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Please Help: Mesh Size and Design for Royer 121 Style Ribbon Mics
Old 21st January 2013
  #1
Gear Maniac
 
🎧 10 years
Please Help: Mesh Size and Design for Royer 121 Style Ribbon Mics

Hello,

I'm building a pair of ribbon mics with the same dimensions as the Royer 121. I have Samar transformers, ribbon machines, xlr connectors, and capsules on hand.

I've looked online for information on mesh design. Does anyone have any details on what sort of mesh I should be purchasing? I'd like to get mesh with the correct opening size and shape.

I appreciate your help.
Old 22nd January 2013
  #2
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Richard Crowley's Avatar
 
🎧 10 years
What does "correct" mean? Unless you actually have the capsules and shell from a Royer 121, then you aren't really making a "clone". You are making a new ribbon mic of unknown potential performance. Experiment with various materials and see how (if at all) they affect the sound. There is no calculation or "rule of thumb" for this. Selection of protective covering over a mic capsule is always a trade-off between mechanical and pneumatic protection for the mic vs. the high-pass filter (and possibly other anomalies) imposed by the materials between the sound and the capsule.
Old 22nd January 2013 | Show parent
  #3
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🎧 10 years
Quote:
Originally Posted by rcrowley ➑️
What does "correct" mean? Unless you actually have the capsules and shell from a Royer 121, then you aren't really making a "clone". You are making a new ribbon mic of unknown potential performance. Experiment with various materials and see how (if at all) they affect the sound. There is no calculation or "rule of thumb" for this. Selection of protective covering over a mic capsule is always a trade-off between mechanical and pneumatic protection for the mic vs. the high-pass filter (and possibly other anomalies) imposed by the materials between the sound and the capsule.
I'm not trying to make a clone of the 121. I only mention that microphone because the mics I'm making are the same basic dimensions.

By "correct" I'm only looking for a ballpark estimate of suitable mesh patterns and opening sizes (aka the size of the holes in the mesh). There are a lot of companies that sell mesh and the opening sizes range from filtering fluids to keeping chickens in the coop.

So again, I appreciate your input rcrowley,but can you possibly give me an estimate of the mesh I'm looking for?
Old 22nd January 2013
  #4
Gear Maniac
 
🎧 10 years
I'm also interested in what metals are used to make microphone mesh as a consumer has the option of buying copper and bronze as well as various kinds of steel.
Old 22nd January 2013
  #5
Gear Nut
 
🎧 5 years
I will comment here, only because I tried an experiment with mesh, and failed. I wanted to make my Shure KSM44's sound more open so I thought I'd remove the mesh. Well it turns out this element is essential to the working of a microphone. It is an electrical shield. Without an effective shield you will have a lot of 60 hz noise.

Therefore, the standard design considerations with any faraday cage will apply. You need to use copper (not brass) for the best shielding. Also you cannot have a mesh that is too open or you will allow RF into your condenser or ribbon element.

I would recommend a kit from the folks who make ribbon mike kits: have you gone to diyribbonmic.com? Just get a complete kit from them. Or a housing (which I bet they'd sell separately with the mesh).

Good luck!
Old 22nd January 2013 | Show parent
  #6
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Quote:
Originally Posted by jkorten ➑️
I will comment here, only because I tried an experiment with mesh, and failed. I wanted to make my Shure KSM44's sound more open so I thought I'd remove the mesh. Well it turns out this element is essential to the working of a microphone. It is an electrical shield. Without an effective shield you will have a lot of 60 hz noise.

Therefore, the standard design considerations with any faraday cage will apply. You need to use copper (not brass) for the best shielding. Also you cannot have a mesh that is too open or you will allow RF into your condenser or ribbon element.

I would recommend a kit from the folks who make ribbon mike kits: have you gone to diyribbonmic.com? Just get a complete kit from them. Or a housing (which I bet they'd sell separately with the mesh).

Good luck!
Alright. Thanks a ton! I'm going to look at those kits to see if they give numbers.

