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How to build a Stereo Microphone and Battery Box

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greenmachine

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I've never done any electronics work but would nonetheless like to build one of these battery boxes, so forgive me if this is a stupid question: I can't figure out, from the circuit diagram and the actual project photos, how is the negative terminal of the battery tied into the circuit. It looks like it's soldered to one of the leads from the resistors. If that's incorrect I would appreciate someone setting me straight. Thanks.

Edited by War Throat
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No resistor on the negative side of the battery. It just ties between the negative of the input and output.

I didn't have any electronics background before this project, and have only been doing it a couple months now. This project has really got me going though. I have completed a direct box, a stereo mic preamp, a guitar preamp, a guitar boost pedal, and mods to a Boss DS-1 Distortion pedal. I also have a few more projects going on, and am in the planning process for a couple more. This can be addicting!!!

That being said, there are no stupid questions. I am still very much in the learning mode, and if it wasn't for people like greenmachine and others willing to answer my stupid questions, I wouldn't have known how to get started.

Edited by woulfer
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i made this, and put up pics onto flikr at flikr. it was really quite easy and in total cost well under 10$ i have 3 electret mics from allelectronics.com that have mono 3/32 plugs, so i made the tin have 2 plugs for that, with a stereo 1/8 in output cord. i made that out of 3 braded strands of the wire inside cat5 cable. right now, my only issue is that i cant really record in stereo, as my computer only has line in as stereo, not mic, and ipodlinux hasnt come out with stereo recording yet. anyway, it sounds great, and is quite solid. feel free to tell me if u think i did something poorly, etc. oh, and the plugs are labeled r and l/m for right and left/mono, for if its going into a normal mono mic jack.

dan

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i made this, and put up pics onto flikr at flikr. it was really quite easy and in total cost well under 10$ i have 3 electret mics from allelectronics.com that have mono 3/32 plugs, so i made the tin have 2 plugs for that, with a stereo 1/8 in output cord. i made that out of 3 braded strands of the wire inside cat5 cable. right now, my only issue is that i cant really record in stereo, as my computer only has line in as stereo, not mic, and ipodlinux hasnt come out with stereo recording yet. anyway, it sounds great, and is quite solid. feel free to tell me if u think i did something poorly, etc. oh, and the plugs are labeled r and l/m for right and left/mono, for if its going into a normal mono mic jack.

dan

what opamp did you use and can you give me the other design particulars.

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i used exactly the circuit diagram from the origional project, then put on 3/32 inch jacks in place of wires directly to the mics to suit the mics that i had. what do you mean, what opamp did u use? this amplifies it up to mic line level, then i have a mixer with a mic input that i have run from the line out of that into the line in of my computer, if that's what you mean. it also orks to use the mic jack on the computer, just not quite as good quality.

dan g

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  • 2 weeks later...

Finally found some time to solder caps to the wires yesterday. (had 4 panasonic mce2000 caps) I'm a noob when it comes to soldering, so I messed a bit with first 2 caps. Then thinking I had enough practice, I soldered the wires to the final 2 caps. I took me a few tries but I thought they were soldered ok.

I ran a test in front of my stereo. Levels in both channels were not the same, but I thought that was just because the caps weren't matched. Uploaded the sample to my laptop and equaled levels in soundforge. Listening through my stereo which was hooked up to my laptop, I was pleased with the result. But, when listening to it through headphones, despite the fact that I equaled both channels, the sound still came mostly from the right channel.

Link to the sample: attempt 1

So, this morning I resoldered the cap of left channel, which again took a few tries. Ran a test in the same setup as yesterday and uploaded the sample. Difference of both channels was 3 db now so I boosted the channel with lower volume till both channels were equal. Listening through headphones now gave a centered sound.

Link to sample:attempt 2

Only Thing that bothers me is that bass is much higher than it was before resoldering the cap. I did remove some bass with an eq which does make it sound better: link

Because of this bass thing and the fact that I needed a few attempts to solder the caps, I'm affraid soldering time was too long (maybe with both capsules, maybe with just the resoldered one). Maybe someone with more experience on making these kind of mics could give me some feedback on my story and the samples, and tell me if I did solder too long or if it all sounds ok.

