Soekris Dam Dac

[randytsuch]

Thanks for the pics Nigel

Made little progress this weekend.

I was wondering what to do about the 3.3V for the isolators and the Amanero. I think I just decided to use a lifepo4 battery, should have been obvious. I do need to create a little power supply for this, but I may just charge when it is not in use for this one, I don't think it will need much power.

I've removed the 3.3V regulator from my Amanero, so I need something to supply this power.

Randy

[nige2000]

I found it very important to give the i2s device it's own power supply ie not from pc
they are more noise sensitive than noise makers

not convinced about the need for i2s isolation once this is done
but my pc must be one of the cleanest powered about maybe thar relieves some of the issue
it can be easily tested with a few batteries

previous tests with isolators I could hear no improvement on my system

[randytsuch]

I found it very important to give the i2s device it's own power supply ie not from pc
they are more noise sensitive than noise makers

not convinced about the need for i2s isolation once this is done
but my pc must be one of the cleanest powered about maybe thar relieves some of the issue
it can be easily tested with a few batteries

previous tests with isolators I could hear no improvement on my system

Yes, I'm sure your PC is much cleaner and more tweaked than the guys at diy. So you may see differences in implementation than what they report.

Randy

[nige2000]

Thinking about that +- 4 volts supply - it has to be those chips next to the 100uF caps.

the chips beside the 110uf caps on the input side of the dac?
cause there the 5v regs

My concern would be - can one depend on the batteries to deliver absolutely stable voltage?

only if there been float charged
its the sheer capacitance

I suspect we will need to use a really good regulator to "charge" those batteries but will the battery be able to maintain a set voltage as well as a voltage regulator on its own?

well a good one at least, u could use a shunt to keep your mind at ease

[rickmcinnis]

I am wondering if SOEKRIS's reg for the ladder is plenty good and the easiest thing, and maybe the best,is to replace those caps with your suggested battery. Would they need to be charged to 4 volts before insertion? Would that reg be capable of bringing them up to 4 volts? It would have to be capable of maintenance.

What about powering the board with an AC supply which would power the regs which would then maintain the batteries? Just replace the capacitors with batteries? Leave the thing on all the time, which I have found to be beneficial for DACs anyway. There is going to be AC involved somewhere with powering the batteries. Would distance make that much difference? Sure would eliminate lots of wire.

AS you say, the batteries are nothing much more than immense cap banks, use them that way.

[rickmcinnis]

Are you saying those 8 fingered things near the bottom of the board next to two caps are 5 volts regulators?

Looked like opamps to me though I have yet to look at what is written on them.

Do you think you can get juli@ to work with KS?

[nige2000]

if the battery cells are depleted the on board regs wont be fit for it

The 8L05A and 9L05A are +5 and -5 Linear regulators [link]. Input to these regulators are the +/- rails (which could be 7 to 15V regulated or unregulated) . The outputs are filtered by 100uF capacitors.

and ive also probed them at +/-5v

[rickmcinnis]

If it has not already been figured out I think I can surmise from what SOEKRIS is saying the +-4 volts regulators are plural - there is not just one of them.

I am thinking there are twenty of them and they are intertwined with those filter chips.

So, close to impossible to power with a 4 volts battery unless you are extremely deft with the soldering iron.

I give up.

Still think a simple substitution of batteries for capacitors would be worth the trouble and hoping the filter situation changes to something good soon.

[nige2000]

my guess is the filters need fixing
then when thats sorted feed dac with +/- 5v and 3.3v lifepo4
bypass 5v regs and 3.3v ldo
replace caps

thats about it any more were at great risk of dead dac

putting this build more or less on hold till there's better filters or there bypassed

[randytsuch]

my guess is the filters need fixing
then when thats sorted feed dac with +/- 5v and 3.3v lifepo4
bypass 5v regs and 3.3v ldo
replace caps

thats about it any more were at great risk of dead dac

putting this build more or less on hold till there's better filters or there bypassed

There are new filters to try. Sounds like they can still be tweaked, but its a start.

Randy