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Gear / Technical Help => Microphones & Setup => Topic started by: digifish_music on November 18, 2007, 02:00:03 AM

Title: Building your own binaural mics ~ $20
Post by: digifish_music on November 18, 2007, 02:00:03 AM
Inspired by the various sites  (http://www.uwm.edu/~type/audio-reports/PanasonicWM-61A_OtherBinauralRigs/WM61A_Webpage_Caps_Mounts.html) showing people building stereo/binaural mics from a set of Panasonic WM-61A capsules (http://www.panasonic.com/industrial/components/pdf/em06_wm61_a_b_dne.pdf). I decided to have a go myself.

Step 1.  Buy some WM61-A capsules on eBay  (http://cgi.ebay.com/Panasonic-WM-61A-Electret-microphone_W0QQitemZ150290456682QQcmdZViewItem?_trksid=p3286.m20.l1116) ($15 for 10 seems good).

Step 2. Note how small the contacts are and realize life will be much easier if you buy some cheap headphones and steal the cable. That way you end up with a nice fully formed right-angle plug but more importantly perfectly tinned/shielded wires ready to use (no cutting, wire stripping or fiddling - the key to a stress free build). $10 for some Sony cheapies, selected due to the low price and right-angled plug.

(http://www.digifishmusic.com/public/images/11-binaurals.jpg)

(http://www.digifishmusic.com/public/images/12-binaurals.jpg)

Step 3. De-solder the headphones (BTW: I dunked the unsoldered ends of the cable in a cup of boiling water to help straighten out the kinks from the knots) slip your shrink-wrap up the cable and and re-solder on the capsules. I didn't even need to apply any more solder, just hold the two together, briefly touch with the tip of the iron and zap! done. The shield-wire goes to the tabbed capsule connector..this is too easy, surely something is wrong  ;D

Step 4. Matching capsules -

Tip for quick-matching the output of capsules.

- Put a bunch of capsules (in a line) face-down on a speaker laying on it's back (you need something with a smooth flat grille, radio?)
- Tune the radio to FM hiss.
- Plug the de-soldered headphone lead into your recorder and put into record mode so you can see the levels.
- Work your way along the line of caps manually connecting the leads to the cap terminals, note the recording level.
- Pick two that are closest. While you are there match up the rest into pairs for later.

(http://www.digifishmusic.com/public/images/13-binaurals.jpg)

Step 5. Test they are working.

(http://www.digifishmusic.com/public/images/14-binaurals.jpg)

Step 6. Shrink-wrap the capsules.

(http://www.digifishmusic.com/public/images/15-binaurals.jpg)

Step 7. Compare to Sound Professional binaurals misc (http://www.soundprofessionals.com/cgi-bin/gold/item/SP-TFB-2)...(normal sensitivity models)...they sound identical...job done.

(http://www.digifishmusic.com/public/images/16-binaurals.jpg)

Took 15 minutes, total cost ~USD $20

NOTES:

1. No I didn't do the mod of cutting the tab and modifying the capsule connections (http://www.hpfriedrichs.com/images-projects/audio-mscheme.gif) as I wanted to retain the S/N for field-recording work. If you want to go that path I think it is definitely better to just buy them complete from  SP or similar vendors. The stock capsule handles around 110 dB so, that's loud enough for me.

2. The ear-clips with my original models are very useful and make them worth the extra $40...I was really doing this just to see if I could...and I could :)

3. Next step, use another two capsules to make a stereo hydrophone...:D (http://taperssection.com/index.php/topic,96012.msg1279094.htm)

4. EDIT: To hear example field recordings from these microphones type in "Panasonic wm61-a" into the search engine at freesound http://www.freesound.org/searchText.php Note: To download the original recordings (high quality) you will need to create an account.
 
digifish
Title: Re: Building your own binaural mics ~ $20
Post by: attheshow on November 18, 2007, 03:00:14 AM
+T for going DIY! Looks good.
Title: Re: Building your own binaural mics ~ $20
Post by: SmokinJoe on November 18, 2007, 11:00:24 AM
This is a great idea for cases where you don't want to bring your other mics...  rainy festivals, salt air party boat jams...  if something bad happens, your not out much.
Title: Re: Building your own binaural mics ~ $20
Post by: run_run_run on November 18, 2007, 12:25:02 PM
h0t +T
Title: Re: Building your own binaural mics ~ $20
Post by: ArchivalAudio on November 18, 2007, 09:55:28 PM
very nice work!
anyone ever look into the Knowles telemetry caps?
I believe that you can still get  (or could a few years back) some sort of Nak 700 caps from them which would be sweet!
Title: Re: Building your own binaural mics ~ $20
Post by: illconditioned on November 18, 2007, 10:48:45 PM
very nice work!
anyone ever look into the Knowles telemetry caps?
I believe that you can still get  (or could a few years back) some sort of Nak 700 caps from them which would be sweet!

+++++++++++T

I've used various Knowles caps, but did not find an appropriate one for taping.
What caps are you referring to?

