How to build a Stereo Microphone and Battery Box

[beefstew]

will it matter if the resistor is carbon film instead of metal film?

[Karl P]

Just wanted to drop a thanks for these projects... Battery box seems to be working great, next up the microphones... A little backwards, but hey!

Thanks again...

OH, BTW - I used the following parts from mouser.com

Caps: 50V 2.2uF 5x11 105° Nichicon Radial Aluminum Electrolytic Capacitors (647-UVZ1H2R2MDD)

Res: 10Kohms 1% 50PPM KOA Speer 1/4Wattt Metal Film Resistors (660-MF1/4CC1002F)

Jack: 3.5mm PCB STEREO BLK (806-STX-3000) Probably could of used a different/better one)

Plugs: 3.5 ST PL-3.5 ST PL (172-2238) Cut to fit...

[curls]

Anyone in the UK made the mic's? I've been trying to source some mic's here but haven't been successful. Digikey want so much for shipping to the UK that I suspect they send someone to deliver them personally. I know I could buy them ready made from Green Machine, but, being a tinkerer, I'd prefer to make my own (and to save money of course)

[gosbwpm]

Anyone in the UK made the mic's? I've been trying to source some mic's here but haven't been successful. Digikey want so much for shipping to the UK that I suspect they send someone to deliver them personally. I know I could buy them ready made from Green Machine, but, being a tinkerer, I'd prefer to make my own (and to save money of course)

Why not try the Rapid Electronics (Colchester UK) 35-0190. I have used these extensively and they are OK see the "DIY Mics" and "Mic Capsules" albums at

http://uk.pg.photos.yahoo.com/ph/g0sbw@bti...t.com/my_photos

The Panasonic 61s maight, arguably, be a little better based on specs but the rapids sound good. The Mic Capsules albums show photos of some triplet mics I have made. Putting the capules in parallell increases sensitivity thereby decreasing self noise for a given record setting. However the triplets are very sensitive and easily overload - more suitable for nature recording than bands, gigs etc. The triples also need a box, similar to Green Machine's to power them to power them.

A single capsule stereo pair of 35-0190s is easily powered by a minidisc's PIP power - no need at all for a powering box. The cost of the 35-0190s is very attractive - only 38 pence each (+P&P and VAT). If you buy 25 or more the price drops to 33 pence each. At this price it is easy to experiment and not worry if you damage them. However the 35-0190 is a little bigger than the Panasonic 61a. Perhaps not quite as stealthy as the Panasonics but a lot easier to solder leads onto. The 35-0190s can be obtained here

http://www.rapidonline.com/searchresults.a...&kw=35-0190

I have compared four of my DIY mics against a commercial Rode NT4

The mics, in order of appearance in the following 1minute 15second MP3 are:

35-0190 single capsule stereo pair

61a single capsule stereo pair

35-0190 triple capsule stereo pair

35-0192 triple capsule stereo pair

Rode NT4

The recording is of a single ticking clock, using a RH910 recording in PCM, manual mode, high sensitivity with recoding volume set at 30. Post recording the play back volume each of four of the mics was adjusted to the level of the loudest one. !5 second tranches were combined to make the MP3 here:

http://uk.geocities.com/g0sbw@btinternet.c...pilationmp3.mp3

There are no prizes for spotting the winner.

The result from the 35-0192 triples is disappointing (it should be the same as the 35-0190 triples as it is the same capsule configured for PCB mounting) probably due to the mounting of this mic on a camera bag rather than a barrier type mounti.

To sum up, don't worry too much about obtaining the Panasonic capsules in the UK - a good stand in is available at very low cost. This assumes that ultra small size is not in portant - a jpeg of giving size comparison is here

http://uk.geocities.com/g0sbw@btinternet.com/PC310090.JPG

Cheers, All the best to All for 2007

[curls]

Thanks for the info. I just put an order in for 10.

Do you mind me asking, what is all the gear for in the photo's?

[tekdroid]

Ghettobox

Oh isn't she pretty?

Created out of necessity, really. I bought the plastic box to house the battery first. Then, the time came to fit the circuitry in there.

Tight space

A circuit board was not gonna fit in this box (even though I had bought all the parts for it). So, I compromised. This was done months ago so the details are a little hazy, but she works, and boy does she work good!

Procedure

The idea was to put the two capacitors together, acting as the main "pipe". The resistors were fastened around the fat capacitor pipe with masking tape (is there anything masking tape cannot do?). Rumour has it resistors & capacitors live together harmoniously. (I have no evidence to suggest this isn't true).

