Audio Creative DDDAC1794 User manual

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Version 1.1
Finally !! The new, highly improved ‘2016’ DDDAC1794 module! De voltage regulation at
the analog side of the system has now an embedded Tentlabs Shunt regulator. The Bias
through the much discussed ‘pin 20’ got a constant current source (CCS) which replaces
the fixed 6K1 resistor. All resulting in the next stage of superb sound reproduction

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Few ps before the work starts...
Of course you will need a good soldering staon. Use one with variable temperature or at
least one with a thermostat to keep the temperature constant. Keep the p clean by wip-
ing every me across a wet sponge. Only keep a lot of n on it when you let it cool of. This
will increase the life me of the p.
Further necessary tools are a ne cable cuer, beak tang and tweezers (or platbek tang).
For easy mounng of the module on the mainboard it is good to use a screwdriver and a
socket spanner.
The construcon me of one module is approximately 30 minutes.

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The construcon
We will start with soldering the resistors. Important point: do not place the 6k1 resistor.
ONLY when you want to experiment with ‘pin 20’ by not using the CCS, in which case you
should NOT install the trimmer and 100Ohm resistors… The SMD parts are already mount-
ed so you only have to install the resistors and trimmer.
De original 6k1 is an opon in STEAD of the CCS.
TIP: only do this to experiment. The CCS is a very nice upgrade you most likely want.
Combining old and new DAC Module boards is no problem at all. They are fully
backwards compable. To do this is up to you of course. But technically it is no problem.

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Let’s start...
First we solder the two 4,7 Ohm resistors on the PCB ...
The bending tool, see picture above, is a very handy tool to make a perfect t. The PCB has
exact this distances.
Let the solder ow nicely round the wires (must be shiny) and cut the wires with the cable
cuer. Cut them directly above the solder pad.

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Than solder the two 100Ohm resistors.
Heat it well and take the me needed to have the solder ow nicely.
Cut the wires and you might want to re-heat /re-solder shortly the connecons, so it even
looks beer. This is not a must, just some perfecon thing …

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Capacitors
Next we will solder the 18 pcs of the 100nF capacitors. Best is to put them on the pcb and
slightly bend the two wires to the outside so they will not fall o the board anymore.
Place the PCB on its back on a at working space. Make sure all capacitors are placed
correctly. Press slightly to make sure this is the case. Now solder all 36 connecons. Cut
them short with the cable cuer.

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It will look like this at this stage...

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The electrolyc capacitors (elcos)
There are 12 pcs of the 10uF and 2 pcs of the 47uF Elcos to be mounted.
When placing the elcos make sure (check AND double check) that the polarizaon (plus
and minus wires) are correct!
A wrong connecon is very dicult to correct aer they are soldered.

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Again, take your me to let the solder ow. Specially the “minus” poles are at the ground
plane which will aract quite some heat in the rst few seconds when the solder p is
placed. So do not “bake” the solder on the pads. Let it ow.

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Specially here it make sense to cut very short (2mm above PCB area) and (oponally)
resolder the connecons. If more modules are mounted above each other we must avoid
that long wires scking out are shortcung against the capacitores on the below deck.
Now the same with the two 47uF capacitors

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In between view of the PCB
The voltage regulators
Before mounng we bend the pins with the platbek tang. Directly aer the thicker part of
the pins.

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Press the connecon pins through the PCB. Solder the middle pin with a small drop while
making sure the voltage regulator is nicely placed on the PCB. (See image).

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Here it is best to cut the wires rst a few mm above the PCB and than solder the two out-
side pins. Do not forget to re-solder the middle pin...
Trimmers
As you can see, the only thing missing are the two blue mul turn trimmers for the CCS...

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Place the trimmers in the correct holes and bend the wires a lile bit to the outside.
Solder the wires and cut them short.
The adjusng of the CSS can only be done aer the dac module is installed on the main
board. The measurement control point is the solder pad directly next to the trimmer.
Here we need a DC voltage of + 40mV (hold the red ‘plus’ of your DMM at this point)
Hold the minus (black) of the mul meter (DMM) to the analog output pin ’com’ from the
main board. Note that if you adjust the ‘le’ channel you also use the ‘com’ of the le
channel and vise versa for the right channel of course
The adjustment is not crical. Nothing can go wrong. Just turn ll you have approximately
40mV. Wait 20 minutes ll the DAC is warm and check and re-adjust a bit if needed.
IMPORTANT!! It is not allowed to connect a sole DAC module to a 12 volt power supply
just to “quickly test” it. This can ONLY be done aer it is mounted and connected on the
main board where the Rload resistors (Ra / Rb combinaon) are also installed

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Unless we tried to be as clear and complete as possible in this con-
strucon manual, we cannot exclude that sll something is unclear.
In that case just email Audio Creave or DDDAC for further help!
Also feedback to improve on text or image is more than welcome
Dick van de Merwe Doede Douma
Audio Creave DDDAC Audio Design