How to build a Stereo Microphone and Battery Box

[lpmaskmancick]

I taken the clips from the clippable ID card's back.

[md-newbie]

I made one of these but my recording was too soft and waaaay too much bass. I used

1.0 uF Tantalum capacitors 35w

.25w 5% tolorance 4.7k ohm Resistors.

I was going to try again with the following:

2.2 uF Electrolytic Capacitor 50V

and either

.25w 5% tolorance 10k ohm Resistors. or

.50w 5% tolorance 10k ohm Resistors. or

Does the wattage value make a difference at all for this on the resistors???

[greenmachine]

If you want bass roll off, use capacitors of lower value.

[coded]

greenmachine,

Thanks for all your notes on this. I had made a battery box about 4 years ago that was just like this and it worked well at loud concerts. I sold it all ( MZ R700 ) but now I wish I had it all back for another concert.

This time around, I want to do something smaller than a MD and altoids battery box. I've got a 2nd gen Nano so I've ordered an iTalkPro to go with that. This time I won't have to change discs in the middle, just cut the wav file. With the inline components + battery input, it should be pretty slick if the recording quality is good. It has a line level mic input that I can set Hi or Low impedance. Any opinions on which setting I will like?

Also, what are people's opinions on reclaimed surface mount components?

I, too would like to pursue using surface mount components, whether salvaged from decommissioned PCBs or new from manufacturers. I'm fairly new to this and electronics in general (recording engineering course is helping to thrust me into this area faster).

I ordered 20 WM-60A's from digi-key yesterday and they'll be in my hands in a few days. Until then, I've only had experience with Radioshack electret capsules. As a result of many attempts and variable results, I'm feeling a bit more confident on soldering skills. SO... I'll be happy to help anyone on the same path, viceversa..

(oh, and not all the 20 capsules will be used for this project.. plan to use some of them for experimental drumkit miking.)

My first post.

[A440]

Welcome, coded.

Let us know the results of your experiments.

[ldzeppelin]

I just finished a copycat of the dental floss battery box to replace the Sound Professionals box I have that has a short in it. I got to use it last week for Split Lip Rayfield and Reverend Horton Heat and I haven't gotten to play with the recording much yet I'm very pleased so far. Thank you VERY much GM for doing this post several years ago. I wish I had something like this when I first invested several hundred dollars on a piece of equipment that isn't as easy to smuggle in and is harder to change the battery out!

Now, I would like to do a new set of mics but as the preferred elements in this post are now discontinued, what is the new standard? Is there one yet? I bought a few radio shack elements that were on clearance for $.47 just to play with so I don't ruin a good set but need to get some good ones. I'd like to try to make a set in a pair of earphones for an even better stealth set.

Thanks again to all who have contributed to this thread!

[greenmachine]

You're welcome. The WM-61's are still available at digikey and other vendors AFAIK.

[mdcplas]

Since the WM-61A is rated at 2 volts.

Couldn't you just wire in a 1.5volt AA or AAA battery 1 for left and 1 for right and just use a capacitor on the line in for left and again for right channel?

This would exclude the resistors since the voltage is under the rated volt.

NM I needed to read the datasheets.

Edited May 12, 2009 by mdcplas

[lloser]

First of all I want to appologize for my lousy English; I'm not a native speaker and hope you don't care.

I'd like to thank Greenmachine for his detailed instructions. Really great. I'm really no expert in electronics, but after buying the needed components and a soldering iron I was able to built the bbox.

But there is one question left. To the mics I meter a potential about 9 V, this should be o.k.

To the recorder I meter about 2 V when I start to meter and then slowly (in 4 seconds) decending to about 0.2 V.

Ist this normal or is this voltage a problem for the recorders input ?

Thanks for your help.

Lloser

[greenmachine]

To the recorder I meter about 2 V when I start to meter and then slowly (in 4 seconds) decending to about 0.2 V.

Ist this normal or is this voltage a problem for the recorders input ?

Most recorders should be able to handle the initial peak. An idea would be to connect the battery before connecting box and recorder.