So, the procedure is (very) basically:

1) Laying some masking tape of suitable thickness on the table, sticky side up.

2) Putting two capacitors on the masking tape, making a "capacitor pipe" for want of a better expression

3) rolling the masking tape around the capacitors

4) putting the resistors on each end (I guess it can be done in the one step as the capacitors. Not sure what I did...)

5) bending the wires with pliers or what-have-you, getting them to go in the correction direction for your case/ wire layout. Soldering the connections.

6) insulating the exposed wires in more masking tape or heatshrink (or whatever) : the pics show them exposed for illustrative purposes. Basically I used more masking tape to insulate the exposed wires from touching each other (making it look even messier, but hey, it works...)

At the end of the day I knew exactly how long to make each wire and which direction to bend it in to fit my case fine (so these can be churned out quite quickly if I need to), but it took some work the first time around; it was more difficult than I had imagined just getting the design to fit right in the case (took me a whole day to get the wires arranged in optimal fashion and the right lengths) but by god did I learn some things

The wires soldered to the audio sockets was obtained by sacrificing a good ol' CD-ROM cable found in PCs (great cheap cable for this, IMO).

Improvements for version 2?

The only one I really want to do is build a custom box not much bigger than the 9V battery itself. I have a soft spot for wood. Wood is good. But so far the need hasn't been strong enough for me to stop being lazy, so I'm happy to report the GhettoBox was a smashing success.

Thanks greenmachine!

[gosbwpm]

Thanks for the info. I just put an order in for 10.

Do you mind me asking, what is all the gear for in the photo's?

Not at all, Curls.

Most of the photos in the various albums are in connection with my amateur radio hobby. I specialise in talking to other hams while I am walking - having my daily constitutional. So far I have spoken to hams in 120 countries on 5 continents - furthest was to New Zealand. This is, relatively, not too difficult provided one has the right gear. Most of the pictures show various aspects of this gear in particular the DIY backpacks and antennas I use.

There are also some albums which are devoted to DIY mics.

Let us know how you get on with the Rapid 35-0190s

Cheers

TomR

[Hygnôse]

The Microphones work great, but my batteryox didn't work yet but the mic in of the RH1 is nice aswell....

[Nathan P]

Here are my boxes, the first one is to the left, it is using nonpolarized caps, but wired wrong and not layed out very well so I built a new one. The new one is using extra resistors from the first one (They are carbon film, but I measured them and they were exactly the same, so it won't matter), and the caps and plug came from an old computer speaker amplifier I took apart (That's kind of my speciality, making stuff from old stuff lol, I built a speaker set from the drivers that were in the computer box, and used an old amp I was given to power it), anyway, the new caps are polarized but they are much smaller and I really can't hear the difference. Overall, the second one turned out much better.

[Karl P]

Just wanted to share a bit. Went to the shack today and noticed they had a few cheap items that you guys might be interested. They have some Hook-on In-Ear 'Phones (33-1106) on sale for like $4.97. I just modified them into a stealth mic. Used a couple WM-61A microphone elements I picked up at www.digikey.com. Used the dremel a bit on the earpiece to accept the mic and BINGO! Instant, relatively covert, stereo mic.

Here's a picture. Disassembly/reassembly is pretty self explanatory. If you're soldering, the rest should be cake!

The price was right too, can't wait to hear the results.

Edited January 6, 2007 by Karl P

[amorans]

I have compared four of my DIY mics against a commercial Rode NT4

The mics, in order of appearance in the following 1minute 15second MP3 are:

35-0190 single capsule stereo pair

61a single capsule stereo pair

35-0190 triple capsule stereo pair

35-0192 triple capsule stereo pair

Rode NT4

The recording is of a single ticking clock, using a RH910 recording in PCM, manual mode, high sensitivity with recoding volume set at 30. Post recording the play back volume each of four of the mics was adjusted to the level of the loudest one. !5 second tranches were combined to make the MP3 here:

Hi I'm new to this board, so let me just say " Happy New Year " to all, and hassle free recording.

I checked out your sample recordings, but couldn't find those listed above, about the clock.

The classical vocal and accompaniment recording on g0sbw mic project sample recording 3ctm3wtm3_30sec.mp3 was excellent,

and I'd really like to know a little more of the recording conditions, and the equipment used.

