Thanks for a very interesting and useful post!
When you hear differences between ribbons with different constructions do the frequency responses match? If they don't match, and you equalize them all to the same response, do they still sound different? I'm trying to understand how much of what you hear results from frequency response differences, how much is from harmonic distortion profiles, and how much is from who knows what?
Few
When you hear differences between ribbons with different constructions do the frequency responses match? If they don't match, and you equalize them all to the same response, do they still sound different? I'm trying to understand how much of what you hear results from frequency response differences, how much is from harmonic distortion profiles, and how much is from who knows what?
Few
Ha "who knows what" I hear that! 
Freq responses all start off EQed to within 1 db . However over time each type seems to sound best with slightly different tayloring. Some flat, some slight down tilt. The differences are subtle but in extended listening differences. The heavyer guage Foil only types dont sound as smooth in the treeble region and they dont seem to have as stable an image under hard drive. Cymbols can sound striking at first but in time I hear less actual detail than the sandwich constructions or the laminated constructions . The laminated versions can sound slightly vailed in comparison at first BUt when built right they are smoother than the foil only types and in time are less fatigueing. The sandwich constructions are a bit lower mass but similar damping as the laminated versions. They have slightly more treeble detail and a more stable image and are the easyest to get a very smooth freq response. The best one seems to be what I call biased flute construction. It has similar sweetness and image stability as the laminated versions with noticably better control under hard drive than any of the others.
In the end it is my opinion that foil only ribbons from about 6 microns thick on up are not well damped and a superior result can be had with sandwich constructions were the damping allows the use of more foil mass.The trick is to get it all balanced.
BTW interesting when setting up for FR test and the signal is a quick 20-20khz sine sweep, you can easily hear the differences in the different ribbons. Some sound harsh others smooth.
Freq responses all start off EQed to within 1 db . However over time each type seems to sound best with slightly different tayloring. Some flat, some slight down tilt. The differences are subtle but in extended listening differences. The heavyer guage Foil only types dont sound as smooth in the treeble region and they dont seem to have as stable an image under hard drive. Cymbols can sound striking at first but in time I hear less actual detail than the sandwich constructions or the laminated constructions . The laminated versions can sound slightly vailed in comparison at first BUt when built right they are smoother than the foil only types and in time are less fatigueing. The sandwich constructions are a bit lower mass but similar damping as the laminated versions. They have slightly more treeble detail and a more stable image and are the easyest to get a very smooth freq response. The best one seems to be what I call biased flute construction. It has similar sweetness and image stability as the laminated versions with noticably better control under hard drive than any of the others.
In the end it is my opinion that foil only ribbons from about 6 microns thick on up are not well damped and a superior result can be had with sandwich constructions were the damping allows the use of more foil mass.The trick is to get it all balanced.
BTW interesting when setting up for FR test and the signal is a quick 20-20khz sine sweep, you can easily hear the differences in the different ribbons. Some sound harsh others smooth.
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cont. from above. The measured distortion profiles of the different types above are really very similar in overall level but yes a little different wiggle hear and their. Probably the the biggest measured differance is impulse response and waterfall between the pure foil types and all the other types with some mechanical damping . The damped versins are quieter. This is a tricky area as you can get a good measured perf easily BUT just as easily suck the life out of the sound. There is a fine line in balancing the type and amount of materials.
From here the issue I focus on are well controled in motion under hard drive and lower crossover points. ( most of my work centers around taking smaller ribbons to lower crossover points). Traditional pleated and flat designs have serious issues below about 1khz in smaller ribbons. The standing wave activity results in a lot of unesasary motion and the sound just falls apart.
From here the issue I focus on are well controled in motion under hard drive and lower crossover points. ( most of my work centers around taking smaller ribbons to lower crossover points). Traditional pleated and flat designs have serious issues below about 1khz in smaller ribbons. The standing wave activity results in a lot of unesasary motion and the sound just falls apart.
Thanks for the reply. Might the audible differences stem from directivity differences? If the surface of a simple ribbon does not move uniformly and in phase, its directivity will change so an on-axis equalization within 1 dB of your fancy ribbons might not truly match the different designs when it comes to in-room auditioning. I'm guessing you've already considered this but I thought I'd toss it into the mix just in case.
Few
Few
The slot acts like a small transmission line, or zero-flair horn segment. Depending on the depth of the slot, the effect can vary from a lift in the top octave to a peak in the midrange. For closed back ribbons, the effect is easy to calculate since the radiation impedance loading the slot can be looked up in the latest edition of Acoustics by Beranek/Mellow for different aspect ratio ribbons. I am not aware of similar data for high aspect ratio dipole radiators. The best approximation is probably to use data for a circular piston of similar width.
Ribbon foil contact problem
Hi
in last several years I made some very nice true ribbon tweeters. I'm using mostly aluminium as body construction and contact with foil. But I've noticed when speaker is not used for long time, ribbon is not working properly. When applying high signal level in let say 20 min. ribbon start to work normally. After some investigation only possible cause could be oxidation aluminium contact. Foil is contacted with 2 pieces of aluminium which are screwed together. But even there is no oxigen seems that aluminium is oxidized.
Idea is to use copper and gold plate surface which has contact with foil.
Any idea and similar problems?
