SPDIF OUTPUT

[kawo]

Would like to ask, CD / DVD ... the SPDIF digital output of the wave has impact on the DAC to it?

 

[ARTISAND]

YES IT HAS. THE CORRECT TIMING IS THE MOST INPORTANT REASON FOR GOOD SOUND.IT"S NAME IS JITTER,THE LESS IS PREFERABLE.THERE ARE CIRCUITS TO RECLOCK THE DATA FROM SPDF OUT TO VERY LOW VALUES,SAY 1-2PS.EXPENSIVE CD PLAYERS HAVE MUCH CARE IN THIS SECTION

 

[kawo]

Thank's

I see the cd player in this site's output to 20 ns.

http://www.acec13.fr/tvc/REMI/SPDIF_HallOfFame.html#Photos_of_measurements

If I like him SPDIF fixes the wave type, DAC will sound better?

 

[renaudagnes]

Please note the new adress of our SPDIF Hall of Shame :

TVC Audio-SPDIF Hall of fame

 

[kawo]

Thank you, it is this web site, do not know the extent of impact on the sound. I also intend to be similar to their own things.

 

[ARTISAND]

You will find on Ebay circuits which minimize jitter to extremely low values.Jims Audio sells one,it"s price is 71$, and it's name SPDFisolator.This circuit is placed between SPDFoutput and DAC,and is a ready made.All you want to do is the supply.

 

[kawo]

Thank you, but I'm not looking for them, my CD player to do by adding a clock timing, I would like to know if the wave type and modified SPDIF rise time reduction will help?

 

[renaudagnes]

Consider this : if you install a very accurate clock in your CD player, you will have a killer. That's the mod to do first !

For the SPDIF output, this is the second step, after the clock. Anyway, if your spdif input circuit in the DAC is a "high jitter" circuit, you lose a part of your efforts : you have to install a SPDIF INPUT in you DAC, bypassing the legacy input circuitry.

Another information : avoid the use of RCA connectors because they cannot handle the 75ohms. Because the RCA is the worst solution, you can here the difference beetwen cables. With the BNC you can select connector and cable that do the job, for instance BNC 75 Ohms from "Radiall" and cable type RG179 from Nexans

The cable and the connectors are 75 ohms. You have to not use the soldering iron by the tool to press the connector on the cable, in other case the difference of material produces a brake of the 75 ohms.

The cost of this kind of cable is something like 40€, the passband is higher than what we need for the signal and everything else is pure ********.

Here is a picture to explain what we have achieve with a very precise clock, spdif output, cable and spdif input from our conception (fs is for femto second and ps to pico second) :

With have installed our SPDIF input in a venerable Wadia 1000 (from 1990) to bypass the Sony circuit well know for it's very high jitter. The whole story is here (in french, but you can use google translation service).

 

[SoNic_real_one]

Consider this : if you install a very accurate clock in your CD player, you will have a killer. That's the mod to do first !

Consider this: The jitter in a transport is not "created" by the local clock! Jitter in a transport is direct result of the mecahical tracking of optical track, wobling of the disc itself, motor and clamp bearings wear, accuracy of the motor PLL loop and so on...

A "superclock" in a bad mechanical transport does nothing to solve the jitter. Is just "wishfull thinking" and people think that they hear a difference when is none to be heard...

 

[macboy]

Consider this: The jitter in a transport is not "created" by the local clock! Jitter in a transport is direct result of the mecahical tracking of optical track, wobling of the disc itself, motor and clamp bearings wear, accuracy of the motor PLL loop and so on...

A "superclock" in a bad mechanical transport does nothing to solve the jitter. Is just "wishfull thinking" and people think that they hear a difference when is none to be heard...

You are wrong. Data coming off the disc is buffered and clocked back out of that buffer to make it's way eventually to the DACs. Only the clock at the output side of that buffer can possibly make any difference. Jitter from the opto/machanical system can never, simply never influence jitter in the digital audio stream.

 

[kawo]

Hi renaudagnes:
Very much agree with you, I was working on a connected CD player and DAC of the PCB, is indeed in the CD player's SPDIF output some jitter, but even worse is that some DAC's input line circuit causes more jitter, so even if the CD player The clock is completely correct, in transmission can cause big problems.

 

[renaudagnes]

Well, I would like to add this point : there is no bad mechanical transport. It works or it's broken. All the data are read by the mechanic. Think about a computer cd player or dvd player : all the information is read (I know perfectly it's not the same format).

After the extraction of the information from the disk, problems and jitter are arriving.

Because of many years of disinformation from the reviews and manufacturer, it's difficult to accept that all the data are read. Why this transport is more expansive than this one if the same data is read ?

Ask yourself who is the owner of the brand ? What is the market ? Ultra expansive components for ultra ROI, not for ultra musical performances.

I have spend few weeks with this baby. Do you want to know more ? It's soooo deceptive !

There is a Philips CDPro2 inside, this is manufactured by Daisy, a french company under license from Philips (who stopped this own production many years ago).