  Richard
Title: Re: Building your own binaural mics ~ $20
Post by: boojum on November 19, 2007, 12:15:29 AM
This fellow goes into a great lesson on how-to, and then shows you how to build the battery box to go with it:

http://forums.minidisc.org/index.php?showtopic=11254
Title: Re: Building your own binaural mics ~ $20
Post by: stirinthesauce on November 19, 2007, 12:47:50 AM
very nice work!
anyone ever look into the Knowles telemetry caps?
I believe that you can still get  (or could a few years back) some sort of Nak 700 caps from them which would be sweet!

primo made the Nak capsules.  They are still available.
Title: Re: Building your own binaural mics ~ $20
Post by: digifish_music on November 19, 2007, 07:20:08 AM
This fellow goes into a great lesson on how-to, and then shows you how to build the battery box to go with it:

http://forums.minidisc.org/index.php?showtopic=11254

Nice find, thanks...

About the mod, it's not clear to me if you need to just swap what terminal is grounded or you need to expose the copper below the circuit board and attach to that. It seems if it's just swapping the grounded terminal then a blob of solder shorting to the case should do?

digifish
Title: Re: Building your own binaural mics ~ $20
Post by: boojum on November 19, 2007, 01:32:08 PM
This fellow goes into a great lesson on how-to, and then shows you how to build the battery box to go with it:

http://forums.minidisc.org/index.php?showtopic=11254

Nice find, thanks...

About the mod, it's not clear to me if you need to just swap what terminal is grounded or you need to expose the copper below the circuit board and attach to that. It seems if it's just swapping the grounded terminal then a blob of solder shorting to the case should do?

digifish


Best bet: write greenmachine who wrote the original series at minidisc. 
Title: Re: Building your own binaural mics ~ $20
Post by: ArchivalAudio on November 30, 2007, 01:46:17 AM
very nice work!
anyone ever look into the Knowles telemetry caps?
I believe that you can still get  (or could a few years back) some sort of Nak 700 caps from them which would be sweet!

primo made the Nak capsules.  They are still available.
do you have any links to any of these primo nak caps... whaere might one find them?
thanx
Title: Re: Building your own binaural mics ~ $20
Post by: fluffy on December 05, 2007, 10:19:44 PM

awesome

man when i made some of these and played back what i had recorded for the first time in a very dark room it scared me so much i freaked and ran for the light switch!! hahahaha  :laugh:
Title: Re: Building your own binaural mics ~ $20
Post by: stirinthesauce on December 06, 2007, 09:27:48 AM
very nice work!
anyone ever look into the Knowles telemetry caps?
I believe that you can still get  (or could a few years back) some sort of Nak 700 caps from them which would be sweet!

primo made the Nak capsules.  They are still available.
do you have any links to any of these primo nak caps... whaere might one find them?
thanx

do a advanced search on here with the word "primo"  search the mic section, yard sale (there is one thread there in particular).  Tons of info.  I know, I did the search myself recently.  Team Nak also has great info but you'll have to sift through the other talk.
Title: Re: Building your own binaural mics ~ $20
Post by: Roger Gustavsson on December 06, 2007, 02:09:18 PM
You can find the Primo CM4052PMI4 microphones on ebay or directly at www.tucker.com. The correct name is EM4052PMI4 and the capsules EM50. I have got an original dokument from Primo on these. 
Title: Re: Building your own binaural mics ~ $20
Post by: illconditioned on December 06, 2007, 02:12:13 PM
You can find the Primo CM4052PMI4 microphones on ebay or directly at www.tucker.com. The correct name is EM4052PMI4 and the capsules EM50. I have got an original dokument from Primo on these. 

I've got a spare pair of these FS if anyone wants them.
(I bought four, but only need two.)

  Richard
Title: Re: Building your own binaural mics ~ $20
Post by: Nick's Picks on December 11, 2007, 02:42:47 PM
well done.

now, if you want to do a full knock off...mount them in a hacked .22 caliber shell.
:-)
Title: Re: Building your own binaural mics ~ $20
Post by: bdasilva on December 12, 2007, 08:38:14 AM
Please.. if this intersts you... Come and join the Yahoo group "micbilders"  We would love to have you.
Title: Re: Building your own binaural mics ~ $20
Post by: Nick's Picks on December 12, 2007, 09:04:04 AM
i know nothing about building mics though....
outside of wiring up panasonic capsules.
:0
Title: Re: Building your own binaural mics ~ $20
Post by: Church-Audio on December 12, 2007, 09:12:00 AM
well done.

now, if you want to do a full knock off...mount them in a hacked .22 caliber shell.
:-)


Actually its a .25 :)
Title: Re: Building your own binaural mics ~ $20
Post by: Church-Audio on December 12, 2007, 09:17:29 AM
When you guys get really good with the old soldering iron you can do my mod to the Panasonic capsule to increase the Max spl. here is a photo That is a 4.7k resistor between the capsule ground and the ground pad on the capsule.

The trace between the two must be cut then the resistor is soldered into place, you then connect your ground wire to the ground side of the resistor and away you go :)

Now You can now enjoy much louder shows distortion free. And its not to difficult to do. I use a 1% metal film 1/8th watt resistor then epoxy the wire onto this and use a brass tube to encase the capsule.
Title: Re: Building your own binaural mics ~ $20
Post by: Nick's Picks on December 12, 2007, 09:28:02 AM
nice soft hands you got there Chris.
lots of lotion, i take it?
;-)
Title: Re: Building your own binaural mics ~ $20
Post by: Church-Audio on December 12, 2007, 09:43:38 AM
nice soft hands you got there Chris.
lots of lotion, i take it?
;-)


LOL yep how did you guess? :)
Title: Re: Building your own binaural mics ~ $20
Post by: Gutbucket on December 13, 2007, 11:09:20 AM
How do the Primo caps compare to the Panasonic's?  I have a lingering project I want to play around with someday, basically a reverse heaing aid for overly loud concerts that would double as in-ear phones for recording monitoring.  I'd mount the caps on the in-ears.
Title: Re: Building your own binaural mics ~ $20
Post by: illconditioned on December 13, 2007, 01:33:01 PM
How do the Primo caps compare to the Panasonic's?  I have a lingering project I want to play around with someday, basically a reverse heaing aid for overly loud concerts that would double as in-ear phones for recording monitoring.  I'd mount the caps on the in-ears.

