Hi Richard,
Your clc got me thinking if I should give it a try on my AyA dac. Right now Im using 600-600 ohm line out trafo & its sounds really really good. It's killing 2 birds with 1 stone. No dreaded dc caps & trafo is also acting as a filter in itself so wondering if adding your clc would improve over what I have now. What's your thoughts Richard ?
Thanks
Your clc got me thinking if I should give it a try on my AyA dac. Right now Im using 600-600 ohm line out trafo & its sounds really really good. It's killing 2 birds with 1 stone. No dreaded dc caps & trafo is also acting as a filter in itself so wondering if adding your clc would improve over what I have now. What's your thoughts Richard ?
Thanks
I'm not familiar with the schematic of the AYA DAC - I did a quick search and seems there might be more than one version out there. One is using AD844 and maybe another OPA861. The CLC needs to feed into a known impedance which is easy if there's a virtual earth (created by negative feedback) but not so straightforward with open loop circuits as then the input impedance of the I/V stage will be unknown.
The trafo's leakage inductance will be acting as a filter but if you know what it is you can tune it with a shunt capacitor (and typically an RC for damping) to give yourself a 2nd order filter, quite useful for reducing the noise into the next stage.
The trafo's leakage inductance will be acting as a filter but if you know what it is you can tune it with a shunt capacitor (and typically an RC for damping) to give yourself a 2nd order filter, quite useful for reducing the noise into the next stage.
Hi again Abraxalito. I mentioned in my post #479 that I have a friend who is working on a pick and place project and the thinking is that the phiDAC board would be a nice test - he's asked if you have a cpd file to go with your gerber set? Apparently a cpd file is needed to correctly place the components onto their boar locations. Cheers.
Hi Richard,
Thanks for the advice. AyA only has 2 versions, early days i/v & buffer stage was using AD op amps now its uses OPA. What interest me in your clc is to see if I can get more out of the dac prior to i/v stage. I don't see a point in killing noise it at the opt stage. Will do more research to see if I can give your clc a try.
Many thanks again
Thanks for the advice. AyA only has 2 versions, early days i/v & buffer stage was using AD op amps now its uses OPA. What interest me in your clc is to see if I can get more out of the dac prior to i/v stage. I don't see a point in killing noise it at the opt stage. Will do more research to see if I can give your clc a try.
Many thanks again
Thanks Abraxalito; it would be a nice bringing together of different DIY hobbies/interests to assemble a PhiDAC board with a DIY pick & place solution.
easyEDA doesn't generate a cpd file. Are there other methods of getting the data into your friend's machine? Some other CAD packages I saw mentioned in my searching I saw create .CSV files, that might be a more promising avenue to explore.
@sumotan - if Pedja's design uses AD844 in open loop (I've seen a circuit with his name on where there's a resistor from pin5 and the output buffer isn't used) then the DS says the -ve terminal input impedance is 50ohm, typical with 65ohm maximum. That kind of magnitude of variation really means each AD844 would need to have its own made-to-measure CLC in order to get reasonably flat FR.
@sumotan - if Pedja's design uses AD844 in open loop (I've seen a circuit with his name on where there's a resistor from pin5 and the output buffer isn't used) then the DS says the -ve terminal input impedance is 50ohm, typical with 65ohm maximum. That kind of magnitude of variation really means each AD844 would need to have its own made-to-measure CLC in order to get reasonably flat FR.
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Thank you. Let me have a chat with him to see if he has any ideas on alternatives - I know he uses KiCad so maybe there is a way of getting your pcb cad drawings into it?
It looks as though EasyEDA will export a csv pick and place file too.
I've asked if he can work with a csv file.
A csv pick and place file would be great if you could manage the export from EasyEDA Abraxalito?
At the moment there are no kits for sale that I'm aware of. Various people bought kits of PhiDAC (in packs of 10) and might still have some available - like @matt_garman.
Eventually there will be kits of the next generation parallel DAC (with transformers) but its not yet fully designed.
Eventually there will be kits of the next generation parallel DAC (with transformers) but its not yet fully designed.
Pick and place file
@nautiboy: Here's the .csv output from easyEDA for the PhiDAC board. Hope its understandable!
Incidentally I've realized that I've not done a full release of the PhiDAC SE design to date, having been distracted by the delights of multiple paralleled DACs. Is there any interest here in having that design available?
@nautiboy: Here's the .csv output from easyEDA for the PhiDAC board. Hope its understandable!
Incidentally I've realized that I've not done a full release of the PhiDAC SE design to date, having been distracted by the delights of multiple paralleled DACs. Is there any interest here in having that design available?
Thanks Abrax. I'll pass it on; I'm sure he'll make sense of it.
On your second point, information gets scattered across a thread so I think its generally a good idea to periodically checkpoint and bring everything together as a 'current release'.
I might be being rather obtuse but I can't quite see how 'keeping info together' fits with the case with PhiDAC SE where the info is mostly absent, apart from a schematic.
I'm still reading up on the PhiDAC so perhaps making an assumption, however, I was just making a general observation.
If my mental accounting is right, I believe there is one remaining PhiDAC kit that is not spoken for. PM me if interested!
This weekend is looking bad in terms of having time to sort out the kits, so for all those waiting, I'm sorry, will likely be another week before I can start on the kit-sorting!
Richard, for your new DAC boards with lots of tda1387 ICs: are you hand-soldering those? If so, I suggest you give the "frying pan" method a try. Basically, use a toothpick to "paint" solder paste on the solder pads of the PCB, and use precision tweezers to place the components. Get a frying pan/skillet going on medium heat, and gently place the PCB on it. Crank the heat up to max until you see the solder paste turn molten. This is the fun part, where surface tension corrects all the components that weren't placed completely straight! Keep the heat going for a few seconds, then kill the heat and use tweezers to pull the board and place it somewhere to cool.
Painting solder paste and placing components is still tedious and time-consuming, but I think it's better than hand-soldering one-by-one. And if nothing else, the results look much cleaner.
...ahh, here is the post where I described this process in a bit more detail, complete with pictures!