There are many kinds of corrugated ribbons used in ribbon microphones (piston style etc.) The main difference I see in these ribbons both DIY and manufacturers is HOW the ribbon is made. Some have sharp perpendicular bends 'V' while others have more of a 'U' style bend. If anyone has any ideas or experience, please share? Which design seems to be more forging while installing it into a chassis truss? Do you know of any sonic differences? (The other style is of a piston style ribbon similar to Beyerdynamic microphones which have are a hybrid of flat surface as well as a couple corrugations on the ends. The flat surface supposedly extends the higher frequencies. Beyerdynamic uses a steel dies to print/press/shape the ribbon to obtain this unique design) Let's get a little Q & A and discussion going... the first image is a V shape the second image is a U shape the third is a hybrid between a flat and V.
Thoughts on Ribbon Microphone; 'CORRUGATION' of aluminum ribbon theory, effects &design?
- Thread starter s wave
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Thanks JUST looked into it! Image is on the bottom left 1st one (This ribbon design is in the Alder Audio H44) nice ~ (oh just ran across another type ribbon in photo bottom/right)
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https://www.soundonsound.com/reviews/alder-audio-h44 <--- SOS review on Alder Ribbons
GermanTech
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That design is pretty cool. corrugated at the ends and vertical in the middle! I have also seen some dies that pressed a similar model without the vertical corrugations - they are stone flat - I guess for higher frequencies. thx
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GermanTech
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Think that the longitudinal corrugations are for stiffness of the middle part. And the 2 transverse corrugations at both ends are for easy moving. Same as a laudspeaker construction with a stiff diaphragm and the suspensions for easy moving the diaphragm.
But I can see a potential for breaking up and thus distortion across that stiffened area..
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I'm sure there are many things to consider with this design, but from what I've heard, the vertical corrugations keep more of the ribbon mass in the area of the motor where there is peak magnetic flux(i.e. right in between the magnets) which which results in better signal to noise. I could be wrong...
GermanTech
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You should be right ....
You should be right ....
A fully corrugated ribbon in standard zig-zag will have more movement at the centre of the ribbon which in turn requires deeper magnetic poles front to rear resulting in a lower termination frequency (the frequency at which the ribbon nulls and stops delivering signal) and also more tension in the ribbon.
Termination frequency, ft = 344 / d
Where 344 is the velocity of sound propagation in air (in metres per second, at a room temperature of 21°C), and d is the shortest distance from the front to the back of the ribbon (in metres)
Rolloff starts at 1/2ft
But after the null point there are additional nulls with output peaks and nulls occurring at higher frequencies:
With the vertical corrugated-centre ribbon having standard zig-zag ends the front to rear distance can be reduced dramatically allowing a much higher frequency response.
Then there is the amount of tension required to prevent excursion outside of the pole pieces - the more tension the worse the low frequency response. There is the weight of the ribbon to consider as well - this becomes really important with transient response, the lighter the ribbon the better the transient response.
The lesser number of zig-zag corrugations acting as the “hinges” for the centre vertical more rigid element would result in faster fatiguing of the ribbon at those ends so a much stronger, lighter material would need to be used.
Termination frequency, ft = 344 / d
Where 344 is the velocity of sound propagation in air (in metres per second, at a room temperature of 21°C), and d is the shortest distance from the front to the back of the ribbon (in metres)
Rolloff starts at 1/2ft
But after the null point there are additional nulls with output peaks and nulls occurring at higher frequencies:
With the vertical corrugated-centre ribbon having standard zig-zag ends the front to rear distance can be reduced dramatically allowing a much higher frequency response.
Then there is the amount of tension required to prevent excursion outside of the pole pieces - the more tension the worse the low frequency response. There is the weight of the ribbon to consider as well - this becomes really important with transient response, the lighter the ribbon the better the transient response.
The lesser number of zig-zag corrugations acting as the “hinges” for the centre vertical more rigid element would result in faster fatiguing of the ribbon at those ends so a much stronger, lighter material would need to be used.
Thank you RoadrunnerOZ 'With the vertical corrugated-center ribbon having standard zig-zag ends the front to rear distance can be reduced dramatically allowing a much higher frequency response.' YES - and I believe there is a Beyerdynamic model that uses a shorter ribbon without the vertical corrugations for even a higher end frequency response. The draw back is aluminum fatigue. BUT I did see a photo once that showed the jig used to make these ribbons. A tool and die setup (2 halves) that actually stamped or pressed the the aluminum ribbon (which included the 2 corrugation on the ends) with a flat center (no vertical corrugations). I would imagine the high forced 'stamping' may be a technique used to strengthen the ribbon? I may be wrong here - maybe someone can chime in on this type of production ~
I read one analysis of the 'air pressure physics' that was saying the lightness of the ribbon (weight/mass/air pressure) works only to a basic point. In other words a ribbon of .8 microns has no advantage in reality over one of 1.8 in the this area?