I have just received my Xmas gift to myself, one Sony MZ-RH1 MD recorder, and am keen to get out in the field with some DIY mics.

regards

NickW

[gosbwpm]

I have compared four of my DIY mics against a commercial Rode NT4

The mics, in order of appearance in the following 1minute 15second MP3 are:

35-0190 single capsule stereo pair

61a single capsule stereo pair

35-0190 triple capsule stereo pair

35-0192 triple capsule stereo pair

Rode NT4

The recording is of a single ticking clock, using a RH910 recording in PCM, manual mode, high sensitivity with recoding volume set at 30. Post recording the play back volume each of four of the mics was adjusted to the level of the loudest one. 15 second tranches were combined to make the MP3 here:

Hi I'm new to this board, so let me just say " Happy New Year " to all, and hassle free recording.

I checked out your sample recordings, but couldn't find those listed above, about the clock.

The classical vocal and accompaniment re cording on g0sbw mic project sample recording 3ctm3wtm3_30sec.mp3 was excellent,

and I'd really like to know a little more of the recording conditions, and the equipment used.

I have just received my Xmas gift to myself, one Sony MZ-RH1 MD recorder, and am keen to get out in the field with some DIY mics.

regards

NickW

Hi NickW

My apologies for not replying sooner.

I had erased the recordings from the FTP server as I thought I needed the space. I have now put them back. The adjusted recording can be found here

http://uk.geocities.com/g0sbw@btinternet.c...pilationmp3.mp3

The recordings prior to the adjustment are compared here

http://uk.geocities.com/g0sbw@btinternet.c...pilationmp3.mp3

Clearly the triplets are the winner.

The classical vocal recording here

http://uk.geocities.com/g0sbw@btinternet.c...3wtm3_30sec.mp3

was a test to see if a simple collapsable barrier rig using the Rapid triples would perform as well as a heavy wooden barrier mounting of the triples. The recording is in fact two recordings of the identical piece joined together. The first 15 seconds is the lightweight, collapseable barrier and the second 15 seconds is the heavy wooden barrier. To my ears there is no difference and it is difficult to hear where the join is.

These test recordings are simply recordings of recordings and are used purely for testing the relative performance of the two triplet barrier rigs. What you are hearing is the quality of the original performance and the masterful recording at that time. I did it by playing back a HiFi test CD, made in the early 1980s, through a simple cheap and cheerful amplifier and exceptionally clear loudspeakers. The speakers were 25 year old BBC LS3/5a bookshelf monitor speakers. The mcrophones were placed exactly midway between the speakers and 4ft. from them so as to make an equilateral triangle. Great recording but, unfortunately, not mine.

I am currently doing more field testing of the lightweigt barrier triplets against my Rode NT4. I will probably make the results available via the Yahoo Naturerecordists group

http://tech.groups.yahoo.com/group/naturerecordists/

I hope this info helps

Cheers

[amorans]

Thanks for your informative reply, Greenmachine,

regards

NickW

[orangezero]

Its interesting coming back here and looking at what everyone else has done.

Probably the best place to ask this. I ripped my old mic right chanel cord, and have a few capsules still around so I was going to build a new set. I've talked with others that said an "ok" way to get two pairs is to measure the resistance over the leads and get ones that are about equal. Not very precise, but a lot quicker than other ways. I've never made a set that was exactly equal....

So, my question is about the capsules. Years ago they recommended a metal housing to surround the mic capsule. I used a small brass tube at the time, and it was easy for me to cut up some alligator clips and solder them on to the brass. I noticed greenmachine didn't use any metal, just heat shrink tubing. I think they recommended metal to fill out the sound somehow, but wasn't sure. Does anyone have any experience with this or recommendations?

I believe mine are the common panasonic caps. I'm not sure if I'll try the modification or not, any comments?

thanks all.

[Simon_W]

Over 150 views since my previous post.. No one who has some experience with these DIY mics with feedback on the samples?

Would love to know if the mics are ruined because of too long soldering or not.

It is quite easy to ruin them I know from experience so I just ordered them as ready to use product from Greenmachine ...

[john10001]

Hi, I have read a lot of posts in this discussion with great interest as I am hoping to built my own DIY battery module. I'm not the brightest bod in the world, but I figure if I can install an afterburner into a GameBoy Advance, this shouldn't be beyond me either.

So far I have just been looking at the different parts I would need for the Battery Box. I found a great site here in the UK http://uk.farnell.com (for the benefit of Brits reading) that seem to sell loads of different electronic components. So far I have found everything I need except for the circuit board. I can find circuit board on this site no problem, but I don't know which one is the right type or if any of these are the right type?

None of the circuit board I can find on the site seems to be similar to the picture of Green Machines board and have holes as large or spaced apart as this. If anyone can point me in the right direction for a small piece of circuit board that would be suitable, either on the farnell site or any other site I'd appreciate it. I guess it would be handy to know of somewhere I could get a steady supply from in case I am doing any other things like this in the future.

