Mechanical improvement of mic build.

[granger.frederic]

KrIVIUM,
the idea is really interesting...
how do you manage the HiZ wires...pins on the upper plate ?
do you think that with this kind of design, the absorption could be efficient on the entire frequency audible range ?
we could even get rid of the rubber suspension shaft ...and maybe avoid a lot of the capsule mount/wires resonances...
we could even do that for the rest of the electronics...

 

[KrIVIUM2323]

I have absolutely no idea how to manage the teflon pin!  But yes wires to teflon pin. Thiw should decouple from body structural vibrations. ;D

But this is a raw idea... open to refinement if the global idea make sense. And multiple brains are more efficient than one.

I have no idea neither if it work for the whole frequency range, i see this more like a step in a multiple step approach.

Getting rid of the rubber mount is not wise from my point of view as it serve to protect the capsule if mic does fall from the mic suspension.

But yes overall it could deal with structural vibration of body, won t protect from airborn vibration though.

 

[granger.frederic]

reducing the possible "movements/vibrations/resonances" of the capsule seems important to me...
that's why i don't like the rubber design...
do you think that it could better or more efficient to transmit the vibrations absorbed by the capsule, into the viscoelastic layer ?
we could mount the capsule inside a peripheral ring (with a screw clamping...), separated with (or without) a thin layer of viscoelastic material also...
this should avoid screws breaking in case of shock...
roughly:

 

[Banzai]

insulator thickness is important...
maybe it's the right wire...but...
how do you measure that "you hear nothing" ?  did you make some tests ?

electrical insulation of PVC is between 10°14 and 10°16 ohms/cm, it seems enough...
i'm still not convinced that a thinner and harder material is the most suitable for capsule connection...
other opinions?
someone?

Hearing tests, done exclusively with ears

Put on headphones, and directly hit wires, capacitors, whatever, in a switched on microphone. If you don't hear noise when you tap, the item isn't causing any microphonics. If you tap and it rings, you have a problem. You can go through a whole mic like this, and solve every issue one by one. It's lowtech, but works.

Not stating a harder and thinner material is more suitable either. Just responding to your question of how a harder material like mppe could be less microphonic than PVC: when construction of the wires isn't identical, you can't compare material specs.

And it's just a personal choice, I prefer ecowire over PVC. I prefer PVC over PTFE too (open up a vintage mic, and it won't have any fancy wire in it either).

 

[granger.frederic]

ears are a good measure instrument after all...

ideas on the innovative conter intuitive concept of "vibrations transmission" from the capsule to a "mechanical absorbing viscoelastic design" ?  or M.A.V.P      ;D

from the creator, KrIVIUM ?

we should talk about the mic shockmount as a lot of vibrations are coming from the floor, and see if we can quickly improve the usual design with few tips...

 

[MS Vienna]

The best way is to try out the options in question and judge the real world results. Even better - have it judged by various good sound engineers in their working environment (alpha & beta testing). Otherwise it is too easy to get lost in theory.

In many companies it´s not uncommon that the development engineers don´t have the greatest respect for the folks in manufacturing and vice versa. It´s smartass vs. working man and communication may not be ideal between them. Both have very valuable knowledge and experience in their field. In good companies that combination leads to great products. Sadly the way things are finally done in manufacturing isn´t always passed "up" to development so details remain undocumented and may get lost over time.

My personal opinion on the capsule wire question:
with the capsule holding assemblies used in many DIY-kits these wires are one of the least things to worry about. First the damping properties of the holder have to be a good match to the capsule in use. Then it´s fairly quick and easy to make a choice when trying different wires. Yet a less than ideal wire would not spoil the sound of an otherwise fantastic microphone.

Just to get the relation:
the weight of LDC capsules ranges usually between 25g (old CK12)  and 50g (K67).
I just weighed a soft PVC insulated wire with 0,75mm diameter and 50mm length: it´s 0,062grams.
Fortunately the laws of impulse transmission do continue to apply here...

Just look at mics with simple mechanical construction that sound very good e.g.  U47 and C12.
I´d try to get that kind of sound quality in a copy-mic first and afterwards think about fancy further improvements. Just my approach.
But new innovative solutions are always interesting.

 

[granger.frederic]

i don't find that c12 and u47 are very simple in term of mechanical construction.
take a look at the capsule holder in the c12 for example...
the best recreations are Flea bodies and the prices are quite high. (but it worth every penny...)
the subject is how to mechanically improve our DIY builds, inspired by those mics for sure...

could you explain the concept of impulse transmission in this case...
why are you comparing the weighs ?

