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

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D

Dougie085

Member
Joined 2005
Ok well if someone can offer some advice on things to check. I'm pretty sure all the jumpers are set correctly. As long as 1 = + and 0 = -. All the wires are connected correctly. I'm getting no sound output though. I had it working fine with a single board in stereo but now nothing. On the outputs I have right negative to left positive and right positive and then the RCA connections connected to the ground and left positive and right positive. Unless your not supposed to use the grounds? There is voltage at the outputs and the connections on all boards. I'm just not seeing anything connected wrong or setup wrong.
 
Russ White

Russ White

Member
Joined 2005
twistedpearaudio.com
Doug, best to use the support forum for this kind of thing so as to keep the SNR down on the thread.

In dual mono mode the output of the channel the DAC is setup for (left or right) will be normal on that side's(left or right) output terminal. The opposite output terminal will be the same analog signal but inverse.

So lets say you have one DAC board setup as mono right channel. For balanced output you need to connect Right + and Left -, and Right - and Left + then you just take GND.

I hope that helps.

Photos etc help us troubleshoot for you.

Cheers!
Russ
 
B

Bgt

Member
Joined 2005
grotel.nl
Russ,
I've tested the Opus on a Bose Home System through optical connection and when I play a normal CD it is OK but when playing a music DVD, its more like a CD with the singer on your screen, it just gives a noise out.
When playing the music DVD through my computer, also with optical connection, it is OK. Any id where it goes wrong and how to solve it.
Thanx, Bert
 
J

JeroenR

Member
Joined 2005
Perhaps someone can help me with connecting a TENT clock to the TP CS8416/PCM1794 (COD) boards. I tried reading the datasheets and found some leads (I think) but this is unknown territory for me.

I attached a schedule that shows the setup I want to use. The connections between the DAC module, receiver module are a guess. I think that the CS8416 needs to be put in slave mode (hence RCBL to ground with R), the clock I calculated as 256*44.1.

Is this enough? Should I put the DAC in master mode (if possible/needed as I could not find it in the datasheet)? Is the frequency correct? What to do with the clock ground? Am I correct about RCBL? And I probably messed up the connections between COD and CS8416

So, lots of help needed. :)

Also, a little explanation would be welcome. I will never be able to design this stuff but at least understand it a bit would be great!!

Thanks,

Jeroen
 

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S

Spartacus

Member
Joined 2002
Hi Jeroen,

are you aware that clocking this way will loose/replicate samples? This can work - I've done it with the TDA1543 in NON-OS, but I wouldn't want to make a prediction with a chip like the PCM1794.

I'm not familiar with th CS8416, but the older Cyrus chips need a word clock and bit clock input when run in slave mode. Google around for phrases like "asynchronous clocking CS8412" etc. You'll need some extra circuitry - to divide down for the word clock.

Truthfully, I'd recommend that you go with an ASRC like the Metronome, or simply use the Wolfson receiver from TP with a 12MHz Tent clock if that's your choice. You'll be sure of getting a good working result this way.

Dan
 
Russ White

Russ White

Member
Joined 2005
twistedpearaudio.com
JeroenR said:
So, lots of help needed. :)

Also, a little explanation would be welcome. I will never be able to design this stuff but at least understand it a bit would be great!!

Thanks,

Jeroen
Click to expand...

Hi Jeroen,

That single input CS8416 PCB is not designed to work in slave mode. So I don't think what you are wanting to do will work, at least not without some board surgery.

Cheers!
Russ
 
Russ White

Russ White

Member
Joined 2005
twistedpearaudio.com
JeroenR said:


Hi Russ,

I noticed that on the board the RCBL is fixed to high. One trace cut and a wire to ground from R7 would do it.... I think (hope).

Thanks,

Jeroen
Click to expand...


Well you would need to input the external clock on the OMCK pin of the receiver, and it is connected to GND. There is no simple way to unconnect it. You would have to cut a pin.

The RMCK (SCK) is output only.

Cheers!
Russ
 
J

JeroenR

Member
Joined 2005
Spartacus said:
Hi Jeroen,

are you aware that clocking this way will loose/replicate samples? This can work - I've done it with the TDA1543 in NON-OS, but I wouldn't want to make a prediction with a chip like the PCM1794.

I'm not familiar with th CS8416, but the older Cyrus chips need a word clock and bit clock input when run in slave mode. Google around for phrases like "asynchronous clocking CS8412" etc. You'll need some extra circuitry - to divide down for the word clock.

Truthfully, I'd recommend that you go with an ASRC like the Metronome, or simply use the Wolfson receiver from TP with a 12MHz Tent clock if that's your choice. You'll be sure of getting a good working result this way.

Dan
Click to expand...

Hi Dan,

No, I am not aware... :)

Can the ASRC clean up the I2s without changing anything else? Will jitter go down when adding the ASRC and Tent clock? I just want a clean signal from receiver to dac, no (asynchronous) reclocking or something like that.

Would adding the tent clock to the wolfson receiver not still mean that the receiver still generates the clock?

Reading a lot of posts on the forum I sort of concluded that clocking DAC directly would be best.

Thanks,

Jeroen
 
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