The power supply for the JM-130, JM-110 and JM-115C is external for several good reasons.
The heat, magnetic fields and weight is removed from the Audio chassis.
The Parasitic capacitance from the power transformer is removed from the audio chassis, and the ground currents they produce resulting in less noise.
The power supply is able to power more than one rack unit, reducing cost and additional
Parasitic capacitance from a second or even third power transformer.
The phantom supply section is designed for a high level of isolation from the A.C. line noise and extremely well regulated and quiet, enabling the best performance from high end mics.
Bipolar +-24 volt, 48Volt.
Dimensions: 6.25" wide, 3.5" High, 8.75" deep.
Weight: 5.5 lbs