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Old 4th March 2004, 08:05 PM   #11
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Hi,

In the "Loudspeaker and Headphone Handbook" by John Borwick there is a very good description how ribbon speakers work complete with the math. There is also an investigation about what the most efficient conductor for the ribbon is. Aluminium has simply the best conductivity Ė weight balance of all metals for use as a ribbon.

Overheating is the biggest enemy of ribbons, they simply melt when severe overloaded. But too much low frequency content will damage the ribbon as well by irreversible stretching it. Therefore donít use 1st order x-overs with ribbon tweeters unless the frequency is quite high ( > 5 kHz).

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Old 4th March 2004, 09:03 PM   #12
medum is offline medum  Denmark
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Quote:
Originally posted by Pjotr
Overheating is the biggest enemy of ribbons, they simply melt when severe overloaded. But too much low frequency content will damage the ribbon as well by irreversible stretching it. Therefore donít use 1st order x-overs with ribbon tweeters unless the frequency is quite high ( > 5 kHz).

My "La Folia" (apogee-clones) consists of a large low-frequence panel and a long ribbon (7 serial aluminium tapes - each about 1m long and 5 mm wide - taped to a common pvc-ribbon. My cross-over is FIRST-ORDER 1kHz and I have often played with full power from my earlier power-amps. Above 1kHz often about 80W into 3 ohm - no problem and no overheating.

Only once, when my wife came to close with the vacumcleaner, the ribbon was damaged , and I had to corrugate it once again.
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Old 4th March 2004, 09:19 PM   #13
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I wasnít talking about very large ribbons like yours JÝrn. But I donít think your expensive Raven ribbons will last long when filtered 1st order at 1 kHz.

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Old 4th March 2004, 09:44 PM   #14
medum is offline medum  Denmark
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Quote:
Originally posted by Pjotr
.....But I donít think your expensive Raven ribbons will last long when filtered 1st order at 1 kHz.


No, I guess not!
25 years ago I had a pair of Gamma ribbon horns. The ribbons popped out quite often, and I repaired by splitting up a folie cap and used the very thin alu to make new ribbons from.....
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Old 5th March 2004, 03:18 AM   #15
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Would those little neodymium magnets that Parts Express help in this situation? More magnetic feild from smaller size, thus closer together.
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Old 5th March 2004, 03:24 AM   #16
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The stronger the magnetic field, the better.

Grey
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Old 5th March 2004, 03:46 AM   #17
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Build a high current amplifier that only swings a few volts, but 15 amps or so and bypass the transformer.
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Old 8th March 2004, 09:21 AM   #18
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I've had great results using a ferrite transformer from a 200W PC switchmode PSU. Contrary to popular belief, they work fine above 2kHz (contributing <0.1% distortion in open loop, even with >10W of power).

Use only one half of the secondary to get a ~12:1 ratio. This gives ~ 144:1 impedance transformation. My ribbons use cheap kitchen alfoil. Cheaper brands are thinner, and have less hardening (which is what you want). Initially, I used cam gears from a car engine to crinkle, but the corrugations were too big (and deep) resulting in the ribbon being too sloppy. I've found some rubber floor grip with 1mm grooves which works great for corrugating.

The thick-foil ribbons work fine until you get to 20mm, then the stiffness of the foil starts to cause some nasty resonances in the horizontal. I tamed mine with a very thin PVA coating. Thinner foil would really help here.

So technically they aren't true ribbons any more...

Soon I will have the transformer inside the feedback loop of the amplifier (like most decent valve amps).

If you dont mind super-directional sound in the vertical axis(makes it sound like you have no ceiling), ribbons offer an amazing amount of detail. The transient response is simply superb.

Oh yeah- and dont bother unless you buy some neo magnets. Check out John Whittaker's site:

http://www.snippets.org/alsr/index.php3#SIZE

Chris
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Old 21st March 2004, 07:16 AM   #19
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I have built several succesfull ribbon/planar drivers from scratch. Much to hard to descibe in a post. For those of you who would like to experiment I have the unobtainable..(trust me on this) .....the thinnest aluminum foil you will be able to find anywhere . 1/2, 3/4 , and 1 1/2 inches wide. I have Lots of it. Practically free for you( I'd like you to at least give me a couple bucks for shipping!). I'll be happy to help you fellows out. Simply contact me.
Ed Schilling
www.thehornshoppe.com
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Old 21st March 2004, 09:48 AM   #20
Variac is offline Variac  United States
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Apparently silver color signpainters leaf is very thin aluminum.
This was recommended by a guy who rebuilds ribbon mics
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