I've experimented with this.  I've got a set of Westone in-ear monitors (molded earpiece).  I run my "hat mics" into the Edirol R09, then headphone out drives the Westones.  If I want to get really geeky I put on ear muffs (to block all outside sound).  Yes, this works, but in the end I just wear Etymotic -25dB earplugs or, if really loud, just solid (molded) earplugs (-30dB or more attenuation).  I don't really need to listen to what is going on, since my hat mics are in about the same place as my ears.

Monitoring is a big problem in general, though.  Even for FOH (sound) guys, I imagine.  The problem is the signal to noise ratio is too low to monitor in the venue.  You really need a sound booth or a back room of some kind.

  Richard
Title: Re: Building your own binaural mics ~ $20
Post by: Gutbucket on December 13, 2007, 05:24:33 PM
Yeah, I sometimes put on earmuffs on over my etymotics to do the same thing.. and yes it does feel dweebish.

I think a new thread is in order, maybe I can rope in some other sources of DIY brain power to put some more thinkin' on this.

http://taperssection.com/index.php/topic,95631.msg1273697.html#msg1273697

Title: Re: Building your own binaural mics ~ $20
Post by: digifish_music on August 07, 2008, 06:55:17 PM
I am just bumping this thread as I now have quite a few field recordings up using these at www.freesound.org

To hear example field recordings from these microphones type in "wm61-a" into the search engine at freesound -

http://www.freesound.org/searchText.php

Note: To download the original recordings (high quality) you will need to create an account.

digifish.
Title: Re: Building your own binaural mics ~ $20
Post by: anechoic on August 07, 2008, 07:27:21 PM
contact Lori Rodriguez at Primomic - contact info below
she was very very helpful
hope this helps!
:)

Primo contact info:
Lori Rodriguez
<lrodriguez@primomic.com>
Primo Microphones, Inc.
1805 Couch Drive
McKinney, TX  75069
Phone: 972-548-9807 ext. 19
Fax: 972-548-1351
www.primomic.com
Title: Re: Building your own binaural mics ~ $20
Post by: marksk on August 08, 2008, 02:15:20 PM
contact Lori Rodriguez at Primomic - contact info below
she was very very helpful
hope this helps!
:)

2nd that!
Title: Re: Building your own binaural mics ~ $20
Post by: Church-Audio on August 08, 2008, 02:27:20 PM
I also have stock of primo mic capsules. I would be glad to sell some to any diy person that might need some in small quantities.

Chris
Title: Re: Building your own binaural mics ~ $20
Post by: anechoic on August 08, 2008, 02:32:25 PM
@Chris
which Primo caps do you stock?
Title: Re: Building your own binaural mics ~ $20
Post by: Scooter on August 08, 2008, 03:51:42 PM
scrounged up this Primo link from text above.  kinda interesting.  20Hz-10k response though....  might be fun to play with, and kinda stealthy.

http://cgi.ebay.com/NEW-Primo-CM4052PMI4-Precision-Condenser-Microphone_W0QQitemZ230243213961QQihZ013QQcategoryZ50590QQrdZ1QQssPageNameZWD1VQQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247 (http://cgi.ebay.com/NEW-Primo-CM4052PMI4-Precision-Condenser-Microphone_W0QQitemZ230243213961QQihZ013QQcategoryZ50590QQrdZ1QQssPageNameZWD1VQQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247)
Title: Re: Building your own binaural mics ~ $20
Post by: Church-Audio on August 08, 2008, 04:22:53 PM
scrounged up this Primo link from text above.  kinda interesting.  20Hz-10k response though....  might be fun to play with, and kinda stealthy.

http://cgi.ebay.com/NEW-Primo-CM4052PMI4-Precision-Condenser-Microphone_W0QQitemZ230243213961QQihZ013QQcategoryZ50590QQrdZ1QQssPageNameZWD1VQQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247 (http://cgi.ebay.com/NEW-Primo-CM4052PMI4-Precision-Condenser-Microphone_W0QQitemZ230243213961QQihZ013QQcategoryZ50590QQrdZ1QQssPageNameZWD1VQQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247)
I have had quite a few pairs of these. They actually sound very good very warm sounding although they are huge! they can be modified to run 2 wire or three wire. And the short cables are easily replaced. They only take a max of 12 volts.

Chris
Title: Re: Building your own binaural mics ~ $20
Post by: Scooter on August 08, 2008, 05:00:24 PM
good to know ;)
Title: Re: Building your own binaural mics ~ $20
Post by: Church-Audio on August 08, 2008, 05:36:23 PM
@Chris
which Primo caps do you stock?


