« Reply #12 on: April 18, 2005, 04:01:01 PM »
Richard - I'm not sure but I suspect that they use the 'lazy mans linkwitz mod' that was discussed in our favorite DIY group. By reversing the polarity of the bias voltage, the FET goes into source follower. If I recall correctly, this only worked with the old capsules that aren't available anymore (the WM-60). I think the 61s need the hack job.
As far as the pin outs go:
1 left bias (-)
2 right bias (-)
3 tip (right output)
4 ring (left output)
and as I mentioned, the whole thing is ground +'ve.
Because the whole thing is 'reverse powered' the wiring convention is not something to copy unless you're using unmodded WM-60s. Otherwise, you'll be reverse biasing the mics. And as far as left/right goes...well, you can just label that after the fact!
I guess this also means that CSBs are out of absolute phase.
OK, I get it now. This is called the "2 wire Linkwitz mod". (If anyone is interested, visit the Yahoo group, micbuilders for details.) Anyway, both WM60 and WM61A are the same. You need to perform minor surgery on both capsules for this. Nothing serious, but you need a steady hand and maybe some bandaids in case you slip with the exacto knife
.
Richard
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Mics: Sennheiser MKE2002 (dummy head), Studio Projects C4, AT825 (unmodded), AT822 franken mic (x2), AT853(hc,c,sc,o), Senn. MKE2, Senn MKE40, Shure MX183/5, CA Cards, homebrew Panasonic and Transsound capsules.
Pre/ADC: Presonus Firepod & Firebox, DMIC20(x2), UA5(poorly-modded, AD8620+AD8512opamps), VX440
Recorders: Edirol R4, R09, IBM X24 laptop, NJB3(x2), HiMD(x2), MD(1).
** This individual has moved to user "illconditioned" **