I am just going to attempt the bog standard 9v battery box to start with. Once I've got all the bits and pieces I need I'll probably need to post back at some point to ask what you solder to what as a lot of the photos I have looked at as well as the diagrams are pretty complex.

Cheers

John

[greenmachine]

I have a few of these little pieces (4x5 holes) of circuit board left. If you PM me your address, i can send you one of these.

[Douflou]

Hello !

I'm french so, I'm sorry for my mistakes!

I want to do the micro and the battery box but in France, the MCE-2000 is unavailable, but the MCE-4000 is (http://www.audiophonics.fr/capsule-micro-electret-panasonic-mce-4000-p-1038.html?osCsid=2aa2efc895d92429bd57031c03b45536).

So, can I make the micro with MCE-2000 capsules ?

Thank you!

[greenmachine]

Any pre-polarized condenser (electret) mic that works with the plug-in-power of the recorder's mic input jack will work, including the mce-2000 and mce-4000. I have preferred the mce-2000 for its lower sensitivity, ultra-linear frequency response and ability to be source-follower modified for very high SPLs. The price was a bit higher though and unfortunately they don't seem to be available here in germany anymore either. The mce-4000's are not bad, but not quite at the quality level of the 2000's. If the Panasonic WM-60/61 were availble in europe, i would probably use these. I am currently looking for alternative sources/alternatives and do welcome pointers/suggestions.

[j-dawg]

Hey guys, I'm a newbie trying this for his first DIY project. I got the parts at the Ratshack and when I got home I realized that my capacitors are the non-polarized variety... Will these work? I read in the thread that the capacitors' job is to block voltage from entering the line-in. Will my non-polarized do this correctly? I'm really scared of frying my MD. Thanks for any advice!

[greenmachine]

Non-polarized ones will work at least as well, but are usually a bit larger. If you don't care for the maximum possible miniaturization, use them!

[Sam24]

Does it matter what kind of stereo jack you use?

I went to radioshack and saw two types. One with (excuse the technical jargon)5 metal thingys on the bottom on the bottom and one with 3 metal thingys on the bottom. They were both 3 conducter.

The 3 metal thingy looked like the picture attached.

Edited March 7, 2007 by Sam24

[greenmachine]

Virtually all stereo jacks have essentially three contacts - left, right and ground. Whether these are to divided into 3 or more pins doesn't really matter, you just need to know the layout (where each pin leads to). The one i used in the sample pictures has 4 pins, in this case the left channel was divided into two pins - for a better fit onto a circuit board, i guess. (please excuse my poor german-english, not good at explaining technical matters)

[Sam24]

Virtually all stereo jacks have essentially three contacts - left, right and ground. Whether these are to divided into 3 or more pins doesn't really matter, you just need to know the layout (where each pin leads to). The one i used in the sample pictures has 4 pins, in this case the left channel was divided into two pins - for a better fit onto a circuit board, i guess. (please excuse my poor german-english, not good at explaining technical matters)

Your help is very much appreciated. Im very new to this

How do I know what goes to where? I know there are right left and ground wires in my output cable. How do I connect those 3 to the 5 contacts?

[greenmachine]

There should be some sort of description coming with it - if not, connect a cable and use an ohmmeter to figure out what belongs where. On the cable, the left channel is usually coated white, the right channel in red, while the other one is ground.

[Sam24]

Ok I took pictures. I think Ive figured it out. 1 is ground, 2 is left, and 5 is right. I just dont know what 3 or 4 are and what to do with them. The cable is red, blue, and gold. I dont know which is which except for red, which is right.

[greenmachine]

3 and 4 are used as opening switches - if you don't need them, simply don't use them. You could as well connect 2+3 and 4+5, it would make no difference for your purposes. The cable in the picture is usually used for headphones, not sure if suited for recording - the individual cables are lacquered instead of wrapped in plastic. If you want to use it, you need to scrape the lacquer off at the ends, otherwise you will have a hard time trying to solder them to the board. Not sure about the colors, use an ohmmeter. As you have figured out correctly, the outer ring of the plug is left, followed by right and ground.

[Jam]

Hi there,

Just found a supplier for the Panasonic WM-61A capsules on Ebay UK for anyone building these mics in the UK (a lot cheaper than Rapid Electronics).

Ebay Link 10 x Wm-61A for £18.99

Ebay Link 5 x WM-61A for £9.95

[valdis]

First of all, let me say thank you for this tutorial. I had been planning to build one of these binaural mics for a while and this topic was all I need to get started!

