On earlier Pearl and PML mics like DC63/96 a small mylar film cap in series with a resistor was used parallel to the input jfet source to ground resistor. That gave it the lift there.
On the Milab VIP 50 a resistor/cap combo was used across the output resistor to add the lift. The VIP 50 has no output transformer and used an opamp with an impedance matching resistor across pin 3 to ground for asymetrical balanced output. Not the best design but with .1% resistors it can work pretty good. You get -60 db CMRR that way. Match those .1% to .01% and you get -80 db CMRR. You will need a great meter and clean probes to do that.
That VIP 50 is an opamp design with a discrete jfet for the front end. A super low noise (.7 nv/hz/sq) SOT23 SOIC RF jfet was used, that lowered the self noise considerably. Dale CMF50 1/4 watt 1% non-ferrous metal film resistors were used everywhere, 1/8 watt sized, very good sound quality. Fitting the SOT 23 jfet in and appling conformal coatings was a challenge. I used Kimber pure silver/teflon wire for that stuff. "Dead Bug" RF construction techiques are used as that is not a through hole part. Every part of that impedance conversion is degreased carefully before the conformal coatings are applied to seal it all up.
Due to current limits of the 48 volt standard I selected Burrbrown OPA1641 opamps, very low noise, jfet inputs, low current draw (1.8 ma) 600 ohm load driving capability and most importantly, rail to rail operation. With the higher output levels I added, it has more headroom that way. Higher output, lower noise, greater headroom, plus much more refined sonics makes these a winner for orchestral recordings.
