Tír Na HiFi

jkeny wrote:

nige2000 wrote:

jkeny wrote:Yea, this looks good so far - is that the schematic for the linear regulators you're using?

no its only a similar one for explanation purposes, i just google images for it actually think it happened to be from twisted pear

Right - the reason I asked was because that schematic shows protection diodes around the voltage regulators which probably helps the whole arrangement work. I'm not sure if it would work without or at least it would be much more precarious without them? Using floating voltages can be very tricky & great care needs to be taken to ensure no voltage feedback into points where there shouldn't be any - that's why the diodes help

Are there diodes on the actual boards?

there is diodes on the +/- out of the boards which conveniently act like a fuse when you get the polarity of a battery wrong oops....
cant see how there could be reverse polarity though unless you make a mistake and connect stuff up wrong?

Each leg is isolated & floating - there is no connection to mains ground

yes this is why it works, and the best thing is you can connect gnd to any point to get the negative voltages

I wonder if this was powering your chipamp & you connected a grounded device to it, would it cause a problem?

im not sure its certainly going to be interesting as the transformers are isolators (from mains) it should really act the same as a battery pack, however its normal for dc gnd to be connected to mains earth and our friend gnd loop can appear with the many links in the audio chain gnding to earth.
one gnd earthing or no gnds earthing might sound best but that's probably not safe or compliant ?

Yep, ground is the biggest forgotten area in audio & keeping it as noise free as possible is crucial where sensitive, low voltage circuitry is concerned. Unfortunately ground is often used as a dumping area for noise in the belief that it is a infinite sink-hole.

gnd the final frontier
we could have a very long thread discussing and trying to understand just that

i assume my power supply needs to be capable of 8 amps at 13.2v to maintain the possible draw on the chips lm1875
this is where things get interesting when monitoring the discharge of the cells
ive seen cells completely discharge when others stay at 3.3v
ive seen 2 amps been pulled into one cell from reg and other regs doing diddly squat

this is likely the reason cells might be dying

ill beef up my ps hopefully achieve over 2 amps per reg and retest
as at 4.5amps draw im only gettin about 20 mins before voltage starts to fall as regs cant keep up on an individual basis

not sure whats goin on
current 4 regs are only capable of 1 amp so if im outputting 4.5 there is a shortfall

will try to rectify this

nige2000 wrote:there is diodes on the +/- out of the boards which conveniently act like a fuse when you get the polarity of a battery wrong oops....
cant see how there could be reverse polarity though unless you make a mistake and connect stuff up wrong?

When you have polar components, the positive pins are expected to be at a higher positive voltage than the pins designated as negative pins. With some circuits this isn't always possible unless diodes are used - which act like non-return valves allowing the electricity to flow in only one direction

gnd the final frontier
we could have a very long thread discussing and trying to understand just that

Absolutely

i assume my power supply needs to be capable of 8 amps at 13.2v to maintain the possible draw on the chips lm1875
this is where things get interesting when monitoring the discharge of the cells
ive seen cells completely discharge when others stay at 3.3v
ive seen 2 amps been pulled into one cell from reg and other regs doing diddly squat

this is likely the reason cells might be dying

No, this is what I was talking about & increasing the power of the charger will not make any difference. The imbalance in discharging of the cells is exactly what I was warning about & what I experienced with my chipamp. I used a bench supply to power my battery series which was capable of 10Amps or so (the chipamp didn't need anything like this amperage) but the cells died as I said

ill beef up my ps hopefully achieve over 2 amps per reg and retest
as at 4.5amps draw im only gettin about 20 mins before voltage starts to fall as regs cant keep up on an individual basis

not sure whats goin on
current 4 regs are only capable of 1 amp so if im outputting 4.5 there is a shortfall

will try to rectify this

I hope you find a solution.

jkeny wrote:

nige2000 wrote:there is diodes on the +/- out of the boards which conveniently act like a fuse when you get the polarity of a battery wrong oops....
cant see how there could be reverse polarity though unless you make a mistake and connect stuff up wrong?