 

[MS Vienna]

could you explain the concept of impulse transmission in this case...
why are you comparing the weighs ?

A lightweight moving object cannot stimulate equal movent in a heavier object when it hits it.
Example: Tie a rope to a heavy rock. The oscillation of the rope will be almost completely reflected when it hits the rock instead of being transmitted to the rock.
Or: a heavy stonewall reflects soundwaves much better than a cardboard wall (which will transmit a considerable amout of it). Ect.

On the other hand tops of acoustic guitars should be as light as possible in order to receive best possible stimulation through string vibration - thats why light and stiff woods like Adirondack spruce are in high demand for this application. Yet heavier sting gauge ( - heavier rope- ) shifts the balance in favour of transmission too. A  .013 string set sounds lounder than a .010 set.

You are right about the C12 capsule mount. Note the very long wires that go all the way up and down to the capsule again. It was a no-expense-spared attempt to isolate the fairly lightweight capsule the best as possible. But the capsule mount in M250/251 is still quite decent as well. I have tried the Aputis ELAM-style mount – it´s a very nice and affordable solution.

 

[Banzai]

why are you comparing the weighs ?

The rubber shore hardness needs to be chosen to suit the capsule weight. The other problem is too soft, and the capsule will hit the headbasket when there's a shock or when you move the mic. Too hard, it keeps the capsule from hitting, but it won't damp any vibrations.

 

[maq3396]

Interesting discussion...

Can someone please post pictures of capsule mounts that they feel offer superior or excellent isolation?

Or...if someone had an idea for a new design that would be welcome as well.

Prototypes are easy to produce.

Thanks
Mac

 

[granger.frederic]

A lightweight moving object cannot stimulate equal movent in a heavier object when it hits it.
Example: Tie a rope to a heavy rock. The oscillation of the rope will be almost completely reflected when it hits the rock instead of being transmitted to the rock.
Or: a heavy stonewall reflects soundwaves much better than a cardboard wall (which will transmit a considerable amout of it). Ect.

On the other hand tops of acoustic guitars should be as light as possible in order to receive best possible stimulation through string vibration - thats why light and stiff woods like Adirondack spruce are in high demand for this application. Yet heavier sting gauge ( - heavier rope- ) shifts the balance in favour of transmission too. A  .013 string set sounds lounder than a .010 set.

for me, the point is not that the wires could transmit vibrations to the capsule but the opposite.
thus from the capsule (self generated and transmitted from the body) to the Hiz wires, and also from the body to the HiZ wires and electronics directly.
also the floor to the schockmount thus to the body...etc...etc...
as long as there are mobile elements , resonances could happen.
That's why i think about resilience of the various elements, and how (and from where) the vibrations are transmitted.
there roughly two concepts for the rubber mount of the capsule:
-soft (u47 like) and it will ABSORB but can allow resonances also...
-hard and it transmit the vibration elsewhere...
i think the quality of the mechanical design is mostly related how the external and internal shockmounts (capsule and electronics) are designed, and this is the topic purpose.

PS: remember that the classic mics were often mounted via swivel mounts...

Once again we should include in the thinking  the shockmount and the cable.
soft elastic loops are great for decoupling vibration from the floor, but this not solve (perhaps it worsened the problem...) the vibrations coming from the cable, especially if the mic cable is twisted on the mic stand (vibration are transmitted from the floor/stand via the cable...), and also like every tensioned material they have a resonance frequency...

on this matter, we should prefer heavy stands with solid tubes and heavy bases, instead of hollow tubes ...
we could even include in the debate, the mic stand base decoupling ...
but i'm probably off topic...

it's a global thinking...there's a lot to say...
it is very interesting and instructive for me...

 

[MS Vienna]

It´s worth to spend some time in experimenting with body materials. I entered my first observation purely by incidence. I made a new body tube for an experimental microphone  because what the engraving of the original body said was no longer inside.
Original tube was a heavy 50x2mm brass tube. I replaced it with 49x1mm aluminium - simply because I had the material handy.
Out of curiosity I recorded an AB comparison with the different housings and could not believe my ears first. There was a quite notable difference. Contrary to my intuition I preferred the light alu tube. Note that both tubes of course were damped inside and didn´t ring.