Can anyone else confirm what jkorten says?

1) Is copper better than brass or should I stick to experimenting with steel or aluminum?

2) Do RF signal problems increase when using more open mesh?
Old 22nd January 2013
  #7
Gear Maniac
 
🎧 10 years
None of the DIY sites give specs on the mesh that they use. I do think it is significant to express that my mics are styled after the 121 as the mesh used in most other ribbon designs is much thicker than the royer grilles, which have a fine weave and are located within the capsule.
Old 22nd January 2013
  #8
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If there is a "rule of thumb" it would be: use the LEAST you can get away with. If "chicken wire" with 1/4 inch holes works, then use it. If plastic window screen from Home Depot works, then use it. If fabric from a pair of panty-hose works, then use it.

But as jkorten says, the various forms, materials and layers of materials between the sound and the mic element are there for the protection of the microphone. From poking fingers, from particles of pizza and hamburger, from garlic breath, from puffs of wind, from electro-magnetic interference, from RFI, etc, etc. The same thing that stops EMI/RFI will probably stop fingers and food particles, but not wind damage. But non-metallic materials are useless for EMI/RFI protection.
Old 23rd January 2013 | Show parent
  #9
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Quote:
Originally Posted by rcrowley ➑️
If there is a "rule of thumb" it would be: use the LEAST you can get away with. If "chicken wire" with 1/4 inch holes works, then use it. If plastic window screen from Home Depot works, then use it. If fabric from a pair of panty-hose works, then use it.

But as jkorten says, the various forms, materials and layers of materials between the sound and the mic element are there for the protection of the microphone. From poking fingers, from particles of pizza and hamburger, from garlic breath, from puffs of wind, from electro-magnetic interference, from RFI, etc, etc. The same thing that stops EMI/RFI will probably stop fingers and food particles, but not wind damage. But non-metallic materials are useless for EMI/RFI protection.
Today I purchased a square foot of .0065 diameter stainless steel mesh from the hardware store. The mesh looks to be identical to that used in my Audix D6 mic. Hopefully this works well. Unfortunately they didn't have any copper mesh. I've noticed that a lot of the DIY kits use copper mesh.
Old 23rd January 2013 | Show parent
  #10
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Quote:
Originally Posted by rcrowley ➑️
If there is a "rule of thumb" it would be: use the LEAST you can get away with. If "chicken wire" with 1/4 inch holes works, then use it. If plastic window screen from Home Depot works, then use it. If fabric from a pair of panty-hose works, then use it.

But as jkorten says, the various forms, materials and layers of materials between the sound and the mic element are there for the protection of the microphone. From poking fingers, from particles of pizza and hamburger, from garlic breath, from puffs of wind, from electro-magnetic interference, from RFI, etc, etc. The same thing that stops EMI/RFI will probably stop fingers and food particles, but not wind damage. But non-metallic materials are useless for EMI/RFI protection.
I find what you're saying to be intriguing, but I've noticed that there seems to be a pattern in how manufacturers use mesh in their capsule designs.

For example, the U87 uses a thick mesh while small condensers like my Miktek C5s or the KM184s have a very thin and fine mesh. Don't these discrepancies account for more than simply stopping EMI/RFI and booger damage to the capsule?
Old 23rd January 2013 | Show parent
  #11
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Quote:
Originally Posted by trubadoor ➑️
I've noticed that a lot of the DIY kits use copper mesh.
You can make mechanical and electrical connections to copper by soldering. You can't solder to stainless steel (or any other kind of commonly-found steel.) I strongly suspect that is why copper (and brass) are popular for DIY mic materials.

Quote:
For example, the U87 uses a thick mesh while small condensers like my Miktek C5s or the KM184s have a very thin and fine mesh. Don't these discrepancies account for more than simply stopping EMI/RFI and booger damage to the capsule?
Certainly. I believe the discrepancy comes from MECHANICAL protection requirements. A large microphone with a "curved" grille needs a larger/heavier mesh to be mechanically strong enough to resist dropping and poking, etc. You will frequently find finer mesh (or fabric, etc.) behind the larger mesh.

