I don't understand the site, but Mu metal usually means a special alloy to protect agains magnatism. Is this aluminum on the site?
Also- could anyone make up a diagram of the magnet orientation?
Do you just line them up along each edge of the ribbon with the poles pointing at the edge of the ribbon?
Are the mags attracting each other or repulsing each other?
Brian- when are you going to make that amp?
Also- could anyone make up a diagram of the magnet orientation?
Do you just line them up along each edge of the ribbon with the poles pointing at the edge of the ribbon?
Are the mags attracting each other or repulsing each other?
Brian- when are you going to make that amp?
Someone was describing a plastic membrane with aluminum conductive strips on it. That's a planar magnetic driver, not a ribbon, although you sometimes see it described as such in sales literature. The term ribbon has cachet in the market place, planar magnetic does not.
The magnets in a ribbon are aligned so that all the magnets on one side have their South pole aimed at the driver element. The magnets on the other side are aligned with their North pole pointing at the element. That way the flux lines travel across the element from one side to the other. Generally the magnets are mounted on a steel frame of some sort that serves as a flux return and makes the field more efficient. When current flows through the element, it develops force at a 90 degree angle to the magnetic field and the ribbon moves.
Planar magnetics, such as the Magneplanar or the old Apogees, use a different strategy.
Ceramic magnets work just fine, although the rare earth magnets are better--just more expensive.
Grey
The magnets in a ribbon are aligned so that all the magnets on one side have their South pole aimed at the driver element. The magnets on the other side are aligned with their North pole pointing at the element. That way the flux lines travel across the element from one side to the other. Generally the magnets are mounted on a steel frame of some sort that serves as a flux return and makes the field more efficient. When current flows through the element, it develops force at a 90 degree angle to the magnetic field and the ribbon moves.
Planar magnetics, such as the Magneplanar or the old Apogees, use a different strategy.
Ceramic magnets work just fine, although the rare earth magnets are better--just more expensive.
Grey
Hello, I designed for the first time a ribbon transducer and is shown in the attached picture. I used aluminum foil for food wraping. I temporary used the magnets n52 as shown but i ordered from Amazon.de N52 neodymium magnets 60mm X 5mm X 3mm. I will use 2 on each side of the ribbon. The ribbon is 60mm X 20mm but my question is if i can increase the width to 30mm in a new design. Overall is sounds good but there is a min in audio level at 6KHz because of a reason which i cannot explain theoriticaly yet. Also i discovered that the power amplifier must have a output 15w at least, but with a series pwer resistor of 8 ohm because the tranducer has 0.1 ohm resistance.
Attachments
![IMG_20220216_100308[2574].jpg](/community/data/attachments/934/934280-215783ad16be77920d837631589abdb9.jpg?hash=IVeDrRa-d5)
Very nice.
Can you do freq and THD plots? Just needs free REW and just your laptop mic to start.
B.
Can you do freq and THD plots? Just needs free REW and just your laptop mic to start.
B.
Thanks. Sure looks good, with quite low THD from 2kHz.
Odd to see that flat trace below 100Hz, about same level at the operating band further higher. Puzzling?
What is the size of the diaphragm? Hard to judge without a reference object in the photo.
B.
Odd to see that flat trace below 100Hz, about same level at the operating band further higher. Puzzling?
What is the size of the diaphragm? Hard to judge without a reference object in the photo.
B.
The diaphragm as i mentioned is 60mm X 20mm and the material is aluminum foil for food wraping. I believe that it has about 10-15 micron thickness. The whole design was designed by me and 3d printed with PETG. Please let me know wher can i find a foil with better quality and lower thickness.
You have to apply an amount of tension to the foil then maybe you can control the 6kHz dip.
Did you simulate the magnetic filed of your arrangement ?
Maybe there could be a problem also.
Rob
Did you simulate the magnetic filed of your arrangement ?
Maybe there could be a problem also.
Rob
The foil which i use is free without any tension. I made it with multiple v shape in crossection. Also the aluminum is not elastic so it cannot be tensioned. Only, if i use aluminum on kapton i will tension the material, but then i will make planar transducer and not a ribbon transducer.
You corrugate the foil so the aluminum act a little like a spring.
I made ribbons from pure aluminium and always put some weight on one side before I fix them.
The weight depends on the ribbon width and material.
Rob
I made ribbons from pure aluminium and always put some weight on one side before I fix them.
The weight depends on the ribbon width and material.
Rob
i think you measured up close looking at the reach of 100 hz. try measuring at 1 meter.
that dip is more likey baffe difraction , or the fact it is rather large tweeter and not a true line source either. move your mic up or down see if it shifts. if so..the problem is not the foil or tension of the ribbon itself but its size/length. bolserst had a nice picture of what happens with large ribbon tweeters/small line sources, usually its a nice wiggle 🙂
To maybe help answer your secondary fundamental magnetic question,....All the many speaker (traditional dynamic magnetic cone & magneplanar, etc) designs, I only see non-nagnetic VC wire used.....Steel (or any other magnetic) VC wire (or foil ribbon) would remain sucked up tight attracted to the pole piece magnet & make quite a bad buzzing sound distorted mess....The weak but additive "electro-magnetic" field force field effect causes the non-magnetic VC wire (spool coiled or linear straight" to be alternatively pulled & pushed away from the pole piece carrying the attached diagram if used....It deff seems to work where magnetic wire or ribbon just gets in the way !! ...I leave the involved physics version up for others !! ....tom