[dumaisaudio]

I've got two Sony ECM-55's that I'm looking to wire into a stereo pair for use with a battery box and my MD NF-810. I haven't made the battery box yet. My question is, the capsules I've seen pictures of in this thread are unbalanced, only having two leads. The ECM's have three leads (red, white, shield), how should I wire them up? I've been scanning this thread, but I haven't seen anything yet, so I figured I'd post. I've also looked around quite a bit on other sites, but I haven't come up with a definitive answer.

[coded]

I've got two Sony ECM-55's that I'm looking to wire into a stereo pair for use with a battery box and my MD NF-810. I haven't made the battery box yet. My question is, the capsules I've seen pictures of in this thread are unbalanced, only having two leads. The ECM's have three leads (red, white, shield), how should I wire them up? I've been scanning this thread, but I haven't seen anything yet, so I figured I'd post. I've also looked around quite a bit on other sites, but I haven't come up with a definitive answer.

not quite sure on the wiring but when you have balanced, you have two signals and one is out of phase (red and white). then the circuit at the other end would have to use both signals to create a cleaner overall signal, in turn canceling out RF and other such interference..

hmm. sorry i can't contribute more..

EDIT:

oops, correction... the two signals are the same, i think one signal is sent out of phase at the circuit end.

Edited May 13, 2009 by coded

[mdcplas]

First of all I want to appologize for my lousy English; I'm not a native speaker and hope you don't care.

I'd like to thank Greenmachine for his detailed instructions. Really great. I'm really no expert in electronics, but after buying the needed components and a soldering iron I was able to built the bbox.

But there is one question left. To the mics I meter a potential about 9 V, this should be o.k.

To the recorder I meter about 2 V when I start to meter and then slowly (in 4 seconds) decending to about 0.2 V.

Ist this normal or is this voltage a problem for the recorders input ?

Thanks for your help.

Lloser

Your seeing the initial voltage because the capacitors have not fully charged. Once charged then your using them as a DC Block. As long as they are charged and not discharged you shouldn't see the 2 volts on the plug again.

I've got two Sony ECM-55's that I'm looking to wire into a stereo pair for use with a battery box and my MD NF-810. I haven't made the battery box yet. My question is, the capsules I've seen pictures of in this thread are unbalanced, only having two leads. The ECM's have three leads (red, white, shield), how should I wire them up? I've been scanning this thread, but I haven't seen anything yet, so I figured I'd post. I've also looked around quite a bit on other sites, but I haven't come up with a definitive answer.

the ECM-55 I think is the whole Mic isn't it not just the Electret. if so then something like this would work best for you. http://www.bhphotovideo.com/bnh/controller...ow_to_High.html

Edited May 13, 2009 by mdcplas

[dumaisaudio]

the ECM-55 I think is the whole Mic isn't it not just the Electret. if so then something like this would work best for you. http://www.bhphotovideo.com/bnh/controller...ow_to_High.html

I'm actually not sure it's the ECM-55. It's one of the models (44, 55, 66, 77), but they don't say the model number on them, and they all look very similar. They're hardwired to an 1/8" connector, but when I plug it into my mic-in jack on my MD, I hardly get anything when everything's at full, and only out of the left channel. I guess the plug-in power isn't enough for it? I'm going to build the battery box first and see if that amplifies it more first. Then I'll work on wiring two together to make a stereo pair.

I'm just going to do trial and error, and I'll try to post my results.

[mdcplas]

I'm actually not sure it's the ECM-55. It's one of the models (44, 55, 66, 77), but they don't say the model number on them, and they all look very similar. They're hardwired to an 1/8" connector, but when I plug it into my mic-in jack on my MD, I hardly get anything when everything's at full, and only out of the left channel. I guess the plug-in power isn't enough for it? I'm going to build the battery box first and see if that amplifies it more first. Then I'll work on wiring two together to make a stereo pair.

I'm just going to do trial and error, and I'll try to post my results.

Well 2 are grounded and the other isn't. I'm not sure which is which though. You can put a multimeter to it and find out. the two wires that buzz back are ground the other wouldn't be

[grahame]

I had a crack at building a battery box today, the end result being:

Not the smallest, but it will do.

