Ribbon Mic Material

[gyraf]

So, anecdotical evidence?

 

[Biula]

The evidence come from comparisons and experiments: "the math first and the ears next".

 

[abbey road d enfer]

The evidence come from comparisons and experiments: "the math first and the ears next".

Please, show us the maths. Some of us are pretty good at it.

 

[Biula]

Exactly, about what part of a 1924 ,well developed and evoluted invention (on which is possible to find tons of patents, studies, documents, diagrams, schematics, etc.) do you lack maths?

Please, show us the maths. Some of us are pretty good at it.

 

[gyraf]

Sorry about the harshness,

it's just that a post like

"For a 20-18.000 Hz capable motor you need a 1 - 1.5 microns aluminium..."

..is quite close to actual misinformation, unless you can back it up with solids. The interwebs are full of such half-a**ed claims about all things audio hardware, the intention of which is most often to discourage experimentation, to smokescreen real information and thereby to corner a market

which is almost the opposite of what we want here

btw BBC has that great monograph on ribbon mics, iirc nowhere calling for 1u ribbons

/Jakob E.

 

[Biula]

Sorry about the harshness,

it's just that a post like



..is quite close to actual misinformation, unless you can back it up with solids. The interwebs are full of such half-a**ed claims about all things audio hardware, the intention of which is most often to discourage experimentation, to smokescreen real information and thereby to corner a market

which is almost the opposite of what we want here

btw BBC has that great monograph on ribbon mics, iirc nowhere calling for 1u ribbons

/Jakob E.

Dont get me wrong, you can indeed esperiment with a 6 micron thick alu foil (is a good choice if you are in trouble with a nightmare- difficult-to-handle 0.6 micron one, say you are at your first attempt in this field...), but is not fair to sell the idea of a perfect fine, workable 20-20000Hz ribbon mike built by a newby with such a material.

 

[a soBer Newt]

The frequency response is a function of the front to back path distance. BBC Engineering Training Manual-Microphones (Robertson) PDF page 125 Here is a link to the BBC Monograph as well.

 

[Biula]

Dont get me wrong, you can indeed esperiment with a 6 micron thick alu foil (is a good choice if you are in trouble with a nightmare- difficult-to-handle 0.6 micron one, say you are at you first attempt in this field...), but is not fair to sell the idea of a perfect fine, workable 20-20000Hz ribbon mike built by a newby with such a material.

Speaking about BBC, the 0.6 micron foil I use is the very same Coles uses in their 4038 model (built on a BBC specific...).

 

[abbey road d enfer]

Exactly, about what part of a 1924 ,well developed and evoluted invention (on which is possible to find tons of patents, studies, documents, diagrams, schematics, etc.) do you lack maths?

I've read my share of articles on ribbon mics, but I have never seen any mathematical relationship between ribbon thickness and HF response.
There are claims that thinner ribbons have potentially better transient response, but not math.
OTOH, the relationship between front-to-back distance and HF response is well documented.

 

[Biula]

I've read my share of articles on ribbon mics, but I have never seen any mathematical relationship between ribbon thickness and HF response.
There are claims that thinner ribbons have potentially better transient response, but not math.
OTOH, the relationship between front-to-back distance and HF response is well documented.

Obviously front-to-back distance is the main parameter in top end limit... but then came the inertia of the ribbon: double the thickness and you double the mass, hence the inertia, hence the top end rollout point moves... you can theoretically have your top end, but you'll never reach it. That's an experimental fact.

 

[JohnRoberts]

It is logical that mass (inertia) could affect transient and/or HF response.

How about some data?

JR

 

[Biula]

Well, is something I've done several years ago: have three different thickness ribbons, mount them on a ribbon mike (in that particular case was a new project of mine, somewhat inspired by the Coles 4038) and run a series of test in the anechoic chamber of the lab. Then, compare the curves AND use your ear evaluation on blind test... surely I can not reiterate all of this just to convince you, but if I manage to find these old data in some of my old folders, then I'll send you.

 

[Biula]

The frequency response is a function of the front to back path distance. BBC Engineering Training Manual-Microphones (Robertson) PDF page 125 Here is a link to the BBC Monograph as well.

2,5×10elev−5 inches is indeed 0,63 microns... This is math. And this is BBC.

 

[Whoops]

like other members here I never seen any documentation claiming that a thinner ribbon would affect (increase) High Frequency response.

It would be great if you showed documentation stating and explaining that

Thanks

 

[Biula]

Just to be clear: my point is NOT that a thinner ribbon would increase high-frequency response, but that (given a theoretical, physically optimized top-end roll-off determined by front-to-rear path length) you must choose a ribbon THIN ENOUGH not to compromise either efficiency and top end due to its mass. This is written in all historical documentation, and the BBC Engineering Training Manual says exactly this, as you can see. This kind of application is a balance of compromise (efficiency, resonance modes of the ribbon, mass, source resistivity, magnets-to-ribbon gap dimension, and ribbon strength all must be considered together): you can only proceed experimentally, take your data and use your ears... or trust who have done it in the past. This is for top performance models: if you are a basic DIY, if you don't have testing facilities or if you do not want to bother with this nightmarish thin aluminium, go for a 6 - 10 microns foil, no problem for me.

 

[Biula]

Another BBC statement, this time from BBC Monograph about resonance modes of ribbons and damping relative to thickness. As you can see, they claim that high-order resonances "kinks" of thick ribbons response can be heard clearly, and this is mostly true as you reach the topmost part of the audio spectrum... in another part of this same document, you can read how also corrugation has a pivotal role in controlling hi-end behaviour, especially on ribbons with high mechanical damping (namely, thin ribbons). Once again, experimental fact....

 

[Biula]

btw BBC has that great monograph on ribbon mics, iirc nowhere calling for 1u ribbons

/Jakob E.

You are right, they do not call for a 1 micron ribbon, they call for 0,6...

 

[gyraf]

.."has been used", still has nothing to do with the initial claim of frequency response

What i read from the above, is that you're prone to getting (resonance or breakup) sound from the ribbon material itself, if it gets into dimensions where it's flexing byproducts are in the audible range. There are ways around this, e.g. beyer's concave'd large flat part of the ribbon..

/Jakob E.

 

[Biula]

The point is that YOU are talking to me about BBC: they are indeed calling 0,6 for their good reasons.
Beyer, a later player in the ribbon mike industry, has a different, modern approach; but this is far from a DIY builder capability, so I'll stay with BBC historical method. Not to be rude, but if you quote BBC Monograph, quote it correctly...

 

[Biula]

My "For a 20-18.000 Hz capable motor you need a 1 - 1.5 microns aluminium..." statement remains true:
point me to a DIY project capable of 20-18000 Hz (+-3dB, as standard) with a 6-10 micron ribbon, if you can...

BTW, I've nothing to sell and nothing to earn in all this: my only intention here is to advise some newby on which way is useful to follow to have great results, staying on the shoulders of the great innovators from the past. But remembering my 40-years journey in this field, I often see underestimation of difficulties and false shortcuts to problems. And this is not good.