modifying jfet

[Sobo]

Hi folks

I am very new to electronics. Some time ago I built a measurement mic using the wm-61a capsule from panasonic and a preamp that was revolved around an opamp. The microphone worked pretty well. I even tried the Linkwitz modification (http://www.linkwitzlab.com/images/graphics/microph1.gif ) of cutting a trace and connecting the casing with the drain of the FET. The resulting mic had a lower output voltage but produced less harmonic distortions although the noise level had increased (maybe due to an improper connection). If I understand correctly the schematic of the modified capsule should look like this: http://imageshack.us/photo/my-images...odcapsule.png/

The problem I have is that I am really confused about what the modification does to the JFET and why there are less distortions. As far as I understand, in the original configuration the JFET is reverse biased and the gate-to-source voltage controls the current flow through the pinched-off channel.

When applying the Linkwitz modification the gate and drain terminal get connected so they basically have the same potential. The jfet is now forward biased and contains many free charge carriers. As the drain-to-source voltage inreases the jfet is further forward biased and the channel resistance decreases, thus giving the current vs drain-to-source voltage characteristics an upward tilt. When the gate-to-drain voltage becomes more negative the conducting channel becomes a bit narrower and the resistance increases. The current vs voltage characteristics should look something like this: ImageShack® - Online Photo and Video Hosting

So basically the JFET now behaves more linear because its transfer characteristics are different?

Could you help me out if my explanation is right or if I completely missed something. Thank you all.