Chandler Limited PSU-2

The PSU-2 is not a general-purpose power supply but part of the Mini Rack Mixer's design. The mixer ships without an internal supply and will not power up without this unit, which needs to be taken into account when ordering. The reasoning behind the separation is familiar to anyone who has worked with sensitive analogue equipment: inside the mixer chassis there are 22 signal transformers, wound specifically for it, and 20 discrete amplifiers. A mains transformer in the same box would create a magnetic field that coupled into those windings and ended up as hum in the audio path. Placing the power supply in its own chassis solves the problem at source.

What it delivers in practice

The unit provides 3 A of continuous current at 28 VDC. That margin matters: a mixer with twenty active stages draws a different current depending on the programme material, and a supply running at its limit shows up as a loss of dynamics and of tightness in the low end. The input accepts 110 to 230 VAC at 50 or 60 Hz, with an internal switch to select between 120 V and 220 V, so the same unit covers different markets. Compared with the previous version, Chandler has upgraded the filter capacitors and the voltage regulators, aiming at a lower noise floor and a more stable voltage under load. Note that the dimensions, weight and output connector type are not published by the manufacturer.