OTOH, smaller mics with smaller grilles don't need such big/heavy mesh to protect the capsules behind them. I believe this is pretty straightforward, what you see is what you get stuff here. I don't believe there is any deep "magic" to the materials, design, and construction of microphone grilles. You may be in danger of over-analyzing this!
Old 23rd January 2013
  #12
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The comments on this thread regarding the OP's request for info on the sort of mesh to use on his "interpretation" of a "Royer-121 like" ribbon microphone have been extremely entertaining.

Posters here have mentioned that using a material like copper is better than brass because of conductivity issues, and that it's apparently a simple matter to design a good mic shield/filter mesh "...to protect the capsules behind them" . With all due respect, IMHO those comments are ill informed.

Anyone who has ever studied the published papers related to ribbon mic detail design would have an entirely different opinion. Occasional articles have been published by the people who have been the leaders in ribbon mic design including Bob Speiden, David Royer, Michael Joly and Shorter and Howard of the BBC.

Royer has commented on the material used in his and Spieden's designs. He has not mentioned the material's composition or the mesh characteristics, but has commented that it is critical to the performance of the Royer line.

Many ribbon mics use a two layer mesh with an outer metallic layer for electrostatic and magnetic shielding and an inner layer for "pop" filtering and to create a low-pass filter. The metals used are not picked for their electrical conductivity since because of the extremely low impedance of the transducer electrostatic shielding is not a significant factor as it is for a condenser mic. Instead the metal used is picked for it's magnetic shielding capability and it's effect on the focus and distortion of the magnetic field around the ribbon. Shorter and Harwood speak of using a "Mu-metal alloy" and Royer won't devulge what he uses although his "ribbed" mic cases inherently provide magnetic shielding. Most mics (even the old RCAs) use a combination of a metal and a fine cloth fabric to provide both electrical and magnetic shielding, and some protection from voice plosive sounds. If you believe Wes Dooley. the type and weight of the silk used in the RCA designs is critical to their sound.

If you survey the literature, you will eventually find that the mesh materials, layering and spacing (some mics use both a close and a more distant outer spaced layer) is critically related to the ribbon thickness and ribbon tension. The mesh creates reflected and standing waves in the mic head-shell, phase shift, and also low pass and comb filtering and its design is one of the many significant factors that makes one mic sound dramatically different than another mic with an apparently similar design.

One of the criticisms of many of the Chinese ribbons is that they (the designers) have paid little attention to the head-chamber shape and materials and treated the mesh/shield as they would in a mic with a condenser capsule. This simply does not work well because of the entirely different spatial characteristics of an asymmetrical, bi-polar ribbon element.

I'm certainly no expert on the design of ribbon mics and the fine details of their mesh requirements, but I have read most of the published papers on the subject (since the early 1980's) and have a lot of respect for the work that has gone into measuring and determining how those factors affect a mic's performance.

If you take the time to dig up the published material on the subject, you will find that it is a lot more complicated than one would think on an intuitive level and it will have a significant effect on how the mic sounds.

There are several papers that discuss the details of ribbon mic design and the interactions between the components including the grill mesh. I'm attaching a "pdf" of one of the more informed and detailed ones for anyone who is interested in the science involved.
Attached Files
File Type: pdf BBC_ribbon_Mic_design.pdf (4.15 MB, 587 views)
Old 23rd January 2013 | Show parent
  #13
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Quote:
Originally Posted by Lotus 7 ➑️
The comments on this thread regarding the OP's request for info on the sort of mesh to use on his "interpretation" of a "Royer-121 like" ribbon microphone have been extremely entertaining.
Ha! I need to reiterate that I in no way, shape, or form believe that I'm building a "copy" or even an "interpretation" of the Royer 121.