I heard that AEA focuses on backward engineering making their starting point at their chosen optimum HF roll-off of 16.5Khz. This seems like a nice way of engineering. DIY and engineers of old used low hertz 'thumping' to dial in the LF and let the highs be where they may?
BBC and others used to use hand pounded aluminum leaf apparently trying to optimize 'cold working' strength?
I still see many possible breakthroughs even from the simplest of ideas. I will post what I just got from ChatGPT 3.5 on it below...
I read one analysis of the 'air pressure physics' that was saying the lightness of the ribbon (weight/mass/air pressure) works only to a basic point. In other words a ribbon of .8 microns has no advantage in reality over one of 1.8 in the this area?
I heard that AEA focuses on backward engineering making their starting point at their chosen optimum HF roll-off of 16.5Khz. This seems like a nice way of engineering. DIY and engineers of old used low hertz 'thumping' to dial in the LF and let the highs be where they may?
BBC and others used to use hand pounded aluminum leaf apparently trying to optimize 'cold working' strength?
I still see many possible breakthroughs even from the simplest of ideas. I will post what I just got from ChatGPT 3.5 on it below...
What are the best ways to improve strength and durability in light gauge aluminum ribbons?
Improving strength and durability in light gauge aluminum ribbons can be achieved through several methods:
- Alloy selection: Choosing aluminum alloys with higher strength and durability characteristics, such as 5000 series (e.g., 5052, 5083) or 6000 series (e.g., 6061, 6063), can enhance the overall performance of the ribbons.
- Heat treatment: Heat treatment processes like annealing, precipitation hardening, or tempering can refine the microstructure of aluminum ribbons, increasing their strength and durability.
- Cold working: Cold working techniques such as rolling, drawing, or extrusion can impart strain hardening, improving the mechanical properties of the aluminum ribbons.
- Surface treatment: Applying coatings or treatments like anodizing, painting, or plating can enhance corrosion resistance and surface hardness, thereby increasing durability.
- Design optimization: Reducing stress concentrations, optimizing geometries, and incorporating reinforcements or ribbing structures can distribute loads more evenly and improve overall strength.
- Quality control: Implementing stringent quality control measures during manufacturing to ensure consistent material properties and defect-free production can enhance the reliability and durability of aluminum ribbons.
- Environmental considerations: Protecting aluminum ribbons from harsh environments, such as exposure to moisture, UV radiation, or corrosive chemicals, can prevent degradation and prolong their service life.
I suspect some TOP ribbon microphone manufacturers use heated rollers or stamp/dies to maybe anneal the aluminum too. There may be an overlooked process here of optimizing the combination of heat/cold and 'pressing' combination and order in which they can be implemented?
I would LOVE to have someone also chime in on thoughts of the paramagnetic effects of aluminum in the ribbon mic sound creation audio signal path. How does the fact that ~ small areas of the aluminum ribbon get magnetized ;have on the audio signal/electricity it makes? Or does it? I would imagine it has to have an effect, is this sonically pleasing? Would it behoove us to explore exactly what this paramagnetic effect has on the sonic quality? tc
I would LOVE to have someone also chime in on thoughts of the paramagnetic effects of aluminum in the ribbon mic sound creation audio signal path. How does the fact that ~ small areas of the aluminum ribbon get magnetized ;have on the audio signal/electricity it makes? Or does it? I would imagine it has to have an effect, is this sonically pleasing? Would it behoove us to explore exactly what this paramagnetic effect has on the sonic quality? tc
OK I am not super big on GPT but figured I would place their answer in
How does the paramagnetic effect of aluminum change the audio signal in aluminum ribbon microphones?
In aluminum ribbon microphones, the paramagnetic effect of aluminum can influence the behavior of the microphone's ribbon element, which in turn can affect the audio signal. Here's how:
Thoughts? Especially more specifically on the 'linearity' effects of the sound? I guess we would have to try to test 2 similar ribbons in the same mic? One of which is much mire highly magnetic? Anyone ever try a test like this? thx in advance...
How does the paramagnetic effect of aluminum change the audio signal in aluminum ribbon microphones?