Hi
in last several years I made some very nice true ribbon tweeters. I'm using mostly aluminium as body construction and contact with foil. But I've noticed when speaker is not used for long time, ribbon is not working properly. When applying high signal level in let say 20 min. ribbon start to work normally. After some investigation only possible cause could be oxidation aluminium contact. Foil is contacted with 2 pieces of aluminium which are screwed together. But even there is no oxigen seems that aluminium is oxidized.
Idea is to use copper and gold plate surface which has contact with foil.
Any idea and similar problems?
I use 'The Solution' contact fluid by van den Hul and have had no problem the past five years. The contact fluid is a bit viscous so it also makes it easier to position the ribbon because the ribbon will stick to it. I use copper foil as contact material for the ribbon.
Well the aluminium IS oxidized and alu oxide is a good insulator.
Aluminium oxidizes immediately and the thin layer oxide protects the aluminium from
further oxidation, that is why Aluminium appears to be not oxidized.
Some contact " stuff" like Gerrit mentioned seems to work well, and -just a thought- maybe an aluminium/aluminium contact works best with some contact solution and soldered (copper) wire tot the contact.
I don't know about using different metals since that might cause oxidation on the least precious metal.
I have not used 'the solution', where can I get some??
To avoid oxidation effects at ribbon termination this is what I do...
Apply small amount of silicone "oil" to ribbon termination blocks,and using 220 grit sand paper, sand the contact surfaces with the oil applied. This makes a little mess, BUT now the termination surfaces have oxides removed AND new oxides cannot form due to being coated with oil. Now use the oil on a rag to wipe surfaces clean. This removes the sand paper grit but keeps surfaces coated with a thin layer of oil wich again doesnt alow oxides to form
Now the termination surfaces are clean, roughed up, and have a layer of oxide inhibiting oil.
The ribbon surfaces that contact the terminations still have oxides. I dont try to sand here with the thinner foils as the foil is too fragile. Instead I apply a thin layer of the oil here.
SO what about the ribbon foil oxides? The surface of the terminations has been sanded with the 220 grit paper. If you look at these surfaces under a scope you see thousands of sharp edges from the sand paper cuts. When the terminations are clamped down on the ribbon foil these sharp edges cut through the ribbon foil oxides to clean fresh foil and sense all surfaces have a coating of the oil everything is done without contact with atmosphere producing an oxygen free, clean connection.
This works well with good solid rigid terminations. If the terminations are too flexible it doesn't work well.
Also have used motor oil this way with good success
When using thicker foils. .0005" and up I have had success with carefully sanding ribbon foil as well as terminations. In these cases I dont go for the larger 220 grit ( that makes the rough sharp edges that dig into foil) but rather use a 400 grit on both termination and foil with oil on everything of course
To avoid oxidation effects at ribbon termination this is what I do...
Apply small amount of silicone "oil" to ribbon termination blocks,and using 220 grit sand paper, sand the contact surfaces with the oil applied. This makes a little mess, BUT now the termination surfaces have oxides removed AND new oxides cannot form due to being coated with oil. Now use the oil on a rag to wipe surfaces clean. This removes the sand paper grit but keeps surfaces coated with a thin layer of oil wich again doesnt alow oxides to form
Now the termination surfaces are clean, roughed up, and have a layer of oxide inhibiting oil.
The ribbon surfaces that contact the terminations still have oxides. I dont try to sand here with the thinner foils as the foil is too fragile. Instead I apply a thin layer of the oil here.
SO what about the ribbon foil oxides? The surface of the terminations has been sanded with the 220 grit paper. If you look at these surfaces under a scope you see thousands of sharp edges from the sand paper cuts. When the terminations are clamped down on the ribbon foil these sharp edges cut through the ribbon foil oxides to clean fresh foil and sense all surfaces have a coating of the oil everything is done without contact with atmosphere producing an oxygen free, clean connection.
This works well with good solid rigid terminations. If the terminations are too flexible it doesn't work well.
Also have used motor oil this way with good success
When using thicker foils. .0005" and up I have had success with carefully sanding ribbon foil as well as terminations. In these cases I dont go for the larger 220 grit ( that makes the rough sharp edges that dig into foil) but rather use a 400 grit on both termination and foil with oil on everything of course
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Here's the link to the product: The SOLUTION contact treatment and protection fluid - Van den Hul B.V. - High End Cables, Phono Cartridges and Electronics
See the link on the page for a distributor in your area. It's expensive, IIRC about €30, but it'll last a long time.
Were the two ribbons measured with the same sensitivity or did you move the curve of the 11 µm ribbon up. If the response in the 6 dB/oct range is dominated by air mass, the ribbon mass should not matter for sensitivity. Why bother with a lighter foil then, if we are going to eq it flat from a much lower frequency anyway?
You mean you ran the return wire from the top ribbon connection close to the gap rather than on the outside of the magnets?
That would compensate its field, reducing modulation of the field in the cap (even if this is more of a problem in Fe magnets compared to Nd).
Maybe the most elegant way to to this would be to cover the insides of the gap with an isolated copper foil on both sides and use these foils as a return.
They just look like that, they're actually light grey. I just rinsed them with tapwater, no special treatment was applied.
They're still in use in my main system
Don't know about cats and kids but air draft is not much of a problem. The air can easily move around them because there's no baffle. Of course the exposed ribbons are still very sensitive so one does need to be careful around them.