Lotus, your input is much appreciated. Thank you for letting me know what you know. I have absolutely no reservation about "over analyzing" the issue. i understand that the mesh element could prove to be vital. Regardless, I want to install something that compliments the mic design and makes recordings sound their best.

That's a reasonable goal, I think.

I'm thinking that my friend could weld the mesh I purchased into the capsules, but if he can't we may have to use some kind of epoxy. Using epoxy just seems like a horrible way to go, but what can I do if welding isn't an option?
Old 23rd January 2013
  #14
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As has been alluded to on this thread by rcrowley, a major function of the mesh is to provide some protection to the ribbon element. That's obviously an important function. I just wanted to mention that from the very limited reading on the subject I've been able to accumulate over the years, the mesh does a lot more (at least in well-designed mics that sound good).

The people who really know what works in a particular design have gained that knowledge through observation or experimentation (probably lot's of experimentation), and for obvious reasons are reluctant to share that knowledge. However, there are articles and papers out there about what works (in specific designs), and reading them will at least get one pointed in the right direction.

I suspect (pure speculation!) that it may take some experimentation to get the optimum configuration for your particular mic, even though it's starting with a "Royer-like" configuration. The material that works on a R-121 is used in conjunction with the restricted ribbon exposure of the "slotted" Royer outer case. If you don't have a outer case wth the horizontal "slots" of the Royer, then it's likely that a different metal mesh plus cloth liner will be necessary. The difference between what's "optimum" and what's "acceptable" may, or may not, be all that important to you.

I believe that Wes Dooley will sell the open silk cloth that he uses to re-line RCA mics (for the inner layer of the perforated metal grill) and there are hundreds of manufacturers of mesh "wire-cloth" in every possible wire diameter, mesh pitch and metal. It's a daunting task to pick a size to start.

FYI: There is a manufacturer you may want to check out who makes mesh wire cloth in some interesting alloys including stainless steel, nickel and Monel-400 (possibly the best for a small-diameter ribbon mic). Take a look at Belleville Wire Cloth for their "filter wire cloth" and "woven wire cloth" selections. If you do choose to use Monel, remember that it generally should not be electrically welded, but if it is, it should be annealed before final use.

I think it's great that you've decided to make your own mic design. That's how Bob Speiden started on the path that led to the Royer "revolution" in ribbon mic popularity.

Have fun and good luck!
Old 23rd January 2013
  #15
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Lotus7 offers some excellent advice. And I was remiss in taking most of that for granted. We agree that "conductivity" is not an issue, and indeed Lotus7 is the only one to mention it in this conversation. Certainly, mechanical and pneumatic protection of the capsule (diaphragm or ribbon) is the prime consideration. Everything else is secondary. If the capsule is damaged, nothing else really matters, does it?

Studying classic designs is very instructive and should be a primary recommendation in any experiment. No particular benefit in re-inventing the wheel. We stand on the shoulders of giants, both historic and contemporary.

Perhaps my statemets were misunderstood to imply that none of the materials or design mattered. Quite to the contrary, many of them can have significant effect on the performance of the microphone. However, my statements were a reaction to the concept that one could somehow discover some simple "rule of thumb" or formula on mesh design.

Thank you, Lotus7 for refering Trubador to one of the classic documents on ribbon mic design. Studying this will reveal many of the factors that are involved when creating a complex assembly like a microphone. Of course, Trubador is limited to what kinds of materials he has available to experiment with. It would likely be easier for Trubador to acquire some moon-dust than get his hands on any exotic metals and aloys like wire-mesh or structural mu-metal. Moderate size pieces of mu-metal sheet material are not even easy to find at prices amateurs can afford. And even then one must take extraordinary measures to preserve the magnetic shielding properties, or else re-aneal the material after forming it. Certainly magnetic shielding is one area we can't really hope to equal commercial products with our DIY designs. I have never seen any serious attempt at magnetic shielding in amateur DIY designs because it is highly impractical for non-commercial experiments.

I should have been more explicit in my encouragement of Trubador to collect various materials and experiment with them, while providing for the protection of the capsule as the "prime directive".

