Dahlberg  Audio  Design.
"The tall neodymium ribbon". Part 3

 Things you will need for the ribbons:

  1: Cutting-table made from glass.
  2. Rotary knife.
  3. A tall and straight ruler (same length as the table).
  4. Aluminum-foil.  0,0105mm.
  5. Mylar-film.          0,002mm.
  6. Window scraper, rubber.
  7. Soap.
  8. Cleaning solvent (isopropyl alcohol)
  9. Spray-bottle
10. Depth calipers. (Or regular ones).
11. Paper and pen.
12. Adhesive spray. (3M Spraymount)
13. Two gluing clamps.
14. One dressed board (artificial  leather), 30x150cm and masking tape.
15. Rubber roller (?). See the pictures.
16. Sponge.

1. The glass-table has to be absolutely clean. Just a small speck can cause a lot of extra work. When that's done the glass-surface is covered with soap (very little water). Then the foil is applied. Great care is not necessary but try to avoid sharp edges.


Foil that needs a little more work.
2. Then you spray the upper side with water (and a little soap to brake the surface tension). Then start to sweep away the water with the rubber window scraper, work from the middle and outwards. Then the foil will be "glued" to the glass and any excess soap under the foil will be removed. 
Small marks can be rubbed out.

Not that bad.

Water and a little bit of soap and the you work with the window scraper.

3. Now the foil has to be cleaned, this can't be done later. I'm using alcohol "isopropyl alcohol" from the pharmacy. Absolutely clean and it vaporizes immediately.  
Now the foil is clean and ready for cutting. Calipers, paper and pen.
4. Time for cutting. Take out the calipers, ruler and the gluing clamps. Decide on a starting-point (say 30mm's from the tables edge) and write that down. Don't make any cuts at this point. Measure carefully.

First cut.

Second cut done and the first piece of waste is picked.
5. My ribbons have a first strip that's 5mm's wide so the first cut will be at 35mm's and the next cut at 35,5mm's. The gluing clamps will hold the ruler in place. It's very important that you do not change the angle of the knife from cut to cut. Take away the excess foil immediately. Next cut will be 3,5mm's further out on the glass and then an additional 0,5mm for the next cut.
Some stuff. Now we are getting somewhere.
6. When the excess foil is removed we have our first strip (no:2) The first one will be completed in a later moment. Now we keep it up until we're almost done with the first ribbon. The last cut is to be left for a later time.
These calipers can of course be replaced with a regular model. Take notes where to make the cuts for the finished ribbons. Don't make any cuts here rigth now. If you look closely you can see a woofer ;-)

7. For each individual ribbon, omit the last cut. This will be done after the mounting of the mylar film. What should be done at this point is that you write down the measurement for the cut. My ribbons are 26,5mm wide so.........
30+26,5=56,5mm for that cut.
Now you just have to keep it up in the same way until you run out of foil.

Time for ribbon  nr:2.

The advantage of  tall calipers is evident.

8. Mounting of the Mylar film. You will need a dressed board and some masking tape.
9. Stretch the Mylar film gently over the sides of the board with the help of the masking tape. Be careful, the film is very thin. The idea is to even out but not stretch the film. 

I'm a little bit short on space so ......

Stretch the film gently too the back of the dressed board with the help of masking tape. I'm working on a better solution for this but...

10. Spray the 3M adhesive on to the film. Don't pour it on  but make sure that it's fairly even. When that is done you will place the board with the film down onto the foil. Make sure it's straight (maybe with a little help from a friend) and then gently press a few times over the board's surface so that the film will stick. Loosen the tape and lift the board to the side. 
11. The rubber roller should be handled with care. Make sure that you do not twist it sideways, you might wreck a lot of work. Go over the whole surface with it to make sure that the film and foil hold together. Light pressure at first and then you can press a little harder.
Just before the application of the adhesive. Rubber roller. Is that the right name for i

12. Now it's time to cut the ribbons apart. Take out the ruler, etc again. Place the ruler at the measured and noted points and make a cut there. Repeat this for every ribbon and one by one they are almost done. For future use the ribbons you don't need right now can be left on the glass, good storage-place.

Make a few spares, they may come in handy. Now all the cuts are done.
13.Cleaning . The first ribbon is loosened from the glass-table, pick it up at one end and pull straight up. The ribbons have a tendency to curl up. This is  not good for the nerves so make sure that you keep it stretched until we have turned it up side down (soap up). The soap is now gently swept away with a wet sponge.  The curling tendencies will disappear at this point.
This is a little bit too exiting from time too time. Be cooool. Some tape too hold it down for cleaning.
14. Corrugation and assembly. For this you will need a corrugating device. Place the ribbon at the center and in an exactly 90 degree angle to the device. Feed the ribbon in so that it sticks and place the guiding-board on top. Corrugate, it's fascinating. If you are unlucky it will get a little crooked, unfortunately you just  have to throw it away. Earlier kapton-ribbons where thicker and they where recorrugateable. Not possible with these ones.

The soap comes of with water. 

Rubber roller (?) again.

Corrugating device.

Ribbon in place before corrugation.

15. Attachment of connectors to the ribbon. Flatten out the corrugation on a 5-6cm surface at one end. A straight piece of plastic will work, that will also come to use next. You hold it in a 90 degree angle on the ribbon and it will work as a support when the connector is placed on the ribbon. Then you fold the short end of the ribbon around the edge of the connector and on to the other piece of tape.  Use the rotary knife to trim of the excess ribbon. Remember that the ribbons are supposed to be shorter than the magnetic gap. One inch seems to work just fine. The same ribbon length in both channels of course.
The spring is giving substantial pressure too the second wheel. Coming along just fine.
16. Put something appropriate over most of the magnetic gap. (To protect the ribbon during assembly). Take the first ribbon connector and push it into the card edge connector. Then lift the second connector and remove the safety sheet with your other hand. Push the second connector into the, well you know where. Center the ribbon at the support-points and push the loose parts into place. It will work better if they are a little wet. Remember the mild force. Assemble the parts.

Corrugation smoothed out. Connector folded down with support. The double coated tape is missing in this picture.

Assembly procedur.




Double coated tape .

Magnet gaps length minus 5cm  = 102 cm .
Ribbon support using latex hose Small bump in the ribbon but..( hmrrm ).

All wired and ready for final assembly!

Part 1   part 2

Ok, now it's all done. I'm truly hoping that these articles will be an 
inspiration for a lot of committed diy enthusiasts. 

Finally, thanks too Per "Pac" Adelsson and all others at Hififorum.nu .  

God luck and best regards. Bengt Dahlberg

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