How to build a Stereo Microphone and Battery Box

[moddhayward]

I'm not sure about the specs of the diode, but it should not be a z-diode. Mic capsules with a higher current consumption will need resistors with a lower value. The higher the value, the better the channel separation. The mini mics I use consume less than 1mA a pair, 6.8 or 10k resistors work nicely.

That's brilliant - thank you! Would you be able to post a photograph of the insides to show us how you made it so neat too? ;-)

[greenmachine]

That's brilliant - thank you! Would you be able to post a photograph of the insides to show us how you made it so neat too? ;-)

You're welcome. Here are the pics:

I've then used electric tape to isolate everything properly and put some heat shrink tube around it.

[mark18]

what's the mAh draw? would a 12 volt, 59mAh battery work?

http://www.batteryspace.com/index.asp?Page...&ProdID=914

[mark18]

one more question - are some caps recommended over others? for example, on the head-fi.org forums, the diyers all like black gate and nichicon capacitors in their audio circuits. would they be of benefit here or would any generic caps/resistors do?

thanks!

[greenmachine]

one more question - are some caps recommended over others? for example, on the head-fi.org forums, the diyers all like black gate and nichicon capacitors in their audio circuits. would they be of benefit here or would any generic caps/resistors do?

thanks!

The mA draw depends on the mic capsules used. It's usually below 1 mA. The mentioned battery should work. I have not been able to hear any differences between capacitors or resistors as yet. If you use resistors with a low tolerance rating (1%), you won't have to match them yourself.

[Hrvoje]

Build one yesterday, recorded with it today. Works great! Thanx for detailed instructions.

I think I'll make few more just for fun.

[greenmachine]

Updated first post with matching information.

[linton]

can you give me a combination for a tight budget

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John Davis

Link Building

[mignal]

For those who are new to soldering and a little concerned about over-heating the module. Over the years I have built many Hi-Fi amplifiers, from Vacuum tube to solid state efforts. Quite often I would use flux (plumbers flux) to good effect, it really does minimise the amount of time the soldering iron needs to be in contact with solder points. For those who are experienced it offers little advantage save for pre-tinning wires.

Let us take the example of soldering the leads to the 2 points on the module. Assuming that we have our screened cable stripped with the copper cores twisted, coat the bare copper ends in the plumbers flux. You need a very fine smear all around, nothing more. Apply solder to the tip of the soldering iron, in other words take a 'bite' of solder - it should float on the tip of the soldering iron. Too much of a 'bite' and it will run off and gravity takes over. Now take your cable lead and apply the tip of your soldering iron to the twisted copper bare end. You should find that the solder very quickly coats the whole of those twisted ends- you have 'tinned' the lead.

Once cool take your tinned lead and once again give it a very fine coat of the plumbers flux. I mean a VERY FINE COAT, wipe off the excess if necessary. Using an old matchstick pick up a very slight dab of the flux and apply it to the centre of the solder point on the module. Again it's just a very, very slight smear and ONLY on the centre of those solder points - too much and there is a danger of the flux running and causing a short between the 2 points. Now place your tinned lead in the centre of the solder point of the module. Apply the tip of the soldering iron and remove it as soon as the solder melts. As soon as I remove the soldering iron I blow on the module to cool it.

It is ALWAYS advisable to do practice runs using spare wire and on solder points where the results don't matter. Save the actual mic. modules for when you are confident of your abilities.

Whilst plumbers flux is given as being corrosive, in over 25 years of using it for electronic applications (namely tinning wires) I have not found it to be a problem when used as per my directions. I see no advantage to using it when soldering components to Printed Circuit Boards.

[mark18]

good advice, that's the way i did it and it made it very easy.

also use some clips on the capsule to act as a heat sink and absorb some of the heat.

[mignal]

I haven't had much time to evaluate my attempt (recently built). I don't have a minidisc or any decent interface to try it so I just plugged it into the Mic. input of my laptop and recorded a few seconds of Nylon guitar playing. Despite a lot of hiss I like the signature of these modules, a little on the bright side but that's fine with me. Let's just say that my previous Samson USB mic. is going to the bin - otherwise known as Ebay.

I'll try the source follower mod sometime soon but I really do need to get myself a decent recorder or interface.

[md-newbie]

Need help confirming my wiring on this as I haven't done anything electrical for 25 years.

Parts used were (2) 1/8" 3.5mm jacks from radio shack, (2) 1.0 uF Tantalum capacitors 35w, (2) .25w 5% tolorance 4.7k ohm Resistors.

