How do you create a planar diaphragm?

[Xaborus]

Hello guys! I'm new to this forum.

I just got done reading, Roger Sanders’ Electrostatic Loudspeaker Design Cookbook but the high voltages required turn me off.

This lead me to become interested in Planar magnetic loudspeakers.

So my questions are:

1. Do diy planar magnetic loudspeakers approach or equal the SQ of DIY ESL?
2. How is the diaphragm created?
3. Are there any threads/websites on here outlining the general build process?

I apologize in advance for the newb questions, which i am sure have been answered before. These threads on this forum are a little hard to navigate

 

[JAMESBOS]

Go to full range planars using neos, you will find all the pics and details you require.

 

[CharlieM]

Hello guys! I'm new to this forum.

I just got done reading, Roger Sanders’ Electrostatic Loudspeaker Design Cookbook but the high voltages required turn me off.

Too bad no one has written a corresponding Cookbook for magnetic planar speakers. I don't know much about them myself except the Maggies I've heard sound really good.

Sanders' book is a great resource, even if a bit dated now, and non specific on transformers and power supplies. A Google search for DIY ESL's will turn up some quite detailed build info and designs, using readily available and fairly inexpensive components. With coated stators and enclosed bias supplies, the high voltages need not be a safety issue. Not to mention; actively bi-amped hybrid ESL's can sound downright spooky.

 

[Few]

To create a planar magnetic (quasi-ribbon, magnetostatic) diaphragm you could adapt the method described in detail here. He describes his nicely refined method for building a driver that's somewhere between a "pure" (what I prefer to call "simple") ribbon and a planar magnetic driver. It's clamped only top and bottom like a ribbon but uses multiple conductors on a mylar backing like a planar magnetic speaker. By spacing the conductors more widely and using a magnet array similar to those used by Magneplanar you should be well on your way.

You could also build a push-pull system with magnets in front of and behind the diaphragm. That approach requires twice as many magnets but guarantees a symmetric magnetic field. This white paper does a good job of describing the design. It doesn't guarantee a homogeneous field, though, and it is likely to create more pronounced acoustic resonances because of the cavity created between the two perforated steel panels typically used to support the front and back magnets. I'm following Magneplanar's lead and going with a single-ended design: an array of magnets behind the diaphragm but none in front.

I don't share the enthusiasm some have for one-way full range planar magnetic speakers. I found the directivity of the large panel ESLs I built to be problematic over the long haul and large panel planar magnetic drivers have the same directivity issues. Large wide-bandwidth panels do have some unique virtues so if the pros outweigh the cons for you then that could still be an option.

If you decide to go the planar magnetic route then check out Magnet4Less as a good source of NdFeB magnets. They pack a lot of magnetic field into a small volume.

Few

 

[JAMESBOS]

Easy built over 60 diaphragms and they all worked, using different materials from blue rubbish sacks to 6 um mylar C. From alu tape with adhesive about 7 um thick, and in widths from 2.25 to 9 mm wide. Been a learning curve and I'm still learning. Have moved on to full range planar headphones built 2 pairs already, which sound wonderful, have another 4 pairs to break up and rebuild.