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Old 20th January 2007, 09:48 PM   #11
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I'm in the process of designing a set of Drivers similar to the Eminent Technology units.

A note about the cost:

You'll most likely spend more money on planar magnetic speakers than electrostatic speakers. The input transformer and power supply will almost certainly be cheaper than enough neo magnets to make a similar sized panel.

Sheldon
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Old 20th January 2007, 09:58 PM   #12
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Quote:
Originally posted by stokessd
I'm in the process of designing a set of Drivers similar to the Eminent Technology units.

A note about the cost:

You'll most likely spend more money on planar magnetic speakers than electrostatic speakers. The input transformer and power supply will almost certainly be cheaper than enough neo magnets to make a similar sized panel.

Sheldon

Care to share with us the info on your Eminent-style drivers?

Electrostats have other disadavantages - they require somewhat more complex and difficult to build frames, and generally must be much larger to achieve the same bass frequencies.
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Old 21st January 2007, 02:56 AM   #13
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Sure thing, I've been working on the solid model drawings for midrange drivers. I'm planning on using lexan frames to hold tensioned mylar. These will be rectangles that are 4 feet high and about 10 inches wide. the frames have a center cutout of 46" x 8". The frames are routered out of a single piece. A pair of the frames are glued to a piece of stretched mylar with aluminum traces etched in place. The pair of sandwiched frames will be fairly rigid, but the front and back magnet holders are the structural rigidity for the entire panel.

the magnet holders are based on easy to machine pieces of bar stock. I have a small milling machine and am designing the pieces so that I can handle them on my small machine, but also so I don't have to if you cut them carefully. The magnet holder assemblies are a series of vertical bars with magnets glued on the backs. There are horizontal bars that will attach to the lexan frames.

The traces on the mylar will be formed by gluing a solid piece of aluminum foil or metalized mylar (still checking the metalized mylar feasibility). I'll mask off the traces with tape and wipe on ferric chloride (circuit board etchant), which etches away aluminum very nicely.

I've already got a reasonable ribbon design drawn up in Autodesk Inventor, and I'm now working on the midrange portion.

The idea is that I'll use a DIY ribbon tweeter from say 4K up, these planar magnetic drivers from 100 (ish) Hz to 4KHz, and a cone driver in an enclosure under the panels. It will use an active crossover much like my ESL's.

he real thing that is giving me pause is the cost of the magnets. The ribbon drivers use like $400 worth of magnets for a pair of 48" long units. And the midrange panels look like they will use like 4 times that many. I'm seriously thinking of reducing the magnetic drive elements but I have to make sure that I have enough sensitivity. I'll be building a prototype panel this summer.


Sheldon
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Old 21st January 2007, 03:32 AM   #14
WrineX is offline WrineX  Netherlands
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Quote:
Originally posted by stokessd
Sure thing, I've been working on the solid model drawings for midrange drivers. I'm planning on using lexan frames to hold tensioned mylar. These will be rectangles that are 4 feet high and about 10 inches wide. the frames have a center cutout of 46" x 8". The frames are routered out of a single piece. A pair of the frames are glued to a piece of stretched mylar with aluminum traces etched in place. The pair of sandwiched frames will be fairly rigid, but the front and back magnet holders are the structural rigidity for the entire panel.

the magnet holders are based on easy to machine pieces of bar stock. I have a small milling machine and am designing the pieces so that I can handle them on my small machine, but also so I don't have to if you cut them carefully. The magnet holder assemblies are a series of vertical bars with magnets glued on the backs. There are horizontal bars that will attach to the lexan frames.

The traces on the mylar will be formed by gluing a solid piece of aluminum foil or metalized mylar (still checking the metalized mylar feasibility). I'll mask off the traces with tape and wipe on ferric chloride (circuit board etchant), which etches away aluminum very nicely.

I've already got a reasonable ribbon design drawn up in Autodesk Inventor, and I'm now working on the midrange portion.

The idea is that I'll use a DIY ribbon tweeter from say 4K up, these planar magnetic drivers from 100 (ish) Hz to 4KHz, and a cone driver in an enclosure under the panels. It will use an active crossover much like my ESL's.

he real thing that is giving me pause is the cost of the magnets. The ribbon drivers use like $400 worth of magnets for a pair of 48" long units. And the midrange panels look like they will use like 4 times that many. I'm seriously thinking of reducing the magnetic drive elements but I have to make sure that I have enough sensitivity. I'll be building a prototype panel this summer.


Sheldon
jesus that sounds pretty scary, because magnepan doen not invest 600 dollars on magnets, ok i understand they get it cheap, but they dont even have neodym magnets they use feriet with a nice 87Db, not bad i would say.
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Old 21st January 2007, 06:22 PM   #15
Few is offline Few  United States
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As was suggested previously, the ferric chloride won't directly bother mylar or kapton. I do seem to recall running into problems, though, when I used it full strength to etch away aluminum foil that I had glued to plastic diaphragm material. I think the aluminum and ferric chloride reacted a bit too fast, and the reaction was so exothermic that the plastic simply melted. It's been more years than I care to admit since I was playing with those prototypes, and something like kapton might be able to take the stress, but just to be sure you might try a few quick tests to get the concentration right before diving in with large pieces of aluminum and diaphragm material.

Few
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Old 21st January 2007, 06:25 PM   #16
WrineX is offline WrineX  Netherlands
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got way enough mylar to test on.
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Old 21st January 2007, 07:21 PM   #17
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Quote:
Originally posted by Few
I do seem to recall running into problems, though, when I used it full strength to etch away aluminum foil that I had glued to plastic diaphragm material. I think the aluminum and ferric chloride reacted a bit too fast, and the reaction was so exothermic that the plastic simply melted.

There's a trick for this that jewlers use when etching.

1. Make a weak ferric chloride solution - for example, take the RadioShack stuff and add a bit more water, say 2 parts ferric chloride to 1 part water.

2. Make an etchant bath in a shallow container - Tupperware works well.

3. Lay the ribbon so that it's suspended in the ferric chloride, so that the face to be etched is facing downwards.

4. Wait a few hours.

The etching will occur very slowly. However, the aluminum salts that are produced will fall to the bottom, and you'll get a very neat etching.
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Old 26th January 2007, 09:35 AM   #18
freccia is offline freccia  Italy
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A good method for etching al on mylar:

50% chloride solution (10%) + 50% oxygenated water (24 vol.)

Also with a sponge.

Clean with little baking soda in water.

Greetings:
freccia
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Old 2nd February 2007, 09:36 PM   #19
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Are you talking about making a full range planar say from 20hz to 20khz? All in one baffle or a combination of ribbon tweeter, midrange and bass? I have built several full range planar speakers using both ferrites and neos. Ranging in size from 7ft high to 21" high the small ones used neos and the 7ft high one used ferrites. By the way the small ones using neos were 3db louder.!!!
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Old 9th February 2007, 07:54 PM   #20
tinitus is offline tinitus  Europe
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My 3-way "hybrid" has just developed into a 4-way

15" woofer.......6" midwoofer ........8" ribbon (1" wide).......4" ribbon (1/4" wide)

Have almost all parts and just need finishing design and do some woodwork

It came true when I discouvered that SuperMagnetMan had some cheap bargains on some mighty strong neo bundles with cosmetic faults

They should be perfect for the 8" with wider magnet gap
And I am making some nice round curved yokes for them too
And a few other tricks

I have had LaFolia fullrange ribbon and know what they can do - so I hope to be back on track now
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