In the picture, the planned solder points are noted

Questions (sorry for the list but i'm new at this).

-Any anticipated probs with the parts I've used? It for a MZ-R70 with Sound Professionals BMC-1 mics

-I'm not sure I have the right/left channels right on the jack (they arent marked but I determined the right by the lower contact point on the plug when inserted.

-I'm not sure is the line on the side of jack is a neg that needs to be wired to anything or a ground..DO I NEED TO WIRE THIS TO ANYTHING?

-Any way this can screw up the mics or the MD if wired wrong?

If you cant see, the plans have:

Positive from battery soldered jointly to 3 pts on the back (2 resistors in and wire from battery)

R1 out soldered on the back to 3 pts (R1 out, C1+, and right of jack1)

R2 out soldered on the back to 3 pts (R2 out, C2+, and left of jack1)

C1(-) soldered to left of jack2

C2(-) soldered to right of jack2

If this is wrong or right, please letme know. I'd like some feedback before I connect. THANKS!

Edited August 28, 2008 by md-newbie

[Hrvoje]

Need help confirming my wiring on this as I haven't done anything electrical for 25 years.

Parts used were (2) 1/8" 3.5mm jacks from radio shack, (2) 1.0 uF Tantalum capacitors 35w, (2) .25w 5% tolorance 4.7k ohm Resistors.

In the picture, the planned solder points are noted

Questions (sorry for the list but i'm new at this).

-Any anticipated probs with the parts I've used? It for a MZ-R70 with Sound Professionals BMC-1 mics

Sounds perfectly good to me.

-I'm not sure I have the right/left channels right on the jack (they arent marked but I determined the right by the lower contact point on the plug when inserted.

As long as you connect to L to the same contacts both on microphone and recorder connector (as well as the remaining R) it is fine, since you did nothing to reverse them. From the image you supplied it is clear that you connected channels in the same order to both connectors.

-I'm not sure is the line on the side of jack is a neg that needs to be wired to anything or a ground..DO I NEED TO WIRE THIS TO ANYTHING?

Yes, BATT NEG should be connected to the third contact on both MIC and REC connector. Circuit has to be closed if you want the flow.

-Any way this can screw up the mics or the MD if wired wrong?

Not sure. As far as I understand it, this is just about powering the microphone. Recorder should not be affected at all as far as recorder side contacts are separated from the power source by capacitors, and that is the case.

Finish it up, test it and give some feedback please.

Hrvoje

[md-newbie]

Sounds perfectly good to me.

As long as you connect to L to the same contacts both on microphone and recorder connector (as well as the remaining R) it is fine, since you did nothing to reverse them. From the image you supplied it is clear that you connected channels in the same order to both connectors.

Yes, BATT NEG should be connected to the third contact on both MIC and REC connector. Circuit has to be closed if you want the flow.

Not sure. As far as I understand it, this is just about powering the microphone. Recorder should not be affected at all as far as recorder side contacts are separated from the power source by capacitors, and that is the case.

Finish it up, test it and give some feedback please.

Hrvoje

Finished it up and seems to work...much lower db on first test so I assume that means its working compared to line in mic jack...still need to test with loud music and compare better but thanks for the assistance and reply!

[TygerBrightly]

Hi!

Thanks first of all to Greenmachine for the info and instructions on building the mics and battery boxes. I have built a number of mics, including the binaural set and an element in a 3.5mm jack, which is ideal for turning the MD into a dictaphone, but can be used plugged into the BB and you have a holder like a pistol grip by the 9v battery, with sufficient lead to not pick up the MD sound! I built the BB box directly onto a broken top of the 9v battery (without circuit board) and even after covering it with hot melt glue, it is really quite small.

As a further touch, I connected it to the battery then wrapped two turns of insulating tape round the top of the battery, covering with hot melt glue to make a shield. When it set and cooled I removed the battery and trimmed the "hood".

Also, bang up to date in 2008, (I am not surprised this thread has lasted so long with such excellent content :-)) try eBay for Panasonic elements in the UK, I got 5 WM61A elements for £9.95 inc postage. (£18 for 10).

Hope this helps, and thanks again for such innovative ideas!

TygerBrightly

[TygerBrightly]

Deleted double post

Edited October 2, 2008 by TygerBrightly

[TygerBrightly]

A couple of questions, if I may please?

When using binaurals on my MD, I find that the batteries drain rather quickly (I know they use power from the mic input). My chewing gum batteries may as well be made from chewing gum, they have faded, somewhat so I tend to use them with the AA battery buddy pack.