Thanks a lot for such a great guide

G.

Edited May 17, 2009 by Grahame

[Strungup]

For anyone interested , here is a Link to my Preamps

http://forums.minidisc.org/index.php?s=&am...st&p=142697

[coded]

Hm.. Had a chance to fully test the mics/ bat box very close to the stage of a show.... Sounds GREAT and never peaked on the meter. Annoying problem is when people out of a quieter area suddenly scream out for 5 seconds, there is a sine sweep over the duration of said bursts.... anyone deal with this and know of a solution?

[coded]

Hm.. Had a chance to fully test the mics/ bat box very close to the stage of a show.... Sounds GREAT and never peaked on the meter. Annoying problem is when people out of a quieter area suddenly scream out for 5 seconds, there is a sine sweep over the duration of said bursts.... anyone deal with this and know of a solution?

No suggestions yet? I might have a theory for now.. when I chose the pair of capacitors (came in a pack of about 15-20 different kinds/ values) and when pairing the two, I noticed while the values matched, they were by different manufacturers and one was just slightly shorter in size. Can this be causing some kind of off-sync effect? You know how when you're mixing two signals closer (or further) apart in time? ... closer to describing it.

[bucsab12]

Hi all.

I am a real noob in the field of electronics but I was really impressed with this incredible DIY guide and I decided that I wanna try and build the microphones (the battery box is a little too tough for me right now but maybe someday...).

thank you very much greenmachine for the guide. It is very clear and I hope I will be able to upgrade my recording equipment with it.

I have some of the components that are needed for the assembly of the mics, and I will buy the rest but the only thing that I can't seem to find is the cable that is shown in the pics in the guide.

I have went through the 26 pages of this thread without finding a real answer on where to get it. The best solutions I found was either to take the cable from a cheap set of headphones or from an RCA to stereo cable but both solutions are pretty expensive. Since I'm a beginner I think one cable may not be enough because I may not succeed on my first try.

It will really help me if someone could add a link to the cable that is used in the guide, preferably from a site in the US like Digi-Key. I couldn't find any angled stereo plugs even on stereo to RCA cables.

Thank you very much in advance.

Yuval

Edited July 6, 2009 by bucsab12

[Malcolm Stewart]

...

I have some of the components that are needed for the assembly of the mics, and I will buy the rest but the only thing that I can't seem to find is the cable that is shown in the pics in the guide.

I have went through the 26 pages of this thread without finding a real answer on where to get it. The best solutions I found was either to take the cable from a cheap set of headphones or from an RCA to stereo cable but both solutions are pretty expensive. Since I'm a beginner I think one cable may not be enough because I may not succeed on my first try.

It will really help me if someone could add a link to the cable that is used in the guide, preferably from a site in the US like Digi-Key. I couldn't find any angled stereo plugs even on stereo to RCA cables.

Thank you very much in advance.

Yuval

I'm in the UK, and I've often found that the most cost effective route for buying the slim cable for microphones etc. is to buy cheap iPod style earphones, and then to cannibalise them simply to get the gold plated plugs and slim cable - not available elsewhere. I made a dummy head mic set-up some time ago, using my own head; and going from ordinary plated plugs to gold plated types acquired from earphones dropped the handling noise quite noticeably.

[bucsab12]

Thank you for the solution Malcolm Stewart.

But doesn't the slim cable of the headphones such as the Ipod ones, only contains two cables inside them so it could only be connected to one microphone? From the pictures in the guide, it seems like there are two cables that are attached and that are only split at the end, close to the point where the mics are attached. Can you explain to me how to attach the slim cable to two mics?

Can you please add some pictures of the mics that you have created?

Thank you very much

Yuval

[Malcolm Stewart]

Thank you for the solution Malcolm Stewart.

But doesn't the slim cable of the headphones such as the Ipod ones, only contains two cables inside them so it could only be connected to one microphone?

...

Yuval

My set-up uses two Yoga lapel style mikes inside wind-reducing Rycote furry covers mounted each side of my baseball cap, and very close to my real ears. From each mike there's a short mono lead to a combiner socket which I clip to my shirt or jacket. The stereo output from this is plugged into an inline socket connected to the ex-earphone lead.

