northsiderap

Microphones - Homebrew DIY Condenser Mics - Here
« on: May 08, 2005, 07:03:14 PM »


Here a picture of my third mic capsule. Things are getting progressively better with each try. This one is a hypercardoid with a 1/2 inch diaphragm. There is a pressure outlet directly beneath both the primary and secondary harmonic of the diaphragm, and other damping holes cocentrically. I drilled them with a hand drill, so they are not exact by any means.



The diaphragm is about 25 microns thick (1 mil) as I cannot find a supplier for the proper material. Any suppliers would be appreciated, or we could do a bulk buy if anyone's interested.  I'm guessing a 5-6 micron diaphragm would not only greatly increase the sensitivity of the mic, but also reveal refinements that I would have to make to the backplate.

The capsule was tested on the reference mic head amplifier, but I have an FET/Transformerized head amp design just about ready. How important are constant current sources in a single FET head amp design? How about with an FET followed by a DC class A and emitter follower output design? How about if the mic is going to have an independant power supply?

Anyone else doing this? Any advice? I'm also doing ribbon mics, but still working on the high frequency response. There's a nice thread on the ribbons elsewhere on this site.
***NorthSideRap.com***


soundguy

Microphones - Homebrew DIY Condenser Mics - Here
« Reply #1 on: May 08, 2005, 07:05:27 PM »
hi there, welcome to the lab!

there are some smart microphone people 'round these parts, stick around.

dave

chips are good with dip...

Microphones - Homebrew DIY Condenser Mics - Here
« Reply #2 on: May 08, 2005, 08:46:34 PM »
Damn, some cool stuff.

gyraf

Microphones - Homebrew DIY Condenser Mics - Here
« Reply #3 on: May 09, 2005, 05:44:12 AM »
Hi Northsiderap,

Welcome here..!

Very cool stuff you're working on...

You may want to look into disassembling polyestercaps for thin diagphragme material. Although it is aluminium, not gold, it works fine. Thinner material will probably get you into a much higher resonant frequency at the same tension.

Be sure to check the microphone meta (a link can be found in the meta-meta):

http://www.groupdiy.com/index.php?topic=256

Jakob E.
..note to self: don't let Harman run your company..

Microphones - Homebrew DIY Condenser Mics - Here
« Reply #4 on: May 09, 2005, 11:14:47 AM »
hey ,welcome to the lab.
nice stuff....I would like to see more pics...and more info on the construction process you used.
what tools didi you use ? what were the raw materials?
to some this might seem obvious but I am a bit of a newbie...so...
any additional info would be great.

also: you will get some great results searching the forum
and reading through the meta-meta....(microphones section in this case)
TIP: also the search engine here uses the AND NOT OR format so ...quotes, parenthisis, and neg pos symbols will not work right. (i skipped over the explanation at the search page and it took me a week or two to realize my searches were not as finely tuned as they could be)
hope this helps.

there are a lot of smart/cool people at this forum. I'm sure you will be pleasantly suprised at the wealth of knowledge and kindness here. i think yoiu will enjoy searching and reading here too... that helps weed out some small questions you might have and at the same time present you with new ideas and questions. ( i guess it's an exponential process... 1 question leads to 2 leads to 4 leads to 8 and on and on....lol)

anyway welcome and have fun
Again your capsule looks nice and your specs are pretty good too.
keep up the good work.
lookin forward to those pics and more info.
later
ts
I need help with  RCA BA-43/ BA-45. RCA BA-25a, RCA BC3 mic pre's, Gates Level Devil, Federal AM-864u, DIY la2a stuff, Altec 436b

dale116dot7

Microphones - Homebrew DIY Condenser Mics - Here
« Reply #5 on: May 09, 2005, 12:36:07 PM »
If you want to metalize your own mylar, you can order 6 or 2.7 micron material from http://www.2spi.com. You can get all of the other consumables for metalizing there.

-Dale

maneco

Microphones - Homebrew DIY Condenser Mics - Here
« Reply #6 on: May 09, 2005, 04:04:30 PM »
Welcome !
and congratulations for your work...my dream is to be able to build one capsule someday...so,any extra info you can share,will be invaluable!

northsiderap

This Capsule...
« Reply #7 on: May 09, 2005, 08:46:01 PM »
Believe it or not, the first capsule pictured took me $5 and 15 minutes to build with only a hand drill, hacksaw, and belt sander. I'm sure I could build it for less and in a shorter time once I got the hang of it or bought in bulk. I'm almost afraid to post my construction and materials technique, I'm afraid that some manufacturer will snatch it out from under me. I've lost credit for big ideas before....

