come off more then 50 mm?
im geting afraid we went to thin to start with. 🙁 we all stretched so many mylar thats eassy because it only stretches a few percent this is 200% or more.. we cant even use our old rigs 🙁. i like the way hes doing it in the youtube video. but this only works with small menbrames. but in the end we dont need big menbrames i think. but the simplest method should be a round frame. but as you got the material i am not sure this thin stuff can do the same as in the video. i think thats 4910 stuff
maybe the scissor strech rig works ? but is allot of work to only make the rig work 🙂 i dont like the shower hose version because i lose all the material i prestretch. its a wastefull way of making a menbrame
https://www.youtube.com/watch?v=uw8FLgiXsmk
and
https://www.youtube.com/watch?v=PgNKeqOCOKE
Last edited:
The free tape can't be used to peel off more tape from the backing.
The adhesion force to the backing is too big, the bare tape breaks.
Perhaps the backing can be removed in parts with some support every 50 mm.
Yes, definitely too 🤐 thin.
oh crap, maybe its easyer to first aplly to rig with backing then remove backing? in one fast sweep. thats what they suggest. hmm getting the backing of already gets to complicated for us , we never make a thing that makes sound 😉
Oh i just thought of an idea, if all the stretching trouble is solved.
We might be able to Eq the EAP by sigmenting on the eap. so we got control on how much it relaxes at wich frequency. we could play with different Bias or resistance on the AC component. aaah i want to build 🙂
We might be able to Eq the EAP by sigmenting on the eap. so we got control on how much it relaxes at wich frequency. we could play with different Bias or resistance on the AC component. aaah i want to build 🙂
any thing tried already ? my material is on the way, they called me today in dutch for a VAT number so i guess its almost here.
i thought long and hard how to use the movement the other way around, by not using the relaxation of the menbrame itself but the active pushing of the 2 electrodes. could not think of a decent idea yet. except for having 2 menbrames horizontal, then put a rigid menbrame or cone or beeboard or whatever in between the 2 menbrames on the edge of the electrodes. so when activated the area where the electrodes are expands.
And the cone moves forward. not sure if this is usefull. since one of the push pull systems still relies on the relaxation, .... hmmmm
ill first try a generic flat menbrame to see if my power suplly is up to the task, then if i can implent an audio transformer (superimpose a AC on the bias). After that i might try to make a backplate for the frame with a cavity in it and a valve to blow in some air and make a dome shaped menbrame. to see if we can get any sound. (thats not push pull so distortion ought to be highish) second option is to put 2 of these menbrames back to back dissmiss the backplate so you have a push pull with air in between. but still dome shaped on both sides. the air will push the menbrame outwards when you activate the eap one of the eap's and expands, the other menbrame will relaxe a bit and moves in the same direction.
just like an ordinairy loudpeaker push pull configuration, with a air spring in between.
i thought long and hard how to use the movement the other way around, by not using the relaxation of the menbrame itself but the active pushing of the 2 electrodes. could not think of a decent idea yet. except for having 2 menbrames horizontal, then put a rigid menbrame or cone or beeboard or whatever in between the 2 menbrames on the edge of the electrodes. so when activated the area where the electrodes are expands.
And the cone moves forward. not sure if this is usefull. since one of the push pull systems still relies on the relaxation, .... hmmmm
ill first try a generic flat menbrame to see if my power suplly is up to the task, then if i can implent an audio transformer (superimpose a AC on the bias). After that i might try to make a backplate for the frame with a cavity in it and a valve to blow in some air and make a dome shaped menbrame. to see if we can get any sound. (thats not push pull so distortion ought to be highish) second option is to put 2 of these menbrames back to back dissmiss the backplate so you have a push pull with air in between. but still dome shaped on both sides. the air will push the menbrame outwards when you activate the eap one of the eap's and expands, the other menbrame will relaxe a bit and moves in the same direction.
just like an ordinairy loudpeaker push pull configuration, with a air spring in between.
Last edited:
- Status
- Not open for further replies.