Re: Tent-Link
Theoretically the TentLink could be better, but trust the coaxial connection for the clock from transport to DAC! The frequency is only 11.xxx MHz. Good coax-connections with B&C-connectors are able to conduct microvolts at frequencies of 500 MHz, so..... it is absolutely unaudible!!!
In the posting of Telstar were two links to the TentLabs-solutions. Read them first, the ask again.
BTW.: Be careful with the names 'XO' and 'VCXO'. I know that even TentLabs is sometimes confusing with the names of their products. I always talk about:
'XO' (which is a very stable not tunable Xtal Oscillator) and
VCXO-PLL (a Voltage Controlled Xtal Oscillator, which voltage controls the frequency (a bit) via a PLL-circuit (Phase Locked Loop)).
The last one is always more noisy than the first one.
With the TentLink you need a VCXO-PLL + SPDIF-enhancer in the transport and an XO in the DAC. The clock-connection between DAC and transport is only to synchronise the VCXO-PLL in the transport to the XO in the DAC.
With my solution, you will ignore the VCXO-PLL. Just put the XO + SPDIF-enhancer in the transport and connect the XO-clock to the DAC. If a DAC should be powered on without clock, it does not harm it.
irgendjemand said:
Theoretically the TentLink could be better, but trust the coaxial connection for the clock from transport to DAC! The frequency is only 11.xxx MHz. Good coax-connections with B&C-connectors are able to conduct microvolts at frequencies of 500 MHz, so..... it is absolutely unaudible!!!
In the posting of Telstar were two links to the TentLabs-solutions. Read them first, the ask again.
BTW.: Be careful with the names 'XO' and 'VCXO'. I know that even TentLabs is sometimes confusing with the names of their products. I always talk about:
'XO' (which is a very stable not tunable Xtal Oscillator) and
VCXO-PLL (a Voltage Controlled Xtal Oscillator, which voltage controls the frequency (a bit) via a PLL-circuit (Phase Locked Loop)).
The last one is always more noisy than the first one.
With the TentLink you need a VCXO-PLL + SPDIF-enhancer in the transport and an XO in the DAC. The clock-connection between DAC and transport is only to synchronise the VCXO-PLL in the transport to the XO in the DAC.
With my solution, you will ignore the VCXO-PLL. Just put the XO + SPDIF-enhancer in the transport and connect the XO-clock to the DAC. If a DAC should be powered on without clock, it does not harm it.
Hello PAOSU,
I am sorry if my question is redundant, but could you please tell me where I could read more about the solution you are describing. I just came across this thread. You have mention on Telstar posting - could you please post the link to it so I could read as well? For a long time I have been aware of synchronizing DAC and transport, mostly thanks to the Tent Lab publishing, and I believe that is the way to go. It seems that your solution even improves that. Not too many people went this rout, which I never understood.
Thank you very much
AR2
I am sorry if my question is redundant, but could you please tell me where I could read more about the solution you are describing. I just came across this thread. You have mention on Telstar posting - could you please post the link to it so I could read as well? For a long time I have been aware of synchronizing DAC and transport, mostly thanks to the Tent Lab publishing, and I believe that is the way to go. It seems that your solution even improves that. Not too many people went this rout, which I never understood.
Thank you very much
AR2
In a hurry:
And the tent link:
http://www.tentlabs.com/InfoSupport/page25/page25.html
between it and the reclocked transport.
It should come close to your solution, right?
You know this already?
And the tent link:
http://www.tentlabs.com/InfoSupport/page25/page25.html
between it and the reclocked transport.
It should come close to your solution, right?
You know this already?
Here is very interesting and well done illustration and explanation on various ways of syncing / connecting CD player and DACs. For interested in subject, press different scenarios for illustration and explanation:
http://www.lessloss.com/page.html?id=44
http://www.lessloss.com/page.html?id=44
AR2 said:
Very nice indeed, but there are at least two BUT-s:
1. A CD-player (here often called 'transport') always needs an internal clock, because powering it on without a clock will harm it! There is NO 'jitter-reason' for it. Whatever you do, make a special circuit to-avoid-full-power-on-if-there-is-no-clock, or simply build in a slave clock (like in the TentLink) to avoid that the transport will be powered-on-without-clock. OK?