Here is another capsule... This one was capsule #2



This one allows for adjustable diaphragm tension, adjustable distance from diaphragm to backplate, and it also pushes the diaphragm forward from the body of the mic to minimize high-frequency reflections in the area of sensitivity. You'll notice that the backplate is rolled off near the edges too. This one cost about $8 to build and a few hours. I'll put up some graphs of this one too, once I re-skin and re-test. It's not shielded so it gets a little noisier than the others... I plan to make it out of brass once I get a nice sound out of it.

Sputtering Does anyone have a direct link to diy sputtering?

By the way, much respect to Gyraf Audio... Without Gyraf's nice looking handmade gear and many many DIY microphone links I would be far behind where I am now... I'm a solid state man as of now, but I can't wait to dig into building my own tube gear someday.
***NorthSideRap.com***

Scodiddly

Microphones - Homebrew DIY Condenser Mics - Here
« Reply #8 on: May 09, 2005, 09:24:25 PM »
Very cool - I'd love to hear some details, though I can appreciate wanting to keep stuff close.  Probably some manufacturers are indeed following these forums.

dale116dot7

Microphones - Homebrew DIY Condenser Mics - Here
« Reply #9 on: May 09, 2005, 11:17:20 PM »
http://www.10000cows.com/deposition_system.htm

Here's where I figured out most of it from:

http://www.ee.byu.edu/cleanroom/metal.phtml

I use a Varian HS2 diffusion pump. It was designed to be used without a vacuum valve to the chamber - ideal for a low-cost operation where adding 1/2 hour to the cycle time is no big deal. I also use a 6cfm refrigeration evacuation pump (Robinair) as the roughing/backing pump. Get a vacuum gauge!!! You'll need a thermocouple gauge for sure, and if you get one to read to 0.2 microns of mercury that's good enough - that's what I use. Make sure to get leak sealant.

http://www.2spi.com
has a lot of the supplies you need.


maneco

Microphones - Homebrew DIY Condenser Mics - Here
« Reply #10 on: May 10, 2005, 12:27:24 AM »
15 minutes and 5 $ !!!!
That's hardcore DIY...you have your body completely tattoed,i suppose  :twisted:

Congrats again!

northsiderap

Sorry....
« Reply #11 on: May 11, 2005, 12:56:40 PM »
:sad:

No tatoos...

The sputtering link is cool as all getout. A little over my head right now, I guess I could figure it out...

Any more info on your setup would be cool.

Since it looks like you've already done the homework, you think there's a way to create a charged high-speed ion or particle stream with a very accurate path? How about in an open-air environment?
***NorthSideRap.com***

maneco

Microphones - Homebrew DIY Condenser Mics - Here
« Reply #12 on: May 11, 2005, 02:50:12 PM »
Quote from: "gyraf"



You may want to look into disassembling polyestercaps for thin diagphragme material. Although it is aluminium, not gold, it works fine. Thinner material will probably get you into a much higher resonant frequency at the same tension.


Jakob E.


If i'd wanted to buy a polyester cap for dissasembling for this purpose,which value/voltage should i ask?
This mics thing is driving me crazy,in a good way  :shock:

dale116dot7

Microphones - Homebrew DIY Condenser Mics - Here
« Reply #13 on: May 11, 2005, 02:56:40 PM »
You'll melt the target (mylar) if you have enough energy for that, I think. It actually will happen if you don't pump down enough and force the gold to evaporate with a high temperature even on my setup. You see the mylar starting to wrinkle and deform. The diaphragms still look ok when they're done but they are not usually as nice because the internal stresses have been messed around with so they don't tension up as evenly. Basically, all of the info on my setup is better expained on the internet than I can do. But I can tell you what to do and what not to do.

