"BTW I wouldn't get too misty eyed about amorphous. Yes they have a technical advantage BUT there is much more to good sound than just chasing theoretical ideals."
Agree, I think one of the best cores is from ordinary toroidal transformers with oriented iron.
Another not so good core I've tested, is a silicon C-core from an old Quad Esl-63!
A mystery due to the fact that the original Quad Esl-63 sounds beautiful...
Agree, I think one of the best cores is from ordinary toroidal transformers with oriented iron.
Another not so good core I've tested, is a silicon C-core from an old Quad Esl-63!
A mystery due to the fact that the original Quad Esl-63 sounds beautiful...
Yea we tested a bunch of "C" cores (Si and amorph) as well but found no issue with them. They were just as good ( at least as ribbon transformers) than the others IF wound properly.
BTW "wound properly", there is no mystery here eather really. Just use multi filliar windings on the secondary and fill in between those winds nice and even with the primary wires.
You can do the foil secondary thing too and thats actually the easyest way to build a transformer IMO BUT often I find that that to get super extended response the Bi filliar wound secondary is easyer. The reason is the foil types will sometimes need multiple secondary layers with primarys between them. A bit harder to build than multi filliar secondary.
In the end a transformer specialist could likley put a finer point on all this BUT for 99.9% of the rest of us we can get about 95% of that type of performance by simply winding things up with Muli filliar secondary (2-3 runs min) and a nice fill in between with the primarry wires.
Also I see some are saying they are getting upwards of 100Khz response from their transformers. Its likley they are measuring them with the ribbon NOT connected. Connect that ribbon load up and you will be hard pressed to get 20K at 3db down. Lots and Lots of interleaving is the biggest thing and it doesnt have to be perfect to get a good result.
Fear not, the ribbon transformer is quite forgiving.
BTW "wound properly", there is no mystery here eather really. Just use multi filliar windings on the secondary and fill in between those winds nice and even with the primary wires.
You can do the foil secondary thing too and thats actually the easyest way to build a transformer IMO BUT often I find that that to get super extended response the Bi filliar wound secondary is easyer. The reason is the foil types will sometimes need multiple secondary layers with primarys between them. A bit harder to build than multi filliar secondary.
In the end a transformer specialist could likley put a finer point on all this BUT for 99.9% of the rest of us we can get about 95% of that type of performance by simply winding things up with Muli filliar secondary (2-3 runs min) and a nice fill in between with the primarry wires.
Also I see some are saying they are getting upwards of 100Khz response from their transformers. Its likley they are measuring them with the ribbon NOT connected. Connect that ribbon load up and you will be hard pressed to get 20K at 3db down. Lots and Lots of interleaving is the biggest thing and it doesnt have to be perfect to get a good result.
Fear not, the ribbon transformer is quite forgiving.
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There does seem to be truth in this. I havent extensivly worked the ferrite core but what little I have done shows this. AND u can get them cheap! BUT if your going wide bandwidth say below 2khz im not too sure if the may be a problem.
However the highs (im talkin above 10K) are effected strongly by the mass of the ribbon anyway. So much so that you often end up with a strongly rising response that you will end up EQing down anyway so any losses way up there may not be an issue. Of course theres the heated debate as to the importance of extreely extended response
INTERLEAVING
The mixing of pri and sec windings basically. So you wind your secondary on the former with equill spacing between each wire so that you can now put the primary windings evenly distributed in between each sec conductor. Basically getting all conductors close to eachother and evenly spaced. Doesnt have to be perfect but try to even it all out best you can.
Guys?
Take Rays advice as I bought a Epcos core similar to the one he is using and it sounds great. Compared to other cores iv tried it's streaks ahead.
Epcos TDK ETD 54 x 28 x 19 B66395GX197.
I was running it today from 2kHz with no strain but when I pushed it to 500hz it didn't very well. They really sound fantastic I build the big Apogee style ribbons but with neo magnets so I have a very good idea of a how a ribbon (planar) should sound. The top end on the transformer are definitely better with more extension and detail.
