• Disclaimer: This Vendor's Forum is a paid-for commercial area. Unlike the rest of diyAudio, the Vendor has complete control of what may or may not be posted in this forum. If you wish to discuss technical matters outside the bounds of what is permitted by the Vendor, please use the non-commercial areas of diyAudio to do so.

Mr White's "Opus", designing a simple balanced DAC

Jump to Latest
#401
thanks j am going to try tonight.

As the shipping, the response is very quick.

The kit is nice, each composant is identificate with the value paste on it. About 20 minutes in order to make it for a beginner like me wich understand nothing to electronic...
Philippe😀
 
#403
gil-garcia said:
it does not work, but as j do not know what is pll j haven't tried.
No sound at all
Click to expand...


Do you have a digital camera? Perhaps you could email me a high resolution picture or two off the forum and I will see if things look OK.

If we are at a total loss you can send back the DAC and we can test it and be sure the DAC is fine. Very sorry to hear this is not working yet, it may be there is just something we are missing.

I would need to use a scope and see exactly what is coming out of your CDPro, but if the MISC pin is really a clock at 2 x SCK then it should work as a master clock. The DAC would just be working at 128fs. But I have no way to know for sure.

Cheers
Russ
 
#404
Ok thanks a lot

J check the opus tonight and make photos.

j have an oscillo if you tell me what j have to test.

j have also the opportunity to order the spdif module in order to test , as the spdif is working with my yamaha AV.

In the standard mode on the cd pro j shoud have I2S 1 FS outpout. Perharps a matter on the transport....

For information j test with car battery and the configuration connectors found on the opus manual
 
#408
Opus DC coupled into TXD works great!

Ok I knew there were benefits a fully balanced signal path. 🙂

I just tested Opus DC coupled into TXD/TXO, it works just fine! No issues at all. In fact it sounds excellent! I am leaving mine this way. Just one note. I use the TXD right after the DAC, like this:

DAC --> TXD --> Joshua Tree --> TXO-2

Also tried omitting the TXD before the Joshua Tree, and that works great too, but you will get a very very slight pop at the higher volume level transitions as the relays switch because of the DC bias.

The TXD module can tolerate common mode voltage of aroound +/- 4V so the +2.5 from the DAC is nothing at all to worry about. And at the output there are just a couple millivolts offset to GND identical on both outputs. This is actually the same as AC coupled!

The only thing really different I noted is that there is a very very faint "chirp" when DC coupled when you turn the DAC off as the PS caps slowly discharge. Nothing that will harm anything, but that chirp is not there when the caps are in place.

To do the modification you simply use a wire jumper in place of C5, C6, C7, and C8.

Very nice to get those caps out of the signal path. 🙂

Cheers!
Russ
 
#409
Re: Opus DC coupled into TXD works great!

Russ White said:
Ok I knew there were benefits a fully balanced signal path. 🙂

I just tested Opus DC coupled into TXD/TXO, it works just fine! No issues at all. In fact it sounds excellent! I am leaving mine this way. Just one note. I use the TXD right after the DAC, like this:

DAC --> TXD --> Joshua Tree --> TXO-2
Click to expand...

How's bass performance with this setup? Does the WM8740 handle the load from the TXD? What about analog filtering?

I tried this type of thing with a PCM1732, but it was hopeless. Muddy bass and very fatiguing sound.
 
#410
Re: Re: Opus DC coupled into TXD works great!

Painkiller said:


How's bass performance with this setup? Does the WM8740 handle the load from the TXD? What about analog filtering?

I tried this type of thing with a PCM1732, but it was hopeless. Muddy bass and very fatiguing sound.
Click to expand...


It sounds excellent. I am leaving mine this way. The bass is a bit tighter as can be expected when you remove the cap from the path. The TXD load is very very easy at 100K. Even the worst case Joshua Tree load of 2.5K is absolutely no problem for the DAC, especially with no cap to form a high pass.

Whats a little unexpected for me is the biggest difference I hear (and I have two Opus built right now so I can A/B pretty easy) seems to be in the low midrange, things like cello and slap bass seem to have better imaging.

Opus sounds excellent with the caps, but it sound even better without if you have gear that can handle the common mode 2.5V.

Cheers!
Russ
 
#411
Hi Russ,

I received my kit yesterday, just 4 days after my order, wow, that was fast (overseas usually takes 7-10 days...). Less than an hour to solder the three PCBs.

I have a question I'm ashamed not having found the answer...
I'm building ChefDeGaar's UGS (full balanced preamp), but right now, I'm in SE configuration.

How can I use OPUS in SE Stereo mode? I'm thinking of a setting with dual double voltage output (to be in SE mode and to gain 3db in noise floor).

Is it a usable setting or am I asking too much of this chip? 🙂

Thanks for your answer.
 
#412
Maousse said:
Hi Russ,

How can I use OPUS in SE Stereo mode? I'm thinking of a setting with dual double voltage output (to be in SE mode and to gain 3db in noise floor).

Thanks for your answer.
Click to expand...

Yes you certainly can. You would just use the +OUT only from each DAC PCB. The voltage output will be half what it would be balanced, but it will work fine. Depending on the gain of the next stage you may not even notice.

Cheers!
Russ
 
#414
Maousse said:
Thanks for your fast answer Russ,

I was looking at a mode where VOUTRP=VOUTRN=Right SE signal and VOUTLP=VOUTLN=Left SE signal, in the idea to gain 3dB in the noise floor.
Click to expand...


It does not exactly work that way.

the outputs are remapped in dual differential mode. Look at the table in the manual on our web site.

http://www.twistedpearaudio.com/docs/opus/opus_dac_manual.pdf

Each DAC in dual differential mode is handling a single mono channel with two identical outputs as the two sides of the DAC are meant to be taken parallel. This is how they gain SNR.

So for the DAC board handling the right channel you would take your output from the terminals marked Left -, and Right +. This will actually be two idential Right + signals. Then you just take GND to your connector as well.

For the DAC handling the Left channel you would take Left+ and Right-.

Cheers!
Russ
 
#416
Maousse said:
OK, the remapping is not possible the way I would like 😛

Well I'll wire as usual SE and will hurry on the UGS 😉

Thanks Russ !

BTW, when will the I�S switch be ready? 😉
Click to expand...


Well I have a lot on my plate right now, so probably not for at least a month or two, but USB receiver and BAL->SE converter coming in the next 3-4 weeks. I plan on ordering those PCBs this week if they test out fine then we will be ready to rock.
 
#420
4real said:
Thanks, I thought so 😉

Are there any plans for an ASRC board? Would be fun to have 😉
Click to expand...


The DAC just takes I2S so if one wanted ASRC it would be added in front of the DAC. Personally, having tried that route, I just don't feel the need. If I want something at 24bit 96K I would rather it actually be encoded that way. 🙂

One key note though. We will be shifting soon to the WM8804 which has incredibly low jitter and should be much more effective at cleaning up the I2S clock than any ASRC.

But what I may do if there is enough interest is create an ASRC module which could be placed in front of the DAC in the chain.

Cheers!
Russ
 
You must log in or register to reply here.
Top Bottom