PliXiR Elite BDC Dual-Output Power Supply Upgrade

PliXiR Elite BDC dual-output power supply upgrade is an alternative to the standard one-output PLiXir Elite BDC model. This upgrade is designed to optimise the audio quality of devices that use an external PSU. This Dual output version will supply 2 x 12V at up to 4Amps.

BDC stands for Balanced Direct Current and the unit uses two stages of regulation for optimal noise performance. As a result the output is both clean and well regulated. Regulation is linear rather than switch mode and this design ensures the best possible noise performance.

The Elite is a cost-no-object unit that delivers the best possible power to your audio equipment and supplies power via a balanced output cable to further improve noise performance.

Why upgrade your power supply?

Most DC power supplies are SMPS units. Switched Mode Power Supplies can be produced cheaply, they also accept a wide range of input voltages. However, the high frequency switching can generate a lot of noise. The noise can be picked up by any nearby cables and can affect the power supply.

Alternatively, linear power supplies produce less noise, but are bulky and generate heat. Noise is produced by the diode bridge, and this is not usually dealt with. The PliXiR units are designed to be optimised to deal with all these issues.

How do SMPS units work?

Switch mode power supplies work by switching on output transistor on and off at a high frequency. The width of the pulses determines the output voltage. The small transformers used also have a feedback winding that tells the control IC what the output voltage is doing.

They have the advantage of being lightweight and cheap to produce, however, they have poor noise performance. In fact most are mounted in a metal enclosure to mitigate noise radiation. However, this is not done with cheap units that inject noise into the air and mains supply.

Linear power supply advantages and disadvantages

Linear power supplies have the advantage of better noise performance as well as a fast response to changing load conditions (slew rate). They can use discreet components for the regulator circuits or Op-amps. The disadvantage is that they need large and heavy transformers especially if the current output is more than a few Amps. There is also the problem of mechanical and electrical noise. The output transistor needs to be mounted on a substantial heatsink. As a result, the PliXiR units are designed with only the best components, as well as having a balanced output.

Multi-stage power supply

PliXiR’s range of DC power supply upgrade units have a two-stage regulator circuit. The first pre-regulator stage acts as a noise filter and is a class A design, with an open loop. This results in a very high gain. The second stage is the regulator itself and is a closed-loop design.

The first stage also takes some of the load off the second stage. Furthermore, this noise filter effect stops noise from getting into the mains supply as well as the output. As a result, the second stage has an optimal slew rate and output impedance. In other words, even under heavy load, the supply remains clean.

Finally, the output is balanced to further reduce noise pickup from the cables. This is similar to the noise reduction achieved by balanced XLR audio leads. Ground loop problems are eliminated as well as cutting noise by half. A balanced system requires a bigger transformer, however, the performance advantages outweigh this. Notably, the connecting leads, to the equipment, are also balanced. These optimised power supply units will provide a noticeable improvement to the audio performance of the connected unit.