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

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#345
EvilYoda said:
I can't wait for the USB module to be out! My soldering iron's going to get a lot of use this summer 🙂
Click to expand...


They will be ordered as soon as I see the DAC PCBs and determine they are fine.

This is the first batch of PCBs I have ordered since switching to new PCB software (DipTrace), and I just need to verify that everything went well. After that there will be several new designs, some related to this DAC. 🙂

Cheers!
Russ
 
#346
longitude said:
Hi,

Is it good idea or possible to connect pin 1 and pin 3 of balanced output to provide unbalanced output?

Since my amp only receive RCA and I would like a simple solution.

like this one:
http://www.mediacollege.com/audio/connection/xlr-rca-1.html

Thank you!
Click to expand...


I am not sure if that will work (I have not tried it). I am pretty sure looking at the data sheet you cannot do that, because the minimum load for the output is 1K and that would short the -OUT to GND. So I would not try it. I do know you can simply take one end of the balanced output. This will get you a good signal, but it will be 6db down from the balanced output. A few have done this with the beta boards with fine results.

We will have an excellent Balanced to SE converter module very soon. That is the best solution for SE output. It will be ordered along with the USB module.

Cheers!
Russ
 
#349
Hi Brian and Russ,

Very nice work performed on this DAC, great modularity.
I'll place my order when USB module will be ready.
Don't know how much time it will take, but in Opus I trust too, so I'll wait. 🙄

For USB module you said it can be used as a standalone part.
It will powered by USB port, BTW a question : will USB induce instability ? Do you plan to use external power source ?
 
#350
korben69 said:
Hi Brian and Russ,

For USB module you said it can be used as a standalone part.
It will powered by USB port, BTW a question : will USB induce instability ? Do you plan to use external power source ?
Click to expand...

Yes, the USB module will be bus powered.

There should be no instability, but when using the USB module as a standalone DAC the noise and distortion will suffer slightly, but keep in mind, the main idea is to use the USB module to simply feed digital I2S to an Opus, so analog performance of the USB module is of secondary importance. More important is keeping it simple and inexpensive.

The USB module with the Opus DAC proper should sound very good. 🙂

BTW the wait will not be very long. I already have it laid out.

Cheers!
Russ
 
#353
Searched for an answer.... Windows accepts multiple sound cards, the only problem is synchronisation.

WM8740 accepts external master clock, and you provided pins on your board. So a Tent clock would do the job.

Foobar supports multiple ASIO outputs and has a plugin for simple digital low and high pass filters, applicable to each single channel.
 
#354
thomaseliot said:
Searched for an answer.... Windows accepts multiple sound cards, the only problem is synchronisation.

WM8740 accepts external master clock, and you provided pins on your board. So a Tent clock would do the job.

Foobar supports multiple ASIO outputs and has a plugin for simple digital low and high pass filters, applicable to each single channel.
Click to expand...


Excellent! 🙂 That is actually an application I would love to try!
 
#356
asio & foobar

[offtopic]
some year ago i tried just that but foobar supports sound output to only one soundcard at a time. Connecting a number of usb audio devices is of course supported by windows. USING multiple usb soundcards at the same time is (was?) not supported by Foobar.

using a multichannel usb card should work with something like asio4all though 😉
If you don;t use asio4all or another asio device provider you're stuck with windows' kernel audio mixer (which sucks).

Now that I think of it, can't asio4all bundle a number of usb devices into one asio device ? hmmm...
[/offtopic]
 
#357
Hello,

I was looking at the service manual from my CD Player trying to find the I2S lines.
I found 3 lines between DSP and the Filter/Dac IC.
these are
SCK: Serial bit clock
SRDATA : serial data MSB first
LRCK : L/R discriminating signal

is this the I2S data bus?
Will it work with the OPUS DAC?

If not I can always use the TX output but I have to buffer it to get a Coax S/PDIF output because my CD only has a TOSLINK :bawling:
 
#358
promitheus said:
Hello,

I was looking at the service manual from my CD Player trying to find the I2S lines.
I found 3 lines between DSP and the Filter/Dac IC.
these are
SCK: Serial bit clock
SRDATA : serial data MSB first
LRCK : L/R discriminating signal

is this the I2S data bus?
Will it work with the OPUS DAC?

If not I can always use the TX output but I have to buffer it to get a Coax S/PDIF output because my CD only has a TOSLINK :bawling:
Click to expand...

I believe it is the digital out. You will have to check if it is right or left justified or I2S. Then check the WM8740 data sheet to see if the format is supported (it probably is). Then you just have to set the correct jumpers on the board. 🙂

Now you just need the master clock to use it with the Opus. You could could use an external clock or the CDP clock if you can find it.

You should also be able to take the net that goes to your TOSLINK jack and run that along with GND to an RCA. That would get your SPDIF too.
 
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