Power Supply – Power Bank

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Re: Power Supply – Power Bank

Postby rastus » 13 Apr 2016, 00:39

An ultra low noise power supply produces much better sound than the standard noisy SMPS that comes with the Raspberry Pi.. Try a battery pack to see (and feel) the difference. It's not just a matter of a linear supply is best, an ultra low noise SMPS will produce similar results, even better than the battery pack. Sbooster have an ultra low noise SMPS power supply specifically designed for the Raspberry Pi, they are pricey though. The iFi iPower 5V ultra low noise SMPS will also produce similar results, and these are affordable. A linear power supply will produce good results, DIY is cheaper than buying a pre-built finished/boxed one.
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Re: Power Supply – Power Bank

Postby smallfat » 13 Apr 2016, 01:05

Battery power will drop after long time listening.
No one know when power drop will affect function and performance.

LPS is the king.
haha

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Re: Power Supply – Power Bank

Postby rastus » 13 Apr 2016, 02:59

Indeed, as a battery pack's power drops the performance (for powering the Raspberry Pi) also degrades. But for a very cheap comparison with the wall-wart that comes with the Pi, it's a no brainer. Anyway, I have always been of the opinion that Elvis is THE king. But to each his own, opinions are like arse-holes (everyone's got one). I have a custom built box type LPS (5V for a Raspberry Pi 2 Model B and 12V for a DSPeaker) on order. A friend has offered to loan me his SBooster (Raspberry Pi compatible). I spoke to the distributor of iFi Audio in Australia, the iFi iPower won't be available for another two months. But, I will be doing a comparative analysis on these three products.

You may want to look into other very highend offerings (very expensive):

Teddy Pardo based on the SuperTeddyReg...
http://www.teddypardo.com/powersupplies.html

Naim based on the Discrete Regulator...
https://www.naimaudio.com/sites/default ... _FINAL.pdf

Obviously the extremely high price of these products defeat the low price of the Raspberry Pi. I want price (low) + performance (low noise), and simplicity (plug and go).
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Re: Power Supply – Power Bank

Postby PeteB » 13 Apr 2016, 03:27

Raising a Raspberry Pi with a 40-dollar DAC to audiophile level is not a simple (or cheap) proposition.

I plan to build and try a linear supply at some point, but it will not be this week (or next) ;)

I agree that a linear power supply usually gives the best results. I am somewhat biased, because I also prefer class A/B amplifiers, preamps with low-noise regulators, toroidal transformers, line filters at the power in, etc.

A switching supply CAN be designed for clean power, but this gets expensive, and the fact is that most manufacturers just do not do this, and most people are used to listening to music with a little noise mixed in, just like we are used to a compressed dynamic range, something that definitely would not be acceptable in a concert hall or in a studio.

With a Raspberry Pi, the situation is more complicated because its digital circuitry produces noise by itself, independent of the power supply. So, for best results, you would have to have separate power supplies for the Pi and the DAC... more expense.

The HiFiBerry DAC+ Pro has an option for separate supplies. It is possible that the best result for the least amount of money would be using the conventional switching supply for the Pi, and a very small linear supply (or battery) for the DAC.
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Re: Power Supply – Power Bank

Postby PeteB » 13 Apr 2016, 03:49

rastus wrote:You may want to look into other very highend offerings (very expensive):

Teddy Pardo based on the SuperTeddyReg...
http://www.teddypardo.com/powersupplies.html

Naim based on the Discrete Regulator...
https://www.naimaudio.com/sites/default ... _FINAL.pdf

Obviously the extremely high price of these products defeat the low price of the Raspberry Pi. I want price (low) + performance (low noise), and simplicity (plug and go).

This is mostly correct, but there are better regulators than the 317, so comparing to that old beast is really not quite right.

If money is no object (or almost), you can definitely buy your way to perfect sound, but you also need the speakers (or headphones) to match (!)

You can build a decent linear supply using a line filter/shielded transformer/soft switch diodes in the rectifier/low noise regulator and some decent low ESR capacitors for much less than those products (as long as you only need 2~3A of current for a DAC or a pre). At low voltage, and low ripple low ESR caps do not age all that quickly, they just need to be paired with something else.

....

Back to power banks, I am sure some will provide cleaner power than others, I just do not know which ones those are!
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Re: Power Supply – Power Bank

Postby rastus » 13 Apr 2016, 05:29

I am using the Verbatim Duel Port 5200 mAh Power Pack with the Raspberry Pi 2 Model B (edit: and Geekroo PiFi DAC+ v2.0 (Hifiberry DAC+ compatible) running RuneAudio for 2.1 speakers music (16bit 44.1kHz to 24bit 192kHz FLAC) and Openelec for 7.2 speakers movies). The Verbatim has duel output DC 5V/2.5A (perfect for the Pi) and single input DC 5V/2A (allows faster charging time), got it from Australian Woolworths supermarket for $24.95AU. I would avoid any power packs with 1A output, and 1A input (longer charging time).
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Re: Power Supply – Power Bank

Postby rastus » 14 Apr 2016, 15:11

For those (like me) that can't solder for shiit. Both the iPower and SBooster power supply solutions are "specialised SMPS". With the iPower being the cheapest of the two, they are both compatible with the Raspberry Pi.

