Topic: Unpowered electrets..suggestions?

[scotianbill]

This is my first post...please be gentle.

I've been making my own mics and battery boxes for several years now and have some very good results using them with either an edirol or MD recorder. I mainly base my stealth mics on the wm61a capsule.

Now, I want to make a pair of unpowered mics..ones that plug directly into the "mic in" on a microtrak. I find that the wm61s arent suited for this as they need 9-10v power...correct?

Can someone suggest a pair of electrets that i can use that have proven results? They need to have a high spl tolerance as I record mostly in loud clubs and concert halls etc.

Getting a battery box into some shows can be a daunting task when patted down..so the unpowered option should be a little easier to conceal.

Suggestions? Comments?

[fmaderjr]

I find that the wm61s arent suited for this as they need 9-10v power...correct?

Are you sure about this? The MTII provides more plug in power than most recorders (close to 5 volts) and the MT 24/96 will even power my DPA 4060's correctly. I don't know about your capsules, but most mini-mics do fine with around 5 volts plug in power, even if they are typically used with 9 volt battery boxes.

[nl]

FWIW, I've run my Church Audio CA-11's on plug in power with my Marantz PMD620 (often) and Microtrack II (occasionally) at very loud shows successfully. Both of these recorders provide close to 5 volts of plug in power.

[12milluz]

I haven't looked at the datasheet in awhile but I swear, WM61s run on 2-10 volts.

Edit: yep I was right: http://www.panasonic.com/industrial/components/pdf/em06_wm61_a_b_dne.pdf

[ArchivalAudio]

I would bet the plug in power would work...

I was gonna say un-powered electrets?  that's like jumbo shrimp! an oxymoron... as I'm sure aware Electrets need power as as in electricty...

The Plug in power should power those tiny mics

[acidjack]

^^ Though I believe it should be mentioned (not that I am any expert on the engineering side of things) that if you are recording sources that are very loud, you will need to add resistors to the mics to prevent overloading.  I believe the Church "4.7k mod" that does this involves putting a 4.7k resistor in the plug that goes into the recorder... but again, not my area of expertise.  The point being, plug in power can work with the WM61a, but if you're recording louder sources you'll likely need to modify them a bit, even if your deck provides a decent level of plug in power.

[scotianbill]

Without seeing the 4k7 mod, I am guessing that it is just attenuating the input signal ?

I still have some wm61s so I will make a set with the 4k7 mod in place and try them at my next outing.

Thanks for all the comments.

[SmokinJoe]

I believe the 4.7k mod was chosen as a solution particular to AT853's.  Then it has been used on other cases with varying success, but it's not a universal solution to all electrets.

For the Panasonic caps there is something called a Linkwitz mod which works well to prevent overload.  I haven't done it, but I've read that it works well.  I'm not an expert in the specifics, but I expect it will OK with the 5'ish volts PnP.
http://www.mp3forkidz.com/mic/mod.html

[scotianbill]

Thanks again.

I have heard of the linkwitz mod, but never done it. I will try it though..

[John Willett]

The Sennheiser ME 2-ew and MKE 2-ew run fine from the plug-in power on my Olympus LS-10.