My first working mic,thanks Marik!

[maneco]

...nothing out of this world,of course...just a wm61 capsule,linkwitz modded,and the same circuit you used in the ecm8000 upgrade...a 10cm copper tube,that just fits in the male xlr,and i have a new mic in my (poor)armory...

Thanks a million for all your work and inspiration ! :thumb: :thumb: :grin:

 

[Chuck78]

Pics???

 

[bcarso]

Maneco, do you have a link to the so-called linkwitz mod?

 

[maneco]

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

 

[ambi_doug]

paperclips!

thank you!

this may be just what i have been looking for.

 

[maneco]

the paper clip also helps making a connection to the shell of the electret...once again,my advice is to read the whole thread in the ecm8000
mod,many pages,because the advices there are useful for any electret,and you'll find a nice electret driver,phantrom powered....

Good luck in your experiments!

 

[ambi_doug]

i've come to the conclusion that soldering the capsules to the paperclips isn't the way i want to do it - since soldering to the aluminium cases is next to impossible.

i'm using blu-tac for now

(see .sig for updates to my electret ambisonics project - new photos and (crap) audio today!)

 

[bcarso]

Thanks for the link maneco. Wow that's easy! I was thinking there was going to be serious internal surgery involved.

"i've come to the conclusion that soldering the capsules to the paperclips isn't the way i want to do it "

Fortunately you don't need quite the low resistance like the ribbon mic terminations do.

What do you guys find to be the effective low frequency cutoff of these capsules, typically? It would tell us roughly what the internal high-meg resistor is. Also, I assume that the R is tied to the case as well as the ground side of the electret element?

 

[maneco]

The problem is i did not see any resistor inside of it...that puzzles me,because there should be soemthing around 1 giga...maybe the capsule is prepolarized or something like that ...i don´t know

 

[moosapotamus]

[quote author="maneco"]...a wm61 capsule,linkwitz modded,and the same circuit you used in the ecm8000 upgrade...[/quote]
I built a couple of those myself. I like 'em a lot. Thanks (again) from me, too.

~ Charlie

 

[Scodiddly]

[quote author="maneco"]The problem is i did not see any resistor inside of it...that puzzles me,because there should be soemthing around 1 giga...maybe the capsule is prepolarized or something like that ...i don´t know[/quote]

Those little capsules don't have a resistor exactly. The FET is designed to have a sort of leaky diode junction which acts in place of the 1Gohm resistor. Cheap, but that's where the noise in these capsules comes from.

 

[Mendelt]

I bought some WM61a's and some WM61b's a month ago.

modding the a's is easy but since the aluminium of the case is very hard to solder you have to cut away part of the case to get to somewhere you can solder.

modding the b's involves a lot more cutting but you have more surface to solder the earth connection when you're done.

When i get home i can try to post pic's if anyone is interested.

 

[Svart]

I did this quite some time ago and layed out a board to work inside of the ECM8000 mic. there is no high value resistor, really there isn't one at all, it's just a JFET, a Panasonic part:

http://www.semicon.panasonic.co.jp/ds/eng/SJF00032BED.pdf

I still have the Circuit maker files for the boards if anyone wants them..

Find much info here:

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

and here:

http://www.linkwitzlab.com/images/graphics/microph1.gif
http://www.linkwitzlab.com/images/graphics/microph2.gif

And to answer your other question Bcarso, I'm getting rolloff around 20hz with these modded parts. the unmodded parts are a little higher than that, maybe around 30hz unlike the datasheet testing shows..

 

[Mendelt]

[quote author="Svart"]
I still have the Circuit maker files for the boards if anyone wants them..
[/quote]

I still have your files on my server.

www.mendelt.nl/ecm8k_svart/

Hope that's ok

 

[Svart]

totally cool. I still have the originals too. found them while organizing the folders the other day..


:thumb:

 

[moosapotamus]

Hey, can anyone describe how to take the capsule end of the ECM8000 apart?
I tried everything but a hacksaw. :roll:

Here's my layout of Marik's modified scheme...

Thanks
~ Charlie

 

[Mendelt]

The top of the EMC8000 is glued so you need to heat it to soften the glue then you can get it off.

I dont know if the capsule will survive but the panasonic ones are only a few dollars.

Are you sure your layout will fit? Svart's layout uses axial capacitors that stick out less to fit the ecm8000 body.

 

[moosapotamus]

Ah ha! Glued?! Thank you!

Yes, I do have the panasonic capsules, so I don't care about frying the existing one.

I haven't tried my layout for actual fit, yet. I'm sure it will be tight, tho. Especially with that big poly cap (C2) on the side of the board. Actually... looking at it some more, that cap could probably be moved more to the center. Anyway...

Thanks again for the 'glue' tip.

~ Charlie

 

[maneco]

Hi Charlie!

I built mine on a piece of breadboard,and had to lay the caps to make them fit inside my copper tube...i think it's better to leave the ecm 8000 as is ,and build the new one from scratch ,using a panasonic wm61 capsule ...i used a couple of 2n5457,but other fets may perform better,something like j201... :thumb:

 

[moosapotamus]

Thanks, maneco. Glad you found a way to build it that you are happy with.

I think this modified circuit with the panasonic capsule sounds much better than the stock ecm8000. So, if I can fit mine into the ecm body, I'm going for it.

The pinout on my layout is for the 2SK389GR dual monolithic jfet (K&K audio).

Thanks
~ Charlie