Troubles to build mic body

As you know I tried to build my mic (here the topic http://www.groupdiy.com/index.php?topic=46132.msg578581#msg578581)
You have positively influenced me and I tried.

Now the issue is to find a body for the mic.
Well, it should be  the classical tube and I have 2 ways to cheap on it:

- Do it my self
- Try to find a body of another mic.

The first item, is possible. But I have not the necessary tools to make a beautiful job.
To buy the necessary material, it will cost much more than the microphone itself.

The second solution is: to buy a very cheap microphone and dismounting it so that I can use its pipe to put on it my electronics etc.

I've seen prices etc and anyhow it costs also quite a lot, to be only the body what I need.

I found a  very cheap dynamic mic by the brand Gatt. It is the classical mic which basket is ball.
The price is 15€ http://www.stb-music.com/index.php?id=9013 (the website tells 11 euro but in the shop I pay it 15)
The overhead mic of Gatt costs about 30 euro.

What do you think about the idea to buy it and to put inside my electronic with my capsule ? (TSB 165A)
Is the shape of the basket influencing negatively the microphone's response ?

What you'll choose at my place, please?
I really would like to read some your opinion about because it will be very helpful

http://www.groupdiy.com/index.php?topic=42181.0

There are a few sample pages at http://www.homemademicrophones.com/ that might be useful.

You might like to look at how I made mic bodies for my projects, using the tools and materials I have available. You will find quite a few pics on the micbuilders site Photos section, under Zephyrmic LDC Mic Build. If you have any questions about how i did it, please don't hesitate to ask. I am very happy to share what I can.

Kindest regards,

zephyrmic

zephyrmic said:

You might like to look at how I made mic bodies for my projects, using the tools and materials I have available. You will find quite a few pics on the micbuilders site Photos section, under Zephyrmic LDC Mic Build. If you have any questions about how i did it, please don't hesitate to ask. I am very happy to share what I can.

Kindest regards,

zephyrmic

Click to expand...

I'm looking it You did beautiful works. I say: wonderful ones!
i will look each photo I will note down the questions and I will ask to you

I start already I hope I don't bother you

i'm building a Small Diaphragm Mic (I will use a TSB165A ).
The circuit is ready and now it's workling very fine.

Now, the diameter of the XLR is 16mm the capsule 16.5 and I need some suggestion/idea

SITUATION:

In commerce I found (on mty town there is only "Brico Center"  :-\ ) pipes in Al  external diameter: 20mm max.
The internal diameter is too little due the electronic.

If I go to look copper pipes, there is the 22mm. It costs 25 euro! (the pipe is 2mt long and there is no way to have little sections of it)
The price is extremely high considering the rest of the components and the mic itself.
Moreover is copper, it means: it will be black or green anyway very bad to look, in a while.

What i found, is a neck of a cleaning tool that's in Al and it's 22 mm diameter. Price: 2.5 euro I found it today.
It's coated by PVC dark gray, and it's quite elegant.


ISSUES

How to reduce the 22mm to 17 mm in order to adapt the diameter of the XLR?
How to create a "cap" for the capsule side?

I was looking for in hydraulic division but it was not successful (I brought with me my electronics in order to see if it fits or not etc)

I really need some idea. Perhaps I don't consider evident things "under my eyes" (it's a manner to say) but I would like to complete my mike.
The idea is to build also a 2nd one in order to get the Stereo Pair for my use.

I'm really excited to the idea, but a little discouraged due the few material I have and few tools I have to elaborate things.

