So the question remains ... what can be an easy substitute to glue and mylar. Since I have made a couple of ribbon tweeters, I decided that this build needs to go a bit lower in frequency response. This also makes it possible to use thicker diaphragm material. I am still using a 46 micro farad cap in series to filter some lows.
Another common point of preference is the wire vs alu foil, though alu foil is better at dissipating heat, wires are much much easier to work with. I went with 11 micron Superwrap Alu foil because I know how it behaves. It is advisable to soap up and wet the foil to relieve any tension it may already have.
For the diaphragm, I decided to use common cello-tape or some polymide/BOPP tape. I wanted a very thin tape and ended initially with kapton, although the tape is 25 microns only, the adhesive backing cumulatively makes it 60 microns which was a bit outside my boundary. I finally got some 38 micron 'Wonder' tape. Obviously, using such strips of tape will not move any air for any bass like them commercial planars but then again I like this method. Another purchase was a corrugating device or tube squeezer for corrugating the alu-foil.
The magnets I use in this project are 4cm by 2cm by 1 cm in dimensions. Per speaker, I employ about 52 magnets. Their arrangement differs from the conventional speakers since I didn't want to use glue. So I made 2 frames out of MS that I had used for my first ribbon - 43 cm by 25 cm. I then placed N-S-N-S magnets across the frame which solves the problem of glue and also prevents the magnets from flying away from its adjacent partner in the column. MS frame also holds the magnet down. The drawback of this approach is definitely the lower magnetic field you get since we are 'shorting' opposite poles. None the less my priorities can afford to over see these drawbacks, at least for now.
For the conductor design I decided to pursue the route of matching the impedance of my super cheap 'Jansen' amp - 4 ohms. The task of cutting alu foil to 4mm and sticking one strip at a time on the cello-tape (great way to test your patience) is a rather stressful but I am used to it now. The below link is the calculator I used for the impedance.
I will explain how to use this calculator. Its fairly easy. I believe it used the formula of Resistivity that is R= Rho*L/A. You need to just input length, width and thickness of your conductor. The length of my conductor is around 47 cm pre-corrugated and 43 cm after corrugation, which is also the length of the frame. I use 3 strips of cello-tape with 4 strips of 47 cm long alu-foil corrugated per strip. So the length is 47 cm*3*4 = 564 cm. The thickness is 11 micron (the thinner the foil the higher is the impedance) and width of one strip is 0.4 cm. This gives me a value of 2.2047 Ohms. Mind you this calculator is for trace resistance of copper clad boards and hence you need to multiply the result with 1.585 which is the ratio of resistivity of Alu to Cu. Therefore, I have around 3.5 ohms and I am pretty sure this is acceptable for the 4 ohm amp.
Clemson Vehicular Electronics Laboratory: Circuit Board Trace Resistance Calculator
For more details refer picture.
Cheers,