Single AC To Dual DC Rectifier Power Supply Ripple Rejection Improvement

I did many trial on this PCM56 DAC. This DAC is become my experimental tool for the next better DAC projects. If you not yet following my post before, so please visit the building process and the upgrades of my PCM56 DAC in here here here.

In this post, I will make another experiment. Previously, the power supply in this PCM56 DAC is intended to using batteries. This is before changed to single AC input power supply that I think will be more simple to use. This single AC is convert to half-wave dual DC power supply here. But the problem is this DAC unit still using small capacitors that calculated when using the batteries. The capacitors are only 100uF on each rail voltage and for sure not sufficient to reduce the ripple on rough half-wave rectifier conversion.

So in this post, I will replacing the small capacitors with the bigger one to improve the ripple rejection.

On the photos bellow, I did another experiment when using very large capacitors. This is only to know what different in sound quality between them. The result is more relaxing sound, more smoother, and the background noise seems quitter and darker.

So using the larger capacitors value like this in DAC power supply circuit really give benefit to reduce voltage ripple. This can be see it in oscilloscope for sure. The next problem is how I put those giant capacitors inside this tiny portable size DAC?

While it is impossible to put this giant capacitors inside this DAC, so should I find the smaller one. This is the Nichicon LXZ and I think will be more suitable for this upgrade.

This new capacitors require me to make new power supply board. This is including re-arrange the voltage regulators to the new position. Again, I also changing the voltage regulator IC from the 7805 7905 to the adjustable LM317 and LM337 regulators.

The digital voltage regulators still using 7805 supply to CS8412 and 74HC04. The location of this regulator is replace beside the CS8412.

The multi board like this gives me flexibility to put any components wherever I feel suitable as long as they are fit inside the casing.

The benefit using larger capacitors is to improved the ripple rejection. It directly effect to the better sound quality because all DAC are basically need clean power supply.

As I always said, building DAC is power supply sensitive. You can push hard on the analog section but when the power supply sections are neglected, you will not get the optimum sound performance from the DAC IC itself.

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