When you have polar components, the positive pins are expected to be at a higher positive voltage than the pins designated as negative pins. With some circuits this isn't always possible unless diodes are used - which act like non-return valves allowing the electricity to flow in only one direction

gnd the final frontier
we could have a very long thread discussing and trying to understand just that

Absolutely

i assume my power supply needs to be capable of 8 amps at 13.2v to maintain the possible draw on the chips lm1875
this is where things get interesting when monitoring the discharge of the cells
ive seen cells completely discharge when others stay at 3.3v
ive seen 2 amps been pulled into one cell from reg and other regs doing diddly squat

this is likely the reason cells might be dying

No, this is what I was talking about & increasing the power of the charger will not make any difference. The imbalance in discharging of the cells is exactly what I was warning about & what I experienced with my chipamp. I used a bench supply to power my battery series which was capable of 10 Amps or so (the chipamp didn't need anything like this amperage) but the cells died as I said

concur the cells are discharging at dissimilar rates, however if the permanently connected supplies connected in parallel are able to suistain the large individual current draws maybe it will work

ill beef up my ps hopefully achieve over 2 amps per reg and retest
as at 4.5amps draw im only gettin about 20 mins before voltage starts to fall as regs cant keep up on an individual basis

not sure whats goin on
current 4 regs are only capable of 1 amp so if im outputting 4.5 there is a shortfall

will try to rectify this

I hope you find a solution.

so do i :)

brute force charging capability seems to alleviate the unbalanced discharge problem,
could be looking at needin a 3a supply per cell (2amps + insurance)

wonder now am i been way over the top thinking the two chips will need a 100w power supply capability ?

nige2000 wrote:brute force charging capability seems to alleviate the unbalanced discharge problem,
could be looking at needin a 3a supply per cell (2amps + insurance)

That's great news.

wonder now am i been way over the top thinking the two chips will need a 100w power supply capability ?

So you have 2 X 4 cells @ 10Watts per cell - 80W

Have you tried 4 of those SMPS boards instead of linear reg boards - they put out about 2Amps per board?

jkeny wrote:

nige2000 wrote:brute force charging capability seems to alleviate the unbalanced discharge problem,
could be looking at needin a 3a supply per cell (2amps + insurance)

That's great news.

wonder now am i been way over the top thinking the two chips will need a 100w power supply capability ?

So you have 2 X 4 cells @ 10Watts per cell - 80W


Have you tried 4 of those SMPS boards instead of linear reg boards - they put out about 2Amps per board?

the problem is i often see only 2 cells, more or less doin all the work therefore each cell ps needs to be at least twice as powerful

my bulb is 100w
i had read somewhere the chips will use 48w at 15v (so thats times two)

i had thought of using the smps boards but i dont have 4 of them and also id prefer to keep it linear
oh and a couple of transformers are gettin warm so might need to get new transformers

no surrender :)

everything lookin good so far

actually think ive gone way over the top with amperage capabilities of these regs but hey better too much than to little

I'm going to call the PS system a success
And move to the chip amp bit
I started out with lm1875 with cheap caps and resistors and +/- 15v DC from audiowind reg
Sound was very ordinary
Changed out caps and resistors for film ones and it cleaned up sound substantially
I then got two lifepo4 cells one at - side and one at + side of the audiowind reg now giving +/- 18.3v
Dynamics and reverb increased
Out of curiosity I then gathered up 6 cells complete battery power around +/- 10v and the noise floor well dropped through the floor and a layer of micro detail appeared

The problems are now
Gut feeling PS needs to be +/- 15v or above for best sq
That's 10 cells per speaker channel and that's getting expensive for experiments

Jk mentioned a guy that uses a heap of capacitance at diyaudio in his experiments and he has used an NXP btl chip with good results and I think I'll try that at least as an alternative
http://www.diyaudio.com/forums/blogs/ab ... oject.html

preliminary tda8561 setup on a drill battery sounds good



had it on lifepo4 the other day at 16.5v noise floor and dynamics are second to none