Em123, 125, em135 and (EM63. but I only have two of these) The others I have quite a few of.




Chris
Title: Re: Building your own binaural mics ~ $20
Post by: anechoic on August 08, 2008, 06:37:26 PM
I sent you a pm about the EM-125
Title: Re: Building your own binaural mics ~ $20
Post by: marksk on August 09, 2008, 06:09:46 PM
i don't see the em-63 on their site, is it similar to the em-68?

the 68 says it can be configured as a 2-wire or 3-wire mic. is this done by wiring two of the terminals to ground?
Title: Re: Building your own binaural mics ~ $20
Post by: illconditioned on August 09, 2008, 07:43:23 PM
i don't see the em-63 on their site, is it similar to the em-68?

the 68 says it can be configured as a 2-wire or 3-wire mic. is this done by wiring two of the terminals to ground?

Em68 has three wires (two on the PC board, one to the case).  You can run either two wire or three.
I don't know the color of the wires though.

If it is like AT853, then there are three: shield, yellow and red.
There are three possibilities:
- short yellow to shield, red to miniplug: this is two wire
- put a 4.7k resistor between yellow and shiedl, red to miniplug: this is two wire "4.7k mod"
- keep three wires, red, yellow, shield > 3 wire battery box

Internally all AT853 mics use the third option, with a 5.1k resistor inside for a load.  So, the 4.7k mod is OK.  Disadvantage is it loses pprox 6-12dB gain, but to avoid distortion it is well worth it IMO.

  Richard
Title: Re: Building your own binaural mics ~ $20
Post by: anechoic on August 09, 2008, 07:58:11 PM
mod'ing Behringer ECM8000 mics:
http://www.directap.com/Microphones.htm
you can pick these up for around $50 USD new
I'm sure you can find them around used as well
Title: Re: Building your own binaural mics ~ $20
Post by: anechoic on August 09, 2008, 08:17:54 PM
scrounged up this Primo link from text above.  kinda interesting.  20Hz-10k response though....  might be fun to play with, and kinda stealthy.

http://cgi.ebay.com/NEW-Primo-CM4052PMI4-Precision-Condenser-Microphone_W0QQitemZ230243213961QQihZ013QQcategoryZ50590QQrdZ1QQssPageNameZWD1VQQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247 (http://cgi.ebay.com/NEW-Primo-CM4052PMI4-Precision-Condenser-Microphone_W0QQitemZ230243213961QQihZ013QQcategoryZ50590QQrdZ1QQssPageNameZWD1VQQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247)
I have had quite a few pairs of these. They actually sound very good very warm sounding although they are huge! they can be modified to run 2 wire or three wire. And the short cables are easily replaced. They only take a max of 12 volts.

Chris


@Chris
it's hard to tell from the photo on eBay but these Primo mic bodies won't take the EM-23 caps...will they?

edit: the eBay spec says the Ø is 14 mm
the EM-23 spec states the cap Ø is 21 mm
so I guess they won't
what would be a good replacement cap that has a better self-noise and top end?
:)
Title: Re: Building your own binaural mics ~ $20
Post by: Church-Audio on August 09, 2008, 08:21:17 PM
scrounged up this Primo link from text above.  kinda interesting.  20Hz-10k response though....  might be fun to play with, and kinda stealthy.

http://cgi.ebay.com/NEW-Primo-CM4052PMI4-Precision-Condenser-Microphone_W0QQitemZ230243213961QQihZ013QQcategoryZ50590QQrdZ1QQssPageNameZWD1VQQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247 (http://cgi.ebay.com/NEW-Primo-CM4052PMI4-Precision-Condenser-Microphone_W0QQitemZ230243213961QQihZ013QQcategoryZ50590QQrdZ1QQssPageNameZWD1VQQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247)
I have had quite a few pairs of these. They actually sound very good very warm sounding although they are huge! they can be modified to run 2 wire or three wire. And the short cables are easily replaced. They only take a max of 12 volts.

Chris


@Chris
it's hard to tell from the photo on eBay but these Primo mic bodies won't take the EM-23 caps...will they?
:)

No these are smaller capsules they were used on a pair of nak capsules I forget the model number but they are identical. These were analyser capsules they all come with a calibration chart! Its a pretty good deal but again not much action about 14k

Chris
Title: Re: Building your own binaural mics ~ $20
Post by: digifish_music on August 09, 2008, 11:40:59 PM
mod'ing Behringer ECM8000 mics:
http://www.directap.com/Microphones.htm
you can pick these up for around $50 USD new
I'm sure you can find them around used as well


Thanks for the (great) link.

About the (miss attributed) "Linkwitz Mod" is actually the "Lyman Miller" mod.

While this may improve the mics high SPL performance, but does so at the expense of S/N for quiet recordings. I am disappointed how quickly people rush to this mod without thinking of the intended application for the mic.

digifish
Title: Re: Building your own binaural mics ~ $20
Post by: Church-Audio on August 09, 2008, 11:51:52 PM
mod'ing Behringer ECM8000 mics:
http://www.directap.com/Microphones.htm
you can pick these up for around $50 USD new
I'm sure you can find them around used as well


Thanks for the (great) link.

About the (miss attributed) "Linkwitz Mod" is actually the "Lyman Miller" mod.