If I use the home built battery box as designed by GM, the power is supplied, so the MD unit lasts longer but, the sound is somewhat different. There is a nice brightness when the mics are used on their own, but it tends to change with the BB added (still connected to the mic input). I wish to use the system for background sound for Video recording presence ambience and general wildlife birdsong and stuff, so the full spectrum (including bright treble) would be useful. I wonder if it is due to the rating of the capacitors in the BB?

1) Is it worth building another battery box with different specs for general work, or should I just use the (little bulkier) 2xAA extra power pack I made, plugged into the 3v socket (or the even bulkier 2xD cell unit)? In the BBs I made, I have used so far 47uf 10v, 22uf 16v, 100uf 25v and 33uf 50v caps, but have the following pairs in my bits, if any would be more suitable: 47uf 25v, 1uf 100v, 4.7uf 63v and a 2.2uf 50v pair of one light and one dark blue(?)

2) In making a mono BB for a single mic capsule, would you suggest different values of resistor/capacitors, as stereo separation is no longer an issue?

Incidentally, the extra power packs I have made are a 2.5mm power jack soldered to an open lead 9v battery clip and then attached to twin AA or twin D cell battery boxes which have the 9v connections on top. I used a white tippex pen to write "3v only" on top of the battery snap clip, so a 9v battery is not inadvertently attached. The clips I got were the type that enclose the connections, so they cannot short in a pocket or case.

So sorry about the double post. I tried to edit it and it sent a duplicate instead of the edited original. How can I delete the second one please?

Edited October 2, 2008 by TygerBrightly

[greenmachine]

A couple of questions, if I may please?

When using binaurals on my MD, I find that the batteries drain rather quickly (I know they use power from the mic input). My chewing gum batteries may as well be made from chewing gum, they have faded, somewhat so I tend to use them with the AA battery buddy pack

Electret mics usually consume only up to about 1mA. It shouldn't have a significant effect on the recorder's battery life.

If I use the home built battery box as designed by GM, the power is supplied, so the MD unit lasts longer but, the sound is somewhat different. There is a nice brightness when the mics are used on their own, but it tends to change with the BB added (still connected to the mic input). I wish to use the system for background sound for Video recording presence ambience and general wildlife birdsong and stuff, so the full spectrum (including bright treble) would be useful. I wonder if it is due to the rating of the capacitors in the BB?

1) Is it worth building another battery box with different specs for general work, or should I just use the (little bulkier) 2xAA extra power pack I made, plugged into the 3v socket (or the even bulkier 2xD cell unit)? In the BBs I made, I have used so far 47uf 10v, 22uf 16v, 100uf 25v and 33uf 50v caps, but have the following pairs in my bits, if any would be more suitable: 47uf 25v, 1uf 100v, 4.7uf 63v and a 2.2uf 50v pair of one light and one dark blue(?)

The capacitors, as long as their rating is greater than approx. 1uF, shouldn't have a significant influence on the sound character. All they do is to filter direct current from the battery (1st order high pass filter).

2) In making a mono BB for a single mic capsule, would you suggest different values of resistor/capacitors, as stereo separation is no longer an issue?

You could use a somewhat lower value for the resistor, down to approx 1 kOhm.

Incidentally, the extra power packs I have made are a 2.5mm power jack soldered to an open lead 9v battery clip and then attached to twin AA or twin D cell battery boxes which have the 9v connections on top. I used a white tippex pen to write "3v only" on top of the battery snap clip, so a 9v battery is not inadvertently attached. The clips I got were the type that enclose the connections, so they cannot short in a pocket or case.

Why not just use a 9V battery? most electret mics can handle up to approx. 10V.

[TygerBrightly]

Thank you so much for your reply, and the excellent information within.

It is probable my MD units' chewing gum batteries are a bit useless, then, as I suspected, and I should perhaps use the extra battery pack certainly when recording. It is a relief to hear that the mics do not drain the battery

QUOTE

Incidentally, the extra power packs I have made are a 2.5mm power jack soldered to an open lead 9v battery clip and then attached to twin AA or twin D cell battery boxes which have the 9v connections on top. I used a white tippex pen to write "3v only" on top of the battery snap clip, so a 9v battery is not inadvertently attached. The clips I got were the type that enclose the connections, so they cannot short in a pocket or case.

Why not just use a 9V battery? most electret mics can handle up to approx. 10V. ENDQUOTE

The twin AA or D cell power packs are meant for the MD unit (3v) only; I use a 9v battery for the mics' battery box That is why I have marked the top of the 9v clip, so I don't inadvertently plug 9v into the Minidisc!

