DIY planar using aluminized mylar

[oshifis]

I tried 1% natrium hidroxide (= sodium hydroxid?) with good results. It removes both the photoresist and the aluminium. The material I tried on was aluminized food wrapping foil that I intended to replicate the diaphragm of a pair of orthodynamic headhones. I stuck with the photocpying. I wanted to use the other good side diaphragm as the mask in order to duplicate the faulty side, but the photoresist (Positiv 20) was not evenly distributed on the aluminium surface. It collected in spots like the aluminium were greasy. Perhaps it needed some washing with benzine or whatever so that the photoresist attached better.

[Steve Dunlap]

am planning to try something a bit novel with the mid-range planars --an isobaric planar design where I have to membranes on each side of a center spacer and a sealed space between. That will give me twice the current handling even as it improves the sensitivity by placing each membrane into the higher flux area near the magnets. I don't know of anyone that's tried this before.

Koss did this in their Model 1 electrostatic for the bass panels. They were triple instead of double like you plan.

[DavidJanszen]

Originally Posted by Steerpike

Some photoresists use sodium hydroxide as a developer.
This will remove the aluminium - and quite fast too. (I've done it to get clear film from coloured gift-wrap)

yes but be careful -- if you get it on your skin, it won't hurt right away, but it is burning nonetheless.

[tinitus]

Such p-p design with double diaphragms have no advantage
P-P magnet system on the other hand may be very effective, apart from all the drawbacks

Tho, p-p diaphragms with reversed phase converts the dipole into a bipole, which ought to result in more low end, if its big ebough
Or what else might happen in relation to the complete speaker design

But I dont see how two such soft diaphragms which are completely non pistonic will work in unity
At worst they may work against each other, with all sorts of issues following

But please, do build it
And afterwards you will think if only you had used the time, money and effort to perfect an ordinary proven good functioning principle
There is nothing left to invent about this

[DavidJanszen]

Originally Posted by Gustava

where I have to membranes on each side of a center spacer and a sealed space between. That will give me twice the current handling even as it improves the sensitivity by placing each membrane into the higher flux area near the magnets.

With ESL's, this can provide more membrane motion for a given set of voltages, which is good because those voltages are limited by various danged bits of reality. As has been pointed out, it was implemented by Henry Kloss briefly. It is currently being used by M-L in their CLX bass panel. You may note that this has never been done for any but bass panels. Anyone care to venture a guess as to why?

With MSL's, I think there should be a similar benefit at least in taking double advantage of the static B field, and as you point out, allowing higher total current density. But as with ESL's, you will find that this arrangement does not work for high and midrange frequencies. The fact that no one is doing this at all may mean something further. Have you done a patent search?

Oop, didn't think about the field interaction between the two membranes. Please don't flog me if it is destructive.

And of course, in any event, p-p is better than single ended, adn your state ment about getting into the stronge part of the field implies single-endedness.

[jrubins]

This sounds quite interesting.
Please keep us apprised of your progress

[båndsei]

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I have tried a planar with 2 membranes,It can`t be used for midrange but works for bass .Sensivity is not better than with one membrane.
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[tinitus]

Originally Posted by båndsei

I have tried a planar with 2 membranes,It can`t be used for midrange but works for bass .Sensivity is not better than with one membrane.

A push-pull planar woofer would ofcourse have P-P magnet design, and still a single diaphragm/membrane, and gets expencive