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In Reply to: RE: Jpp for DAC as Master (using 24/88.2) yields an additonal 4ps of Jitter posted by cics on March 31, 2008 at 08:38:13
Did you made all the necessary modifications in the control software of the RME to put it on Slave?
Also, did you terminate to 75 Ohm the WC input on the RME? In the manual it says that the WC input is not terminated:
"When shipped, the word clock input is not terminated. Termination with 75 Ohm is available via jumper X105 on the Expansion Board.
The HDSP 9652’s word clock input can be high-impedance or terminated internally, ensuring maximum flexibility. If termination is necessary (e.g. because HDSP 9652 is the last device in the chain), bring jumper X105 on the Expansion Board into position 75 Ohm."
If properly setup it is very unlikely for the DAC to have more jitter when clocked internally than when it receives the clock from the soundcard. Did you repeat the measurements to see if they are consistent?
Did you made all the necessary modifications in the control software of the RME to put it on Slave?
Yes.
Also, did you terminate to 75 Ohm the WC input on the RME?
Yes.
Other points:
When I measure with RME as master, Clock card is disconnected from main PCI card. It's not good enough to just disconnect the BNC cable.
You cannot have both dCS and RME as Master - you hear abnormal click sounds.
- RE: RME setup - Sunya 01:24:40 04/01/08 (8)
In Reply to: RE: RME setup posted by cics on April 01, 2008 at 01:16:59
What do you mean the Clock card is disconnected? If it's disconnected how can the RME be still the Master? The Clock card has both WC Out and WC In so, whether the RME is Master or Slave, the Clock card should always be connected.
To set DAC as master, the sync button is pressed which causes the DAC to switch from slave to master. In master mode, it either syncs to the clock input signal (if present) OR its own internal clock.
What you're suggesting (I think) is to set RME as master AND DAC as master. A cable is then connected to RME's clock out and to DAC's clock in. Having two masters is not something I would try.
No. You said that when you set the RME as Master and DAC as Slave you didn't also use the Word Clock Out of the daughter card (because you disconnected it) to slave the DAC. You used a simple S/PDIF out signal and the DAC had to extract the clock from this signal instead of receiving an Word Clock from the RME to its Word Clock input.
Also, if the DAC is set to Master how can it sync to an external clock input? If it syncs to an external clock signal it is not the Master anymore. A digital device is Master when it syncs to its internal clock only.
Also, if the DAC is set to Master how can it sync to an external clock input? If it syncs to an external clock signal it is not the Master anymore. A digital device is Master when it syncs to its internal clock only.
This is specific to dCS. As far as I know there are no standards defined. For Scarlatti DAC, the sync button has 2 'master' options: WClk (external master clock) & Master (internal master clock). The remaining option is called Audio (for slave).
I see... The first "master" option, WClk, is just the name for slaving the DAC to an external Master Clock, so technically the DAC is not the Master, it's just slaved to an external Master Clock.
This embedded clock is then recovered by DAC's receiver chip.
Why didn't you use the Word Clock Out of the RME when set to Master? At least this way the clock would not be embedded in the SPDIF signal...It doesn't make any sense for the DAC to have lower jitter when it has to extract the clock from an SPDIF signal than being directly controlled by its internal oscillator.
That configuration won't work. DAC as slave recovers clock from SPDIF. Other clock connections are not used.
Then how did it work with the Scaralatti Master Clock? How does it matter if the DAC receives the clock from the external Master Clock or from the RME card through the same BNC connector? Is it because the file played is upsampled at 88.2 or 96 and the Word Clock input will not accept these sample rates?
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