That made me think a bit and I became aware that most of the great sounding microphones are fairly lightweight compared to their physical size and feel a bit cheap in the hand. The U47 with it´s light alu housing, the M251, the C24. Also the U87 - very light and delicate housing tube. Can be dented almost with an evil gaze.
From a purely theoretical standpoint it does not make sense. Also from a marketing standpoint. Still it can work very well.

Isolation of micstands is a very good point. For many years I use my selfmade IsoPads - see attachment. They are made of soft foam, a fairly stiff foam and cardboard sandwiched in between.  Very effective and cost nothing.

 

[KrIVIUM2323]

Fred,

reducing the possible "movements/vibrations/resonances" of the capsule seems important to me...
that's why i don't like the rubber design...
do you think that it could better or more efficient to transmit the vibrations absorbed by the capsule, into the viscoelastic layer ?

i agree, but as i stated before i don't see that from a practical point of view this is wise: if the mic fall from mic shockmount the rubber stand does flex and allow to dissipate a part of the energy.

The flex can be huge, and the capsule may hit the grid from headbasket as i already seen (broken sadlle mount in u87ai, but astonishingly no marks on the headbasket or other parts of the body!).

This is one of the reason you see a white plastic 'cap' over the capsule, it serve to transmit the shock energy to the backplate and not to diaphragm or the fixing ring and help protect them.

But yeah, if you want optimal (ideal?) sound captation i do think you need an isostatic condition.

I don't understand what you mean by 'transmit vibration... into viscoelastic layer": the dampening don't have a direction, it works bidirectionnal.

As i see it, the vibrations you are worried about are airborn transmitted (produced by the spl of the sound source), and i don't see how you could deal with that without impacting soundwave captations of capsule.

The CLD idea is more to help isolate the capsule from structural born vibrations, so solid transmitted through the body parts.

As pointed this could be from the ground/mic stand/ cable (solid vibration transmission) but from airborn source too ( mic body parts resonnance from exposure to high SPL source).

I do see your point about the capsule isostatic condition but for the topic's subject (try to improve stock chinese mic) and for the moment i would prefer to stay with 'typical' capsule mount system as it may be used by most.

From an ideal theorical point i do think you may be right. 

MS Vienna:

The best way is to try out the options in question and judge the real world results. Even better - have it judged by various good sound engineers in their working environment (alpha & beta testing). Otherwise it is too easy to get lost in theory.

100% agree.
 

Just look at mics with simple mechanical construction that sound very good e.g.  U47 and C12.

I do agree with Fred, those are no so simple mechanical construction. I find the chinese mic to be much more simpler in their structural point. This may or may not be easy to improve them and as you stated, only real world implementation will tell 'the truth' (and if possible objective observation of outcome).

Thank you for explanation about " the concept of impulse transmission". Totally make sense.

Banzai,

directly hit wires, capacitors, whatever, in a switched on microphone. If you don't hear noise when you tap, the item isn't causing any microphonics. If you tap and it rings, you have a problem. You can go through a whole mic like this, and solve every issue one by one. It's lowtech, but works.

that totally make sense too (as your comments about whole structure versus material with wire. I must admit i like lowtech solution... probably because i have always complicated answers and idea...

The other problem is too soft, and the capsule will hit the headbasket when there's a shock or when you move the mic. Too hard, it keeps the capsule from hitting, but it won't damp any vibrations.

I'll add too that that if too soft or too hard there is not ideal damping of vibrations: most (if not all) 'suspended' damping system are tuned. They do have an efficiency range which is dependent from mass and shore hardness.

Maq3396,

Can someone please post pictures of capsule mounts that they feel offer superior or excellent isolation?

This is not as easy as it seems. It'll depend from your end goal. For example the Elam/c12 mount is not absorbent at all. In the case of the Elam it seems (to me at least) this have been taken into account in some of the electronic choices made too : read the Thread about Brauner VM1 mod: the grid resistor is low which mean filtering of low end content, T14/1 is low core transformer so low end is reduced and the mic to be vocal oriented... not many low end acoustical contents in that case, so insulation of capsule is not as critical from low end point of view. And if you add to that the multi chambered internal construction with much less resonnant material than metal... all this contribute to the choices made about capsule mount in my view.

Try the same type of capsule mount in a K47 equipped  u47 mic body could lead to very different result... Well, i suppose...

Do you have a 3d printer accessible? If yes this could be very interesting at a moment or an other.

