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In the Forum: Didital Things
In the Thread: Myth of CD clocking = True/False
Post Subject: Re: jitter-shmiter...Posted by Thorsten on: 3/7/2006
Hi,

 Romy the Cat wrote:
I heard 4 (!!!!) complete contradictory descriptions how high level of jitter manifest itself subjectively – interesting that they all derived from the engineers whose credibility is very high (not juts the audio-tweakers who fart sound out of their audio components by changing capacitors).


Of course you would. Jitter is just another type of distortion where the one-dimensional "single number" thing does not work. The key is actually the spectrum.

 Romy the Cat wrote:
For instance the Museatex original transport coupled with Bidat using Meitner’s C-lock synchronization mechanism that has NO MEASURABLE JITTER at all.

 
Sorry, but the physics of making an oscillator demand, require that it has jitter and without liquid nitro cooling of the electron ics you never get low enough noise to claim "no measurable jittter".

 Romy the Cat wrote:
The explanation from Lavry Forum that you linked does sound very reasonable. What is unreasonable to me that with objectively better clock in my TL0 I got that that horrible sound…


It makes complete sense, actually.

Jitter with a fairly low frequency (for example a fairly noisy supply with a nice deal of "pink" LF noise) can make for a nice, warm sound without obviously affecting resolution etc.

The problem is that some people wish to sell "silver bullets". So they claim "clock so and so" reliably improves sound. It certainly changes the sound and Joe Public has paid 500 Greenbacks to have the clock installed "by a professional" So it must be an improvement, nah?

I have seen stuff like this - the professional actually applied a clock with a 5V output to a 3.3V logic chip that is explicitly rated for NO MORE THAN +V [3.3V] input, so everytime the clock output went above 3.3V (that is on every single clock pulse) the protection circuit of the CD chip clamped the clock, throwing noise currents into the supply line and causing a near short circuit load on the clock modulating itr's supply a lot more than intended. I'll not even mention the stuck down by dual layer sticky tape "never connected" supply, sufficient to say that the clock was best with the "never connected" supply genuinely "never connected" and the original state restored.

The machine came into my hands for "fixing" because it actually tended to lock up and refuse to play CD's!!!! The Joe had paid nearly a grand to have his player "improved". It was worse than stock, sonically and actually just did not work properly at all!!!! I ended up doing a big mod job on the player, which the guy subsequently liked a lot so that he considered even the total mod expense (mine and the earlier bad attempt with "boutique parts and modules") of nearly 2k5 well spend. Maybe I should charge more?

So, what is the lesson?

You cannot just "chuck clock at it" (unless "it" is a thief and the grandfather clock is the only weapon the law allows you to protect your home or you happen to only have a Makarov), a "clock" like so many things in audio needs to be designed into the circuit properly, understanding both clock and circuit.

Just connecting the wires a few mm out of the ideal position can throw a few 100pS (audible) jitter into the combined circuit, even if the clock itself has "0pS" Jitter (not that any has).

The LC Audio Clock at least accounts for differences in logic levels but instructions rarely account for grounding et al completely. A COMPETENT tech should be able to install such a device correctly, if he can be bothered to obtain the datasheets for the IC's in the player and to analyse the actual circuit.

Ciao T

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