Many thanks,

TygerBrightly

[TygerBrightly]

On second thoughts, I could use a 9v battery for the MD units (with a resistor of course). Would it give longer recording times using a 9v battery, and what is the optimum resistor value if it is viable, please?

Many thanks,

Tygerbrightly

[greenmachine]

On second thoughts, I could use a 9v battery for the MD units (with a resistor of course). Would it give longer recording times using a 9v battery, and what is the optimum resistor value if it is viable, please?

Many thanks,

Tygerbrightly

That won't work, you might end up with damaging the unit. Stick to 3V or whatever they need.

[md-newbie]

OK I built one of these and tried it out for a test. not a loud show but the bass came in wayy too high and the recording level was verry low (used automatic levels on a mz-70).. should i change the resistors or capacitors in some way?? my build is posted earlier

[greenmachine]

a good mic position is important for a clear sound. try to place them as high and close as possible without any muffling barriers between the sound source and the receptors.

a battery box does not pre-amplify, so it is normal that the line-in levels are not too high.

[Kain_]

Here is what I'm currently using for live recording :

Cheers.

Franck.

[waterworks]

Who says nerds aren't cool!

[underclocker]

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?

[greenmachine]

Without having owned one, you'll most likely want to use the low setting. For loud concerts even this might pre-amplify too much. You'll have to try and see.

[Neilyboy]

I was bored today so I threw one together works great!

Very nice tutorial!! Thanks so much for all of the great information

Neil

[Giant_Rick]

What a great tutorial!!

I'll try to build both mic and battery box next week; will they work only with MD recorders or even with recorders such as Zooms, Edirols, Microtaks,..?

Anyone knows a place to buy the microphone capsules in Europe (I live in Italy, but I can buy from France, Spain, Portugal, Switzerland, Germany, Osterreich,....)?

Thank you.

Cheers!

[greenmachine]

It works with recorders equipped with a line and/or mic input. Try http://www.schlotzhauer-versand.de/ in Germany.

[Giant_Rick]

It works with recorders equipped with a line and/or mic input. Try http://www.schlotzhauer-versand.de/ in Germany.

Thank you for your reply!!

After writing my previous post, I went to the site you linked me (I missed it in the first post!) and found the mic; unfortunately shipping cost to Italy are 17 €.

Since I don't speak a word of German, could you please tell me what I exactely need in German language, in order to buy the stuff quickier than with my system (I look at picture and I decide if I need it or not)?

Danke!

[greenmachine]

Try this link, it's an overview of their mic capsules: http://www.schlotzhauer-versand.de/index.p...d3375895ba68c30

[Giant_Rick]

After some researches, I've found this site: www.banzaieffects.com

It's very expensive but it has almost everything. They even sell Panasonic WM-61A! Unfortunately they're 2,50€ each...

I'll place my order in a few days.

One question: how many mics should I buy (approximately) in order to get a matched couple? I mean, I can find a matched copule every 10, 20,.. mic? Or what?

And 1.2 mm heat shrinkable wire will work?

Sorry for asking too many question and being a sort of pain in the arse..

[greenmachine]

About 8 or 10 should be a good start. The heat shrink tube should be slightly larger in diameter than the capsules i.e. 6+ mm.

[Giant_Rick]

Thank you for your kind reply!

Edited January 17, 2009 by Giant_Rick

[Giant_Rick]

A friend of mine digs into electronic, so I managed to help building the mics and teh battery box; we'd like to build a preamp as well. What one should we build? How many dB and watts should have a preamp for MDs?

We looked at this preamp and we like it. (can we replace the 51pF capacitor with something else? And can we use only one pot for both channels? Is it ready to be used as MD preamp or do we need to do something else?),

And if we build both preampand battery box, hwo should I fill them? I thought something like MD recorded > preamp > battery box > microphones. Is it right?

Thank you for your help!

[IndustrialLive]

Can somebody tell me what I am doing wrong in my design? I attempted four times, but none of the times worked.

Edit: Nevermind, I figured it out thanks to Neilyboy.

Design.bmp

Edited January 29, 2009 by IndustrialLive

[dreamer69]

Hi. Im a complety stupid in electronics. Can someone do to me a battery box and I pay it by paypal?? thank you. Private message please.

[lpmaskmancick]

My homemade rig. I don't have MD rec, I have a flash recorder, it works good with it.

Edited February 18, 2009 by lpmaskmancick

[Giant_Rick]

Nice work! What did you use for the clips?