I don't understand. The math suggests untwisted 7 gauge wire is sufficient for 20khz into 0.1 ohms @ 12 inches.
I don't see how I will need anywhere near welder currents in a ribbon design either.
Even if I'm swinging 80A p-p that only doubles the voltage requirement into a 12 inch 7 gauge wire. Double of almost nothing is still almost nothing.
I don't see how I will need anywhere near welder currents in a ribbon design either.
Even if I'm swinging 80A p-p that only doubles the voltage requirement into a 12 inch 7 gauge wire. Double of almost nothing is still almost nothing.
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kitty..
I have built "full range" ribbon array as you are proposing here. I hate to bust it on ya but want to save you some serious trouble. It doesn't work well below about 200hz. There apear to be two issues.
1- the losses associated with the gaps between ribbon edge and magnet faces. It kills dynamics.
2- the ribbons do not move as a piston at the lower frequency and you end up with peaks and nulls from one to the next that can cancel pressure one to the next. There are other issues as well BUT these were deal breakers for me.
Also what Gerrit says about HF and low resistance is very true and you may run into an issue there too.
In the end I built a full range ribbon with a single large ribbon with large baffle. Two protos. One with 1" ribbon and one with 2" ribbon. This worked well and is some of if not the best sound I have ever heard. You would be surprised how loud and low a simple 2 inch wide ribbon about 6 feet tall with 48 inch baffle can play.
I have built "full range" ribbon array as you are proposing here. I hate to bust it on ya but want to save you some serious trouble. It doesn't work well below about 200hz. There apear to be two issues.
1- the losses associated with the gaps between ribbon edge and magnet faces. It kills dynamics.
2- the ribbons do not move as a piston at the lower frequency and you end up with peaks and nulls from one to the next that can cancel pressure one to the next. There are other issues as well BUT these were deal breakers for me.
Also what Gerrit says about HF and low resistance is very true and you may run into an issue there too.
In the end I built a full range ribbon with a single large ribbon with large baffle. Two protos. One with 1" ribbon and one with 2" ribbon. This worked well and is some of if not the best sound I have ever heard. You would be surprised how loud and low a simple 2 inch wide ribbon about 6 feet tall with 48 inch baffle can play.
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I'm not sure I catch your meaning. Are you saying a 2 inch wide ribbon can or can't go below 200hz?
Also do you know what the current peak requirement of your design was? I'm currently designing the amplifier based upon 20A peaks but I don't really have any data on how much current I will actually need in such a set-up.
Also do you know what the current peak requirement of your design was? I'm currently designing the amplifier based upon 20A peaks but I don't really have any data on how much current I will actually need in such a set-up.
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Sorry that wasnt clear.
The array of ribbons doesn't work well, BUT a single tall ribbon does work well.
The gaps between magnet faces and ribbon edge will still need to be small ( about 1mm or less)to go low.
If you took the large 2 inch wide ribbons from an Apogee and closed up the gaps and put it on a wide baffle it would be very similar to what I did that worked well.
As far as the current needed I am not sure but you should be able to calculate that.
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So you're saying even with less than 1mm gap, an array won't work well?
At all frequencies or just low frequencies?
How was your array built and configured?
Was it something similar to this?
With a custom magnet I can make the distance between each ribbon in the array less than one mm in theory, that's assuming I can keep the distance between the ribbon and the magnet stupidly close.
2mm between ribbons is probably a safer bet.
I recall you telling me before that destructive interference is a result of a spacing issue. Is 2mm not enough?
I am really hoping to parallel ribbons.
Do you know what the impedance of your 2 inch ribbon was?
At all frequencies or just low frequencies?
How was your array built and configured?
Was it something similar to this?
With a custom magnet I can make the distance between each ribbon in the array less than one mm in theory, that's assuming I can keep the distance between the ribbon and the magnet stupidly close.
2mm between ribbons is probably a safer bet.
I recall you telling me before that destructive interference is a result of a spacing issue. Is 2mm not enough?
I am really hoping to parallel ribbons.
Do you know what the impedance of your 2 inch ribbon was?
How so?
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Arrays of ribbons work OK above about 200 hz BUT below that the standing waves that those structures produce cause cancellations and bass energy is lost, so even with gaps very small you still have losses.
For an example of these standing waves watch the ribbon on the left in this vid...
