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Old 6th July 2012, 03:20 PM   #1
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Default Transformer-less Ribbon Driver?

Ive recently got a pair of Fountek NeoCD3.5H (its a horn-loaded version), and they may/may not be a true 'ribbon'. The driver uses a polymer diaphragm with foil laminate, i think. Maybe its vacuum deposited.... I don't know.

Anyway, its low resistance, so requires a transformer to make it a manageable load for an amplifier.

But what if instead of a Aluminium ribbon, the ribbon would be conductive, but with a greater resistance?

Has this been done?

You could theoretically i suppose, find a good material, that in the correct thickness or cross-sectional area, would give a 2" ribbon a Resistance of 8 Ohms; for example.
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Old 6th July 2012, 04:01 PM   #2
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What is the difference between a resistive ribbon or adding a series resistor? Either way you lose sensitivity. The transformer does the matching with minimum losses.
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Old 6th July 2012, 04:15 PM   #3
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thinner foil = higher Resistance= lesser Current flowing= lower Efficiency= need more power

thinner foil = lower thermal capacity

more power & lower power handling = ribbon fails

Aluminium has good power handling, good damping properties, low structural resonances and pretty stable when corrugated or similar
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Old 6th July 2012, 04:32 PM   #4
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of course. Efficiency. One too many beers again. What would be the penalty for using copper instead or an alloy? Say duralumin. I guess im looking for an experiment lol
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Old 9th July 2012, 09:21 AM   #5
dheming is offline dheming  United States
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Beryllium foil would be fun to play with. Shame it's so expensive even for a small piece.
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Old 10th July 2012, 02:09 AM   #6
andyr is offline andyr  Australia
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Quote:
Originally Posted by mondogenerator View Post
Ive recently got a pair of Fountek NeoCD3.5H (its a horn-loaded version), and they may/may not be a true 'ribbon'. The driver uses a polymer diaphragm with foil laminate, i think. Maybe its vacuum deposited.... I don't know.

Anyway, its low resistance, so requires a transformer to make it a manageable load for an amplifier.

But what if instead of a Aluminium ribbon, the ribbon would be conductive, but with a greater resistance?

Has this been done?

You could theoretically i suppose, find a good material, that in the correct thickness or cross-sectional area, would give a 2" ribbon a Resistance of 8 Ohms; for example.
I've used a 5' long x 1/4" wide ("the thickness of a butterfly wing", according to the marketing blurb) corrugated aluminium ribbon for about 20 years ... as the tweeter in my Maggies. It has a resistance of 2 ohms. Later Maggie ribbons are only 3/16" wide and have a resistance of 3 ohms.

Regards,

Andy
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Old 10th July 2012, 02:25 AM   #7
a.wayne is offline a.wayne  United States
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Very low mass can be an issue , power handling aside, sound is thin sounding and has no percussive energy ..
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Old 10th July 2012, 09:14 AM   #8
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interesting, those ribbons must be extremely fragile. I had considered metalised mylar, or vacuum depositing on a similar film. Eg a large wide ribbon, micron level thickness conductor. In that way i could trial different metals, tho i guess Fe and Ni are bad ideas.
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Old 10th July 2012, 09:52 AM   #9
andyr is offline andyr  Australia
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Originally Posted by a.wayne View Post
Very low mass can be an issue , power handling aside, sound is thin sounding and has no percussive energy ..
You obviously have never heard any "true-ribbon" Maggies.

Hie thee to thy nearest Magnepan dealer.

Regards,

Andy
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Old 10th July 2012, 12:55 PM   #10
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copper will not work, too much mass... there is an equation that puts all the pieces together. add mass and the sensitivity drops like a stone. Aluminum turns out to the best compromise so far.

Duralumin is simply an old aluminum alloy - no longer made, but a similar one exists today.

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