Here an artikel from Germany:Ribbon III: Ein Übertrager für Bändchen-Lautsprecher - Michael Gaedtke
Bernt Båndsei
Bernt Båndsei
Hehe! I owe you a visit, boet. You must show me what you are up to. Perhaps I can somehow contribute to your efforts (even if it is just a sympathetic shoulder!
).Has anyone managed to conquer a aircore transformer? I think the trick is to perhaps get a fair amount of inductance in the primary? I've experimented with this but I found the efficiency fairly low compared to a transformer but the sound is superb. I've spent many hours thinking what transmission audio ribbons are using to step the impedance that is not a transformer any thoughts?
Transmission Audio Inc.
Best answer here by far.
Cu corrodes when in contact with Al.
In industry where electrical cabling can have copper conductors which mate to an aluminium 'lug' or collar a grease is applied so that when thw two conducting faces are mated with pressure the grease excludes air from the joint. This must be renewed periodically.
On the AL/Cu connection thing...
I have 17 plus years experience making connections between dissimilar metals. Most of this in wet and or salt speay/ salt brine environment. It is best of course to mate same metals together, However after years of experaments with many so called " electrical greese" , the best by far is simple silicone dielectric paste or even just 100% silicone that come in spray can. Its a thin oil like substance.
Clean the conductors, apply the silicone , connect and forget. No need to return and re do the connection every once in a while. The silicone never drys out and just simply lasts seemingly forever.
Now as far as the ribbon connection goes. This is more important than most realize because if this connection is not to a very high level , then its resistance will change over time altering the ribbons sensativity and causing distortion.
Again best to make AL to AL connection , BUT even Cu to Al can work if you do the following... This method was developed over many years of ribbon development and is the method I use to manufacture the Dynaplaneaudio ribbons...
1- learn how to handle the ribbon so that you never touch it
2- Using 100% silicone spray (thin oil like substance), spray some on the ribbon connection blocks and spray some on a small piece of 220 grit sand paper.
3- sand the ribbon connection blocks to an even sheen always keeping them wet with the thin silicone fluid.
4- wet a paper towel with the silicone fluid and while keeping everything wet , wipe the ribbon connection blocks clean of all grit etc. Do this untill the paper towel/rag whatever shows no cantamination. usually 2-3 wipes will give a clean looking paper towel.
5- with the connection blocks clean and wet with the silicone fluid, install the ribbon and tighten clamps.
This method has two important points. By keeping the clamps wet at all times the fast oxidation of aluminum is avoided. If you sand aluminum with NO silicone fluid then the aluminum is exposed to the air and it emediatly forms an oxide layer than can insulate the clamp from ribbon and over time this gets worse. Keep the clamps wet all through the process.
The other important point is the sanding. Sanding with 220 grit not only gets down to clean aluminum, it makes a bunch of very small sharp edged peaks/ valleys in the clamp surface than can break through any oxide on the ribbon foils surface when clamp is tightened.
I have 17 plus years experience making connections between dissimilar metals. Most of this in wet and or salt speay/ salt brine environment. It is best of course to mate same metals together, However after years of experaments with many so called " electrical greese" , the best by far is simple silicone dielectric paste or even just 100% silicone that come in spray can. Its a thin oil like substance.
Clean the conductors, apply the silicone , connect and forget. No need to return and re do the connection every once in a while. The silicone never drys out and just simply lasts seemingly forever.
Now as far as the ribbon connection goes. This is more important than most realize because if this connection is not to a very high level , then its resistance will change over time altering the ribbons sensativity and causing distortion.
Again best to make AL to AL connection , BUT even Cu to Al can work if you do the following... This method was developed over many years of ribbon development and is the method I use to manufacture the Dynaplaneaudio ribbons...
1- learn how to handle the ribbon so that you never touch it
2- Using 100% silicone spray (thin oil like substance), spray some on the ribbon connection blocks and spray some on a small piece of 220 grit sand paper.
3- sand the ribbon connection blocks to an even sheen always keeping them wet with the thin silicone fluid.