Thanks in advance

ps. Test setup was mics>spsb1 (batt box @95hz)>sony mz-nh600. Also recorded a sample with sp-cmc-2>spsb1 (batt box @95hz)>sony mz-nh600 to compare with the self made mics, if anyone's interested.

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nobody comes here anymore, theyve moved on.

i dont have a loot of experience soldering electrets, but i soldere a great deal, and i always try to heat the thing im soldereing up the least possible, epecially if its an lectronic componant as opposed to wires, etc. my gues is that there is a good chance that, dpending on how long you had the iron on the contact, you partially melted part of the mic inside the casing, which is causing the distortion. i reccomend getting new electrets, and practicing soldering bits of wire together before doing the mics. try soldering 2 wires with only 2 mm or so stripped without melting any isulation. you have to do it fast, but it comes with practice, and if you can do that, you can quickly solder the mic, making sure not to damage it. my technique is to melt solder, then tin the wire with the melted solder so it heats up faster because there is more surface area contact, and only the part you want to solder is heated up. tin both sides like that, then melt them together quickly. letting them cool between solders is a good idea too, so the heat isnt tranferred inside the componant very much. allelectronics.com has 65 cent electret mics that are pretty good, but shipping is 7$ no matter how much you get, so i usually stock up when i shop there. as to you not getting a good contact, lightly sand the contacts, then tin them and there should be perfect conduction if its done right, whitch its relitivly easy to do. hope it helps.

dan g

Edited by patcheswfb
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  • 3 weeks later...

Great info on diy mics and battery boxes.

Does anyone know where to get the omnidirectional electret condenser mics in the UK, 20Hz to 20Khz?

Mouser has them but postage to the UK is far too expensive.

I have checked Maplin but the best they have is "50hz to 13Khz".

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Anyway I can't find shielded cabling. Would the unshielded give me problems in a theatre setting where there shouldn't be much EM interference?

Beware of mobile phones!

I always ask my neighbours on concerts to turn off their phones COMPLETELY, not just the ringer :)

So, does anybody know for sure if mic cable shielding can help protect from mobiles?

If so, where do you connect the shield? Do you leave it unconnected to recorder and mics?

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Great info on diy mics and battery boxes.

Does anyone know where to get the omnidirectional electret condenser mics in the UK, 20Hz to 20Khz?

Mouser has them but postage to the UK is far too expensive.

I have checked Maplin but the best they have is "50hz to 13Khz".

I can send you capsules which are almost 20Hz-20kHz - they have some 6dB roll-off @ 18-20 kHz, which is easily corrected in software applying this graph:

[attachmentid=1585]

Here are some recordings made with these capsules:

http://www.stereo.org.ua/Events/Jazz/ednist-2006

(note: the 50 Hz hum you can notice on this festival recordings was really in the audio system of the venue)

Pricing: $2 apiece. $1.5 if you buy 10 or more, $5 shipping (from Ukraine)

Official name for the capsules: KPCM-6B

post-25114-1144750947_thumb.jpg

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splumer

Definately worth having a go. I attempted the battery box the other night and I managed to build one. Not as neat as GreenMachine, as my shcematic reading skills are not great. However I was very pleased with my attempt, just going to look for a small tinned box of mints to house the creation :D

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I'm in Australia, i was just wondering and have been unable to find anything appropriate here, searching for microphone capsule yeilds nothing at all the major electronics stores and the part number WM-61A doesn't help and doesn't even return a response on the Panasonic - ECG website.

any suggestions as far as where to buy and what i should search for

cheers

stephen

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QUOTE(atrain @ Apr 17 2006, 11:06 AM)

did you try radio parts

http://www.radioparts.com.au/

& jaycar

http://www.jaycar.com.au/

i assume you allready tried tandy & dick smith

dunno if t0fler did, but I have checked those stores and I can tell you those Panasonic capsules (or equivalent) don't seem to exist here. As if live recording on the cheap was some ultra-niche

yeh i had a look at jaycar and DSE and couldn't find anything.

anyother places? or atleast somewhere with reasonable shipping prices to australia?

