Omni electret elements...many questions....

[therecordingart]

I was going to start building a binaural head and was going to start with the Panasonic WM60AY, but they are discontinued.

-Is there an element out there that is just as good or even better?

-I'd like to not use batteries and power these elements with phantom power. They are only rated to take a max of 10vdc. How do I bring down the 48v to 10v?

Any help with this would be awesome.

 

[Martin B. Kantola]

[quote author="therecordingart"]
-Is there an element out there that is just as good or even better?[/quote]

Try the WM-61A and also look for on the web for a clever mod (by Siegfried Linkwitz) that gives you lower distortion at high SPL's. If you are willing to spend more money, there are probably other and better options. I've used some from Sennheiser.

[quote author="therecordingart"]
-I'd like to not use batteries and power these elements with phantom power. They are only rated to take a max of 10vdc. How do I bring down the 48v to 10v?[/quote]

Again, Google is your best friend, there are many ways to go. Try "electret microphone powering" or something similar.

Martin

 

[skipwave]

I've used the WM61A and the three-wire Linkwitz mod:

http://www.mp3forkidz.com/mic/mod.html

From the thread in the Black Market where mshilarious is selling WM55 capsules.....

[quote author="mshilarious"]Rather than cut the traces, I float the whole capsule above ground in common drain configuration and buffer the output with another transistor which also splits phase. If you want the lowest possible output impedance, follow that with the usual output pair, but I find that unnecessary. Be sure to isolate the capsule from the case, and shield it.

Resulting SPL with this capsule should exceed 126dBSPL at less than 1% THD--actually higher, but above that SPL my test system distortion rises enough to make a precise measurement difficult.

You will also get reasonable performance by simply using the internal FET as a phase splitter straight to the output, and that keeps noise and interference to a minimum. In that configuration, the capsule doesn't need to be shielded so much, but it should still be isolated from the case.

Digikey has a 10mm rubber mount that is handy for this type of circuit.[/quote]

 

[Svart]

look for the thread where Marik and I completed a cool little mic using those parts..

 

[skipwave]

[quote author="therecordingart"]-I'd like to not use batteries and power these elements with phantom power. They are only rated to take a max of 10vdc. How do I bring down the 48v to 10v?[/quote]

Scodiddly's simple phantom power scheme:

http://scotthelmke.com/phantom-power-2.jpg

 

[moosapotamus]

Here's some that I built...

http://moosapotamus.net/THINGS/mics.htm

Another slight variation on the phantom powered WM-61A mic, similar to Scott's scheme.

~ Charlie

 

[Guest]

http://www.jamminpower.com/PDF/Phased-Array%20Microphone.htm

 

[Guest]

[quote author="moosapotamus"]Here's some that I built...

http://moosapotamus.net/THINGS/mics.htm

Another slight variation on the phantom powered WM-61A mic, similar to Scott's scheme.

~ Charlie[/quote]

Charlie, you have an error on schemo (C1, R1)

 

[SSLtech]

[quote author="Wavebourn"][quote author="moosapotamus"]Here's some that I built...

http://moosapotamus.net/THINGS/mics.htm

Another slight variation on the phantom powered WM-61A mic, similar to Scott's scheme.

~ Charlie[/quote]

Charlie, you have an error on schemo (C1, R1)[/quote]

It agrees with the board layout though... if the boards work, then the schemo works. I'd say that the schemo is drawn correctly in terms of explaining the board... but I reckon you may want to try moving the "in +" connection to the OTHER end of R1... -Is that what you mean also, Wavebourn?

Keith

 

[Svart]

Ok, check here:

http://www.groupdiy.com/index.php?topic=3626&postdays=0&postorder=asc&start=15

Marik and I did these and they sound great.

 

[Guest]

[quote author="SSLtech"][quote author="Wavebourn"][quote author="moosapotamus"]Here's some that I built...

http://moosapotamus.net/THINGS/mics.htm

Another slight variation on the phantom powered WM-61A mic, similar to Scott's scheme.

~ Charlie[/quote]

Charlie, you have an error on schemo (C1, R1)[/quote]

It agrees with the board layout though... if the boards work, then the schemo works. I'd say that the schemo is drawn correctly in terms of explaining the board... but I reckon you may want to try moving the "in +" connection to the OTHER end of R1... -Is that what you mean also, Wavebourn?

Keith[/quote]

I mean if R1 is not a load and C1 is not a coupling capacitor they are worthless the same as the upper emitter follower (except bias current). However arranged such a way it will work producing half of output signal (asymmetrical).

 

[SSLtech]

yes, but if you move the + in connection to the other end of R1 (junction with C1 instead of junction with D1) then the idle side comes to life...

...as I read it...

Keith

 

[Guest]

[quote author="SSLtech"]yes, but if you move the + in connection to the other end of R1 (junction with C1 instead of junction with D1) then the idle side comes to life...

...as I read it...

[/quote]

Exactly.

 

[moosapotamus]

[quote author="Wavebourn"]
Charlie, you have an error on schemo (C1, R1)
[/quote]
:shock: Well, they sound pretty decent...

[quote author="SSLtech"]yes, but if you move the + in connection to the other end of R1 (junction with C1 instead of junction with D1) then the idle side comes to life...
[/quote]
...but, I guess I'm gonna have to try that.

Thanks
~ Charlie

 

[Guest]

[quote author="moosapotamus"][quote author="Wavebourn"]
Charlie, you have an error on schemo (C1, R1)
[/quote]
:shock: Well, they sound pretty decent...

[quote author="SSLtech"]yes, but if you move the + in connection to the other end of R1 (junction with C1 instead of junction with D1) then the idle side comes to life...
[/quote]
...but, I guess I'm gonna have to try that.

Thanks
~ Charlie[/quote]

Welcome! :wink:

 

[SSLtech]

Oh yes, they'll sound fine, but with this circuit correction, you'll have approx 6dB more output, and REAL balanced (symmetrical) output as opposed to quasi-balanced (asymmetrical) output.

Just move 1 wire to a different takeoff point and you'll see what we mean!

:thumb:

Keith

 

[moosapotamus]

I just moved that wire and I like it. I'm not sure I notice much increase in output, but the noise level is dramatically reduced, the mids seem fuller/mellower sounding and the high end is a lot less harsh. I was pretty happy with these as utility room mics. Now I think I might like them even more.

Thanks, again
~ Charlie

 

[Guest]

[quote author="moosapotamus"]I just moved that wire and I like it. I'm not sure I notice much increase in output, but the noise level is dramatically reduced, the mids seem fuller/mellower sounding and the high end is a lot less harsh. I was pretty happy with these as utility room mics. Now I think I might like them even more.

Thanks, again
~ Charlie[/quote]

Welcome again!

Meanwhile, I have another problem... How to make a phased array.
To sum signals from mics directly before amplification, or to amplify each of them then sum?

The first approach is cheaper, of course...

 

[mshilarious]

moos, use the XX connectors, there is more room inside. If you make your PCB 12mm x 30mm, and round the outside edges just a hair, you can dispense with the chuck entirely.

Also these capsules have much more THD off the drain pin than source. So try a phase splitter off the source and you should get at least 6dB more SPL handling.

 

[moosapotamus]

[quote author="mshilarious"]So try a phase splitter off the source and you should get at least 6dB more SPL handling.[/quote]
Thanks for the additional tips! What would that phase splitter look like? Can you maybe point me to an example?

Thanks!
~ Charlie