Wolfson WM8740 DIR9001 PCM2706 DIY DAC

[dtses]

your toroidal should be fine with 2x10v and 2x15 for opams.
Anyway something of 20-25VA with 2x15v and 1 or 2 x9v secondaries would be far enough for this dac.

[cobretti]

20VA transformer is overkill. You need no more than 9 + 9V for digital part (8VA total) and no more than 2x15V for analog part 6VA is more than enough. I wouldn't go with secondary voltages too high because it would create more heat on input stabilizers.

[dtses]

Found some info in the net regarding usb cables, for instance, is there really any point buying some highly reviewed WireWorld Ultraviolet USB for the dac? Mine currently is connected via ordinary computer grey & thick 1m usb cable

[cobretti]

No, there is no point. I also use a basic grey cable.

[dtses]

added toss link input, works great now the dac is even more versatile and beautiful will add some pics later

[2noisy]

Hi everyone

sorry for bumping an old post,but i have few questions about this board,so..
let me first say that my knowledge in electricity is not that great ,
i recently purchased one of this boards,assembled one
(so by this thread most of the capacitor are fake ones),
it sound really great compared to my M-audio FTP stereo outputs
(it connects to a Sure TK2050 2*100w with Audio1st input caps mod)
now for my few dumb questions,
when i connect the board with USB or coaxial,i notice that when a sound is produced there's also a very short "after-sound" immediately after the sound produced ,it's more noticeable in short sounds ,is that amazingly annoying phenomena called "feedback" ?
will changing all big caps will help with this?
or changing the LM's stabilizers ?
(I'm using a single R-core transformer 30va 15v*2 9v*2 if its related somehow)

thank you all for helping a noob & sharing,
otherwise uneducated guys like could not manage in this great hobby !

[Nomdi]

Hi everyone !

Does anyone succeeds in adding
optical input ?
I m in serious trouble...
I tried Torx173 and Torx177 with strange results :
I cut the connection between 26c32 and DIR9001.
just a switch to connect the torx, no logic glue,
only inductance and capacitor...
the 5v comes from the 26c32 regulator.
the results ? very weird !
it works but the sound is very loud using
optical input... after a few minutes all smd
regulators get very hot and sounds starts to crack...
And last but not least the DC offset goes crazy !
the protection device of my amplifier start every time
because theres too much dc !!!
if you look at schematics you can see that
the input ground is floating ...
is it the reason to this phenomenon ?
should I use pulse transformer ?
any advice would be appreciated !
thanks to all !

[dtses]

check the scheme here
works fine for me. the only thing is that I use dac's coax input with that.

[Nomdi]

@dtses

Thanks !
but are talking about the Conrad adapter
or the 74HCT04 schematics ?
in the first case it seems ok because the
dc adapter has no connection with the dac
so you got a galvanic isolation ...
I have doubts about the second solution but I want to implement
the solution onto the board...
I ve ordered Scientific conversion transformers to
give a try...
I will tell you the results...
Best regards

[dtses]

Originally Posted by Nomdi

@dtses

Thanks !
but are talking about the Conrad adapter
or the 74HCT04 schematics ?

pls refer to post 5 . It works fine, unfortunately I have no camera with me to show you, but it's very simple to add it to the dac.