Please Help - Phantom power problem

[khstudio]

Before reading farther: Should pin 1 of the XLR mic input be connected to the chassis ground. From the looks of the schematic it should connect to the chassis & input tranny grounds (Core & secondary GND) Right now I only have pin 1 to the circuit ground, where the input tranny is connected but the circuit ground FLOATs from the chassis. Would this cause the problem below?


I just finished a mic pre & the phantom power seems to be flipping the phase but only with condencer mics when compaired to a store bought pre. Dynamics mics seem to be phase correct.

This it on a PM1000 rack job.
http://www.groupdiy.com/index.php?topic=14629

I was doing a shootout between the PM1000 & a Presonus MP20:
with a 57 they both sounded similar(phase wize) but the PM blew it away.

When I tested with a U87 the PM1000 sounded funny so I fliped the phase switch & it sounded great. The Presonus sounded normal WITHOUT the phase switched :? But when I did switch it on the Presonus it sounded EXACTLY like the PM1000 when it was sounding bad.

Confussed?
It's fine with dynamics & backwards with condensers :?:

Please help. This thing is done besides this issue :!:

Does this seem right that the 48v goes into the center-tap then has to go thru the switch which has several different paths & resistance for each... I'd think it would change the current the mic is receiving?



Kevin

 

[Mundox]

Phantom Power should go direct to the mic input connector via 2x 6.81k resistors. I don't really understand the schematic you put but phantom should not go through the Gain switch.
And your circuit ground should connect to the chassis at one point only.