Certainly the geometry and density of the magnetic structure, the material, thickness and geometry of the ribbon, and the characteristics of the transformer are primary factors in the performance of any ribbon mic, and apparently Trubador has already made those design decisions. In modern times, we have a great advantage in magnetic materials orders of magnitude better than even a few decades ago, so DIY ribbon mics have become practical and that is an exciting development.

I would encourage Trubador to acquire a wide variety of materials to experiment with. And to "publish" his adventure here or a similar forum for audio experimentation. Thank you, Lotus7 for balancing my statements and bringing some valuable additional concepts to the discussion.
Old 23rd January 2013 | Show parent
  #16
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🎧 10 years
Quote:
Originally Posted by Lotus 7 ➑️
As has been alluded to on this thread by rcrowley, a major function of the mesh is to provide some protection to the ribbon element. That's obviously an important function. I just wanted to mention that from the very limited reading on the subject I've been able to accumulate over the years, the mesh does a lot more (at least in well-designed mics that sound good).

The people who really know what works in a particular design have gained that knowledge through observation or experimentation (probably lot's of experimentation), and for obvious reasons are reluctant to share that knowledge. However, there are articles and papers out there about what works (in specific designs), and reading them will at least get one pointed in the right direction.

I suspect (pure speculation!) that it may take some experimentation to get the optimum configuration for your particular mic, even though it's starting with a "Royer-like" configuration. The material that works on a R-121 is used in conjunction with the restricted ribbon exposure of the "slotted" Royer outer case. If you don't have a outer case wth the horizontal "slots" of the Royer, then it's likely that a different metal mesh plus cloth liner will be necessary. The difference between what's "optimum" and what's "acceptable" may, or may not, be all that important to you.

I believe that Wes Dooley will sell the open silk cloth that he uses to re-line RCA mics (for the inner layer of the perforated metal grill) and there are hundreds of manufacturers of mesh "wire-cloth" in every possible wire diameter, mesh pitch and metal. It's a daunting task to pick a size to start.

FYI: There is a manufacturer you may want to check out who makes mesh wire cloth in some interesting alloys including stainless steel, nickel and Monel-400 (possibly the best for a small-diameter ribbon mic). Take a look at Belleville Wire Cloth for their "filter wire cloth" and "woven wire cloth" selections. If you do choose to use Monel, remember that it generally should not be electrically welded, but if it is, it should be annealed before final use.

I think it's great that you've decided to make your own mic design. That's how Bob Speiden started on the path that led to the Royer "revolution" in ribbon mic popularity.

Have fun and good luck!
Thanks for all of this great info! I plan on researching the different metals this evening.

Why, specifically do you recommend Monel-400 mesh?

Also, do you have any suggestions for attaching the mesh behind the vents (the Royer has 12 of them) if not by electric welding or epoxy?

It may be possible to fabricate a mesh screen that is securely attached to the ribbon bracket, but doesn't touch the capsule itself.
Old 23rd January 2013 | Show parent
  #17
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Quote:
Originally Posted by trubadoor ➑️
...Why, specifically do you recommend Monel-400 mesh?
Again, I'm no expert but am only parroting something I've read. I remember an article which implied that when the shield was close to the magnet structure it was usually best to use one of the steel alloys that would block an external magnetic field, but would nor become magnetized itself and Monel was one of the alloys that could be used. On large body mics like the old RCA 44'a and 77's the metal shield is apparently far enough away that it's magnetic properties are not as important. On mics like the Coles 4039 they seem to use a very close magnetic shield (Mu-metal ??) and damper and then a more distant external protective shield.

Mu-metal may be an even better choice (according to the BBC guys), but I've never seen it made in mesh and it's even harder to fabricate than Monel.

Mu metal is usually available as thin sheet metal and would have to be perforated, which is probably not a DIY operation anyone would want to do.

I know that David Royer has commented on the metal alloy used in the R-121/R122 bodies and that the magnetic properties are part of the design, so the mesh materials magnetic properties possibly are not all that important (since the body does most of the magnetic shielding.