In aluminum ribbon microphones, the paramagnetic effect of aluminum can influence the behavior of the microphone's ribbon element, which in turn can affect the audio signal. Here's how:
- Magnetic Field Interaction: Aluminum is a paramagnetic material, meaning it becomes weakly magnetized when subjected to an external magnetic field. In ribbon microphones, the ribbon element is typically made of thin aluminum foil suspended within a magnetic field generated by permanent magnets. When sound waves cause the ribbon to move within this magnetic field, the changing magnetic flux induces an electrical signal in the ribbon, capturing the audio signal.
- Damping Effect: The paramagnetic properties of aluminum can also introduce a damping effect on the ribbon's movement. As the ribbon moves in response to sound waves, its paramagnetic properties cause it to resist changes in the magnetic field, damping its motion. This damping effect helps to control the ribbon's response to fast transients and prevents it from oscillating excessively, contributing to the microphone's transient response and overall sonic characteristics.
- Frequency Response: The interaction between the paramagnetic properties of aluminum and the magnetic field can influence the frequency response of the microphone. The damping effect and the ribbon's mass may affect the microphone's response to different frequencies, contributing to its overall tonal character and frequency sensitivity.
- Linearity and Distortion: The paramagnetic effect of aluminum can also impact the linearity and distortion characteristics of the microphone. Nonlinearities in the ribbon's response due to its paramagnetic properties may introduce harmonic distortion or coloration to the audio signal, contributing to the microphone's unique sound signature.
Thoughts? Especially more specifically on the 'linearity' effects of the sound? I guess we would have to try to test 2 similar ribbons in the same mic? One of which is much mire highly magnetic? Anyone ever try a test like this? thx in advance...
I would imagine the paramagnetic force to be relatively tiny compared to the reactive damping effect of induced magnetic fields in the ribbon element caused by the motion of the ribbon between the magnetic poles, this being the opposite of the paramagnetic effect. I would assume the paramagnetic effect being statically the same as when in motion. If the paramagnetic effect remains a constant then response characteristics should only be affected at very low signal levels where the effect is proportionally high. The mass of the ribbon would also have a direct bearing on the amount of attraction between the foil and the magnetic poles based on the number of free electrons which cause this effect, 1 per molecule. This attraction would tend towards aligning the ribbon in its already set position between the magnet poles of the motor. There are videos which show the aligning of aluminium between magnetic poles - the length axis of the piece being directly between the poles but this attractive force is apparently very weak when compared to the reactive/repulsing force of the ribbon motion from sound waves producing current in the ribbon. There would likely be far more influence from stray magnetic fields from lights/dimmers headphones etc.
Shure have developed a ribbon nano-material they call Roswellite:
https://www.shure.com/en-US/performance-production/louder/what-is-this-stuff
Used in:
https://www.shure.com/en-US/products/microphones/ksm313?variant=KSM313/NE
And:
https://www.shure.com/en-US/products/microphones/ksm353?variant=KSM353/ED
The choice of transformer and also basket shielding etc would have the most effect on response/performance as well as profiling of the magnetic poles (there are patents around for curved and cylindrical magnetic pole ribbon motors with some manufacturers making these)
Shure have developed a ribbon nano-material they call Roswellite:
https://www.shure.com/en-US/performance-production/louder/what-is-this-stuff
Used in:
https://www.shure.com/en-US/products/microphones/ksm313?variant=KSM313/NE
And:
https://www.shure.com/en-US/products/microphones/ksm353?variant=KSM353/ED
The choice of transformer and also basket shielding etc would have the most effect on response/performance as well as profiling of the magnetic poles (there are patents around for curved and cylindrical magnetic pole ribbon motors with some manufacturers making these)
Makes sense - but we are mainly talking about just one paramagnetic effect of the aluminum; in a sense of how magnets try to align/dampen. But isn't there an effect of an electrical sound signal going through the ribbon? That it is some how changed? Let alone areas where the sound originates? thx for nice post.
Minor correction - Roswellite™ was developed by Robert Crowley and Hugh Tripp (of Crowley & Tripp) in 2006. The company, designs, and patents were acquired by Shure, Inc. in 2009.
The reactive effect of a ribbon passing through a magnetic field is what generates current which in turn creates a resistance to motion, even without a load (eddy currents) - then the back effect is also governed by the impedance characteristics of the ribbon and the transformer load used and further upstream by the loading of the transformer output - cables, preamp etc. There is as much involved with making a suitable transformer as making the mic motor itself.
yes indeed - thanks for that - credit where it’s due!
If electricity passing through a single wire produces an magnetic field; doesn't it make sense that the aluminum ribbon (acting as a single wire) will change/affect that magnetic field? (and therefore is changing the field in which the ribbon vibrates in) just wondering ty.