What to do - you will have leaks. Be prepared to stop them up. Get new O-rings (if you have O-rings in your fittings) that are rated for high vacuum service. Have some Celevac or something like that handy. Have plenty of high-vacuum grease available. You will need a good vacuum gauge that reads to 0.2 microns. Make sure you get a big enough backing pump. If your diffusion pump requires a 5cfm backing pump, get at least 6 or maybe 10. That's extra insurance for leaks, which you will have. Put a guard around the bell jar. You don't see one on my photo (that was for the photo shoot only). But get one and use it. Get gloves and use them. Fingerprints have to boil off from inside the chamber before you can do a good evap - this can take an hour or more. Get a high-vacuum book from the library, and read it.

What not to do - don't buy anything until you figure out how much it's going to cost in the end. I spent probably $2000 to build the beast and run it for maybe 50 diaphragms. Was it worth it? Maybe. Educational? Yes. Fun? Yes. Frustrating? Absolutely.

If you can find a used sputtering or thermal evap machine for less than $3000 or $4000 with pumps and in working order, I'd recommend buying it instead of building.

gyraf

Microphones - Homebrew DIY Condenser Mics - Here
« Reply #14 on: May 12, 2005, 02:51:11 AM »
Quote from: "maneco"

If i'd wanted to buy a polyester cap for dissasembling for this purpose,which value/voltage should i ask?


Get a cylindrical polyester capacitor, at a length that is somewhat larger than the width of the membrane material you need (as you'll need to cut off the ends where the electrodes are mounted)

Lower voltage = thinner material

Higher value = bigger roll of material

A 110V "motor start" or "motor run" capacitor will probably work nicely.

Jakob E.
..note to self: don't let Harman run your company..

maneco

Microphones - Homebrew DIY Condenser Mics - Here
« Reply #15 on: May 12, 2005, 08:40:58 PM »
I found the right cap├ácitor! Yeah!   :grin:  :grin:

I work repairing medical machines,and from some junk liquid magnetic fluid measurement units,i salvaged a biiiig capacitor with many turns of the needed coated film...around 10cm wide...so my experiments may lead somewhere
Thanks again for all the advice!  :thumb:  :thumb:

maneco

Re: This Capsule...
« Reply #16 on: May 12, 2005, 08:51:09 PM »
Quote from: "northsiderap"
Believe it or not, the first capsule pictured took me $5 and 15 minutes to build with only a hand drill, hacksaw, and belt sander. I'm sure I could build it for less and in a shorter time once I got the hang of it or bought in bulk. I'm almost afraid to post my construction and materials technique, I'm afraid that some manufacturer will snatch it out from under me. I've lost credit for big ideas before....

Here is another capsule... This one was capsule #2



This one allows for adjustable diaphragm tension, adjustable distance from diaphragm to backplate, and it also pushes the diaphragm forward from the body of the mic to minimize high-frequency reflections in the area of sensitivity. You'll notice that the backplate is rolled off near the edges too. This one cost about $8 to build and a few hours. I'll put up some graphs of this one too, once I re-skin and re-test. It's not shielded so it gets a little noisier than the others... I plan to make it out of brass once I get a nice sound out of it.

Sputtering Does anyone have a direct link to diy sputtering?

By the way, much respect to Gyraf Audio... Without Gyraf's nice looking handmade gear and many many DIY microphone links I would be far behind where I am now... I'm a solid state man as of now, but I can't wait to dig into building my own tube gear someday.


Could you post some construction details of this mic? i know the previous one is TOP SECRET ,but i'm eager to build something,now that i found a suitable membrane in a big capacitor
Thanks!

northsiderap

Here ya go...
« Reply #17 on: May 12, 2005, 09:05:17 PM »
[EDIT]

***NorthSideRap.com***

maneco

Microphones - Homebrew DIY Condenser Mics - Here
« Reply #18 on: May 12, 2005, 11:10:40 PM »
Awesome!!!
Many,many thanks...it's an incredible example of creativity and inventive...hats off for this...i have no words... :thumb:  :thumb:  :thumb:

...and i'm ready now for my first "..your microphones are more important than me!!!!..."

(i've already heard something like " ...those *****es in your concerts are more important than me!!!! ...")

maneco

Microphones - Homebrew DIY Condenser Mics - Here
« Reply #19 on: May 24, 2005, 04:54:28 PM »
Well,today i finished building my first capsule,tested it with a simple 1 fet + 1 bc560 head amp,and i am happy that al leats it sounds   :grin:

I hope my experiments get better with time...all i can say is that the method shared here works,and it's worth the effort...thanks again,NOrthsiderap!! :thumb:


 

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