I need your help

If you look in my Photos section, you will note that I used a couple of cheap electret mic bodies I had that were too good to throw away. I was able to accommodate the TSB165A capsule in the head section, where there is also a small perfboard with the J305 FET and associated components directly behind the capsule, so that the gate lead is soldered directly to the tab on the backplate of the capsule, to reduce stray capacitance. The rest of the circuitry I was able to mount on perfboard and place it in the area that was once occupied by the AA battery in the original mic. So you can make the circuit board quite small, if need be.
I have found the scrap metal yard a good source of tubing, or, for what you need, even an aluminium outdoor chair that has outlived its usefulness as a chair.
For you, don't forget that you need some slots or openings behind the capsule in your body, to retain the cardioid characteristic of the capsule. Make sure there are sufficient openings so as not to restrict the passage of sound into the back of the capsule. To mount the capsule, you could either use a foam or silicone ring made to the right size, or even a suitable washer of aluminium, glued in place with some contact glue. For the mesh on the end, that could be formed out of a scrap of expanded aluminium or even use a mesh pencil container, as you see in my photos. I also suggest that you include some synthetic fibre, such as in cushions, speaker enclosure lining, or similar, to dampen any resonances in the body, once you  install the circuit board. A;sp a layer of indulation tape around the circuit board is good insurance against any shorting to the body.
As to the LR connector, you make a ring to fit into the body from aluminium flat of suitable thickness to take up the difference between the XLR and the body. If you work it right, you could also use that as the mount for your circuit board, so that the whole assembly is kept in place with a couple of screws through the body and into the aluminium ring.
Hope that gives you something to go on. Any further advice I am happy to supply.
Kindest regards,
zephyrmic

I will check what it's possible to do with the material I can buy.
I will check in other shops in the next days.

I will be back to you at soon i have some material
I thank you very much for the suggestions related the cuts back the capsule. I didn't know their meaning. Could I eventually make holes instead of cuts?
It will be much easier for me, with the tools I have.

BTW: I finally ordered the capsules TSB165A. I hope they will ship them soon

zephyrmic said:

As to the LR connector, you make a ring to fit into the body from aluminium flat of suitable thickness to take up the difference between the XLR and the body.

Click to expand...

The issue is that there is not any foil or list with variuos thikness. It looks alike strange but ihere in Belgium there is poverty of material choices. The "Europe's Downtown"  :-\

I give you an example: about the Net: I found the required one. They sell only 1mt x1mt (1 square meter) and not less. Price: 27 euro
Similar issues I have with little pieces of material to adapt thikness. I will try to buy little couplings and cut them on measure

Good info on how to build a ribbon mic from artur fisher:

http://www.diyaudiocomponents.com/ribboninfo.php?sub=index

Could I eventually make holes instead of cuts?
It will be much easier for me, with the tools I have.

Yes, holes will be fine, but make sure that you have enough so as not to impede sound getting to the back of the capsule. Also loosely put some fibre in behind the capsule where the holes are to cut down on any body resonances.

zephyrmic said:

As to the LR connector, you make a ring to fit into the body from aluminium flat of suitable thickness to take up the difference between the XLR and the body.

Click to expand...

The issue is that there is not any foil or list with various thikness. It looks alike strange but ihere in Belgium there is poverty of material choices. The "Europe's Downtown"  :-\

What you need here is not foil, but solid aluminium flat bar. I know that in the local hardware store they sell stuff like 10mm x 3mm thick relatively cheaply. Again, you could use other metal that you can get your hands on, such as copper, soft brass, etc. and form that into a ring to take the XLR connector. For example, see what I did on my LDC condenser mics, where I used a mount for a shower curtain rail, and used some copper pipe scrap to match the diameter of the socket with the shower curtain base. You could even use some plastic material to house the XLR in the tube, so long as you made sure that the body of the mic was properly grounded.

By the way, I meant to mention that the aluminium chair I was referring to is the outdoor folding type. Often they are seen where the material on the seat and back perishes, and the aluminium frame is put out in the rubbish. I was thinking that sometimes brooms have aluminium handles, and you may be able to find one of those that has outlived its usefulness. Hope those tips are helpful to you.

Kindest regards,

zephyrmic

hello Zephyrmic

I thank you very much for your suggestions, I didn't replied yet, because I'm waiting for the capsules.
At soon they are delivered I will go ahead with the project.
The pipe of the cleaning tool is the only one material and type available with the correct price and measures.

Here in attachment how I will go further on.

the first image shows the internal part, following your suggestion, to close the pipe avoiding the resonances.
I will put a thick felt with ( holes. A big one to make pass the wires through, and 4 little ones. Two of them fix the felt to the PCB by 2 rigid copper wires, and the other 2 serve to support mechanically the capsule.
This should minimize also little "bumps".

