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IanCanada's Latest RPi GB Goodies Impressions... and your tweaks, mods and hints...
IanCanada's Latest RPi GB Goodies Impressions... and your tweaks, mods and hints...
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Old 18th February 2020, 12:37 PM   #1271
Markw4 is offline Markw4  United States
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Quote:
Originally Posted by misterdog View Post
I would guess at a weeks work to design/prototype/populate/test/troubleshoot...
If it were that easy then lots of good quality AK4499 dacs would already be on the market. Also, the Chinese ones on the market so far don't seem to be luring a lot of buyers. We still aren't getting user reports on how they sound.
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Old 18th February 2020, 01:35 PM   #1272
soundcheck is offline soundcheck  Germany
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Hi there.

Just a comment from the sideline. (I'm not running Ians devices anymore)

I made bad experiences with plain supercaps on the output. I'm talking about the Allo Shanti in particluar - because that's what I have here.
But the solutions you're discussing over here are not much different - as far as I see it.

I very well understand the huge temptations behind running these pure power
supplies. The first supply of this kind (I was aware off ) used for audio I had the pleasure to enjoy in 2011.

People tend to forget some important subjects though.

First of all Supercaps are very dangerous devices.

Looking at all these DIY solutions over here and elsewhere and looking even at professional solutions (e.g. Allo) I find that the turn-on and turn-off behavior towards the load is not properly handled in many cases I've seen.

1.
IMO it's not a good idea to discharge the supercaps over the load. That can lead to
very strange situations, since the load remains for quite some time on voltage levels
that let the load float in a grey zone. That's not good.

2.
The discharging can take forever. You have to be very careful unplugging the loads.
You never know where you're at.

3.
Then - in my case - I experience nasty turn on and off thumps/strange noises.
I called it "cap-sucker noise". There's a lot of stress on the system.


(4.) The charging cycle also needs to be carefully engineered. But that's not that
critical and much easier to accomplish.



Conclusion:

Low noise and low ESR = ultimate power

....is not everything.

And yep "Everything Matters" ...
.
...even device and user safety.

********

To fight all this mess, I introduced relays after the supercaps. The relays are controlled
with an ESP8266 and fired by an external 5V source. That pretty much solved
all my issues I had with that supercap solution.
Sideeffect: By having the ESP in the loop I now have a nice remote control unit in place and can nicely control and time-shift my supercap power rails.

What remains an open topic to me is the "bleeding part". Allo mentioned once that they have taken care on that part.

Enjoy.

Last edited by soundcheck; 18th February 2020 at 01:46 PM.
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Old 18th February 2020, 11:12 PM   #1273
wlowes is offline wlowes  Canada
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Default Caps are dangerous but have their place

I fully agree with Soundcheck's warning that supercaps can be dangerous. I think Greg has covered this well earlier, but always good to remind. In fact all caps can be pretty dangerous. I build tube gear with pretty big power supplies. A cap bank charged with 600 volts is absolutely lethal. The supercaps I use at 2.7V 50F are pretty tame by comparison, but if you have any doubts about safety, steer clear and experiment at your own risk.

As far as turn on / off issues, I have seen non other than it can take time for a circuit to discharge. In the wireless coms business in which my former company used them they were used as an uninterruptible power supply. In the industrial application it was important to know if there was a power outage. By having a supercap, you could have enough time for a device to detect an outage on the grid and continue operating long enough to communicate the outage so that a central control system could take appropriate steps. In fact the processor was pretty similar to a Rpi. When the grid lost power, the supercap kept the processor going for 5 minutes. When the charge died so did the processor. My setup is identical. I turn on the Rpi (and the dac) and leave it on 7/24. DACs and clocks work best when they are powered up and warm all the time. If there is a brief power flicker or failure, the Rpi does not even see it. If you power it down deliberately, just leave it for a few minutes until the LED's all go out. You get a small bump in sound quality, and I would argue that the circuits are protected from power failures.
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Old 19th February 2020, 06:18 AM   #1274
soundcheck is offline soundcheck  Germany
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My post was not meant to be just a warning.

