I can, but float charging may degrade the sound quality and also break the isolation.
For LifePO4 battery, you don't need doing so because of the discharging time is very long and the voltage also keeps stable. However, on the other hand, for the ultra capacitor, the discharge time could be too short (a couple of minutes) except you use the 3000F monster.
If we don't care about the sound quality, then we don't have to waste that much time and effort to develop a complicated power supply like this.
Regards,
Ian
I'm not saying to keep it like that all the time, only during charging.
If the LifePO4 battery lasts so long then why not remove the relays between the battery and the load and simply use relays between the charger and the battery?
That removes one source of unwanted impedance where it matters most.
But then again, is there really a concern of breaking isolation when the regulator is disabled? I would think no relays are required.
Sure, the sound won't be as good during charging but you would be forced to wait while the batteries charge in either scenario.
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Hi Ian
I stumbled across this thread after following your proposed UltracaP PS in the other thread; another great project!
Where I live LifePO4 batteries are fairly expensive so if I need only a 6.6V supply with around 100 - 150mA current draw would I need to populate the board with the full 10 batteries or could I get away with less (say 4), or does your design require the full 10 batteries?
Thanks
I stumbled across this thread after following your proposed UltracaP PS in the other thread; another great project!
Where I live LifePO4 batteries are fairly expensive so if I need only a 6.6V supply with around 100 - 150mA current draw would I need to populate the board with the full 10 batteries or could I get away with less (say 4), or does your design require the full 10 batteries?
Thanks
ian
waiting for you to present your integrated solution to adopt the ultracaps in the correct way to feed dac and IV (possibly with a +- 5V dual supply) I would like to know what you think of this design solution ;
https://scholarcommons.scu.edu/cgi/viewcontent.cgi?article=1006&context=elec_senior
waiting for you to present your integrated solution to adopt the ultracaps in the correct way to feed dac and IV (possibly with a +- 5V dual supply) I would like to know what you think of this design solution ;
https://scholarcommons.scu.edu/cgi/viewcontent.cgi?article=1006&context=elec_senior
Does this mean that in my simple potential use case scenario of powering an Allo Boss 1.2 separately from the raspberry this battery PSU would be " sub-optimal"or rather "totally useless"?
Thanks and apology for the simple question!
I think that is a bit extreme. You can achieve improved sound with a battery supply and downstream LDOs, like those on the Allo Boss DAC. Even better, use the Allo isolator and power it with a solution like Ian's battery supply. In that case, you will be using two levels of downstream LDOs (on the isolator and the DAC).
This is not as great as pure battery power directly to the DAC, but it is certainly better than using (for example) an SMPS and tying the pi and the DAC to the same supply.
So if you have an Allo Boss, adding an isolator and Ian's battery solution is going to be an improvement. I have built a similar (but not as sophisticated) solution which I posted here in the Slimdevices forum.
Cheers
Whit
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I have tried to supply power to Allo using the battery, but I think the improvement is not obvious. It is speculated that Allo's reclock can be more improvement. Ian's FIFO is really much better, so I am looking forward to Ian's battery module.
Here is what I have found playing with Pis and Allo Boss DACs:
Pi + Allo Boss + crappy SMPS wall wart > worst sound
Pi + Allo Boss + crappy SMPS + common mode choke/cap filter > better
Pi + Allo Boss + linear 5 volt supply with LM1804 regulator > better
Pi + Allo Boss + Allo Isolator + 5 V linear to Pi and LiPo battery to Isolator and DAC > best so far
Note that I am using the original Boss, not v1.2 (may upgrade soon).
All this is completely subjective, of course, but I am listening to the DAC connected directly (through an Alps attenuator) to a McCormack DNA.5 amp, driving Martin Logan Aerius i's. Any harshness or other crap in the sound is pretty much immediately revealed and hurts my ears. I am finally happy with the current combo. My build is here:
pi based systems - Page 6
This is certainly not the end of the road for me, but serves as a reference for more experiments.
Cheers
Whit
Thanks, I just bought Boss 1.2 that already provides the possibility of separate power to Pi and Dac.
Do I really need Isolator? In case, rather than the Allo one, I would use Ian IsolatorPi that I own already.
I have not taken a decision yet on which Linear PSUs to buy for PI and Dac.
One convenient option seemed to be HDPlex 200, but the new model is not available yet and when it will be is not known....
HDPLEX 200W Linear Power Supply Multi Rail Output
I'm sure UpTone JS-2 would be a very valid solution technically speaking, but a little to expensive for my use case
JS-2 Linear Power Supply – UpTone Audio
Trying also to understand when Ian battery solution will be available for purchase.
Wow - I would say you are trodding into serious overkill territory with either of those
. But you would have an upgrade path for future higher-end DACs. Nevertheless, I agree with Ian that a LiFeO4 or Ultra Cap supply is going to be better for the clocks and DAC.I would say that if you are willing to roll your own, you can build a perfectly good linear supply (or supplies) with your own transformers and regulator boards sourced from China (via eBay) for a lot less money. I initially used a dual adjustable linear board which I think cost $12. I added a 25 VA toroid for $20 and wired it all up. (I subsequently built my own rectifier/filter/regulator board but that's not strictly necessary). This may not get you into the millivolt ripple range, but the Pi won't care and the LDOs on the Allo isolator (don't know about Ian's isolator) will take care of the rest to a fair degree.
I would claim that this would be "good enough" for the class of DAC we are talking about (the Boss).
The main benefit of either isolator is to galvanically remove all electrical connections between the DAC from the Pi, which is loaded with noise on its supply, ground rail and all the GPIO pins. That noise will be there regardless of the type of supply used for the Pi - but better with a linear one.
Good luck!
Cheers
Whit
LifePO4 power supply PCB layout and dimensions
LifePO4 power supply PCB layout and dimensions
LifePO4PowerSupplyDimensions by Ian, on Flickr
Ian
LifePO4 power supply PCB layout and dimensions
LifePO4PowerSupplyDimensions by Ian, on Flickr
Ian
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