 

[granger.frederic]

yes i have one
i can print in PVC or ABS and various other materials...
results are ok if i hand finish the items ...
i have also a milling machine (20 micrometers precision) that can machine various ceramics and composites materials.
i need some STL files as i'm not comfortable with CAD software



i'll try to explain me more clearly in English.(not easy)
in a ideal world, i would like a mic (body+shockmount+stand+cable) which transmit the less possible vibrations (not only low freqs, but also mid freqs), to the capsule and ALL the hiz elements, coming from the floor.

and in the same time, a system that can damp the vibrations through the air (mainly low freqs), absorbed by the capsule and the capsule wires.(supposing that the body is airtight otherwise it is a real resonant cavity...)

of course, the idea is to modify the chinese (or inexpensive) bodies ans shockmounts available for the DIY community.



Banzai, i'm prudent with the "tapping method" because for me, it doesn't represent necessarily well all the types of vibrations submitted to a mic...

KrIVIUM, in the c12 and elam capsule mounts, there are some felt dampers and in both case, a peculiar mechanical articulation that we could observe closely...

 

[KrIVIUM2323]

Fred, from the description of your gear i bet i know what is your dayjob now! ;D

My answer was to Maq3396, but if you have a 3d printer too... then it s nice!

I'll give a more in depth explanation tomorow, but i don t see how you can escape from the effect of airborn variation.

I was aware of the felt dampers, not from the mechanical articulation. Could you explain how it perform?

About the "tapping method", gently grind/shred the cable and you should have whole spectrum of possible mechanical issues.

 

[Banzai]

I'll add too that that if too soft or too hard there is not ideal damping of vibrations: most (if not all) 'suspended' damping system are tuned. They do have an efficiency range which is dependent from mass and shore hardness.

Absolutely! Even things as simple as shockmount elastics, they need to be adapted to the weight of the microphone to work properly.

 

[KrIVIUM2323]

i think the quality of the mechanical design is mostly related how the external and internal shockmounts (capsule and electronics) are designed, and this is the topic purpose.

I tend to agree but i'll add that the overall build and strategy used about the mechanical aspect could impact too.

Like every thing the whole mic body does have a resonance frequency and depending of choices made this can shift this frequency around the audible spectrum.

I may be wrong but for the sake of arguments i will give a view: intuitively i would say that u47 for example should have a resonant frequency more in the low end: it seems much more rigid/stiff in mechanical than an Elam mechanical for example.

The parameter to take into account in that is that the lower the resonant frequency the more 'vibrationnal' power it have and it may be more difficult to damp effectively.

Think about a church bell and some crotales. Both have same form factor (more or less) both have same material (more or less) both may have same sustain (it seems is probably longer with the bell because of volume). If you try to damp the bell you'll need much more damping force than the crotales...

You see the point?

This may explain the differences between the two body MSVienna experienced: as a whole the body structure as a whole may be more efficient in damping the remaining vibration (as both were damped) in the lightweight aluminium than in the brass body tube.

This lead me to think about the overall structure of mic body and where vibration are transmited and where and how we could try to improve that.

So i've done some other sketches.

Let's look at the airborn vibration transmission first:

In the picture linked the parts exposed directly to airborn vibration are, the capsule and holder (in green) the plate supporting them (lightgrey) the whole headbasket (including the mesh which i didn't draw- green), the body tube (red) and to a lesser extend but still the end bellcap (dark grey).

This is thru only if there is no unclosed holes in each parts described (headbasket plate(light grey) comes to mind first but this could be the case with other parts too, body tube or headbasket).

 

[KrIVIUM2323]

Then lets look at solid transmission inside the mechanical structure:

we have the 'outershell' with the headbasket, the body tube and the end bell which are probably in direct contact with each others.
Each do transmit vibration from one to the other.
Being of different material (but most likely metal) they may have different resonnant properties and different frequency too.

It may be noted than in some body type (u47) the bolts used to mount the electronics part to the rails may be in contact with the body tube (this is the cas in the differents iteration of u47 body i have at have). This is another point of solid transmission.

 

[KrIVIUM2323]

Then we have the headbasket where there is 2 potential point of contact, between the capsule holder and the plate and the headbasket and the plate.
For this last one it may depends... in some case the headbasket may attach to the bodytube and not to the plate.

 

[KrIVIUM2323]

Then we have the inner parts,
mostly the rail.

They do have multiple point of contact: to the bellcap, to the supporting plate, to the body tube (through the bolt or mounting hardware) and to the electronic plate (pcb, turretboard,...).