Power Supply – Power Bank

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Re: Power Supply – Power Bank

Postby PeteB » 16 Apr 2016, 15:37

rastus wrote:
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....



No, you are correct. I suggested a separate thread (sorry, I should have been more accurate), here:
http://www.runeaudio.com/forum/post12964.html#p12964
(Just to keep the discussion out of the Raspberry Pi3 thread)

I agree that linear supplies are generally an improvement. Not necessarily with the selection of the supply. There are some good ones on ebay, with a description of the regulator and transformer used. Some bad ones too, but quite a few good ones, for reasonable prices.

The place to go to collect information is diyaudio, or a similar web site. Not all people there build up from component level. My opinions are generally ummm... biased(?)... and you can find quite a few discussions and recommendations there.

It is worth it to read up on transformers, and why some are better for audio than others, shielding etc. Lots of information on the internet about that. Same goes for filters and capacitors, even if you never solder one.
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Re: Power Supply – Power Bank

Postby rastus » 16 Apr 2016, 16:20

PeteB wrote:It is a good, basic, linear supply....


No, The SBooster is a SMPS.... I clearly stated that in the original post. I said, "Both the iPower and SBooster power supply solutions are 'specialised SMPS'."

PeteB wrote:Again, this is a VERY basic...


No it's not.

PeteB wrote:...VERY inexpensive supply, the rest is just marketing.


I think it is a very EXpensive supply, for what it offers. That's why I added the iPower, because it's less expensive (and still only a SMPS too). But, people are trying the iPower and with positive results (even comparing it with a linear power supply). I don't know, I haven't tried it.. yet.

PeteB wrote:An improvement over a switching supply, to be sure, but NOT a high-end audio-grade linear supply at all.


Nope, and I didn't present it as anything more than what it is.

PeteB wrote:This is something you can try with the power banks, b/c you can unplug them from the wall outlet...


I always run my Pi with the battery pack disconnected from the wall socket. The battery itself would introduce noise if it was plugged into the wall socket and charging, every time it 'switched' been charge and discharge (supplying the Pi).

And now I'll throw the cat among the pigeons: even a linear power supply IF NOT built correctly (with quality components, etc) will introduce noise and do no better than a SMPS, maybe even worse under some circumstances.
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Re: Power Supply – Power Bank

Postby PeteB » 16 Apr 2016, 16:47

Must have looked at a different one, sorry. This one, with the toroidal transformer, rectifier and filter, sold as a "switch mode adapter upgrade"?

https://www.sbooster.com/botw-pp-eco/

(picture on green background)

edit:

and here, for £ 195.00? Clearly described as a "Raspberry Pi Linear Power Supply - by Sbooster"

https://markgrant.co.uk/linear-power-supply/187-raspberry-pi-linear-power-supply-by-sbooster.html
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Re: Power Supply – Power Bank

Postby dunghnguyen » 16 Apr 2016, 19:39

It is so expensive against to RP2 price :(
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Re: Power Supply – Power Bank

Postby dunghnguyen » 17 Apr 2016, 02:07

I tried 2 cases:
1) switching adapter Asus 5VDC, 1.35A
2) Power bank battery Asus 9600mAh, 2.4A

Both 2 cases run well. No any signal that lacks of power. But my ears recognized the case of battery the sound is clearer, more detailed, the sound stage looks full, more confident.

Looking around options for a linear power supply that its price seems extremely high against to what the ears can get. I think the sustainable way is to invest for a toroidal transformer with filter to supply power for my amp (Denon 720ae, it is normal EI transformer) that this solution I could diy at the cost of linear power for RP2 that many tried / got better results.
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Re: Power Supply – Power Bank

Postby rastus » 17 Apr 2016, 02:21

dunghnguyen > The previous page, and pages, of this thread does have a lot of information and recommendations (with links to further reading), both low and high priced, from many people (other than myself).

Edit: Including a link comparing both the El transformer against the Toroidal transformer. Also, the design and addition of newer low noise technology applied to SMPS's. A lot of good reading from many people in this thread.
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Re: Power Supply – Power Bank

Postby dunghnguyen » 18 May 2016, 16:17

Image

This one is 50VA, out 9VDC-3A looks too much for my DAC (9VDC-1.3A) so I intend to add in 1 additional linear rectifier/regular board to have another out 5VDC-2A using for Pi 2/C2
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Re: Power Supply – Power Bank

Postby uimitechnology » 20 May 2016, 12:39

if you want to buy power bank look our uimi power banks with high battery capacity support ....uimitech.com
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Re: Power Supply – Power Bank

Postby LC1 » 22 May 2016, 09:26

rastus wrote:I think it is a very EXpensive supply, for what it offers. That's why I added the iPower, because it's less expensive (and still only a SMPS too). But, people are trying the iPower and with positive results (even comparing it with a linear power supply). I don't know, I haven't tried it.. yet.


I have been reading this thread with interest.

I'm very tempted by this iPower thingy, having read the positive reports on that artofsound thread (not everyone was impressed, but it seems to depend on your set up), and I am very close to purchasing. I did briefly consider a linear supply, but the size/cost of them has put me off.

My question, if anyone can help me to understand, is what other hardware tweaks might help to improve the SQ on my system (which is already pretty good, of course)? I have only the most basic computing/electronics knowledge, but would love to make some changes if they are affordable and will make an audible improvement.

I currently have a Pi type B with an IQAUDIO i2s DAC, my music on a 128gb usb pen drive in the Pi, and amp is a SMSL SA60 with a Toshiba SMPS (which I thought might be marginally better than the SMSL stock one). Crucially, I currently have the Pi networked by ethernet cable rather than via wireless, which I have only just seen might be a significant source of noise.

Which aspects of this set up are likely to be giving the most noise into the system? How much noise comes from the ethernet compared to the SMPS of the pi?

Would an IFI ipower be beneficial for the amp too, or not so much? Bang for buck is important, so I am less interested in areas where there is diminishing returns on the ££s spent!

(NB I have reason to suspect that the electrics in this old house are very far from perfect!)

Any thoughts would be greatly appreciated :)
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Re: Power Supply – Power Bank

Postby PeteB » 22 May 2016, 13:25

Something like the ipower will not help if you have noisy mains and/or bad grounds (earth connection). Neither will a conventional linear supply. For that you would need a large isolation transformer($$$), and/or large line filter($$) inline with the mains before the power supply. Or that battery bank (least expensive).

None of that including a battery bank will stop noise from the ethernet cables or (in my case) the HDMI cable.

As you said yourself, ethernet "might be" a source of noise, but it does not mean it "will be" a source of significant noise in your case (or anybody's). For me personally, "might be" is not a reason to spend several hudred dollars on power supplies. Especially since a WiFi dongle can fix that for $10.

With just a single connection to an audio system (WiFi instead of wired ethernet, no HDMI, no powered USB hub), and a stock 2A supply, my Pi2/DAC+ combination has very low noise, and extremely low distortion (also assuming volume control disabled), even with poor mains power.

Image

In the test above, with a less-than-perfect 1KHz test signal, 48K sample rate, 16-bit resolution, harmonics peak at -100db and noise is down around -110. That is almost studio quality sound.

When I start adding other things, and other connections, the noise goes up, and eventually becomes audible. No power supply can prevent that.

Neither a linear supply nor a better smps will prevent noise from the ethernet cable, or the HDMI cable (something I recently found out while testing).

Don't get me wrong, I am a big believer in clean power, and I used to design and test power supplies as part of my job. I could go on and on about the benefits of good power supplies in audio, but the fact is that you get most of the same benefits from simple and cheap solutions.
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