2. I do not believe in 'special cables', interconnects', 'interlinks' with gold-plated cinch plugs with carbon wires and/or special braids which are not soldered but clamped, etc. etc., or whatever they are called and costing a fortune. I even do not believe in 'line induced jitter'.
As an (analog) radio engineer, I know what the problems are. A decent 50/75 ohm cable with B&C-connectors will always satisfy if the EMC-problems will have been solved. For here this takes too much for explanation (if you do not force me)....
3. 'They' do not talk about an extra PLL-VCXO to enhance the clock from the receiver. Not every source (at least in a professional environment) will have more than one output connection: SPDIF or AES/EBU. In case a decent extra PLL-VCXO in the DAC is a second best solution!
In general: WHAT IS THE JITTER-PROBLEM (apart from building a low noise oscillator)? Why is it not enough to reclock the signals just before the DAC's (PCM's) with a low jitter clock?
Apart from cross talk and other coupling of circuits, digital circuits work digital most of the time, but during the switching they operate analog. In other words: jitter never will be 'filtered out' completely by reclocking it once. We should do this as many times as possible at any possible level.
Therefore enhancing (=reclocking) the SPDIF in the transport helps!
Question: Could reclocking the data between receiver and digital filter be of help? I never saw this and I never tried....
Holier-then-thou attitude?
In my Philips CD-player CD624, the system clock (for the decoder etc.) runs at 11.xxx MHz.
For the 'transport'-part a micro processor (uP) is active. It has its own clock, a piezo-resonator on 4 MHz. From my radio-experience I know that it is not wise to put more than one oscillator in 'one box'. With a signal generator I tried if the uP was sensitive to its clock-control-frequency. It seemed to function well up to 8,5 MHz. I decided to devide the system clock by 2 and control the uP with it so that it runs now on 11.xxx / 2 = 5.5xx MHz.
Was this audible? NO, not to me!.
The mechanic is faster and the remote control should be updated as well! (600 kHz iso 470 kHz).
Are there more holier-then-thou attitude people here?
In my Philips CD-player CD624, the system clock (for the decoder etc.) runs at 11.xxx MHz.
For the 'transport'-part a micro processor (uP) is active. It has its own clock, a piezo-resonator on 4 MHz. From my radio-experience I know that it is not wise to put more than one oscillator in 'one box'. With a signal generator I tried if the uP was sensitive to its clock-control-frequency. It seemed to function well up to 8,5 MHz. I decided to devide the system clock by 2 and control the uP with it so that it runs now on 11.xxx / 2 = 5.5xx MHz.
Was this audible? NO, not to me!.
The mechanic is faster and the remote control should be updated as well! (600 kHz iso 470 kHz).
Are there more holier-then-thou attitude people here?
PA0SU said:
There is very little written on this subject and that is why I posted it. They are certainly trying to sell their products, but I assume that readers will take it just as a one bit of information in the big story. I like animation.
I completely agree with your points, particularly on the one regarding the CD player with/without the oscillator. I also have the same opinion on cables, and I would avoid that conversation for any price here on the forum. Some people believe in that, I believe in circuit topology and well executed designs.
AR2 said:
Sorry that I have forgotten to answer an already 'old question'. I offer nothing. I'm just an old [retired] (rather fanatic) DIYer and have loose connections to people who mix their hobby with commercial interests like Rob de Lugt with his Audio4 and Guido Tent (TentLabs). Audio4 produces eg. step up transformers for ESLs following my concept.
Back to the question: TentLabs offers a XO3.2 (I think...) which is a low jitter clock in combination with an SPDIF enhancer. It has at least two clock outputs, one for the transport itself and one for the connection to the DAC.
In the mean time the Eindhoven-group has developped a new digital filter etc. on FPGA. This programmed FPGA has SPDIF-input a clock output for whatever transport and 24-bit digital output 8x oversampled for PCM63 and PCM1704.....
The 8x oversampling has been programmed 'in one stroke' and not: 2x, 2x, 2x as the commercial filters do to save hardware.
Moreover the FFT-filter has been made as long as possible.
It sounds marvellous !!!!!! The differences are unbelievable.
The 8x oversampling has been programmed 'in one stroke' and not: 2x, 2x, 2x as the commercial filters do to save hardware.
Moreover the FFT-filter has been made as long as possible.
It sounds marvellous !!!!!! The differences are unbelievable.
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