Again, I have absolutely no first-hand experience in this area and am only repeating stuff I've read, so take any of my comments with a grain of salt.

Quote:
Originally Posted by trubadoor ➑️
Also, do you have any suggestions for attaching the mesh behind the vents (the Royer has 12 of them) if not by electric welding or epoxy?
Just guessing, but if I were in your shoes, I'd try to use an assembly method that allowed easy removal/replacement of the mesh. It could be neat to have a mic who's HF response peaks could be changed by switching the mesh pitch or density. I'd try just rolling the mesh into a cylinder that was slightly larger in diameter than the inside diameter of the mic body so that it's own natural expansion kept it pressed up against the vents. Maybe a couple of very small flat-head machine screws (non-magnetic stainless steel possibly #2-56 size) could be placed at locations to retain the ends (edges) of the mesh cylinder. It would be easy to attach a couple of machine screw nuts to the inside surface of the mesh with epoxy to retain them inside the shield. The couple of screws would keep the mesh cylinder in place and provide a good ground for electrostatic shielding.
Old 24th January 2013 | Show parent
  #18
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Quote:
Originally Posted by rcrowley ➑️
..I would encourage Trubador to acquire a wide variety of materials to experiment with. And to "publish" his adventure here or a similar forum for audio experimentation. Thank you, Lotus7 for balancing my statements and bringing some valuable additional concepts to the discussion.
Rich, Thanks for your kind words. You hit the nail on the head with your "re-inventing the wheel" comment.

It's unfortunate that there isn't really a lot of design info out there about the fine details of mic design, especially in the ribbon mic area. With what little does exist, you have to "read between the lines" and fill in a lot of blanks.

My main point was to try to encourage trubadoor to read what little does exist, do the research and to experiment, and to stimulate the discussion on the thread. There are plenty of people here who openly contribute very helpful advice almost every day, and having many knowledgeable persons thinking about an issue or problem has GOT to result in some great "out-of-the-box" ideas.

Building your own ribbon mic is a great project, but IMHO it can also be a challenge and undoubtedly will be a "learning experience". I've made plenty of design "mistakes" over the years, but sometimes understanding and correcting the "error" can ultimately result in the most progress.

I'm putting away the soapbox now -- Carry on!
Old 24th January 2013
  #19
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Remember that Monel metal and mu-metal are at opposite ends of the spectrum. Monel is completely non-magnetic. I believe that is why they use it in small-body ribbon microphones, so that it doesn't disturb the magnetic field that the ribbon operates within.

OTOH things that are sensitive to external magnetic fields (like phono pickups, mic input transformers, many dynamic microphones, CRT monitors, etc.), all benefit from additional shielding against external magnetic fields. Who remembers back when "computer speakers" were advertised as "magnetically shielded" when we were all using CRT monitors? Nowdays, nobody cares about "magnetic shielding" in speakers because LCD/plasma displays don't care.
Old 24th January 2013
  #20
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"...Monel metal and mu-metal are at opposite ends of the spectrum. Monel is completely non-magnetic. I believe that is why they use it in small-body ribbon microphones, so that it doesn't disturb the magnetic field that the ribbon operates within." Rcrowley

The capsules I'm using are made of 309l stainless steel; an alloy that is not magnetic. The steel mesh I have is also not magnetic. I'm confused by Lotus 7s suggestion that mumetal is a good choice for grill design if what Rcrowley is saying above is true. It seems that the ribbon capsule should be free of magnets accept for the magnetic field created by the magnets in the ribbon motor.
Old 24th January 2013 | Show parent
  #21
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Quote:
Originally Posted by trubadoor ➑️
"...Monel metal and mu-metal are at opposite ends of the spectrum. Monel is completely non-magnetic. I believe that is why they use it in small-body ribbon microphones, so that it doesn't disturb the magnetic field that the ribbon operates within." Rcrowley

