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Floric  
#21 Posted : Thursday, January 6, 2011 5:26:05 PM(UTC)
Floric

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Hi,

thank you for the answers. But why does my Opus (the actual one) know that there will come a 44.1/48kHz signal? (Remebmer: No source connected, even if the input is shortened, I have noise) The 44.1 signal comes because my actual source is a cdp. But if a 96kHz source came instead of the cdp, the problem would remain the same because then the osr must be set to medium. How do I get this combo to handle 96kHz signals? Has the 96kHz source to be active when I switch on receiver and DAC?

So at the moment I have a workaround but no solution. Don't get me wrong, I just want to solve the problem.

Best regards

Flo
Brian Donegan  
#22 Posted : Thursday, January 6, 2011 5:41:10 PM(UTC)
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Remember that a shorted digital input is not the same as 0-bits being transmitted over S/PDIF. What's happening is that your source is not sending 0-bits when idle, unlike your Teac which does and is silent (IIRC).

How are you getting your SPDIF? Simple coax or Optical?
Floric  
#23 Posted : Thursday, January 6, 2011 6:39:59 PM(UTC)
Floric

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Hello Brian,

Quote:
Remember that a shorted digital input is not the same as 0-bits being transmitted over S/PDIF


O.k. I know the difference.

Quote:
What's happening is that your source is not sending 0-bits when idle,


It's quiet.

Quote:
unlike your Teac which does and is silent (IIRC).


Yes. But I want to know if it is possible to get silence in every case when no signal is applied - no matter what source I am going to connect. In my test setup its a cdp but in the living room there is a cdp and a dvd. The dvd is capable of paying cds too.

If I switch on the system, the dvd connected but switched off (like it always is when I switch on the plugboard where all the gear is connected to) I want the setup to be silent until I inserted a cd (or dvd) and I chose the right sampling rate.

What do I have to do?

Quote:
How are you getting your SPDIF? Simple coax or Optical?


Almost all the tests were made with a coax connection. But I also tried a toslink adapter (from tp) powered up but with no source connected.

To explain: I am building a preamp with integrated DAC with the possibility to connect several analog and digital sources. At the time I was odering the parts, the mux was not in stock, so I ordered a wm8804 and built a relais board to switch the spdif sources. Thes relais board is up and running - it works with the old dac. But for the tests I don't use it. The tests are only done with a wm8808, an opus, supplied by a lcdps and a Ballsie, supplied by an other ps (other transformer) I built of my own.

In the future I want four digital inputs (two coax and two optical) for the cd, the dvd and the computer and ... . And I don't want any noise - no matter which source I am going to connect. I see that it is necessary to choose the right sampling rate but I do not understand why the sampling rate I chose would affect if there is noise or not.

With the solution like it exists now, I am able to set up the system to run with one input at a fixed sampling rate that is 44.1/48kHz with no noise. But if I wanted to watch a movie with 96kHz sound (stereo) on the dvd or listen to 96kHz samples from the computer, I would choose the according sampling rate (as far as I understood the datasheet I would have to choose it before powering up) and power up the system. I want the system to remain silent no matter if there is a source connected or not. But at the moment it won't.

So I want to know if there is a possibility to get the behaviour I want. If yes, what's my error right now? If not, what do I have to do to get it? It might be necessary that the spdif source is powered up before the receiver/dac, but is this really necessary?

Sorry for the long (and complicated?) answer. Now I have to sleep - it's deep in the night an this side of the planet.

With best regards

Flo

Edited by user Thursday, January 6, 2011 6:44:23 PM(UTC)  | Reason: Not specified

Russ White  
#24 Posted : Thursday, January 6, 2011 8:59:51 PM(UTC)
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You can use a Metronome module between the SPDIF receiver and the Opus to make the sample rate always the same.

The WM8741 has to know the sample rate, the WM8740 does not. That is why you saw the difference.
Floric  
#25 Posted : Saturday, January 8, 2011 5:44:38 AM(UTC)
Floric

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Hi Russ,

will the Metronome mute the audio stream when there is no valid signal applied?

Just for completness my recent experiment:

1. swiching on the dac (with pre and power amp)
2. switching on the source (the cdp)
3. changing cd

With the following configurations (Phillips cdp)

- osr low (1. silence, 2. silence, 3. clicks)
- osr medium (1. noise, 2. silence, 3. clicks/noise)
- osr high (1. silence, 2. silence, 3. silence)

Teac cdp:

- osr low (1. silence, 2. silence, 3. silence)
- osr medium (1. noise, 2. silence, 3. silence)
- osr high (1. silence, 2. silence, 3. clicks)

The music is reproduced in every case - no critical listening but sounds good. In my opinion, here is a lack of logic.

Did not try out other sources, because the main issue takes place before any source is applied.

Best regards

Flo
io  
#26 Posted : Monday, January 10, 2011 2:51:49 PM(UTC)
io

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Hi

Auto mute can be used to unlock the receiver output of an inverter (HC7404), the DAC mute feet bound.

io
Floric  
#27 Posted : Friday, January 14, 2011 1:33:06 PM(UTC)
Floric

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Joined: 11/5/2006(UTC)
Posts: 24
Location: southern Bavaria

Hi io,

thanks, did not understand: where do I get the signal for Auto mute (input of hc7404) from?

regards

flo
io  
#28 Posted : Saturday, January 15, 2011 1:54:03 AM(UTC)
io

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Hi

WM8804 HWMODE lock / unlock pin (CSB 5) __74HC04__WM8741 mute pin
Floric  
#29 Posted : Saturday, January 15, 2011 2:52:42 AM(UTC)
Floric

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Joined: 11/5/2006(UTC)
Posts: 24
Location: southern Bavaria

Thank you very much

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