To refresh my memory, I've opened the inline socket attached to the lead from the cheap head/earphones, and there's 3 wires. There's a common earth, and colour coded enamelled signal leads. These are only insulated by the heat soluble enamel, hence the compact size.

I can plug the gold-plated stereo connector directly into my Minidisc or into the battery box, as preferred. (As this lead is carrying DC to power the mikes, I guess it's more susceptible to noise from minor corrosion or tarnish, and the gold plating is a bonus.)

Hope I've made it clear.

NOTE: I've now moved from Minidisc to a Sony PCM-D50 solid state recorder. It's bigger than Minidisc, but I can see the screen easily, it's intuitive to use, and since getting it, I've not used my Minidisc recorders at all. There's simply no contest. (It's what the Minidisc interface should have been!)

[bucsab12]

Thanks Malcolm for the answer.

Being a total noob, it is hard for me to understand everything that you explained. I am sure it is a great solution but it is too complicated for me at this point. Even the DIY that was posted with photos is not 100% clear to me, not because of the guide itself (which is amazing and very clear) but because of my lacking in knowledge and experience in electronics.

About your recorder, I have read some amazing reviews about it and I would love to buy one but it is too expensive for me at this point at around $500. I am thinking of buying a Zoom H2. I know there are some quality differences between the two recorders but I think I will start from the cheap stuff and if I will like the world of recording, I might buy a more professional recorder like the Sony.

Thank you for your help

[pattycakes77]

i had purchased a battery box years ago and now i want to build my own similar to what was matched with my mics. i took the HUGE battery box apart to find that it was super small, i don't know why they put it into such a large shell except to make me think i was getting my money's worth. anyway, i've checked the hand drawn schematic in this thread and it looks very similar to what was inside my battery box, my question though is: the + lead from the 9V battery was disconnected when i disassembled the battery box and i'm not sure what it went to. the negative lead is connected to the two resistors though, which seems backwards compared to the schematic shown in this thread. originally the mics and battery box mated via an XLR connector, what i want to do is hard wire the mics directly to the battery box and have a 1/8" plug come out of the battery box to go into my recorder. i made one of these years ago so this is not totally new. i guess what i'm asking is, would there be something wrong with replicating my old battery box with the +/- reversed from what the schematic here says, and if so where would the + from the 9V go then? also, if i do follow the schematic from the picture, where does the ground from the 9V battery attach to?

thanks from an electronics novice.

[mark18]

anyone try this with smd components? if so, what did you use? i'm thinking this can be made smaller by using smd components. use 6 1.5v watch batteries, though i'm not sure how long it would last and what the trade off in cost would be for the batteries.

i did make one using this schematic in a mint tin. mounted the jacks in the bottom of the tin, so the only way you can tell it's a battery box is to turn it over. i mounted the capsules in 1/4" diameter brass tubing. covered it with shrink tubing and riveted on an alligator clip. came out VERY nice.

[StillBurnin]

I want to make a mono mic with 2 capsules. I presume I would only use half the circuit(ie 1 resistor and 1 Capacitor) but with 2 panasonic capsules connected how would the resistor and capacitor values change?

Or just connect the L+R outputs together from the stereo circuit?

Any help gratefully recieved.

Cheers

Steve0

[lpmaskmancick]

I've made a wiring diagram in sPlan 7.0 beacuse green machine's one is not available. Luckily I drew on a piece of paper the diagram and I find it and made it in sPlan.

[Giant_Rick]

Thanks for saving!

[coded]

anyone try this with smd components? if so, what did you use? i'm thinking this can be made smaller by using smd components. use 6 1.5v watch batteries, though i'm not sure how long it would last and what the trade off in cost would be for the batteries.

i did make one using this schematic in a mint tin. mounted the jacks in the bottom of the tin, so the only way you can tell it's a battery box is to turn it over. i mounted the capsules in 1/4" diameter brass tubing. covered it with shrink tubing and riveted on an alligator clip. came out VERY nice.

hey mark, any luck with the smd's? i had also thought about watch batteries, like you said. ultimately, i was unsure where everything should go to cut down on outer clutter/ tangled wires. also, with my last build (no smd's), i encountered audible artifacts when someone close by suddenly burst over the volume on stage. how can that be fixed?

