PS BYOB Dual voltage vs PS Dual Voltage

Hi Huy

A number of people have used the recent supercapacitor power supply to power their rPi with Allo. Both battery PS & supercapacitor PS will do the job fine.

Could you be more detailed about the sound quality between the battery PS and supercap PS? Since I cannot buy both so I would like to know the difference (though I know for sure both will do the job fine).

I am a member of Allo club, some are like me, they are curious about your two versions of PS. You answer would be helpful for us.

Thank you.

It depends on what the PS is being used to drive in the audio chain.

So for instance when I changed from battery power to supercapacitor power in my DAC with nothing else changed, the sound seemed faster, more precise, just that bit more focused - as a result the sound objects in the soundfield were perceived with more soldity, the soundstage more holographic with perhaps more snap to the sound. This is relative to battery power which itself produced these characteristics when compared to stock PS powering the DAC

I'm pretty sure that these perceived audible characteristics have something to do with the dynamic noise floor which to me means that when an audio device is processing data, if the power supply is generating fluctuating electrical noise as it dynamically sources current to the devices being powered, then this results in a noise floor which is fluctuating. This is low level but form my research I believe our auditory perception is picking this up because it is changing. Here's a way to think of this & do an experiment which will illustrate - put a single hair under your finger - can you sense it is there? Now roll the hair with your finger & you can easily sense its presence. Similarly a steady state signal (or noise) at a low enough level is not perceived but when it fluctuates or forms a pattern, we are more sensitive to its presence

This noise floor has much more possibility to be just static noise when a power supply is not based on active devices - it's the dynamic nature of the noise that is sensed by our auditory perception. The fact that we can "listen through" the relative static surface noise of vinyl/tape is testament to how our auditory perception can ignore such noise when it's constant. That's why some have discovered that a voltage regulator on the output of battery or supercapacitor power is detrimental - it introduces some dynamic noise because of the feedback nature of it's design.

This also explains, for me, the reason such improved power supply can have an audible effect when powering digital only devices in the playback system - the dynamic noise is somehow getting through to the final D to A stage of the playback system - it may be on the ground connection between the devices, it may be through common mode noise on connections between devices, it may be through some other avenue?

Now this is my conjecture & there will be some that say this is BS because measurements don't demonstrate this dynamic noise floor fluctuation. I agree that measuring this aspect is probably difficult but that isn't a reason to dismiss it completely as I'm sure measurements will eventually be done which will hopefully illustrate what I'm saying. Until then I'll use my ears & my logic to try to comprehend.

I have written a bit about the difference on my webpage here

" So any power supply being used in this situation needs to be immune to all these fluctuations in timing, current delivery. If not immune then the result is usually dynamic noise on the ground which has downstream effects on audio quality.

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LiFePo4 batteries & supercapactitors are both capable of satisfying these requirements & the only difference between them appears to be the speed of the current delivery. High capacity supercapacitors often have a very low impedance (this value is a measure of the ability to deliver current quickly - the lower the impedance, the faster the current delivery). The LiFePO4 batteries have an internal impedance of <8mohm - the supercapacitors I use (Nesscap/Maxwell 350F ) have impedance <3.2mohm. This should mean that the supercapacitors can deliver current faster than the batteries. This seems to be borne out in the listening, supercapacitors appear to have slightly faster. However, pcb traces & wires will negate this impedance difference so perhaps the audible difference is due to some other factor?

Both batteries & supercapacitors are still unfazed & stable when delivering the needed current. This means no dynamic noise is created in the ground plane which ultimately affects the audibility

Thank you for going the extra mile to explain for me. I will include your explanation together with my review for the Allo club. Your answer will definitely help some.

I am going to order the super capacitor PS. I'm going to use this with Raspberry Pi 3 and Allo Digione Signature. Please check their power specs here:

https://www.amazon.com/clouddrive/share/B7x0ZLqAyLVrkjSMovke784OuES7L30rtfrir03ztoB/6JcAdK5PQTa7rm2IYxrBWw?_encoding=UTF8&*Version*=1&*entries*=0&mgh=1

I don't know what to choose when I order your PS:

Voltages: Up to 7V

Enter single voltage value required at both outputs: ?

Please advise.

Thank you.

You just need a ISO-PS with dual 5V outputs so choose 5V

"The “dirty power” needs 5V /2-3A (RPI power). The “clean side” needs about 100mA and accepts from 5V to 6V."

Got it, thank you!