DIY microphone project

[Rullknufs]

Hello!

In the second and third year in Swedish high-school you spend 100 hours on a project you choose yourself. You can do research in a specific area, or construct something. I was planning on making a microphone.
I'm not sure yet what i would use the microphone to, but it would be really nice if it could be used for measuring speakers/room and also record voices/singing and maybe instruments like guitars. When i don't use it for recording stuff it would be cool having it connected to my computer for skype, ventrilo and such.

I haven't set up any budget yet, but i would like to keep it pretty cheap. I have acces to a metal/wood and electric workshop at school so tools should be available.

I have no experience of sound recording or microphones at all. Would be nice if you could help me show some different possible builds in difference price ranges. Remember this is mainly thought to be a school project, so try to keep it somewhat cheap. All the parts must be available in europe (preferably in Sweden).

[sreten]

Hi,

Very easy to make one, very difficult to make a decent one, and dirt cheap
to buy electret inserts that perform very well, that you simply cannot make.

Making a microphone (rig) would involve copious quantities of research.
You cannot build something well without understanding it. And there is
a lot to understand regarding various mike types, mic input types, mic
powering options, different mike technologies, mikes for different purposes,
mikes for different SPL's etc, the list goes on, e.g. stereo mikes, noise
cancelling mikes, lavalier mikes etc.

Any tranducer can be pressed into service as a mike, e.g. headphone
inserts, small speakers, and not many people know big speakers
can work quite well as farfield ambience mikes at a push, but
none of these compete with a mike designed for the job.

Its a huge subject to take on, you might want something simpler.

rgds, sreten.

[Rullknufs]

Well, i got 100 hours time in school to do this, and i am willing to spend some free time just to learn stuff. Since this is something that i'm a little interested in i think it wouldn't be a problem as long as i know what to read about.

If i have to narrow down the uses, i want it to record voices, intruments like guitar and violin and maybe be able to record speakers too.

I don't need a high-end microphone. Just something that works better than the regular computer headset microphone.

A little off-topic. But a future dream would be having my own recording studio, so i'd probably need to learn all of this sooner or later. And it would be quite cool to record some of my musically gifted friends with the microphone i want to build.

[ChrisA]

Originally Posted by Rullknufs

Hello!

In the second and third year in Swedish high-school you spend 100 hours on a project you choose yourself. You can do research in a specific area, or construct something. I was planning on making a microphone.

What do you mean by "construct"? Some people claim to be "building" a PC when they buy a mainboard and disk drive then place both into a chassis. Takes about 15 minutes. One could build a microphone like that and there are several web sites that tell you how in detail. Here is one:
http://sound.westhost.com/project93.htm

The more interesting interpretation of "construct" means to make the tiny mechanical parts in the mic capsule. I can't imagine doing the required engineering and machining in only 100 hours. So I think this project is either going to be simple so hard that it could years while you studied to relevant engineering and learned how to use specialized equipment. A third option is a "science fair" type project. Not a practical mic but a bread board device that shows how one works.

I don't need a high-end microphone. Just something that works better than the regular computer headset microphone.

This is not a realistic goal unless you decide to "build" the microphone by buying comerical microphone capsule.

I'd say the same thing if your project where to build a clock. Like the mic project there is not much middle ground. Your either buy a clock mechanism and put it in a case or you machine gears from brass. The project would be either 10X to easy to 10X to hard.

If you have an interest in audio a small amplifier is a reasonable project where you can adjust the scope of the project to match the time available. Or maybe an AM radio.

[sreten]

Originally Posted by Rullknufs

Well, i got 100 hours time in school to do this, and i am willing to spend some
free time just to learn stuff. Since this is something that i'm a little interested
in i think it wouldn't be a problem as long as i know what to read about.

Hi,

Wouldn't life be great if you knew what to read and what to ignore.

The technicalities of microphones are way beyond the scope of any
school subject I've ever seen and my understanding comes from years
of studying and understanding all the related apposite technologies.

100 hours is nothing if you don't know where to look, it seems you don't.
I have no idea what parts of the theory required you simply don't know.

The simple fact given what you are interested in, if you knew the facts,
you would simply buy microphones to suit, that is the way it works.

All transducers are complicated, and building microphones very difficult.
Any sensible approach is really the electronics for a quality capsule.

I's suggest building a pair of speakers, the other end of the chain.
Just as complicated in reality, but far easier to simplify the theory.
IMO a simpler/better stepping stone towards understanding issues.

In the end you just have transducer theory, for any type.

rgds, sreten.

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[Rullknufs]

Well. To get a high grade for this project you need to do good paperwork. Write a good report. So it doesn't really matter if the build is very simple. I know people who have made bbq grills and such. And then there's people who don't create anything at all, just write a report about something they've done some research about.

So if it's just assembly a microphone, that would be well enough if i just do the paperwork needed

[Michael Koster]

You won't find any useful answers here. No one on this board is very familiar with microphone design and construction.

You can construct a microphone at some level. Sign up on this board:

Group DIY - Index

And research posts having to do with mic construction on the "Drawing Board" list there.

Also familiarize yourself with the following concepts:

Microphone capsule types
Microphone directional patterns
Microphone sensitivity
Microphone signal to noise ratio
Microphone impedance and signal level
Microphone phantom power

You should have a basic understanding of AC and DC electronics to take on this project and know how to use a voltmeter, how to solder, etc.

You might spend about 40-50 hours on basic research to know if it's really what you want to do and settle on an approach, 10-20 hours getting parts and planning, and 30-40 hours building and testing.

Make sure you know what you're going to plug it into

Also you might want to be prepared to spend substantially more than 100 hours...

There are also the "Aurycle" microphone kits.

Good luck,

Michael

[sreten]

Originally Posted by Michael Koster

No one on this board is very familiar with microphone design and construction.
Michael

Hi, Really ? Says who ? A fairly pompous statement I must say, rgds, sreten.

There are plenty of us who understand the issues far more than the poster.

[PeteMcK]

some links for you:
http://www.stefanavalos.com/micropho...s/diymic01.htm
WM-55A Mod
Transsound Electrets
DIY Microphone Projects
Stereo Microphone
Dismantling four Transound electret microphones

I bought some electret inserts about a year ago, with good intentions, haven't done anything with them yet....

Should be easy to make, just get hold of an electret insert (for recording, Unidirectional is best), & build a simple pre-amp, for me the housing is the hard part, haven't come across anything suitable yet (but haven't been looking too hard)

[Rullknufs]

This seems like it will be maybe too difficult after all.
Since i've already planned on making some sort of woofers for my speaker setup, i could just do that and write a good report about it. And since i know more about that than about microphones, it should make it easier for me.