[Decius]

I'm planning to build a box but I'm totally new to this and hence lost as to how i can optimize it for my mic.

This is a schematic provided by the manufacturer: http://www.sanken-mic.com/upload/pdf/jp/wiring/2wirebasis_e.pdf

Can anyone explain to me in layman terms what exactly the purpose of the resistor and capacitor are on this diagram? From all the research I've done, all I have gathered is that the capacitor "cleans" the signal in some manner.

However, I'm reading places where they say there may be a DB gain as a result of the resistor. How can there be a gain if the voltage is reduced?

I completely realize these may be stupid questions, but I took woodworking.

[Malcolm Stewart]

I'm planning to build a box but I'm totally new to this and hence lost as to how i can optimize it for my mic.

This is a schematic provided by the manufacturer: http://www.sanken-mic.com/upload/pdf/jp/wiring/2wirebasis_e.pdf

Can anyone explain to me in layman terms what exactly the purpose of the resistor and capacitor are on this diagram? From all the research I've done, all I have gathered is that the capacitor "cleans" the signal in some manner.

However, I'm reading places where they say there may be a DB gain as a result of the resistor. How can there be a gain if the voltage is reduced?

I completely realize these may be stupid questions, but I took woodworking.

The actual microphone capsule, within the dotted lines on the left of your diagram, requires power to work the FET amplifier. (A FET (Field Effect Transistor) is used because it has the best characteristics for these types of microphone which have a very high impedance - i.e. take very little current.) This power is supplied via the 10kohm load resistor, although I wouldn't describe it as a "load" resistor in this application. The 1 microfarad capacitor stops the DC voltage from the supply upsetting the amplifier (triangle with "Output" as label), and passes the alternating signal from your microphone to the amplifier's input.

If you've got little experience in this area, please do try to stop electrostatic voltages from damaging the electrical components when you're assembling things. For example, try not to wear nylon clothing, and if possible have all your components on a conducting metal surface e.g. aluminium foil, on which your forearms can rest. Also, do make sure that your soldering iron is electrically SAFE. I'd advise Googling for "ESD" and "static safe working".

e.g.

http://en.wikipedia.org/wiki/Electrostatic_sensitive_device

http://www.hakko.com/english/static/pages/esd.html

Damage from static discharge may be instantaneous, or it may weaken the component, and problems will arise later. Hope I haven't worried you, but a few basic precautions should help you have it working first time.

[TEKWRX]

Just want to say "thanks" to everyone in this thread, especially GREENMACHINE. Built my battery box today with parts from Radio Shack, and seems to be working fine (tested in my car's sound system cranked way up ) Total cost was around $20, less the half the cost of buying pre-built.

[valdis]

I had an old set of Koss Sparkplugs here and a pair of Panasonic electrets and tried to make some binaural mics.

I cut the wires from the earplus, picked the left wire and soldered the two tiny wires to "left mic" (signal and ground), doing the same for the "right mic".

I was able to mount these mics on the earplug facing outwards. This way I can wear them the same way as usual but as recording devices.

The only recording machine I have at the moment with me is my laptop with Windows Vista (a Toshiba A200-221), which I used for testing. I connected the mics to the mic input, right clicked the volume icon, went to sound specs and confirmed the mic input was set to record in stereo. Then I used Windows Recorder and captured the sound of a shaking matchbox around my head.

Listening to the audio file with my headphones, there isn't any channel separation, no binaural effect.

What have I might done wrong?

[valdis]

Nevermind, the mic input in mono, althought Vista and Audacity see it as stereo.

[cosmicmonster]

So that's what they look like inside! As the proud owner of both of these gems it would be quite remiss of me if I didn't share some of the spoils. As soon as the gallery is back up and running I'll post some samples.

So, the gallery isn't alive anymore? By the way, thanks this is an awesome project!