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The "zero" ohm full range ribbon
The "zero" ohm full range ribbon
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Old 11th June 2018, 11:26 PM   #11
WrineX is offline WrineX  Netherlands
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i would just use strips of magnet. meters long rubber magnet that is, and then the thickest i could find. its not strong but thats not key, key is having low excursion and allot of it.

i use 3 mm thick rubber magnet allot, and as well 4mm thick. and i can get it up to 6mm thick. still weak though. but its all about surface area. pahsing is not an isue since you dont want to play fulrange on 4000 ribbons since it acts as a huge planar, so dispersion will be terible if you play it fullrange
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Old 11th June 2018, 11:37 PM   #12
hellokitty123 is offline hellokitty123  United States
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Could you elaborate on how you would build this array? What is the advantage of your suggested configuration over mine?

It seems like mine would be superior because custom magnets can be made less than 1 mm thick which means many ribbons can be arrayed right next each other. But then again I don't completely understand your suggestion.

The dream would be for me to create a modular expandable array.
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Old 12th June 2018, 12:16 AM   #13
WrineX is offline WrineX  Netherlands
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well with the idea you wont combat the dispersion. it is the size that emits high frequency that is the problem so no mater how you put them horizontal or vertical it does not mater.

if the size is small dispersion will be better the bigger you make the combined emiting surface (without using angles) the worse it gets. thats the reason why they are so small in width to have at least good horizontal dispersion. so you will end up with a ribbon tweeter, and allot of ribbons that do the rest. but to do the rest there are beter and more efficient option to do so
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Old 12th June 2018, 12:45 AM   #14
hellokitty123 is offline hellokitty123  United States
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So you're saying a bigger tweeter array will give worse dispersion than a smaller one? When you say size do you mean width, length, or total area? If I were to do this it would be a multi way array using active crossovers.

You said there are better options for "the rest"? You're saying ribbons are inferior at lower frequencies even with lots of surface area? I think I must misunderstand, one consistency I've seen is that people claim full range ribbons are among the best sounds things they've ever heard.

With such low mass they have greater control and lower distortion without the sound degrading issues of planar. Surely a massive full range ribbon is superior to other technologies?

Last edited by hellokitty123; 12th June 2018 at 12:49 AM.
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Old 12th June 2018, 01:07 AM   #15
WrineX is offline WrineX  Netherlands
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I mean indeed width length. which gives you the surface area BIG is bad for dispersion up high. i think max one wave length is often used, as for tweeters max 1.7cm up to 20khz. of course you can use bigger and have slightly different dispersion. but going fullrange on a big panel is not pleasant. yeah about the options i think it is almost impossible to make a true ribbon go low. and using allot of small ones to have any magnetic field is an option but costly and a hell of a work to make allllllll those ribbons, and even then question remains if you will blow them out of the gap with each low note. in theory yes best way. practical absolutely not. why not go for ESL ? you can make an esl with lighter and thiner membrane then a ribbon.

i wonder by the way how many people have heard a full range ribbon? since apogee is not one of them for instance. also just a planar , bit more fancy looking but still no ribbon in the low end, same goes for the carvers. also woofers or planar. as far as i know

Last edited by WrineX; 12th June 2018 at 01:09 AM.
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Old 12th June 2018, 01:56 AM   #16
hellokitty123 is offline hellokitty123  United States
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Quote:
Originally Posted by WrineX View Post
I mean indeed width length. which gives you the surface area BIG is bad for dispersion up high. i think max one wave length is often used, as for tweeters max 1.7cm up to 20khz.
So maybe a more traditional ribbon tweeter and a larger mid/bass?
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Originally Posted by WrineX View Post
yeah about the options i think it is almost impossible to make a true ribbon go low. and using allot of small ones to have any magnetic field is an option but costly and a hell of a work to make allllllll those ribbons, and even then question remains if you will blow them out of the gap with each low note.
I suppose I can use a cone woofer with servo feedback without it being a huge deal. It's mostly the treble and midrange I'm concerned with.

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in theory yes best way. practical absolutely not. why not go for ESL ? you can make an esl with lighter and thiner membrane then a ribbon.
Esl is expensive and difficult to make. There are a lot ways it can go wrong and you need to have just the right tension using just right materials, ect, ect. Ribbons just "work". Plus ESLs require extremely high voltages and are a reactive load which comes with its own non linearities and issues. I'm sure this is only touching the surface on their issues. I recall doing some reading on ESL a while back and it is a deep subject to get involved in. Which just means there are a lot of compromises. I don't like compromises.

Part of the reason I want to make this ribbon array is so will not require voltage amplification at all. In a pure parallel configuration with thick interconnects there would be barely any resistance and thus require almost no voltage. I would aim for milivolts. This means the amplifier and DAC will have almost no voltage variation which also means better performance.