I've mentioned a potential solution - my solution - to cope with this IMO serious issue.

If I'm not mistaken Ians battery supply comes also with relays on the output.
LiFePOs are as dangerous as supercaps. Therefore the very same logic that applies to batteries applies to supercap supplies or buffers.

Last edited by soundcheck; 19th February 2020 at 06:21 AM.
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Old 19th February 2020, 01:33 PM   #1275
wlowes is offline wlowes  Canada
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Quote:
Originally Posted by soundcheck View Post
I've mentioned a potential solution - my solution - to cope with this IMO serious issue.
I think I am missing the urgent issue you cite. My solution to turning off the streamer is a $5 toggle switch. Works like a charm. Click. Job done. I use one switch to control all the power supplies to the digital side, and another to control all the power supplies to the tube output amp. That way it is easy to leave the digital stuff powered all the time at very little cost, and only power up the tube gear when you want to make music. Given it's working perfectly, I feel I am missing what the issue is that prompt your warning/alarms.
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Old 19th February 2020, 02:07 PM   #1276
soundcheck is offline soundcheck  Germany
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Ah. OK. Didn't realize you still live in the dark ages of manually toggling switches.
That's been another live on my side. Sorry for the ignorance.

I simply can't live with a DIY system based on "toggle-switches" (for every DC rail!)
or on-system control knobs anymore. No wonder you're leaving it on 24/7.


Enjoy.
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Old 19th February 2020, 02:20 PM   #1277
sq225917 is offline sq225917  United Kingdom
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Send a message via MSN to sq225917 IanCanada's Latest RPi GB Goodies Impressions... and your tweaks, mods and hints...
I have my dac board powered separately from the rest of the stack, with supercaps on each rail. I've never had any issues of any kind with turn on thump or anything else. I mostly leave the dac board powered up 24/7, but it probably gets tur ed off fully at least once a week.
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Old 19th February 2020, 02:56 PM   #1278
soundcheck is offline soundcheck  Germany
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Folks.

Simply look at Ians LiFePO supply. There's been a very valid reason why he's chosen
to go for relays on the rails.

My experiences with the Shanti were even confirmed by Allo. They just ignored it.


And if you turn off every single DC rail with a switch like wlowes, fair enough.
"Lab-style" operations is a pretty common approach to stereo over here. I've been doing it for years myself. I simply can't run such as system in a real-life environment.

And NO. Wasting kWatts of energy on 24/7 operations to hear "potentially" a tiny bit more this or that, nope you can't expect me or anybody else to jump on that a train.

Enjoy.
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Old 19th February 2020, 06:11 PM   #1279
randytsuch is offline randytsuch
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IanCanada's Latest RPi GB Goodies Impressions... and your tweaks, mods and hints...
If a pi/dac setup uses 5 a @ 5v, then 15 watts. Comes out to 131 kw-hrs/yr.
From my quick google, an average fridge is 12 times higher energy consumption.

I leave mine on 24/7. Individual choice obviously, I still have manual switches.

I also just did a quick estimate, I think my energy cost is about $25/yr to leave it on.
Maybe I'll start turning it off

Randy
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Old 19th February 2020, 06:16 PM   #1280
MikeyFresh is offline MikeyFresh  United States
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IanCanada's Latest RPi GB Goodies Impressions... and your tweaks, mods and hints...
Quote:
Originally Posted by randytsuch View Post
If a pi/dac setup uses 5 a @ 5v, then 15 watts. Comes out to 131 kw-hrs/yr.
From my quick google, an average fridge is 12 times higher energy consumption.

I leave mine on 24/7. Individual choice obviously, I still have manual switches.

I also just did a quick estimate, I think my energy cost is about $25/yr to leave it on.
Maybe I'll start turning it off

Randy
Typo there, you meant 3a @ 5v
I leave mine on 24/7 too!
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