YouTube
My arrays were built as 36 inch long ribbons next to each other. Similar to what you show. The exact configuration wouldn't matter. ribbon next to ribbon operating at lower freqs will see cancellations due to the peaks and nulls of the standing waves.
The destructive interference is an issue at the higher frequency's. Im not sure really what will happen as I used my arrays only to about 1khz then handed off to single ribbon.
You can look up the resistance of aluminum on line and do calcs from there based on your foils cross sectional area and length.
Or this is what I usually do...
Take whatever foil you plan to use and wet a glass mirror or window with water and lay the foil flat on it. I usually start with a sheet around 10 by 10 inches. Now carefully mark the foil every 1/4 inch along one side. Now do the same to the opposite side. Now using a fabric cutter wheel, cut a zig zag pattern of slits so that you end up with a continuous foil trace that zig zag back and forth across the entire sheet. You now have a 1/4 inch wide foil trace thats very long. If each trace is say 9 inches long and there are 40 of them then you have around 360 inches of 1/4in wide foil. Now carfully spread this out so the zig zag traces are not shorting to each other.
Now Take your ohm meter and short the leads together by touching them to the foil with leads only about 1/4 inch away from each other. Take this ohm reading. This is the reading that you will subtract from your long foil trace reading. Its the meters lead resistance and the contact resistance to the foil.
Now measure your long foil trace resistance and subtract the meters lead resistance.
Now you have a reference ohm measurement of that foil u can use to calculate any length/ width ribbon of that same foil.
For an example of these standing waves watch the ribbon on the left in this vid...
YouTube
My arrays were built as 36 inch long ribbons next to each other. Similar to what you show. The exact configuration wouldn't matter. ribbon next to ribbon operating at lower freqs will see cancellations due to the peaks and nulls of the standing waves.
The destructive interference is an issue at the higher frequency's. Im not sure really what will happen as I used my arrays only to about 1khz then handed off to single ribbon.
You can look up the resistance of aluminum on line and do calcs from there based on your foils cross sectional area and length.
Or this is what I usually do...
Take whatever foil you plan to use and wet a glass mirror or window with water and lay the foil flat on it. I usually start with a sheet around 10 by 10 inches. Now carefully mark the foil every 1/4 inch along one side. Now do the same to the opposite side. Now using a fabric cutter wheel, cut a zig zag pattern of slits so that you end up with a continuous foil trace that zig zag back and forth across the entire sheet. You now have a 1/4 inch wide foil trace thats very long. If each trace is say 9 inches long and there are 40 of them then you have around 360 inches of 1/4in wide foil. Now carfully spread this out so the zig zag traces are not shorting to each other.
Now Take your ohm meter and short the leads together by touching them to the foil with leads only about 1/4 inch away from each other. Take this ohm reading. This is the reading that you will subtract from your long foil trace reading. Its the meters lead resistance and the contact resistance to the foil.
Now measure your long foil trace resistance and subtract the meters lead resistance.
Now you have a reference ohm measurement of that foil u can use to calculate any length/ width ribbon of that same foil.
I watched the video. Wouldn't it be difficult for those standing waves to exist if each ribbon in the array was small enough?
The wavelength of a 20khz signal is 17mm so a 1-2mm distance between ribbons should not be a problem I'm assuming?
Well, my whole idea is that if I use many small ribbons in parallel, even if the magnets are weak they can be expanded until a surface area of sufficient size is reached to provide good enough SPL.
That's why I placed horizontal bars within the magnetic structure here
So I can mechanically separate a continuous ribbon into many small ones.
That's why I placed horizontal bars within the magnetic structure here
So I can mechanically separate a continuous ribbon into many small ones.
How wide should the magnets be from the front to the back?
Okay I've thought about it long an hard. Clamping a ribbon between two magnetic bezels requires expertise beyond my capabilities and I doubt I will find anyone to help me.
Lowmass, what is the general power requirements of your DIY full range ribbon speaker you keep talking about, and how much would it cost to build?
Okay I've thought about it long an hard. Clamping a ribbon between two magnetic bezels requires expertise beyond my capabilities and I doubt I will find anyone to help me.
Lowmass, what is the general power requirements of your DIY full range ribbon speaker you keep talking about, and how much would it cost to build?
well lets see heres a ceramic magnet about right size to do a 1 to 1.5 inch wide ribbon. I would orient these so you have a ribbon slot thats 7/8" deep and stack them in three's to get a reasonable field uniformity and strength across ribbon. So to do a 6 feet tall ribbon with 3 rows deep of magnets on each side of each ribbon. Thats 12 rows of magnets total so you need about 460 magnets which comes to about 100$ total. Just a moment...