4- wet a paper towel with the silicone fluid and while keeping everything wet , wipe the ribbon connection blocks clean of all grit etc. Do this untill the paper towel/rag whatever shows no cantamination. usually 2-3 wipes will give a clean looking paper towel.
5- with the connection blocks clean and wet with the silicone fluid, install the ribbon and tighten clamps.
This method has two important points. By keeping the clamps wet at all times the fast oxidation of aluminum is avoided. If you sand aluminum with NO silicone fluid then the aluminum is exposed to the air and it emediatly forms an oxide layer than can insulate the clamp from ribbon and over time this gets worse. Keep the clamps wet all through the process.
The other important point is the sanding. Sanding with 220 grit not only gets down to clean aluminum, it makes a bunch of very small sharp edged peaks/ valleys in the clamp surface than can break through any oxide on the ribbon foils surface when clamp is tightened.
on cores.....
If you want a cheap and readily available core and wire bobbin that will work well I would just goto some place like Digikey and buy a ferrite core like example below . The bobbins will usually show on same page.
B66363G0500X187 EPCOS (TDK) | Magnetics - Transformer, Inductor Components | DigiKey
This type of core will work well for DIY and the round bobbin makes winding by hand easy. and dont get too concerned about the type of material. N97, N87,etc will all work at the frequency's we see in audio. Those different materials are optimized characteristics for very high frequency operation and have no noticeable effect at audio freq.
That said the biggest difference you will see between these ferrite cores and laminated silicon iron cores is their saturation level. In a given cross sectional area the silicon iron core is much better in that it can handle more flux than the ferrite. This is really only an issue when trying to use the transformer below say 1khz. Once you get down below that freq the power requirements start really rising and with it the flux in the core. The ferrites saturate hard and fast. The sil iron laminates saturate much softer and at higher power.
In one of my designs I take the ribbon to 500 hz. In this we use a laminate sil iron core that is good to around 100 hz on 200 watt system. This to completely avoid possibility of saturation. ferrites were tryed and they worked well , BUT the sil iron gives a measure of saftey from saturation under hard drive in a reasonably sized unit. A ferrite to do the same would be quite a bit larger.
As far as freq response goes I see in test no advantage ferrite or silicon iron or even amorphous at audio freq.
If you want a cheap and readily available core and wire bobbin that will work well I would just goto some place like Digikey and buy a ferrite core like example below . The bobbins will usually show on same page.
B66363G0500X187 EPCOS (TDK) | Magnetics - Transformer, Inductor Components | DigiKey
This type of core will work well for DIY and the round bobbin makes winding by hand easy. and dont get too concerned about the type of material. N97, N87,etc will all work at the frequency's we see in audio. Those different materials are optimized characteristics for very high frequency operation and have no noticeable effect at audio freq.
That said the biggest difference you will see between these ferrite cores and laminated silicon iron cores is their saturation level. In a given cross sectional area the silicon iron core is much better in that it can handle more flux than the ferrite. This is really only an issue when trying to use the transformer below say 1khz. Once you get down below that freq the power requirements start really rising and with it the flux in the core. The ferrites saturate hard and fast. The sil iron laminates saturate much softer and at higher power.
In one of my designs I take the ribbon to 500 hz. In this we use a laminate sil iron core that is good to around 100 hz on 200 watt system. This to completely avoid possibility of saturation. ferrites were tryed and they worked well , BUT the sil iron gives a measure of saftey from saturation under hard drive in a reasonably sized unit. A ferrite to do the same would be quite a bit larger.
As far as freq response goes I see in test no advantage ferrite or silicon iron or even amorphous at audio freq.
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Silicon grease works fine for the ribbon connections. Where I live here in CA, no problem, just too arid. You can make an air core transformer if you do it the way I made windings, but it takes a large amount of turns. Using ferrite and winding my way is still the best. Frequency response is probably into the megahertz, and efficiency is very high. Probably how the ribbon tweeter manufacturers do it. The idea works fine to at least 30MHz which is how they do it for wide band high power transistor amplifiers.
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