While this may improve the mics high SPL performance, but does so at the expense of S/N for quiet recordings. I am disappointed how quickly people rush to this mod without thinking of the intended application for the mic.

digifish

Yes that is true about the mod.. The site is kinda scary though this picture scared the crap out of me...
Title: Re: Building your own binaural mics ~ $20
Post by: Church-Audio on August 10, 2008, 12:55:54 AM
While this may improve the mics high SPL performance, but does so at the expense of S/N for quiet recordings. I am disappointed how quickly people rush to this mod without thinking of the intended application for the mic.

That's really not true per se.  It very much depends on the following circuit.  The inclusion of a source resistor greatly reduces distortion at all levels, not just the very high SPLs where you might hear clipping.  But besides, it doesn't necessarily increase self-noise.

The schemos on that site are all source follower configuration, where the gain of the FET is essentially unity.  If the following stage is nearly as noisy as the capsule noise, then yes, you will degrade self-noise.  But the noise limitation of these capsules isn't the FET, it's the capsule itself.

Where you might run into trouble is with a "two-wire" configuration, where you are operating the capsule FET in common source configuration.  If you increase the value of the source resistor above your bias supply resistor, you will attenuate the capsule signal, and the self-noise of the following amplifier stage could become a factor.  This can be avoided by selecting suitable values for the two resistors, and also a suitable supply voltage.

Or you may simply be feeding a noisy preamp, such that even unity gain results in a noise level below the equivalent input noise of the preamp.  But that's not a mic noise problem, it's a noisy preamp problem.

Incidentally, many of the conclusions about the circuits on that website are basically wrong or misguided.  For example, if you want to simplify the circuit, why keep both PNP transistors with one ground-referenced?  When with the same number of components, you could pull a balanced signal off the capsule FET as a phase splitter (as in the Schoeps circuit)?  The advantage of Schoeps is an extra 6dB of sensitivity, which is gonna help that preamp noise problem, to be sure.

I also love his last circuit--NOT!  Seriously, he's afraid of zener diodes?  That's because he hasn't filtered them properly!  Again, study the Schoeps circuit and see how it is done--the zener regulation of the capsule has some series resistance to improve the function of the filter capacitor.  He hasn't done that, that's why he goes zener-less.

But that comes at a cost--he has to select the value of R7 to work within a relatively narrow range of phantom supplies.  There's really no reason for that; any electret mic should be designed to work from 12V to 48V with no fuss.  So I think Behringer has built a better circuit than he has, although I agree there are redundancies in Behri's circuit and probably components that could be improved in quality.  Still, Behri has made some better decisions--6V for the zener is plenty to keep the capsule happy, and it is less noisy than a 12V zener.  Therefore, Behri's noise filtration works better, even though I don't think either is adequate.  Of course, Behri didn't use the source resistor, so their SPL handling will be limited.

I love his statement that he hasn't tested his last circuit.  How does he know it is quieter?  It might be, it might not.  12V zeners are noisy beasts, and very inconsistently so.  He could select a particularly bad zener and think he was a genius for omitting it, but that is still no substitute for a better circuit design.

I suspect most of his circuit improvement comes from the higher quality of WM61A over the Behri capsule (NOT a Panasonic capsule, despite what you might hear on the interwebs), and of course the addition of the source resistor.  The rest of his circuits are rubbish compared with the well-known Schoeps.

Rubbish wow... Wonder what you think of my circuits... BTW did you get my pm?  ;)

Chris
Title: Re: Building your own binaural mics ~ $20
Post by: Kindguy on August 10, 2008, 03:14:22 AM
Love the DIY great job Tzzzz around.
Title: Re: Building your own binaural mics ~ $20
Post by: Church-Audio on August 10, 2008, 10:30:33 AM
scrounged up this Primo link from text above.  kinda interesting.  20Hz-10k response though....  might be fun to play with, and kinda stealthy.

http://cgi.ebay.com/NEW-Primo-CM4052PMI4-Precision-Condenser-Microphone_W0QQitemZ230243213961QQihZ013QQcategoryZ50590QQrdZ1QQssPageNameZWD1VQQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247 (http://cgi.ebay.com/NEW-Primo-CM4052PMI4-Precision-Condenser-Microphone_W0QQitemZ230243213961QQihZ013QQcategoryZ50590QQrdZ1QQssPageNameZWD1VQQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247)
I have had quite a few pairs of these. They actually sound very good very warm sounding although they are huge! they can be modified to run 2 wire or three wire. And the short cables are easily replaced. They only take a max of 12 volts.

Chris


@Chris
it's hard to tell from the photo on eBay but these Primo mic bodies won't take the EM-23 caps...will they?

edit: the eBay spec says the Ø is 14 mm
the EM-23 spec states the cap Ø is 21 mm
so I guess they won't
what would be a good replacement cap that has a better self-noise and top end?
:)

There is no cap I know of that will fit on this mic. But improvements might be able to be made to the existing capsule to improve the top end
Think about the mic capsule housing it self. Part of the problem with this mic is the silly little phase plug they put in front of the capsule.

Chris
Title: Re: Building your own binaural mics ~ $20
Post by: Church-Audio on August 10, 2008, 11:14:42 AM
Rubbish wow... Wonder what you think of my circuits... BTW did you get my pm?  ;)

Chris


OK rubbish is a bit strong . . . but if you use the same number of components as the long-published and oft-copied Schoeps circuit, but build a materially worse circuit, that's not very good!  I mean I've built plenty of mics that had higher output impedance, lower SPL handling, lower efficiency than the traditional PNP output pair (and I have built better circuits too).  But I always had a different reason for that--either size, or parts count, or intended application, etc.  Every circuit is a compromise.