If you want to do a 2 inch wide ribbon then the easy way is I would take the same magnet and turn it so the ribbon slot is 1.875 inch deep and stack 3 deep again. Now you need about 990 magnets at about 200$ total.
At 2 inch wide it becomes much harder to get a uniform field so usually you do a different magnet configuration where the magnets a oriented differently than I describe above but the above does work. For info on the better magnet orientation you will need to look at DIY ribbon dipole tweeter, reductio ad minimum. I cannot give info here as I haven't done it. Also with a 2 inch wide you almost have to use a separate less wide ribbon for the treble as the 2 inch wide ribbons high frequency dispersion is not good.
As far as power requirements go it really not bad. with magnets close to ribbon like this and even with the ceramic magnets (grade 5 or better) you end up with around 88 db sensitivity with a ribbon designed to get around 4 ohms. So even a 50 watt amp will get you into the 105 db peak range. Understand however that although you will get bass from such a ribbon you cannot play loud at 40 hz! maybe to around 90 db max and thats with a baffle at least 48 inches wide and help from the room. If you want to play above this level you will need a sub. crossed at around 100hz
One last note. Its very difficult to make a long ribbon straight enough to fit in the slot with less than 1mm gaps. multiple foam bits every 6-8 inches or so to hold ribbon can help a lot. I would build a small version of whatever your going to do and experiment. Get all your ducks in a row before you start down the road of all the frustrations involved with getting this one done well.
Just putting a ribbon in a slot with big gaps is easy. Small gaps is easily an order of magnitude more difficult wich is in part why we only see tensioned film designs used in these cases like the Infinity IRS.
If you want to do a 2 inch wide ribbon then the easy way is I would take the same magnet and turn it so the ribbon slot is 1.875 inch deep and stack 3 deep again. Now you need about 990 magnets at about 200$ total.
At 2 inch wide it becomes much harder to get a uniform field so usually you do a different magnet configuration where the magnets a oriented differently than I describe above but the above does work. For info on the better magnet orientation you will need to look at DIY ribbon dipole tweeter, reductio ad minimum. I cannot give info here as I haven't done it. Also with a 2 inch wide you almost have to use a separate less wide ribbon for the treble as the 2 inch wide ribbons high frequency dispersion is not good.
As far as power requirements go it really not bad. with magnets close to ribbon like this and even with the ceramic magnets (grade 5 or better) you end up with around 88 db sensitivity with a ribbon designed to get around 4 ohms. So even a 50 watt amp will get you into the 105 db peak range. Understand however that although you will get bass from such a ribbon you cannot play loud at 40 hz! maybe to around 90 db max and thats with a baffle at least 48 inches wide and help from the room. If you want to play above this level you will need a sub. crossed at around 100hz
One last note. Its very difficult to make a long ribbon straight enough to fit in the slot with less than 1mm gaps. multiple foam bits every 6-8 inches or so to hold ribbon can help a lot. I would build a small version of whatever your going to do and experiment. Get all your ducks in a row before you start down the road of all the frustrations involved with getting this one done well.
Just putting a ribbon in a slot with big gaps is easy. Small gaps is easily an order of magnitude more difficult wich is in part why we only see tensioned film designs used in these cases like the Infinity IRS.
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88db @ 4 ohm is not bad ... 50W is like 3.5A rms, doable within class A without getting creative.
I have so many questions it crazy. I don't even know where to begin.
Where to source such a long ribbon without spending $700
How to build the baffle
How to design the "slot" and locking mechanism
etc
etc
I can't seem to find a beginners guide on this stuff.
I am terrible at crafting projects, as an understatement. I really need all the details.
I have so many questions it crazy. I don't even know where to begin.
Where to source such a long ribbon without spending $700
How to build the baffle
How to design the "slot" and locking mechanism
etc
etc
I can't seem to find a beginners guide on this stuff.
I am terrible at crafting projects, as an understatement. I really need all the details.
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ok well then u will need to start by getting hands dirty. Ya gota make things to avoid huge dollar mistakes from adding up quick. I dont have time to help through ALL the details BUT......
I would start by learning how to make a ribbon 1st. Get that one down long before u dive into the other stuff.