I haven't done the math but a huge array such as this in parallel would make the ribbons almost 0 ohms so the interconnects will make up the majority of the resistance. The impedance will be flat as ruler and the sheer surface area will make each individual ribbon produce vanishingly low distortion upon their already extremely low distortion.

I can't even see a comparison between ESL and ribbons, ribbons seem to win every time, assuming a proper array can be made.

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Originally Posted by WrineX View Post
i wonder by the way how many people have heard a full range ribbon? since apogee is not one of them for instance. also just a planar , bit more fancy looking but still no ribbon in the low end, same goes for the carvers. also woofers or planar. as far as i know
Not many people I'm sure. I only know of a few people I've talked to that have heard such a thing and I'm pretty sure it was DIY.

Last edited by hellokitty123; 12th June 2018 at 02:04 AM.
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Old 12th June 2018, 02:07 AM   #17
anatech is offline anatech  Canada
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The "zero" ohm full range ribbon
Hi hellokitty123,
Of course you realise you're just trading one set of problems for another by trying to go all current without voltage gain. Now inductance is your problem instead of capacitance. That and the extreme energy loss that high current causes. That's why current technology is a mid range impedance where everything is controlled a little easier. With your plan you will find that connections will become a major problem instead of being just one small concern.

At the end of the day, executing your plan will require voltage gain to overcome connection and wire impedance. All of a sudden speaker wire lead length becomes a variable that matters a great deal. On top of that, if your ribbons heat up, the resistance will also increase.

All I can say is that there is a reason why the state of the art is what it is. To each his own I guess.

-Chris
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Old 12th June 2018, 02:43 AM   #18
hellokitty123 is offline hellokitty123  United States
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In a huge parallel ribbon array using thick interconnects and a current source amplifier the inductance issue should be negligible at best, I would imagine. Normal amplifiers have both capacitance and inductance to deal with as well as voltage and current device lienarities. A current source amplifier ignores back EMF and parasitics in general and into a near short the device linearities are effectively current dependent only. Wire impedance is a relatively straightforward problem to solve. I think the bigger issue is ensuring the current gets shared equally across the ribbons. A tiny mismatch in wire length can mean a big difference in current sharing when resistances get so low.

If my understanding is correct, SPL in a ribbon is not effected by power but current only. The magnetic field across the ribbon for a given current will be the same regardless of the resistance. Meaning the ribbons should require almost no effective power as resistance becomes close to zero as current requirements do not increase in a parallel configured ribbon over a series configured ribbon but the voltage requirements decrease greatly.

Instead of trading a set of problems, I just reduced them.

Last edited by hellokitty123; 12th June 2018 at 03:10 AM.
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Old 12th June 2018, 08:08 AM   #19
Gerrit Boers is offline Gerrit Boers  Netherlands
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With very low impedance any inductance will be a serious problem as it will act as a low pass filter. With a traditional ribbon tweeter the transformer has to be as close as possible to the ribbon to reduce the inductance of the circuit. Here's a picture of a transformer driven ribbon I made:
connected-ribbon-small.jpg

What looks like a single strip of copper foil are actually two strips separated by very thin polyester foil. This is done to keep the inductance as low as possible. Here's a picture of the test jig:
ribbon-measure-simulation.jpg

The ribbon is simulated by a 50mΩ Caddock film resistor. If the two foil strip are separated by 1mm thick plastic in stead of the thin foil the HF response drops by 30% !!! For my minimal ribbon design I decided to drop the transformer and just use a series resistor and a powerful amp.
Ribbon-minial-test-amp.jpg

The series resistor is 2Ω consisting of 4 0.5Ω 100W film resistors. You might think this is a space heater but it isn't because the high frequency audio (>2kHz) is mostly peaks (up to 16 amps). In normal use the resistors don't even get lukewarm. With the series resistor the ribbon is essentially current driven as the series resistor is 2Ω and the ribbon just 30mΩ. The non-inductive film resistors are also a very benign load for the amp, near perfectly resistive. The minimal ribbon is described in this thread: DIY ribbon dipole tweeter, reductio ad minimum
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Old 12th June 2018, 01:01 PM   #20
hellokitty123 is offline hellokitty123  United States
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Ah yes I forgot about the low pass filter factor. A current source amplifier will brute force through the RL filter but at the expense of increased voltage swing which I don't want.

How much inductance could thick interconnects in twisted pair config possibly have?

Doing some quick internet math, 7 gauge wire @ 1FT is sufficient to pass 20khz into a 0.1 ohm load. This doesn't count using smaller gauge wires in a twisted pair configuration that equate to a larger gauge. Twisted pair config should significantly reduce gauge required.
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