But that last circuit of his really annoyed me, paraphrased:  "zeners are bad; here's a circuit I haven't tested!"  Well, test it before you say it's so great next time!  And he says that circuit is "perhaps the ultimate"?  Actually, I'm not even sure it would work properly--when he removed the zener, he also removed the DC source for the PNP, leaving just the capsule FET.  I might build that myself and check it out.  But if you ask me, build this circuit:

http://www.epanorama.net/circuits/microphone_powering.html#phantom

Under "better phantom powering circuit"


PS I did see your PM, but even that is a bit much for me.



Yeah I do have to admit its pretty lame to have published a circuit that he has not even tested and say its better then a circuit with a zener diode.
Title: Re: Building your own binaural mics ~ $20
Post by: SparkE! on August 10, 2008, 12:10:59 PM
Rubbish wow... Wonder what you think of my circuits... BTW did you get my pm?  ;)

Chris


OK rubbish is a bit strong . . . but if you use the same number of components as the long-published and oft-copied Schoeps circuit, but build a materially worse circuit, that's not very good!  I mean I've built plenty of mics that had higher output impedance, lower SPL handling, lower efficiency than the traditional PNP output pair (and I have built better circuits too).  But I always had a different reason for that--either size, or parts count, or intended application, etc.  Every circuit is a compromise.

But that last circuit of his really annoyed me, paraphrased:  "zeners are bad; here's a circuit I haven't tested!"  Well, test it before you say it's so great next time!  And he says that circuit is "perhaps the ultimate"?  Actually, I'm not even sure it would work properly--when he removed the zener, he also removed the DC source for the PNP, leaving just the capsule FET.  I might build that myself and check it out.  But if you ask me, build this circuit:

http://www.epanorama.net/circuits/microphone_powering.html#phantom

Under "better phantom powering circuit"


PS I did see your PM, but even that is a bit much for me.


Ha! That's great!  He removes the zener diode and does nothing to provide the regulated voltage to bias the FET.  Actually, it will bias at the Vds breakdown voltage for FET that's trying to be the low noise front end of the signal chain.  Not only that, but the FET also becomes the DC bias path for the bias resistors in the output stage.  I've seen this circuit somewhere else before and I'm thinking that this guy doesn't do any of his own design work.  I think he pulled that off of a message board somewhere.  Cut and paste. ;D
Title: Re: Building your own binaural mics ~ $20
Post by: anechoic on August 10, 2008, 05:00:40 PM
very good thread and nice to have so much brain-trust here! :)
debunking DIY audio can save us all from audio mythology and bad information
thanks to all for weighing in on this schemo
:)

 
Title: Re: Building your own binaural mics ~ $20
Post by: moooose on August 11, 2008, 03:22:50 AM

Em123, 125, em135 and (EM63. but I only have two of these) The others I have quite a few of.

Chris


Chris, PM sent regarding caps
Title: Re: Building your own binaural mics ~ $20
Post by: run_run_run on August 17, 2008, 07:22:57 PM
I build a set and ran them in the rain night 1 for the up north fest.  They sound great, should work fine if your in a good location and the sound is good.

http://www.archive.org/details/eo2008-08-08.wa61s

I went into a 9 volt battery box, I am assuming they benefit from that vs plug in power on my iriver? 
Title: Re: Building your own binaural mics ~ $20
Post by: digifish_music on August 17, 2008, 09:04:45 PM
I build a set and ran them in the rain night 1 for the up north fest.  They sound great, should work fine if your in a good location and the sound is good.

http://www.archive.org/details/eo2008-08-08.wa61s

I went into a 9 volt battery box, I am assuming they benefit from that vs plug in power on my iriver? 

+T thanks for sharing, I downloaded the MP3 .zip. As you say if you are in the right spot, it's hard to justify the extra $400+ for a set of better mics :)

Mic placement & baffling have a big impact with omnis.  The only issue these mics have is that they are a little more noisy than fully good professional small diaphragm condensers, but you are not going to notice that recording bands. This field recording (for example) I was sitting between the mics (laid on a bench) acting as a baffle, the result is excellent IMO...

http://www.freesound.org/samplesViewSingle.php?id=53799

http://www.freesound.org/samplesViewSingle.php?id=53800

http://www.freesound.org/samplesViewSingle.php?id=54167

digifish.
Title: Re: Building your own binaural mics ~ $20
Post by: anechoic on August 18, 2008, 12:44:32 PM
@digifish
your recordings are interesting but to my ear there is a large 'hole' in the center of the stereo stage
which might be exaggerated by using your body as a baffle instead of something like a Jecklin disc
but this is common on many of the baffled omni recordings I've heard

speaking of interesting stereo stages
check out this binaural recording done by composer Enrico Coniglio:

http://www.touchmusic.org.uk/TouchPod/Sapientumsuperacquis.mp3

made with OKM's->Zoom H4 @ 96kHz/24bit

I like the spread and depth of the recording
enjoy!
:)
Title: Re: Building your own binaural mics ~ $20
Post by: run_run_run on August 21, 2008, 08:05:18 PM
This sounds really good

