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Note for those doing the Linkwitz mod with the Panasonic Mic elements...

post #1 of 6
Thread Starter 
If you decide to do the Linkwitz mod to the Pansonic WM-60AY electret microphone elements http://www.linkwitzlab.com/sys_test.htm (about 2/3 of the way down in the section labeled Microphone), I suggest you carefully take a look at the battery box schematic for it and the one posted on http://home.earthlink.net/~gottapes/micdiyers/main.htm in the Wiring Schematics- Binaural Stereo Mic section. With the modded Panasonic mics, the power supply in the battery box has to be reversed in polarity. If used with a "normal" one such as the battery box from MicDIYers or "mic (plug in power)" input of your recording device, there will be a lot of hissing type noise and the microphone's sensitivity to low frequencices is decreased when compared to the battery box/mic input being used with a normal mic. I've made a battery box with a DPDT switch to toggle between normal and reversed power supply and it works fine with microphone and line inputs (recorder's own power is bypassed when using a battery box) and normal/modified mics. I've also tried wiring a modded Panasonic mic reversed so that it would work with the "normal" battery box setting/mic input, it's a small mic for non quality recording such as quick notes, lectures etc (in mono obviously), and the signal being inverted because the new output is tied to ground doesn't seem to be a problem. If use with a stereo pair, I doubt it'd be a problem since both will be in phase, but I'm not sure and haven't tried since I have made the appropriate changes to my battery box to accommodate both versions of microphones.
post #2 of 6
that's one of the things i don't like about the linkwitz mod, i don't like having to carry around a batterybox (although when a battbox is necessary, i do prefer linkwitz modded capsules).

but i saw another mod somewhere. you cut the trace like the linkwitz mod, and then you connect a resister (~200 or so ohms) between 2 and 3. you tap the signal from 3. and you can use it with a regular battery box, or the plugin power from the recorder.

just wondering, do you have blending problems with your battbox? it seems that the right channel will leak some of the signal into the left, and some of the left signal will leak into the right channel. is there any way around this aside from using a 3 wire setup?
post #3 of 6
Thread Starter 
Carrying a battery box is no biggie for me since I don't go around constantly recording stuff (at the moment!) and if I need to I have that small mono one with reversed connections and will make a small stereo T or clip-ons with the regular elements later on. Also I have a vest with lotsa big pockets.

I've noticed that even if the modded capsules are a bit lower in sensitivity (can't be sure though since I haven't had at least two pairs that were similar to each otherimpendance wise *before mods to compare), they seem to sound cleaner with less noise and Mr. S Linkwitz mentioned in his article that at moderate levels, the elements in their standard configuration distort quite a bit. I think I've read about that resistor mod or at least something similar from one of the links posted on Headwise, a DAT recording article or something? Gives me another reason to order more capsules and some surface mount resistors among other things =D

*BTW, I matched them by measuring it's impendance (ok, more like DC resistance), it seems to be working for matching up sensitivities (and strangely enough, my first random pair for initial tests were matched).

I haven't really noticed any blending/crosstalk problems with my battery box, I'll try wiring up a mic on only one side of a stereo cable to test though. I would expect very very minimal crosstalk actually, since power is received from the input and are both connected to the power source by the 10k resistors, though I doubt it's be very noticable unless you were only listening to one channel that's supposed to be blank and it would be at such low levels to be unnoticable with recorded stuff).

edit update: I noticed about the same amount of crosstalk without the battery box as well as with so I think it has more to do with the recording device or maybe the shared ground of the cable (similar problem mentioned for the V6's cable which would cause some crosstalk). Still, it doesn't seem too bad and I guess you could think of it as built in crossfeed? I only really noticed when I had my MD recorder on full volume wearing the "micless" side of my ex70's, with the mic picking up wind noises and the recording level maxed.
post #4 of 6
yep, the modified capsules are lower in sensitivity, which imho can be a good thing. last week i went to a few depeche mode concerts, and they turned the volume way up. the capsules were giving out such a strong signal that they were driving the mic amp in my minidisc recorder into heavy distortion (and i bet the capsules themselves were distorting like crazy). so the next day i had to use linkwitz mic's with a battery box (with an l-pad attenuator). i just plugged it straight into the line in, no extra amplification needed!

to match mic's, i hook them up to my computer, and then play some frequency sweeps through my speakers, and monitor the mic levels on my computer with something like cooledit. works pretty well, (though high frequencies present some problems)

btw, i think the mitey mike II from audioexpress uses the same panasonic caps with a similar mod. i know the mod was published some time ago, but i can't seem to find out what the mod was. anyone know?
post #5 of 6
skippy, what is this "l-pad attenuator" that you are talking about and where can I find the schematics for it?
post #6 of 6
it's just one resistor in series and one resistor to ground. in a schematic it forms an "L", hence the name. all it does is attenuate the signal.
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