| kva |
Hi
I have a Marantz CDA 94 dac. I am planning uppgrading the crystal clock in it. I have though not found any crystal clock in it!
I have a schematic (not complete) and there is no clock! Why?
Is it possible to build a clock with passive components?
Regards
Kristian |
|
|
| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by kva
I have a Marantz CDA 94 dac. I am planning uppgrading the crystal clock in it. |
Why?
| quote: | Originally posted by kva
I have though not found any crystal clock in it!
|
Not surprised. And even if you did find one, it would usually not be used to clock the data, the Yamaha receiver that has it's own clock uses it for other purposes.
| quote: | Originally posted by kva
I have a schematic (not complete) and there is no clock! Why?
|
Because DAC's usually don't have clocks?
| quote: | Originally posted by kva
Is it possible to build a clock with passive components?
|
No, oscillation implies the presence of an amplifying element somewhere.
Sayonara |
|
|
| Guido Tent |
| quote: | Originally posted by Kuei Yang Wang
Konnichiwa,
Why?
Not surprised. And even if you did find one, it would usually not be used to clock the data, the Yamaha receiver that has it's own clock uses it for other purposes.
Because DAC's usually don't have clocks?
No, oscillation implies the presence of an amplifying element somewhere.
Sayonara |
Here's the answer
http://www.tentlabs.com/ProductEnti...DAC/XO-DAC.html
worlds' only true clock upgrade for external DACs
cheers |
|
|
| kva |
Thank you for your answer.
Regards
Kristian |
|
|
| Kuei Yang Wang |
Konnichiwa,
It is not as such (if you don't mind me saying) an upgrade, as it does not replace an existingfunctional block with a higher performance one, but rather a significant modification, which adds previously unavailable functionality.
That said, IIRC, the DA94 actually contains a secondary, discrete "slow mode" PLL (The LHH-1000/DA12 certainly does and the DA94 is ALMOST identical in all key particulars) which is really not much worse than a VCXO (it also contains opto insulation between digital module and DAC and signal reclocking before the opto insulators), so the benefits of fitting the XO-DAC may be much less than in other DAC's, having no secondary PLL whatsoever.
Given the age of the DA94 the best course would probably to start replacing all the aged and degraded electrolytic capacitors. Of course, many other DAC's can benefit drastically from a secondary PLL, for example in the form of the XO-DAC.... And applying the "link" connection goes down a further route of (potential) improvement.
Sayonara |
|
|
| Elso Kwak |
The Twin dac designed by Mirko Wetzig already has a 125 MHz Vite clock on board for Asynchronous Reclocking.
Another example of commercial use without my consent of one of my ideas communicated in personal email. Really unbelievable.
http://www.twindac.com/
Funny thing is I no longer use the AD1865 and the Asynchronous Reclocker, hahahaha.
:rolleyes: |
|
|
| Guido Tent |
| quote: | Originally posted by Kuei Yang Wang
Konnichiwa,
It is not as such (if you don't mind me saying) an upgrade, as it does not replace an existingfunctional block with a higher performance one, but rather a significant modification, which adds previously unavailable functionality.
That said, IIRC, the DA94 actually contains a secondary, discrete "slow mode" PLL (The LHH-1000/DA12 certainly does and the DA94 is ALMOST identical in all key particulars) which is really not much worse than a VCXO (it also contains opto insulation between digital module and DAC and signal reclocking before the opto insulators), so the benefits of fitting the XO-DAC may be much less than in other DAC's, having no secondary PLL whatsoever.
Given the age of the DA94 the best course would probably to start replacing all the aged and degraded electrolytic capacitors. Of course, many other DAC's can benefit drastically from a secondary PLL, for example in the form of the XO-DAC.... And applying the "link" connection goes down a further route of (potential) improvement.
Sayonara |
Hi Sayonara
I did not know the Marantz in such detail. In this particualr case, the designers did their job, allthough I have to note that not all SRC's are muically transparant
I do not belive in optocouplers by the way. Getting the performance right (g no added jitter) os a hell of a job, and if you do the layout the correct way around, you do not need the isolators.
That said, the main clock clocking the SRC ofcourse should be very good
Thank you for your eleboration |
|
|
| Kuei Yang Wang |
Konnichiwa,
| quote: | Originally posted by Guido Tent
I did not know the Marantz in such detail. |
I do as I used it's schema to help me re-building the very similar Philips LHH-1000 DAC.
| quote: | Originally posted by Guido Tent
In this particualr case, the designers did their job, allthough I have to note that not all SRC's are muically transparant |
Guido, no SRC.
The thing is mid 1980's technology, TDA1541, SAA7220 Digitale filter, exceedingly well build, locks on 32/44.1/48KHz and has a two layer PLL, the first "fast" one in the receiver and a slow one with several seconds as timeconstant (guess from time to lock when signal applied and schematic) following that. The signal then goes to the SAA7220 Digital Filter, Loads of glue logic inbetween too and from there to a reclocker, from the second PLL clock. The main lines to the DAC then pass through Opto-Isolators (pretty good ones!), the whole thing is 16 Bit 4 times oversampling.
| quote: | Originally posted by Guido Tent
I do not belive in optocouplers by the way. |
It's a matter of implementation and philosophy. I merely pointed out that Marantz used them, in the late 1980's. And that (age), together with the NE5534 Op-Amp's is the biggest performnce prohibiter for what could be a most excellent DAC.
Sayonara |
|
|
| Guido Tent |
| quote: | Originally posted by Kuei Yang Wang
Konnichiwa,
I do as I used it's schema to help me re-building the very similar Philips LHH-1000 DAC.
Guido, no SRC.
The thing is mid 1980's technology, TDA1541, SAA7220 Digitale filter, exceedingly well build, locks on 32/44.1/48KHz and has a two layer PLL, the first "fast" one in the receiver and a slow one with several seconds as timeconstant (guess from time to lock when signal applied and schematic) following that. The signal then goes to the SAA7220 Digital Filter, Loads of glue logic inbetween too and from there to a reclocker, from the second PLL clock. The main lines to the DAC then pass through Opto-Isolators (pretty good ones!), the whole thing is 16 Bit 4 times oversampling.
It's a matter of implementation and philosophy. I merely pointed out that Marantz used them, in the late 1980's. And that (age), together with the NE5534 Op-Amp's is the biggest performnce prohibiter for what could be a most excellent DAC.
Sayonara |
Hi
This sounds like a properly designed concept
On the optocouplers: I sahve the experience it is easier to get the things right by layout than by using optocouplers. But maybe the commercial department wanted them in...... |
|
|
|