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  • 2 weeks later...

in responce to the shielding question, i connected it to the ground conductor when the mic entereed the box, and it seemed to work well. i am running the mic throuogh a hung ceiling, past several flourscant lights, then past a computer moniter, and i still have almost no interference. i also have a seperate grounding cable going to a ground as well too, that helps a lot.

dan g

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  • 2 weeks later...

has anyone in the UK (or elsewhere) made a battery module that I could possibly purchase off them? I don't have access to a soldering iron or glue gun so it'd be a little hard to make myself, but i've got an archos gmini 400 that records via an unpowered line input and a little stereo electret mic and i don't really wanna spend ~£80 on a preamp or ~£40 on a battery module (sound professionals website looks like the only real option, and there's is just under $100 shipped to the UK :oO). my minidisc broke a few weeks ago, only 2 years after i got it :( didn't feel like getting another after that.

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gee, greenmachine, update the post already, you could make loads :D

anyways... kindly pointed out in another thread, the author of these guides is actually selling the things himself.

check out http://greenmachine-audio.95mb.com/de-order.html (gm standard/pro are the mics, gm-sp is the power thing, click the links at the top (mik, zubsomething) for more info on them. or look for gm-audio on ebay. by the looks of it, the battery module comes in at just under £30 to the UK, only other option i've found close to that is the classic battery module from microphone madness (http://www.microphonemadness.com/products/mmcbmminminc.htm) which is just over £30 to the UK (from the US, which may bring around 20% tax on top of that). no idea which is best, i wish i could just make my own for a few quid and see if it's any use at all. why can't mp3 recorders just power their line in sockets :(

Edited by pepsi_max2k
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Sorry for the delay. PM me or send an email directly to [attachmentid=1635] and I'm sure we'll find a satisfying solution. Shipping costs are low. My pricing isn't fixed. As long as you are happy, i'm happy as well. :D

post-6863-1147038197_thumb.png

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thanks. i'd have probably emailed you sometime in the future anyway, it's just that i'm not really recording anything at the moment, i just wanted to know where i could get one when I needed to really.

i've already got a small battery box that came with a mic that kinda works, but runs off an AA 1.5v battery, and i remember having some problems with it in the past when I used it with my minidisc, but i've not had any real chance to try it out yet (lack of interesting/loud gigs to go to) so for all i know it works fine, and would save me buying another. but i was kinda hoping it wouldn't, and that the mic would break aswell, then i could get a battery box *and* mics off you as they both seem to come highly recommended :)

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What kind of mic is it?

technology wise, no idea, but it's one of these:

http://www.altra.net.pl/sklep/product_info...products_id=124

it was cheap (off ebay) and the recordings don't sound too bad, good enough for me anyway. i recorded this with the mic plugged straight into an md's mic socket: http://www.inaudible.co.uk/temp2/The%20Cri...wps%202005).mp3

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Maybe this post is little bit off topic, but still. Could anyone know how to build shotgun type microphone? I need shotgun mic for my camcorder, but i don't want to pay so much money and i can't find any good information about them. Could anyone help me out and tell me how shotgun mics work? Alot thanks!

Edited by pisialvar
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Shotgun mics are highly directional mono mics, they work much like a tele lens - they focus on the sound directly in front of them and isolate surrounding sounds to a great part. Good for speech, but not so great for ambient recordings.

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Shotgun mics are highly directional mono mics, they work much like a tele lens - they focus on the sound directly in front of them and isolate surrounding sounds to a great part. Good for speech, but not so great for ambient recordings.

Yes, i acknowledge, but that's also the reason why i need it- for camera, recording interviews and directional sound capturing. But could you tell what is it needed for making one? Or what is the main idea to follow? Or can it be done with simple stuff at all?

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The second is called a shotgun microphone. Here, the microphone element is placed within a tube that has equidistant slot openings on the sides. This results in producing sound wave interference inside the tube and wave cancellation of sounds arriving at the slots simultaneously, in other words, from 90 degrees right and left of wherever the microphone is aimed. In effect, this sound wave cancellation increases the relative sensitivity of the microphone in the direction that it is pointed.

from http://www.oldbird.org/mike_home.htm, and check out the last post at http://www.camcorderinfo.com/content/a_sho...or_the_kids.htm, most of which i'm sure you know already but i'm bored...

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