Linear Power Supply with fancy audio-grade caps is any better than similar high-quality ones

[Ducnguyen2k10]

I had a big online fight with this guy making so-called “hi-end” linear power supply.
I said the capacitors he’s using in his LPS should not provide better DC output than the same parameter capacitors!
I challenged him to show the oscilioscope of his LPS DC output measurement but he tried to avoid.
I don’t see the neccesity to use audio-grade capacitors in the LPS.
Additionally, this guy and some of his friends argued that LPS is essential and should improve SQ when using to power ethernet switch, and DC-powered equipments in the chain of audio system. 
Does anyone here has experience and knowleage to prove me wrong!?

[The Computer Audiophile]

Hi everyone, please keep in mind this post is in the Objective-Fi sub-forum and all discussions need to exclude the subjective. 
 

If you want to discuss the subjective part of this topic, please open a thread in another part of the forum. 

Thank you. 

[yamamoto2002]

This is my understanding about this topic,

 

LPS is better than switching power supply for audio use because SMPS emits audible high-pitched sonic noise that is caused by coil whine or MLCC piezoelectric effect and it can be heard by ears, if you cannot hear it, your kids may point out the source of high pitched noise source and it is disgusting experience 🥺 , also it is obstacle of clean high resolution recording.

 

Recent electrolytic capacitors designed for SMPS tends to have low ESR characteristics and LPS voltage regulator negative feed back design becomes difficult with low ESR capacitors, and it may cause unwanted oscillation in the worst case. electrolytic capacitors marketed for audio are designed to be used as LPS capacitors and it has relatively high ESR values.

[Ducnguyen2k10]

5 minutes ago, yamamoto2002 said:

This is my understanding about this topic,

 

LPS is better than switching power supply for audio use because SMPS emits audible high-pitched sonic noise that is caused by coil whine or MLCC piezoelectric effect and it can be heard by ears, if you cannot hear it, your kids may hear it and it is disgusting 🥺 , also it is obstacle of clean high resolution recording.

 

Recent electrolytic capacitors designed for SMPS tends to have low ESR characteristics and LPS voltage regulator negative feed back design becomes difficult with low ESR filter capacitors, and it may cause unwanted oscillation in the worst case. Audio grade electrolytic capacitors are designed to be used as LPS filter capacitors and it has relatively high ESR values.

Thank you for your response.

I have some more questions for you:

- For such SMPS that I found to power DAC, laptop or my Nuc, they all have switching frequency much higher than human hearing (upper limit of 20kHz). How is it possible my kid can hear it?

- For the sake of your argument, in case I use SMPS that operate within human hearing range, does it has amplitude high enough for my kid to hear it? If I use that such SMPS to power my properly designed DAC, will it bypass the filter circuit and power regulator within the DAC and results as noise in the analog output? 

[yamamoto2002]

I don't know exact mechanism but my worst SMPS emits 4kHz audible noise. and another one is 10kHz. But most certainly those devices switching frequency is higher than that. May be it is related to power load fluctuation.

 

I read somewhere, super sonic high pitched sound can be heard when it is very loud (140 dB SPL or so), one example is dentist medical drilling machine that is touched to your teeth.

 

43 minutes ago, Ducnguyen2k10 said:

If I use that such SMPS to power my properly designed DAC, will it bypass the filter circuit and power regulator within the DAC and results as noise in the analog output? 

it should be the same.

 

Following is the SMPS audible noise gallery 🙂

 

This is the worst SMPS I have.

 

This is very audible.

 

 

I cannot hear this.

 

Sometimes I can hear this, don't know why...

 

 

 

[yamamoto2002]

6 hours ago, Ducnguyen2k10 said:

I don’t see the neccesity to use audio-grade capacitors in the LPS.

 

Every LPS design book should have a description about negative feedback stability and capacitors. This is a good internet article I found: https://www.electronicdesign.com/power-management/article/21193554/a-simple-method-to-determine-esr-requirements-for-stable-regulators#:~:text=Engineers often have trouble analyzing and achieving stability,provides the control loop zero%2C stabilizing the regulator.

 

This PDF has a oscilloscope screenshot of unstable LPS of low phase margin (Figure 4): https://www.ti.com/lit/pdf/slva115

 

Typical electronics products have 5 to 8 years of life but audio equipment often used for 20 years or more, some people stay powered it 24/7, this may be considered to design audio electrolytic capacitors, Arrhenius equation is used to determine electrolytic capacitor lifetime.

[Ducnguyen2k10]

7 hours ago, yamamoto2002 said:

 

Every LPS design book should have a description about negative feedback stability and capacitors. This is a good internet article I found: https://www.electronicdesign.com/power-management/article/21193554/a-simple-method-to-determine-esr-requirements-for-stable-regulators#:~:text=Engineers often have trouble analyzing and achieving stability,provides the control loop zero%2C stabilizing the regulator.

 

This PDF has a oscilloscope screenshot of unstable LPS of low phase margin (Figure 4): https://www.ti.com/lit/pdf/slva115

 

Typical electronics products have 5 to 8 years of life but audio equipment often used for 20 years or more, some people stay powered it 24/7, this may be considered to design audio electrolytic capacitors, Arrhenius equation is used to determine electrolytic capacitor lifetime.

Thank you so much for your response. 

[yamamoto2002]

This is another example of acoustic noise recording from SMPS while GPU runs a convolution task.

It is very audible, sound is somewhat resembles to Platypleura kaempferi cicada.

 

NvidiaTitanV_RunTasks.flac

[MarkusBarkus]

9 hours ago, yamamoto2002 said:

somewhat resembles to Platypleura kaempferi cicada.

@yamamoto2002 you are the best!