Ok, there is the famous power stage and an exotic tube output stage. But in term of audio numeric, it is zero intelligence. The CDPro2 is with is stock quartz, the spdif output is +50ppm of error. I have modified DACs with our own VCXO set for high precision which tolerate +/-20ppm of error. This High end player is unable to lock on this dacs.

The sonic performance is not so bad, better than average component, but by far less than what you can achieve with an ultra low jitter system and a good DAC.

If you use a normal DAC behind the CD7, you will conclude the CD7 is superior. Of course, because of the SPDIF output of the CD7, your DAC cannot sound correct.

 

[Eric Juaneda]

Hi macboy,
Hi SoNic_real_one,

Data coming off the disc is buffered and clocked back out of that buffer to make it's way eventually to the DACs. Only the clock at the output side of that buffer can possibly make any difference.

You are right, but the jitter is result of clock noise itself and global environment noise due to electronic design, electrical, electromagnetic, ionic, vibrations...
You can have a very clean clock, putted on noisy environment result in noisy clock data. This probably what SoNic_real_one want to say.

Any electronic signal (digital or analog) can't be independent of its environment.

 

[SoNic_real_one]

Well, I would like to add this point : there is no bad mechanical transport. It works or it's broken. All the data are read by the mechanic. Think about a computer cd player or dvd player : all the information is read (I know perfectly it's not the same format).

PC data doesn't care about exact timing. Audio data cares. Imagine that the CD mechanism is spinning at 1/2 speed. You will have perfect data in the end, but the resulted audio will be 1/2 slower. For audio, timing is as important as the actual data value.
Imagine the speed constanly variable around the "right" speed (because of the tracking and focussing errors that need to be corrected on the fly). That slight variation will result in jitter. The optical drive mechanism has a PLL loop that is fed by the system clock, but the exact timing of data coming "out" is influenced by the mechanical and optical performance. A superclock won't fix that.

 

[Eric Juaneda]

Hi SoNic_real_one,

Imagine the speed constanly variable around the "right" speed (because of the tracking and focussing errors that need to be corrected on the fly). That slight variation will result in jitter. The optical drive mechanism has a PLL loop that is fed by the system clock, but the exact timing of data coming "out" is influenced by the mechanical and optical performance. A superclock won't fix that.

Yes there is jitter in reading information from CD, but this jitter has no impact on audio rendering. All jittered data coming from disc feed a µP and a memory. At this point data coming from disc are only encoded digital data. The µP extract audio data, time, track...

[Note that µP + memory is equivalent as PC architecture]

At this point, the system performs data transfer, and any jitter in data transfer could not affect sound (Fortunately!). Sound is affected by jitter only at digital to analog process (or analog to digital process). Because digital to analog process must be performed with real time respect, low jitter is very important. Reading data from any support is not a real time process.

The real time crystal oscillator mastering the DAC chip also masters the output data coming from the µP + memory.
>>Jittered data at the input of µP + memory.
>>unjittered data at the output of µP +memory. The µP must ensure to avoid memory overflow or empty memory.

Reading data from file on a computer or CD in CD player use same architecture: µP + memory.

 

[wakibaki]

Many people think they can hear the effect of jitter, but there is little EVIDENCE that the jitter due to a typical SPDIF is audible.

For those who are obsessive about the issue it is possible to reduce playback jitter to levels which are almost certainly inaudible by any stretch of the imagination (a few pS) by using a carefully designed solid-state playback system.

w

 

[SY]

PC data doesn't care about exact timing. Audio data cares. Imagine that the CD mechanism is spinning at 1/2 speed. You will have perfect data in the end, but the resulted audio will be 1/2 slower.

Is that true? I would think that you'd hear the music at normal speed, but there would be long and frequent dropouts as the data buffers empty and refill.

 

[abraxalito]

His thinking is somewhat twisted (of course PCs care about timing) but basically he's saying that if you changed the crystal in your CD player to 5.6MHz you'll get audio out one octave lower and it'll play for twice as long. All other things being equal its correct.

 

[stratus46]

YES IT HAS. THE CORRECT TIMING IS THE MOST INPORTANT REASON FOR GOOD SOUND.IT"S NAME IS JITTER,THE LESS IS PREFERABLE.THERE ARE CIRCUITS TO RECLOCK THE DATA FROM SPDF OUT TO VERY LOW VALUES,SAY 1-2PS.EXPENSIVE CD PLAYERS HAVE MUCH CARE IN THIS SECTION

1-2 pS is insane and I flatly don't believe you can measure that, much less hear it. Timing jitter of 1 part in 11 MILLION? I want to see this ABX tested.

As a true old fart. Bah, Humbug

G²

 

[remi207]

Hello

[comment]1-2 pS is insane and I flatly don't believe you can measure that, much less hear it. Timing jitter of 1 part in 11 MILLION? I want to see this ABX tested.[/comment]

The phase noise analyser Agilent E5052A can measure less 1-2 ps. The tvc clock module have a phase noise very low, See the graph. The rms jitter is calculed from 10Hz to 4 Mhz offset of phase noise.