The capsules I'm using are made of 309l stainless steel; an alloy that is not magnetic. The steel mesh I have is also not magnetic. I'm confused by Lotus 7s suggestion that mumetal is a good choice for grill design if what Rcrowley is saying above is true. It seems that the ribbon capsule should be free of magnets accept for the magnetic field created by the magnets in the ribbon motor.
SORRY, attribute my "mu-metal" comment to failing memory and not checking references. I "thought" that the Shorter and Harwood BBC paper mentioned that one of their inner shields was mu-metal. I checked the text I remembered, and they clearly state the inner screen was Monel, which, of course makes much more sense. (they do both start with "M").

The section I'm referring to is page 9. sec. 2.3.4.

No excuses (but it's been a while since I read that article).
Old 24th January 2013
  #22
Les
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I guess i'll comment. We do a lot of grilles.

First, I think a typical metal fabric of mumetal would have far too much reluctance to be much of a magnetic return path or magnetic shield. Far better just to use proper hum bucking ribbon configuration.

Metal fabrics provide electrostatic shielding, but it's much more of an issue with condenser microphones and the like.

Also, we often use grilles as an acoustic element to modify the sound. So less/more open is not always better. A classic example was our old Shure 300 series ribbons...the outer grille was only about 50% open and used as a wave plate resonator. Many others use this configuration. It evens out the off axis response change due to front back path length variation. A careful balance of
wave plate, diffraction from magnetic structure, and front/back path length can make very smooth off axis responses...a real attribute to ribbons and single diaphragm figure 8 condensers.

We use fine mesh material as an acoustic resistance element as well.

Our materials of choice are 304 stainless, a nonmagnetic austenitic alloy, and 260 brass electroless nickel/phosphorous plated.

We deep draw the material. 304 work hardens significantly making a durable structure but has limited drawing ability. For some shapes we use fully anealed 260 brass where 304 would have too much springback. The brass work hardens as well...just not as much as the 304.

We solder to 304 but I can't say it's fun or easy. Very aggressive fluxes are required.
Old 24th January 2013 | Show parent
  #23
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Quote:
Originally Posted by Les ➑️
Our materials of choice are 304 stainless, a nonmagnetic austenitic alloy, and 260 brass electroless nickel/phosphorous plated.

We deep draw the material. 304 work hardens significantly making a durable structure but has limited drawing ability. For some shapes we use fully anealed 260 brass where 304 would have too much springback. The brass work hardens as well...just not as much as the 304.

We solder to 304 but I can't say it's fun or easy. Very aggressive fluxes are required.
The mic capsules we're using are made of 304 stainless. I'm happy to learn that it is possible to solder with this alloy as I recently purchased some .0065 stainless mesh.

Can you reference the kind of flux you use to solder the 304?
Old 24th January 2013
  #24
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Les,

Great to have some input from someone who actually has experience building mics and who has mic machining expertise. I know of your previous experience at Shure Bros.

Are you currently producing any ribbon models?
Old 25th January 2013
  #25
Les
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trubadoor, we use harris stabrite 95/5 Sn/Ag and staclean flux. We have to be lead free for ROHS.

Again, we do solder 304SS but I can hardly recommend it!

Lotus We do have a new ribbon mic coming out at Summer NAMM. We may have a few production models at AES Nashville in may too. We're currently studio testing it.

I don't want to advertise here but i'll pm you some prelim info if you want.
I'ts not the usual ribbon mic.

I'm also a mic design consultant for Electrovoice, but they won't let me talk about what i'm doing there!
Old 25th January 2013
  #26
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Here are the capsules for the mics I'm building. Built from 304 Steel.
Old 4th February 2013 | Show parent
  #27
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Priceless Information

Quote:
Originally Posted by Lotus 7 ➑️
As has been alluded to on this thread by rcrowley, a major function of the mesh is to provide some protection to the ribbon element. That's obviously an important function. I just wanted to mention that from the very limited reading on the subject I've been able to accumulate over the years, the mesh does a lot more (at least in well-designed mics that sound good).

