Frequently asked questions
These are the questions builders have sent over the years. The answers are the ones I gave. Where a chapter goes further, the link is under the answer.
Membrane and foil
What are the membrane-conductor material dimensions?
The stack I used was thin on purpose. The 0.024 mm figure is the thickness of the two layers together, not the width of the ribbon.
- Membrane: Mylar film, 12 micrometers (0.012 mm)
- Aluminium foil: about 12 micrometers (0.012 mm)
- Total thickness: 0.024 mm
See also: Ribbon speaker membranes
Did you use a different material for the mid-tweeter membrane?
No. I used the same combination on both the woofer and the mid and tweeter.
See also: Woofer conductor design , Tweeters
Do you corrugate the bass membrane?
No. The aluminium was thin enough that rattling was not a worry, so I did not corrugate the bass membrane at all. Thicker foil may have problems. I cannot be sure.
I have found a material other than Mylar for the membrane base. What should I watch for?
Do not forget to test the base plastic for humidity. Mylar, Kapton, Kevlar, whatever you have found: stretch a piece over a cup, or anything like that, then take it into a sauna or some other humid place. If the tension holds, it is all right. If it does not, change the material.
See also: Ribbon speaker membranes , Tips and tricks
I cannot find aluminium foil wide enough. What did you do?
Have you tried the packaging companies? In the US I went to a chocolate and candy factory and came away with a roll of chocolate aluminium on waxed paper, a meter and a half wide.
See also: Tips and tricks
Magnets
How can you tell which face of a magnet is north and which is south?
Look for the polar bears. That is the North Pole. I am joking. I do not know a formal way, short of a magnetometer. It does not change anything if you simply decide that one face is north and the other is south. I wrote N on one side of a reference magnet and S on the other, then used that magnet to line up all the rest.
See also: Magnets
Have you had any experience using electrical coils instead of magnets?
No. I have not tried that. This build uses permanent magnets.
See also: Magnets
Building the ribbons
How did you corrugate the mid-tweeter membrane?
I used a Lego plate and a stick. Other people have built high-tech machines for this job. I did not have the money for that.
See also: Tweeters
The woofer ribbon is probably the trickiest part to make. Why?
More than tricky, it is a lot of work, and it is delicate. If something goes wrong, you can destroy a lot of that work.
See also: Woofer conductor design
Other loudspeakers
How do Apogee, Magnepan, MartinLogan, Dali, and similar loudspeakers compare with yours?
I cannot make that comparison. I have not sat in front of a factory-built magnetostatic or electrostatic pair for a real listen. The closest I have come is a pair of MartinLogan speakers, and those are not the same thing.
Have you heard Apogee, Magnepan, MartinLogan, Dali, or similar speakers?
Only indirectly, for most of them. I left Denmark a year before I even tried La Folia. In Chile there were not enough hi-fi people to justify anyone bringing Apogee speakers into the country. I am in Mexico now, and I would still have to travel to the capital, or to the United States, to sit in front of a pair and give an opinion. That did not happen. I did enjoy a pair of MartinLogan speakers. They are not the same thing.