The picture in the middle shows the mic inside the pipe with the donut that adapt the pipe to the XLR.
I will let you know what solution I will find for it. At the moment I'm in the darkness, with the available material, but I will study a solution

The third picture shows the ""finished"" microphone. There is the net that protect the capsule and the holes as I asked to you, instead of cuts, just behind the capsule.

I hope it's a good project

I have done some microphone experiments myself. Maybe you are interested to see how I did it. I am very happy with the result.

RuudNL said:

I have done some microphone experiments myself. Maybe you are interested to see how I did it. I am very happy with the result.

Click to expand...

Ik heb het gezien en ik denk dat het super is!
"the mesh from the Kitchen equipment" GREAT! here the idea Like this tool


The way in which you mounted the capsule is exactly what I thought to do with my mic.
I'm really happy it works.

About the Pipe, how you made so beautiful side-cuts please?

I really would like to hear a .mp3 with them

thank you RuudNL

About the Pipe, how you made so beautiful side-cuts please?

Click to expand...

It was just a matter of drilling holes close together.
After that you need a file (and a lot of patience!) to get the right shape...

RuudNL's way of mounting the capsule as per his photos is a good way of doing it. Rather than a felt ring, I would suggest  that some synthetic fibre between the back of the capsule and the PCB would be best, in between and around the solid wires that mount the capsule. The cutouts in the mic body are not too hard to do, and you just need patience to get them right. Good way to go, although holes of sufficient size and number will do the job as well. To look good, they need to be drilled accurately to get even spacing. For the mesh, we can get quite cheaply here in the Chinese goods stores a flat mesh splatter guard that sits over a frypan. They are a good source of mesh.

Good luck with the mic bodies. Let us know how you get on.

Kindest regards,

zephyrmic

zephyrmic said:

RuudNL's way of mounting the capsule as per his photos is a good way of doing it. Rather than a felt ring, I would suggest  that some synthetic fibre between the back of the capsule and the PCB would be best, in between and around the solid wires that mount the capsule.

Click to expand...

I thought that perhaps I can use the type of things  men stick underneath the chairs to avoid noise due friction against pavements. They cost almost nothing

zephyrmic said:

Good luck with the mic bodies. Let us know how you get on.

Kindest regards,

zephyrmic

Click to expand...

be sure, I'm really excited to the idea to finish the first and to try it.
I will post some picture here as well

IMHO it is very important if you want to create an unidirectional microphone, to make the openings on the rear side of the capsule big enough. Smaller openings will produce a lot of coloration, especially for sounds coming from the rear.



I wonder how manufacturers produce microphones like this with very small openings behind the capsule, and still produce an excellent sound quality. I did experiments with shapes like this, with very disappointing results. Also I found it is very important to add some sound absorbing material behind the capsule. Omitting to do so will result in audible resonances from the air in the metal tubing.

RuudNL said:

Also I found it is very important to add some sound absorbing material behind the capsule. Omitting to do so will result in audible resonances from the air in the metal tubing.

Click to expand...

yes I think the proportions on my design, are the ones I will make. I mean: big holes (instead of cuts) directly behind the capsule.

About the absorbtion material and its position: do you mean: to put it to close the pipe, I mean directly after the holes/cuts ? Or also immediately behind the capsule, before the holes/cuts in the pipe?

About the absorbtion material and its position...

Click to expand...

I meant: inside the pipe, behind the rear openings. Just to damp the resonances of the air inside the pipe itself.

Hi RuudNL

I have received (finally) the 2 capsules (I have to inquiry the invoiced costs because not correct at all 2.5USD total cost + shipping against 7.5 euro each one payed out + shipping).

I connected the capsule to my circuit and: I was disappointed. It sounds very "harsh" ... too brilliant without Basses ... very very metallic ... both capsules the same issue.

What's wrong with the circuit ? The old omnidirectional capsule of 1euro (100Hz - 10kHz bandwidth) was working much better