The Wailers

http://bt.etree.org/details.php?id=517973
Title: Re: Building your own binaural mics ~ $20
Post by: marksk on August 26, 2008, 01:53:57 PM
can the 4.7k mod be done on the em-135? i see a small solder joint from the center of the capsule to the earth pad, but nothing to the case. does the small solder joint get cut to do the mod, or can it not be done to this capsule?
Title: Re: Building your own binaural mics ~ $20
Post by: travelinbeat on August 26, 2008, 02:51:24 PM
Could anyone recommend some nice stealthy mic capsules that I can use in this technique to record high-volume situations in Croakie mounts?
Title: Re: Building your own binaural mics ~ $20
Post by: run_run_run on September 03, 2008, 06:05:22 PM
who needs high priced mics
http://www.archive.org/details/waybacks2008-09-01.Panasonic_WM61_Omnis

indoors balcony rail split about a foot
Title: Re: Building your own binaural mics ~ $20
Post by: rastasean on September 03, 2008, 06:17:02 PM
who needs high priced mics
http://www.archive.org/details/waybacks2008-09-01.Panasonic_WM61_Omnis

indoors balcony rail split about a foot


Hey Seth,

You make a great point.
Can people really tell the difference between your style mics and schopes when its the same music, same location, same recorder, etc. I would like to think I can but I know I can't at all.
Good music + good mic position + good PA mix would generally make the best type of recording. If I get a pair of schopes and take them to a slipknot show [insert crappy music here] I can probably get a good recording but the music will be crappy.

happy taping!
Title: Re: Building your own binaural mics ~ $20
Post by: run_run_run on September 03, 2008, 06:29:07 PM
its all about location, room and the mix. In these case the three where great, and the 61s where more then up to the task.
Title: Re: Building your own binaural mics ~ $20
Post by: illconditioned on September 03, 2008, 07:07:12 PM
who needs high priced mics
http://www.archive.org/details/waybacks2008-09-01.Panasonic_WM61_Omnis

indoors balcony rail split about a foot


Hey Seth,

You make a great point.
Can people really tell the difference between your style mics and schopes when its the same music, same location, same recorder, etc. I would like to think I can but I know I can't at all.
Good music + good mic position + good PA mix would generally make the best type of recording. If I get a pair of schopes and take them to a slipknot show [insert crappy music here] I can probably get a good recording but the music will be crappy.

happy taping!
I agree that 90% of it is performance, then placement, then room/PA/soundsystem.

But I also observe that if you have an imperfect placement and/or soundsystem, a better mic will still give a "listenable" recording.  I think it comes down to the fact that humans have a great ability ot "filter out" noise (the so-called "coctail party effect").  But to filter out noise, they need to be able to hear it clearly.  So, a "clean" recording of a slightly bad room might sound better than a "muddy" recording of the same room.  This is just my own theory, but I've certainly made a lot of recordings in less than ideal situations.

Another point is diminishing returns.  The $2 Panasonic capsule is actually very good, and this was not available just a few years ago.  These are reasonable quality and consistent (due to mass production).   But if you spend $100 or even $1000 for a mic, you will get an improvement in sound.  How far you want to go is up to you, though..

By the way, I have some Panasonic recordings at my website http://Soundmann.com.  Now I'm particularly fond of the Countrman B3, which are about the same size as the WM61 capsule, but they have (imo) a much more detailed and natural sound than the Panasonic.  Of course they are approx $150 each, so not for everyone.

 Richard
Title: Re: Building your own binaural mics ~ $20
Post by: run_run_run on September 03, 2008, 08:03:28 PM
I would have used my nak Omni's, but my 9100 is getting worked on. I don't plan on ditching the naks, but the 61s are a great back up / 2nd set of mics.
Title: Re: Building your own binaural mics ~ $20
Post by: run_run_run on September 04, 2008, 10:06:23 PM
any good low costs cards caps out there?
Title: Re: Building your own binaural mics ~ $20
Post by: illconditioned on September 05, 2008, 12:17:27 AM
any good low costs cards caps out there?
(good sounding) cardioid caps are *much* harder to construct.

In the small size, my favourite are the Sennheiser MKE40.  These don't have great bass response, but the mids are just beautiful.  Clear and detailed.  I've got some clips at http://Soundmann.com.  They remind me a bit of the Neumann KM184 sound.  Not transparent, but very nice and clear.

I'm not using cards much nowadays though.  Since I have great access at most (local) venues, I'm just using omnis... as close as I can get them.

  Richard
Title: Re: Building your own binaural mics ~ $20
Post by: run_run_run on September 08, 2008, 06:49:18 PM
They sound even better with the UA-5s pre and ADC

http://www.archive.org/details/aod2008-09-06.Panasonic_WM61A_Omnis_UA5
Title: Re: Building your own binaural mics ~ $20
Post by: run_run_run on October 25, 2008, 07:17:54 PM
anyone know where you can find polar charts for the Panasonic caps? I want to compare them to my new C3s to guess how the omni setting would work at a local venue.
Title: Re: Building your own binaural mics ~ $20
Post by: run_run_run on October 25, 2008, 11:27:20 PM
anyone know where you can find polar charts for the Panasonic caps? I want to compare them to my new C3s to guess how the omni setting would work at a local venue.

