jacob explains this himself on the project site.
[quote author="gyraf"]
On the PCB board there's an option for adding a trimmer and a capacitor in order to introduce cathode feedback to the tube amplifier stage. This lowers both distortion figures and output impedance, but cancels out a lot of the "tubey" sound - the reason we bother to make a tube microphone in the first place. The reason I have'nt removed this option, is for purely educational reasons - if you want to do some experimenting yourself. This is also where you can put in various equalizations if you like that. But for the best sound - at least to me - leave the tube undisturbed by feedback and other dirty tricks.
[/quote]
i would guess the idea arose from the neumann u67 microphone, where feedback around the transformer is used - but the u67 uses a output transformer with a tertiary feedback winding - a third winding made especially for feedback (it sits in between the primary and the secondary) whereas in the g7´s lundahl one half of the secondary winding is used for the output and the second half for feedback.
additionally the u67 provides a eq circuit in the feeback path to linearize the treble boost inherent in the k67 capsule.
for a linear capsule feeback is often counterproductive in a tube impedance inverter since it tends to oppress musical nonlinearities, expression and detail. now that sounded already way too audiophile,
at that point discussion (via internet) about sound is very difficult and experimenting and finding out yourself wins over collecting opinions every time, me thinks.
from what i´ve seen, most g7 builders omit the feedback and leave the second half of the secondary unattached, or in parallel with the first half.
-max