I already had here some screened cable with a female 3.5mm jack on one end and a male jack on the other, that I had been using as an extension cable for my headphones, all I needed was the mic capsules that I found in my local electronics shop.

I proceeded to mount it as follow:

1. Pick one capsule and mark it as Left and mark the other one as Right.

1.1. Splitted the cable.

2. Solder the Red wire on the V+ spot of the right mic and the bare wire on grown spot.

3. Solder the Black wire and Bare wire to the corresponding spots of the left mic.

4. Plugged the assembly in the mic-in of my desktop's Creative Soundblaster Live sound card. Opened the corresponding software to monitor the captured sound.

5. Trouble: The mic only captured sound from the left side ("left" mic + black/bare wire)

6. I started to think there might have been a problem with the right mic so I desoldered the wires and soldered the right side wires to the "left" mic and the left wires to the "right" mic.

7. Once again, I only captured sound from the left side which lead me to conclude that both mics were functioning but that I was only getting sound from the left side cable.

Here is a pick:

Now, can someone try to explain why is this happening, please?

Thanks in advance for your help,

Kind regards,

Francisco

[greenmachine]

The right (+) is touching the conductive housing of the capsule?

[valdis]

No, the wires only touch the bits of solder of the capsule, it was just the angle of the shot.

I was told it might also be a problem with my soundcards mic-in input so I jiggled the plug a bit and I got a bit of sound. At least I know its working but why do I get so little sound from one side? Is it possible the capsules are that much mis-matched?

Another thing:

My goal with these microphones is to make field recordings with a binaural effect, however, I was expecting a bigger separation between left and right channels like Ive heard in other amateur recordings. I put one mic in each corner of my desk and jiggled a box of matches near the left channel and then near the right channel while recording it. The sound came out "centered", not more to the right and then more to the left as I was expecting it. What am I doing wrong?

Thanks again for your help,

Regards,

Francisco

[greenmachine]

Most soundcards have one channel (mono) mic inputs. Do you have a MD or other recording device with a stereo mic input and plug in power?

Edited April 11, 2007 by greenmachine

[valdis]

Well, this is my soundcard in the link below but to be honest I cant figure out if the mic-in is mono or not...

http://us.creative.com/products/product.as...lSpecifications

Edited April 11, 2007 by valdis

[valdis]

I've been told by another user that these soundblaster live soundcard's mic-in is mono...

After reading the manual and googling, I still haven't figured out which one of those slots is the line-in...could you help me on this?

Thank you for your time,

Regards,

Francisco

[boojum]

Many sound cards are mono in at the mic. Do you have a line in?? If you do, that will be stereo and what you will have to use.

[Strungup]

Well, this is my soundcard in the link below but to be honest I cant figure out if the mic-in is mono or not...

http://us.creative.com/products/product.as...lSpecifications

On-Board Connectors

Analog/Digital Out (Analog Center & Subwoofer/6-channel S-PDIF Output)

Line In = ( Second stereo line input )

Microphone In =(Mono unbalanced input)

Line Level Out (front) / Headphone Out

Line Level Out (rear)

MIDI / Joystick port

Telephone Answering Device In

MPC-3 Analog CD Audio In =(Line Level Input -Stereo plug)

Digital CD Audio In =( Optical input)

[A440]

Typically a Mic-in input is red and a Line-in input is white. I see a white jack on the photo, so that's probably it.

As on your MD unit, the Mic-in has a preamp behind it and the Line-in does not. So you may not get enough of a signal from your mics to use the Line-in. Try it, and see if you can raise the input level with your recording program (Audacity? Creative's own program?), but the level may just be too low.

[greenmachine]

Or you may get no signal at all - electret mics require "plug in power", which is usually not available at the line-in. A battery box would supply the mics with the necessary voltage, but there would be still no pre-amplification, which usually leads to a (very) low signal unless you record from a really loud source.

If you want to record directly to your computer, you will need either a soundcard with a stereo mic input or an external preamplifier connected to the line-in. A MD recorder with mic-in, set to rec-pause (line/headphone out to line-in of the soundcard) may also be used as an external preamp.

Or get a Hi-MD to record and upload afterwards.

If you want to investigate further on this hardware-related issue, I'd suggest to start a new topic.

Edited April 12, 2007 by greenmachine

[boojum]

I've made two of them.

Battery box #1

Battery box #2

Job well done. Beautiful finishing and photography. Magyars rule. ;o)

[Jamesy]

Nice thread this! I made up some mics recently and they perform well. They're hidden inside some headphones to be descreet. I actually us foam on them too, not pictured, but you get the idea.