Soekris Dam Dac

[Dan155]

nige2000,

I am confused by your replacing the electrolytics with film caps.

I would have thought you would not have wanted any capacitance at all?

Rick, the opamps supplying the DAC will need a certain amount of capacitance in order to maintain dynamic performance. Without caps and with the long leads from the batteries, impedance at high frequencies would go high.

[nige2000]

nige2000,

I am confused by your replacing the electrolytics with film caps.

I would have thought you would not have wanted any capacitance at all?

Rick, the opamps supplying the DAC will need a certain amount of capacitance in order to maintain dynamic performance. Without caps and with the long leads from the batteries, impedance at high frequencies would go high.

maybe it would work fine without the caps
ive never noticed the use these particular caps to be a disadvantage over using none before (with the exception of the clocks)
electrolytics are a different story never seem to be optimal with lifepo4
the fun with caps story is never ending :)

ive ran 2 feet of wire between lifepo4 and devices before without any recognisable loss in sq
which suits my funky testing methods :)

if there is a boxed version :() the wire will be shorter

any more thoughts on bypassin the 4v opamps
i didnt get probing yet the electrolytics were annoying me too much

[Dan155]

ive ran 2 feet of wire between lifepo4 and devices before without any recognisable loss in sq
which suits my funky testing methods :)

Long leads are ok, as long as there is sufficient capacitance at the load. High speed analog and digital devices are more sensitive.

any more thoughts on bypassin the 4v opamps
i didnt get probing yet the electrolytics were annoying me too much

I don't think it's feasible to bypass the opamps, I'd just like to make sure they are the best parts for the job, and the references are nice and quite. It may be possible to replace the -4V reference with a battery.

[rickmcinnis]

And to think I thought you were adamant about no caps after the batteries!

I bet there is nothing we, even you, can do with the ladder power supplies.

I have no problem with caps other than it would be nice to not have to deal with soldering something back on to those pads! Pure laziness! Still wonder if the A123s have as good high frequency response as we think they so will the caps get in the way? Well, damnit, only one way to find out!

Reminds me of the fellow leading the filter experiments at DIYAudio when asked that he try something he said to the requester something to the effect they had no hesitation to ask for someone's time. I know I have fallen into that camp a few times, being the requester that is!

So what cap have you found to be benign?

[nige2000]

And to think I thought you were adamant about no caps after the batteries!

thought i mentioned it before 1uf and lower film seem not to cause bottlenecks

I bet there is nothing we, even you, can do with the ladder power supplies.

maybe not

I have no problem with caps other than it would be nice to not have to deal with soldering something back on to those pads! Pure laziness! Still wonder if the A123s have as good high frequency response as we think they so will the caps get in the way? Well, damnit, only one way to find out!
Reminds me of the fellow leading the filter experiments at DIYAudio when asked that he try something he said to the requester something to the effect they had no hesitation to ask for someone's time. I know I have fallen into that camp a few times, being the requester that is!

So what cap have you found to be benign?

yea a-b testing plus build/rebuild is far more time consuming than just a bit of soldering
really need to test stuff for yourself its more productive for the cause

kinda hoped you guys would have something half built/modded by now

[rickmcinnis]

nige2000,

AS I am about to transition, finally, to battery power here (along with PC) I am finally seeing your BIG plan clearly.

I am wondering if it can be taken a small step further.

You are using plus/minus seven volts using four cells

You have removed the 3.3 volts reg and replaced with a battery.

You have removed the 5 volts regulators which means the four volts regulators are being fed seven instead of 5 volts. This is a brilliant move but I wonder if you are stressing the four volts regs with the extra two volts which makes me think that unless something else is needing more than five volts (this is where the question lies) why not just use five volts at the input?

Are those blobs I see int he picture the jumpers - looks like one is between pins 1 and 8 and the other between 1 and 2 - am I seeing this correctly?

Are you getting any additional heating from the extra voltage?

I am assuming you are still listening to the DAM.

Does that serial port require more than five volts? Does anything?

Thanks and take care,

[nige2000]

nige2000,

AS I am about to transition, finally, to battery power here (along with PC) I am finally seeing your BIG plan clearly.

I am wondering if it can be taken a small step further.

You are using plus/minus seven volts using four cells

not any more switched to 5v when i took out the 5v regs

You have removed the 3.3 volts reg and replaced with a battery.

yes

You have removed the 5 volts regulators which means the four volts regulators are being fed seven instead of 5 volts. This is a brilliant move but I wonder if you are stressing the four volts regs with the extra two volts which makes me think that unless something else is needing more than five volts (this is where the question lies) why not just use five volts at the input?

using 5v now

Are those blobs I see int he picture the jumpers - looks like one is between pins 1 and 8 and the other between 1 and 2 - am I seeing this correctly?

yes these are jumpers

I am assuming you are still listening to the DAM.

Does that serial port require more than five volts? Does anything?

Thanks and take care,

all works like stock
except i have two switches one between the batteries and the dac and one between the linear power supplies and the batteries
this is to prevent battery drain

[rickmcinnis]

See that those are jumpers for the 5 volts regs - should have looked.

So the big question is: is there any reason to use more than 5 volts as an input voltage?

Thanks,

[nige2000]

didnt like to chance much more than 5v
a bit afraid of the blue smoke

think the 4v opamps might not be fast enough to respond to the fast transients the way id like
although it is much improved from stock

[rickmcinnis]

5 volts is plenty.

I must have missed you saying you had lowered the input voltage.

So the UMANAGER still works?

Looking forward to the new firmware and the doubling of taps for the filters.

Doubt that will remove all problems but the thing sounds pretty good to me with spzzzzrt's latest filters.