iFi Audio iPower (reasonable):
"By generating a signal identical to the noise signal but in the exact opposite phase, it actively cancels all the incoming noise. With ANC+® (Active noise Cancellation) the power line is filtered for audio band and RF noise. The measured noise floor of 1uV (0.000001V) is at the measurement limit of what even the most sophisticated Audio Precision equipment is capable of."
http://ifi-audio.com/portfolio-view/accessory-ipower/

Review:
"I kept the iPower in my system for three months and went back and forth several times between the iFi and my home-brewed 5A/50W linear power supply without noticing any major differences. Actually without noticing any minor differences either. To be honest I cannot be even sure if there are audible differences between the two and this is probably the biggest compliment one can do to a switching mode power supply."
https://parttimeaudiophile.com/2016/04/ ... -streamer/

The SBooster (expensive):
"The BOTW P&P ECO 5V - 6V is suitable for use with the Raspberry Pi."
https://www.sbooster.com/botw-pp-eco-5v ... pc-upgrade

"With the BOTW P&P ECO audio upgrade the purification of the current starts immediately there where the polluted current enters the upgrade. A dual stage mains filter and an earth line choke clean the current from high frequency pollution before the current reaches the transformer. The transformer is a custom-made audio grade transformer with electrostatic shielding."
https://www.sbooster.com/botw-pp-eco/

Edit: Added italics for quotes.
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Re: Power Supply – Power Bank

Postby PeteB » 16 Apr 2016, 13:25

@rastus: The Sbooster pic shows a very ordinary design, with a line filter, a (very) cheap toroidal transformer, and a simple rectifier and filter, absent any of the parts normally used in a good audio power supply. It is a good, basic, linear supply made with inexpensive parts, in a plastic box, with a simple regulator on the output, single sided circuit board, and inexpensive bulk capacitors.

I also see no mention of a shield in the description of the transformer, which would be a requirement for a high-end custom toroidal audio transformer. (Compare pics with the one posted above by someone else, showing a transformer made by Talema)

Again, this is a VERY basic, VERY inexpensive supply, the rest is just marketing.
An improvement over a switching supply, to be sure, but NOT a high-end audio-grade linear supply at all.

Btw, there is no such thing as "polluted" current and "purified" current. You can filter high frequency noise with the line filter shown in the pic, but this does nothing else. Any noise which is actually in the audio band will pass right through the line filter.

An example of this is an old refrigerator in the house where I am now staying. When using a simple wallwart supply, or a 5V power brick-type supply, I can hear the noise on the output using a headphone amplifier and a mid-price pair of headphones. However, testing with a bench supply, the noise is gone.

This is something you can try with the power banks, b/c you can unplug them from the wall outlet... and one of the things I had in mind when I started this thread, :D
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Re: Power Supply – Power Bank

Postby rastus » 16 Apr 2016, 14:39

PeteB > I don't really want to get into a 'pissing match', I was just offering some options for those that can't 'do solder' (like me). As for how good (or bad) the power supplies are I'll leave that up to you. I can only go on what others say, like Hans Beekhuyzen using an SBooster direct wired to the HiFiBerry Digi+ for testing purposes...

https://www.youtube.com/watch?v=L83EEDbAMJI

And, Pedja Rogic's article "PSU transformers: EI vs. toroidal, and more"...

http://www.audialonline.com/online-topi ... -and-more/

But then, as I've said so many times before, I know shiit about electronics... so I've asked Clayton to put together one of his Gieseler Linear Low Noise Power Supplies for me (bit pricey, but hey, we only live once, right?).

http://www.stereo.net.au/forums/index.p ... y-release/

As for the "polluted" current and "purified" current comment, I do think you really need to contact SBooster with your concerns, I just cited that from their website. I don't work for them, or have any affiliation with them what-so-ever.

I assume, PeteB, by your lack of negative (for want of a better word) comments about the iFi Audio iPower it should be a goer then, mmmm? As I said before, Elvis really is the King man.
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Re: Power Supply – Power Bank

Postby rastus » 16 Apr 2016, 14:46

PeteB wrote:This is something you can try with the power banks, b/c you can unplug them from the wall outlet... and one of the things I had in mind when I started this thread, :D


Oh, I thought osanto started this thread.... I noticed you didn't start the "Linear Power Supplies - any improvement in sound?" thread in "DIY and tweaks" either. Hey, my bad if I'm wrong ( I have been before).

Edit-1: You did say over there, "I saw that, someone posted a link earlier this year, and I have seen some of his other reviews. I agree with him on the power supply (and most other things)" about Hans Beekhuyzen using the SBooster in that "link earlier this year", right? Or maybe you didn't even notice Hans using the SBooster, LoL.

Edit-2: "If you are willing to DIY..." <---- I am not 'willing', neither are a lot of other people I would surmise. We... need... options. Even bad ones.
Ref: linear-power-supplies-any-improvement-in-sound-t758-30.html#p13366
Last edited by rastus on 16 Apr 2016, 16:30, edited 1 time in total.
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