- start small
- get on ebay and buy some .5 mill ( .0005 inch thick) mylar film. .25 mill film is better BUT it a bit harder to handle.
- goto Target and buy a 5 $ mirror. this will be your work surface to cut foil on
- goto a fabric store and buy a fabric cutting wheel and some extra blades
- goto grocery store and buy some standard (not heavy duty) foil. This foil will be .0007 " thick. Many famous plastic backed multi trace ribbons use foil this thick and get HF extension to 20Khz. Most commercial ribbons will use a hard tempered foil to hold the corrugations well BUT the kitchen foil will work, it will just go slak easier. But for experimenting its fine.
- spray mirror surface with light coat of Windex
- Roll some foil out and work it flat with a soft cloth
- use a long straight edge and cutter wheel and cut some traces on the foil
- peel out the unwanted foil ( the small thin section between traces)
- Take your .5 mill mylar film and tape it around the edges to a picture frame like structure to hold the film flat and tight. just a crude mounting with scotch tape is fine here.
- spray a very light coat of 3M super 77 spray glue over your foil traces
- now simply lay the film on top of the foil traces and work it down onto the foil pressing firmly
- how finish by taking your long straight edge and cutter wheel and cut out whatever width ribbon you want
This is a great way to make cheap plastic backed multi trace ribbons that will compete well with the real deal. And you can make more for next to no money
from here you may want to corrugate ( but you may be suprise how well even a flat ribbon works). I would look up that one here on the forum and see what some others have done
you can get a paper corrugator at craft stores for cheap HOWEVER the corrugations are usually quite large compared to whats best (smaller)
I would start here. If down the road you feel you have this down and want to move on Im sure there will be more help available
I would start by learning how to make a ribbon 1st. Get that one down long before u dive into the other stuff.
- start small
- get on ebay and buy some .5 mill ( .0005 inch thick) mylar film. .25 mill film is better BUT it a bit harder to handle.
- goto Target and buy a 5 $ mirror. this will be your work surface to cut foil on
- goto a fabric store and buy a fabric cutting wheel and some extra blades
- goto grocery store and buy some standard (not heavy duty) foil. This foil will be .0007 " thick. Many famous plastic backed multi trace ribbons use foil this thick and get HF extension to 20Khz. Most commercial ribbons will use a hard tempered foil to hold the corrugations well BUT the kitchen foil will work, it will just go slak easier. But for experimenting its fine.
- spray mirror surface with light coat of Windex
- Roll some foil out and work it flat with a soft cloth
- use a long straight edge and cutter wheel and cut some traces on the foil
- peel out the unwanted foil ( the small thin section between traces)
- Take your .5 mill mylar film and tape it around the edges to a picture frame like structure to hold the film flat and tight. just a crude mounting with scotch tape is fine here.
- spray a very light coat of 3M super 77 spray glue over your foil traces
- now simply lay the film on top of the foil traces and work it down onto the foil pressing firmly
- how finish by taking your long straight edge and cutter wheel and cut out whatever width ribbon you want
This is a great way to make cheap plastic backed multi trace ribbons that will compete well with the real deal. And you can make more for next to no money
from here you may want to corrugate ( but you may be suprise how well even a flat ribbon works). I would look up that one here on the forum and see what some others have done
you can get a paper corrugator at craft stores for cheap HOWEVER the corrugations are usually quite large compared to whats best (smaller)
I would start here. If down the road you feel you have this down and want to move on Im sure there will be more help available
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well you might want to try and make a small ribbon first with some magnets and see if your idea might not be so easy ?? it is not that hard. there are 200000 posts about ribbond pick one and just start building and then when you managed that one you learned allot and can look at the next step.
What do you mean by "traces"? Also why use the mylar instead of a pure ribbon?
My idea is nearly impossible to do even with a small ribbon. I have no idea how to sandwich a magnetic bezel onto a ribbon an manage to get a tight clamp throughout the entire structure when they are trying to repel each other.
Even if I use a poly magnet to have opposing magnets on the clamping sides I will then have the opposite issue where I will never be able to get them apart, especially without destroying the ribbon.
I still think my idea is ideal, it solves so many conventional problems.
But it is out of my league to solve the bezel issue.
And none of them have a detailed guide, just pictures and figures. I think you underestimate how bad I am at craft projects. I will make a lot of expensive mistakes figuring it out on my own.
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