WM8805 upgrade board (cs8414 pins) - dissapointed

[ThorstenL]

Hi,

Originally Posted by jean-paul

Thorsten can you please check if this is right ?

Sounds about right...

The problem is, there is much other work to be done on this DAC, I am unsure the OP either can or is willing to do so...

Ciao T

[stormsonic]

Originally Posted by mfrimu

Stormsonic,
Are you saying those NAND gates introduce jitter? I'se seen some products like Monachy Audio DIP (highly reviewed) that use a similar technique to raise spdif levels...

Thanks

@mfrimu
ThorstenL explained very well.
If you still want input buffer for your CS841x receiver, you will need DIY approach. Schematic can be found HERE.

[jean-paul]

He does not have a CS8414 anymore, please reread the fist post/thread starter. It is about adapting the WM8805 PCB to the DAC board now AFAIK.

Won't you be excommunicated by the politburo at "the other side" for linking to their website ?

[stormsonic]

Yes, thank you, Jean-Paul.
I misunderstand he have malfunctioning WM8805 upgrade board and he is dissapointed. I assumed he want to switch back to CS8414 since he can not distinguish any remarkable sound improvements.

[abraxalito]

Originally Posted by mfrimu

I can't get the schematics, and I'm curious what has been implemented in the circuit.

I have a couple of these on order myself now, if I get more information as a result of that, I'll let you know. Looks to me the fastest way to acquaint myself with the WM8805 which over here is priced under $1.5 so really rather a bargain.

[mfrimu]

Hello,

Thanks for all the suggestions. I purchased this PCB a few years ago and it was at the time the only PCM1704 PCB I could find. I selected the components and built this DAC while enjoying the learning experience and expected the circuit to not be perfect. At that time, all PCM1704 circuits I found were pretty much the same +/- few things.

I appreciate all the input and will implement the buffer bypass and other suggestions shortly. I'm also looking forward for the Cen/Sen/Zen I/V (another thread). I might also test a TUBE output option as I have heard another similar dac with tubes and it sounded noticeably better.

[mfrimu]

Looking at the PCM1704 datasheet there are quite a few 4.7uf and 47uf capacitors. Therese are about 15mm away from the ICs right now. Should they be closer? What about the .1uf and 100uF bypass ? Should they be on the PCM1704 daughter board as close as possible?

Thanks,

[ThorstenL]

Hi,

Originally Posted by mfrimu

Looking at the PCM1704 datasheet there are quite a few 4.7uf and 47uf capacitors. Therese are about 15mm away from the ICs right now. Should they be closer?

Can't do any harm.

Originally Posted by mfrimu

What about the .1uf and 100uF bypass ? Should they be on the PCM1704 daughter board as close as possible?

The 0.1uF bypasses should be SMD ceramic, placed as close to the IC pins (sodered directly onto them if possible) as possible.

And of course, they should present...

Ciao T

[mfrimu]

Thanks,

Also noticed the TORX178 optical receiver output HIGH is at 4v, too high for the WM8805. I searched but did not find any info on TORX to WM8805 circuits. Seems that Torx178 was made in the times of TTL/CMOS crystal receivers. I'd like to keep an optical in for my video player (not that critical). What resistor(s) should I use to attenuate it?

PS: After removing the Buffer Circuit the WM8805 is working correctly. I'm going for a comparison listening session soon and will report.

Thanks for the help!

[ThorstenL]

Hi,

Originally Posted by mfrimu

Also noticed the TORX178 optical receiver output HIGH is at 4v, too high for the WM8805. I searched but did not find any info on TORX to WM8805 circuits. Seems that Torx178 was made in the times of TTL/CMOS crystal receivers. I'd like to keep an optical in for my video player (not that critical). What resistor(s) should I use to attenuate it?

Try 0.1uF in series and then 680Ohm series and 100R to ground.

Ciao T