1: In Peach Wilkins' hideout (Neptune's Bounty), bottom floor. As soon as you come downstairs, it is directly in front of you.
2: On the way to Farmer's Market in Arcadia, the station is located to the left after you go up the first stairs coming from Tree Farm.
3: Go to Winery's basement in Farmer's Market. There is a flooded area with one of them attached to the wall. It is in front of you when you come down the stairs; just keep going forward.
4: In Fort Frolic, from the Atrium bottom floor, go towards the bathrooms. Then, move right and follow the path until you see some small stairs to your right leading up to a door. Go inside, then go down into the basement. The basement is filled with cigars and other stuff. The upgrade station is on the wall.
5: Go to Poseidon Plaza in Fort Frolic. Go to the other end of the bottom floor (the opposite end of where you enter). Go into Sinclair Spirits (the room that has a corpse on a sort of "altar"). In the basement of this store is the station.
6: In Hephaestus Core Room, go down to the bottom floor, and run around (literary). Eventually you will see it attached to the wall.
7: In Hephaestus, Kyburz's office. It is attached to the left wall (back turned to the entrance) in the rear of the room.
8: At the bottom floor of the Mercury Suites area, on the back of the center pillar.
9: In Sander Cohen's secret room, in the Olympus Heights' Mercury Suites area.
10: Go to Atlas' Headquarters in Apollo Square (Fontaine's Home For The Poor area). It is located on the fourth floor. Go down the stairs in the room and look to the right. The station will be in front of you.
11: When you enter Point Prometheus and chase Fontaine, eventually you will end up in a little square, and Fontaine will go behind a locked Museum door. At the opposite end of this square (from where you came) is a dead Big Daddy. Next to it is the upgrade.
12: In the Voice changing labs in Point Prometheus, one of the labs has it.