The people who really know what works in a particular design have gained that knowledge through observation or experimentation (probably lot's of experimentation), and for obvious reasons are reluctant to share that knowledge. However, there are articles and papers out there about what works (in specific designs), and reading them will at least get one pointed in the right direction.

I suspect (pure speculation!) that it may take some experimentation to get the optimum configuration for your particular mic, even though it's starting with a "Royer-like" configuration. The material that works on a R-121 is used in conjunction with the restricted ribbon exposure of the "slotted" Royer outer case. If you don't have a outer case wth the horizontal "slots" of the Royer, then it's likely that a different metal mesh plus cloth liner will be necessary. The difference between what's "optimum" and what's "acceptable" may, or may not, be all that important to you.

I believe that Wes Dooley will sell the open silk cloth that he uses to re-line RCA mics (for the inner layer of the perforated metal grill) and there are hundreds of manufacturers of mesh "wire-cloth" in every possible wire diameter, mesh pitch and metal. It's a daunting task to pick a size to start.

FYI: There is a manufacturer you may want to check out who makes mesh wire cloth in some interesting alloys including stainless steel, nickel and Monel-400 (possibly the best for a small-diameter ribbon mic). Take a look at Belleville Wire Cloth for their "filter wire cloth" and "woven wire cloth" selections. If you do choose to use Monel, remember that it generally should not be electrically welded, but if it is, it should be annealed before final use.

I think it's great that you've decided to make your own mic design. That's how Bob Speiden started on the path that led to the Royer "revolution" in ribbon mic popularity.

Have fun and good luck!


Just wanted to throw you a huge thank you shout out for this outstanding resource that you found in Belleville Wire Cloth - since seeing your post, they have shipped me next day 4 mesh size examples and I have placed my order for nickel wire mesh in the appropriate size. Service by phone much better than internet, but they were able to get me exactly what I needed fast.

Really appreciate when people throw out names of companies that act as a great resource on the forums. A lot of times searching in google does not find you the best company to deal with - Thanks again!
Old 4th February 2013
  #28
Lives for gear
 
Lotus 7's Avatar
Great. Glad they helped. I've known of them for years as suppliers of mesh used for race-car air intake, and cooling duct grills ("gravel strainers"). They do have a wide selection of the stuff and it obviously has many possible applications.
Old 18th May 2014
  #29
Gear Maniac
 
🎧 10 years
I'm posting over a year later, but I did finish my build project last summer!

Here are a few picture of the microphones built from .0065 304 stainless mesh, handmade stainless 304 capsules, DIYAK RE-154 ribbon motors, neutrik connectors, and a matched pair of RT36 Samar transformers.

So far I've used them to record drum sets, accordion, acoustic/electric guitars, violins, and grand piano. These sound beautiful together in blumlein or as a spaced pair. Great River pres sound awesome with these guys.

The mesh is pressed in place between the capsule grill and the ribbon bracket; which is held in place by little screws.
Attached Thumbnails
Please Help: Mesh Size and Design for Royer 121 Style Ribbon Mics-1147761_10153181346430457_2059038649_o.jpg   Please Help: Mesh Size and Design for Royer 121 Style Ribbon Mics-1149231_10153181346590457_887277454_o.jpg   Please Help: Mesh Size and Design for Royer 121 Style Ribbon Mics-1116142_10153181346620457_293754682_o.jpg  
Old 19th May 2014
  #30
Lives for gear
 
Lotus 7's Avatar
Hi trubadoor,

Fantastic to see that you followed through and not only completed the mics, but are happy with their sound.

It had to be a thrill to hear the first signals coming from the first completed mic.

Thanks very much for the follow-up. So often on this forum there are a number of members who contribute a considerable amount of time to try to provide helpful information, and then never know if it actually was of any use.

On this thread, there was a considerable amount of well intended, constructive comments by everyone who chimed -in.

I know I learned a lot, and hope it was helpful to you.
Way to go!!
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