I don't have a chart handy, but WM61A is VERY omni.  It's a true pressure omni rather than an "electrical" omni as in the C3 (which derives its omni from back-to-back cardioids).  You don't see a significant drop in directional response until above 10kHz.
Lacking allot of technical knowledge, that was my gut feeling.  That's what I like about the 61s very omnish 
Title: Re: Building your own binaural mics ~ $20
Post by: Gutbucket on October 28, 2008, 10:39:10 PM
omnish

+T
Title: Re: Building your own binaural mics ~ $20
Post by: run_run_run on November 16, 2008, 04:20:03 PM
Listened to some recordings I made with them on a very pricey Stereo, sounded a tad boring. I think a W-mod something would help them. Thoughts?
Title: Re: Building your own binaural mics ~ $20
Post by: run_run_run on January 25, 2009, 04:40:03 PM
I ran onstage with these last night and I even mic'd a guitar amp
Title: Re: Building your own binaural mics ~ $20
Post by: HarpDoc on January 27, 2009, 09:37:03 PM
I recorded for a couple years with DIY Panasonic mics, with the SPL mod, mounted in Croakies and a hat. Got some respectable recordings, but my CA-11's (in Croakies) are noticeably better.
Title: Re: Building your own binaural mics ~ $20
Post by: digifish_music on January 27, 2009, 10:10:34 PM
I ran onstage with these last night and I even mic'd a guitar amp

Example recordings?  ::)
Title: Re: Building your own binaural mics ~ $20
Post by: run_run_run on January 27, 2009, 11:04:48 PM
I ran onstage with these last night and I even mic'd a guitar amp

Example recordings?  ::)
I was in a jam, I will post it latter
Title: Re: Building your own binaural mics ~ $20
Post by: illconditioned on January 28, 2009, 02:18:23 AM
I recorded for a couple years with DIY Panasonic mics, with the SPL mod, mounted in Croakies and a hat. Got some respectable recordings, but my CA-11's (in Croakies) are noticeably better.
On my website (http://Soundmann.com) I've got some self-made WM61a recordings (with Linkwitz, similar to 4.7k mod).  The sound is very good for starter gear.  That's what started me in this crazy game.

  Richard
Title: Re: Building your own binaural mics ~ $20
Post by: DaveH on June 03, 2009, 12:19:02 PM
I thought I would bump this up, I just got some Radio Shack microphone elements with the wires running out. I looked around here, but did not find any information, or pictures illustrating how to soldier this in with a headphone wire. I've never done anything like this, but it looked like a neat project and I'd like to give it a go. Can anybody provide any tips or pointers?
Title: Re: Building your own binaural mics ~ $20
Post by: ycoop on May 10, 2018, 04:04:02 PM
Zombie bump.

Is this something that could be done as a starter soldering project?
Title: Re: Building your own binaural mics ~ $20
Post by: digifish_music on May 11, 2018, 12:36:44 AM
Sure.

The only issue here are these headphone wires are very fine, so check out some YouTube tutorials on working with them...

https://www.youtube.com/watch?v=WlRyQe-O5ME

PS: I am still using the binaurals I made in this tutorial, so they proved robust. I upgraded my recorder a few times tho ;)

(http://www.digifishmusic.com/images/binauralmics.jpg)
Title: Re: Building your own binaural mics ~ $20
Post by: ycoop on May 11, 2018, 02:39:37 AM
Right on.

I’ve got an electrical engineer friend who is open to teaching me about basic soldering. Should be fun :)
Title: Re: Building your own binaural mics ~ $20
Post by: Hypnocracy on May 11, 2018, 09:27:45 AM
What is a good replacement/substitute for the  WM61-A capsules? Or are the Chinese Panasonic WM-61A102A versions equivalent in sound reproduction?
Title: Re: Building your own binaural mics ~ $20
Post by: ycoop on May 12, 2018, 04:32:23 PM
What is a good replacement/substitute for the  WM61-A capsules? Or are the Chinese Panasonic WM-61A102A versions equivalent in sound reproduction?

Doing some research has led me to the JLI-61A with specs identical to the WM-61A. Haven't been able to find any first hand reports of using them though.

I've also found a design for a battery box to amplify the signal to line level.

http://forums.sonyinsider.com/topic/14343-how-to-build-a-stereo-microphone-and-battery-box/

Edit 5/17:

Decided to go ahead and buy 8 of the JLI-61A capsules on eBay for around $23 total including shipping. FWIW, they claim the design perfectly replicates the WM-61A. I’d imagine at a normal volume show these show too much distortion if used at mic level?
Title: Re: Building your own binaural mics ~ $20
Post by: ycoop on May 23, 2018, 12:47:30 AM
Built these mics using the JLI 61a capsules

(forum tools don't seem to be working properly, so here's a direct link: https://www.ebay.com/itm/Panasonic-WM-61A-Replacement-Microphones/352220785310?hash=item5201feaa9e:g:W2cAAOxybi9ReW5o:sc:USPSPriority!94703!US!-1)

Here's the recordings I made walking around my neighborhood.

https://drive.google.com/drive/u/0/folders/15m5O0c5U3bqpPo_I5qxw6eZsOj8ZSLaj

Sound pretty good to me. Looks like I misjudged the matched-ness of the capsules, with the left one being a few dB higher than the right judging by visual levels alone, nothing that I could notice when I was relistening.

What do you all think?