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]

@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.

 

[Nomdi]

thanks dtses !
Did you try to connect it to the board
through a 7805 regulator ?
I guess that could be the problem...

 

[dtses]

yes, it's connected to the board, just look where you could get +5v to feed 74HCT04.

 

[Nomdi]

ok i ll give it a try
thanks !

 

[Nomdi]

hi @ all !
I guess my problem is more important
that just a Toslink connection .
I ve checked the outputs : the right channel
can be set to less than 0.2 mV of DC offset .
it's ok.
but on the left channel the DC offset is
more than 500mV and cannot be modified
using the 1k trimmer !!! that's the real problem !
i ve checked connections : everything is ok
and all the voltage regulators delivers the right
voltage...
I ve changed the OP AMP many times
but with no results ... the music is here
on both channel but with an anormal
DC offset on the left channel ...
Any idea ?

 

[50AE]

I seem to get interested in this kit. Has someone compared it to this kit: DAC 2496 (AK4393) DAC KIT With CS8416+AK4393+5532 ?

I wonder if I will get much better music playback. My AK 4393 is modded with better caps and regulators.

Can I be able to get 24/96,192 form USB with this?

 

[cobretti]

hi @ all !
I guess my problem is more important
that just a Toslink connection .
I ve checked the outputs : the right channel
can be set to less than 0.2 mV of DC offset .
it's ok.
but on the left channel the DC offset is
more than 500mV and cannot be modified
using the 1k trimmer !!! that's the real problem !
i ve checked connections : everything is ok
and all the voltage regulators delivers the right
voltage...
I ve changed the OP AMP many times
but with no results ... the music is here
on both channel but with an anormal
DC offset on the left channel ...
Any idea ?

Check values of all resistors and capacitors in output stage around the OPamps. It could also be a bad solder joint around trim pot if you say it can not be adjusted.

 

[kmbois]

i love this DAC!

I bought it to replace one my gigaworks DACs and it blew it away sonically.
I am using it in a very revealing setup and this DAC just sounds amazing with very minor tweaks. I removed the rca plugs and hardwired some cables with eichmann bullet plugs and I use the R-core transformer that came with the gigaworks kit. You cannot go wrong for the price.

 

[merlin2069er]

I've got a arduino mega and I've picked up an LCD display for it awhile back.

Just wondering if the code that came with the dac.zip will output anything to a display? It would be cool if it displayed some info.

 

[dtses]

Has anybody done some tweaks regarding opams' power supply? Seems that combination of 7812 & 7912 could be significantly improved by Salas shunt regulator (scheme attached) ...

I'm working on simple headphone preamp (based on LME49720HA) for the dac (att.) and I guess Salas shunt reg would perfectly serve there. So perhaps that could be implemented for output opams as well.

some other improvements?!

 

[cobretti]

I was thinking myself to use Jung super regulators from Sjostrom but don't have enough time to do it. I am not sure if there would be any significant improvement though. I would first try in improve the clock itself and maybe reclock the data, then I would deal with analog output. But the DAC is damn good in its original configuration for sure. Just use brand name components, no chinese fakes.