Linkwitz Mods On Panasonic WM61A Mic - Page 6 - diyAudio
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Old 10th July 2012, 03:04 PM   #51
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Quote:
Originally Posted by teleman View Post
Here is a schematic og WM61 capsule wired for balanced input! The entire article can be found on

Suite101.com: Online Magazine and Writers' Network



PS:Please note that the "Caps" are drawn wrong,but the orientation is correct!
Hi folks,

My first post here, I've lurked on and off for years but figured I'd sign up today to pick your brains! Sorry if this isn't really the right place to ask these questions, but it's specifically about this capsule so..

I do a bunch of DIY Audio stuff, but not quite on the level of you lot. Take a look if you like: Gallardo Sound.

So, I built the circuit (two of them in fact) I quoted up there this morning, so I can power a binaural dummy-head using the WM61As from phantom power. It reads at 12v where the mic connects, and for all intents and purposes it works, having tested it via my usb interface. There's a very strong buzz, but that's another question really.

My main question is, will that circuit work with the Linkwitz mod? I want to be able to use the dummy-head at gigs, and I understand I'll need to do the mod to avoid distorting the capsule. My secondary question is, is the Linkwitz mod really necessary for recording gigs?? I did manage to distort the capsules with the head located about a foot from a crash symbol, but it seemed to handle my mate bashing seven shades out of the kit.

Sorry for barging in with my decidedly amateur questions!
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Old 20th September 2013, 11:32 AM   #52
EUVL is offline EUVL  Europe
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Here is one for Scott (Wurcer).
I hope you are watching.




Patrick
Attached Files
File Type: pdf US2011228954A1.pdf (517.1 KB, 119 views)
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Old 20th September 2013, 12:38 PM   #53
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this is all prior art. every B&K capsule amp has this circuit, it is called bootstrapping.
the drain is getting the same signal as the source to bootstrap away the non-linear drain gate capacitance
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Old 20th September 2013, 02:31 PM   #54
EUVL is offline EUVL  Europe
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Yes, except that Scott did it differently in his article in Linear Audio Vol.3.
And most of th eperformance gain comes from the CCS load, not the bootstrap.


Patrick
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Old 20th September 2013, 02:36 PM   #55
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the CCS load can also be done by bootstrapping into the mid of the source resistor, this will linearize the loading on the source. this methods usually gives a lower noise than a discrete electronic current source.
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Old 20th September 2013, 02:47 PM   #56
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Can you post a (partial) schematics ?


Patrick
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Old 20th September 2013, 08:30 PM   #57
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Quote:
Originally Posted by EUVL View Post
Here is one for Scott (Wurcer).
I hope you are watching.




Patrick
I don't see much new here. Did I show that little circuit with just two bipolars and capsule? It gets as much out of a WM61 as possible, "distortionless" output of volts and no added noise. I sort have gotten tired of explaining that you can't improve the noise except maybe by cutting away the baffle which grossly effects the flatness. People still put in a 2SK170 which makes the noise worse, the WM61 is just too small.

BTW electret microphones do not require an external bias, these guys are very confused. I also disclosed the feedback via the cut pin on the capsule on the micbuilders site years before this, didn't see the point of including it in the article because the capsule where the case is an input is hard to use. Zap or Eric could confirm that.
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Last edited by scott wurcer; 20th September 2013 at 08:39 PM.
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Old 20th September 2013, 09:16 PM   #58
EUVL is offline EUVL  Europe
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Yes you did (the 2 BJT circuit).
Thanks for the hints and comments.


Cheers,
Patrick
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Old 22nd September 2013, 06:45 AM   #59
1audio is offline 1audio  United States
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Unfortunately Panasonic exited the mike business, The WM61A is passing into history. Someone needs to find a successor. For flatness ST has some new MEMS mikes that are quite good with extended low frequency response. The SNR is very limited though. MEMS microphones - STMicroelectronics
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Old 22nd September 2013, 03:55 PM   #60
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Default Panasonic and another question

I have a catalog downloaded on another PC from another company that I found after extracting an ECM capsule from something I tore apart. They have a very broad line with cross references to Panasonic and other mfrs.

I'll come back & post it.

Actually, I think I'll start a new question because the capsule's I'm working on are neither brand.
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