Power supply selection

I have recently finished an amplifier build which includes a V3 mini and DAC board, which I am very happy with.

My next project is a standalone unit using a V3 Pro board with a ES9018 I2S DAC board and an additional input for an amplifier using a DP latching relay.

I have been deliberating over a power supply for it, the DAC board requires 12v DC and the Arylic board and relay 5v. The thoughts are that I just use a 12v SMPS and a 12 - 5v converter (I have a KIM-055L converter) I was reading that if you use a linear regulator then the 5v supply will be less noisy by reducing the power supplies HF switching noise so I thought that it would be interesting to see if this is the case.

I found a LT1963 low noise 5v linear power supply module on eBay, and it’s on its way to me now. I also saw a LC filter module for switching supplies so I bought one of those as well.

I have an old CRO, so once I get all the parts I’ll rig it up with a dummy load (12v light bulbs should be ok I think) and see if there is any noticeable differences in the DC noise.

My other option for a power supply would be fully linear, but I want to see the results of the above before making any decisions.

I hope this might be of some interest to you guys, I’ll follow up with another post once I have some results, meanwhile, I am open to ideas and constructive comments.




Analogue multimeter showing voltage, digital MM showing current, scope probes set at x10 (for a 1 volt signal, the scope input gets a 0.1V signal). The power supplies loaded with a resistive (12v 6.5w light bulb) load and the 5v converters with a 5w bulb.

With the parts that I currently have available, I carried out the following:

Test 1: Using a generic branded SMPS rated 12V 2.5A

Test 2: Using a generic branded SMPS rated 12V 1.25A

Test 3: Using the 2.5A PS with a KIM-055L 5V converter

Test 4: Using the 1.25A PS with a KIM-055L 5V converter

Test 5: As test 4 but using a cloned 5V converter.

Test 6: The 2.5A supply with the inline LC filter

Test 7: The 1.25A supply with the inline LC filter

Update 2, some food for thought?

Results so far
Test 1: When loaded the supply could only achieve about 80% of the rated 2.5A before the voltage dropped off. Trace 1 @ .55A load
Attached photos show results.
In photos showing two traces, the upper trace is channel 1 (power supply output) and the lower trace being a converter or filter:

Conclusions (so far)
The cheap switching power supplies and cloned converter that I tested appeared to be fairly noisy, the switching frequencies can be seen on the traces. The LC filter (which is a combination of Inductors and capacitors tuned to block certain frequencies) appeared to remove some of the power supply switching frequencies and might be worthy of addition tests and investigations.
I haven’t conducted any listening tests, I am always weary of ‘snake oil’ type magical fixes/upgrades to audio equipment, for all I know, manufacturers who power their equipment with switching supplies might already include additional filters to clean up power supply inadequacies.

Future tests will include using a linear 12 - 5v converter used with a switching supply and results for a fully linear supply.

Please note that I have no formal training in electronics, the knowledge I have gained is purely as a hobbyist, the above tests were carried out on equipment that was available to me, more up to date equipment such as a storage or digital oscilloscope would be required to achieve more accurate results than I was able to achieve.

Great testing and conclusions, thanks for sharing the experience.