Phase Locked loops and WEISS MEDEA

[Dr.H]

Hello all,

Was reading reviews of what appears to be an extra-ordinary DAC, the WEISS MEDEA and in an interview with the designer, mention was made of the fact that most PLL's only filter out jitter to about 1kHz and that below this everything else gets through.

Jitter Suppression and clocking: http://www.enjoythemusic.com/magazin...ture/weiss.htm

Quote: "In the MEDEA we employ a two stage PLL circuitry which very effectively suppresses jitter. A common problem with most PLLs used in audio circuitry is that they suppress jitter only for higher frequencies. Jitter frequencies which are low (e.g. below 1kHz or so) are often only marginally suppressed. It has been shown that low frequency jitter can have a large influence on the audio quality though. The MEDEA suppresses even very low frequency jitter components down to the sub-Hertz range."

Dac reviews:
http://www.soundstage.com/revequip/weiss_medea.htm
http://www.tnt-audio.com/sorgenti/weissmedea_e.html
http://www.stereophile.com/digitalsourcereviews/781/

My questions:
1. Anyone willing to spend a bit of time educating the community on how PLL's work?
2. Anyone have any ideas on a PLL (2 stage) that can do what Weiss describes, i.e. "suppresses even very low frequency jitter components down to the sub-Hertz range."?

Thanks
Ryan

[Guido Tent]

Originally posted by Dr.H
Hello all,

Was reading reviews of what appears to be an extra-ordinary DAC, the WEISS MEDEA and in an interview with the designer, mention was made of the fact that most PLL's only filter out jitter to about 1kHz and that below this everything else gets through.

Jitter Suppression and clocking: http://www.enjoythemusic.com/magazin...ture/weiss.htm

Quote: "In the MEDEA we employ a two stage PLL circuitry which very effectively suppresses jitter. A common problem with most PLLs used in audio circuitry is that they suppress jitter only for higher frequencies. Jitter frequencies which are low (e.g. below 1kHz or so) are often only marginally suppressed. It has been shown that low frequency jitter can have a large influence on the audio quality though. The MEDEA suppresses even very low frequency jitter components down to the sub-Hertz range."

Dac reviews:
http://www.soundstage.com/revequip/weiss_medea.htm
http://www.tnt-audio.com/sorgenti/weissmedea_e.html
http://www.stereophile.com/digitalsourcereviews/781/

My questions:
1. Anyone willing to spend a bit of time educating the community on how PLL's work?
2. Anyone have any ideas on a PLL (2 stage) that can do what Weiss describes, i.e. "suppresses even very low frequency jitter components down to the sub-Hertz range."?

Thanks
Ryan

Hi

This may help

http://members.chello.nl/~m.heijlige...tml/dactop.htm

and particularly

http://members.chello.nl/~m.heijlige...l/PLL/PLL1.htm

enjoy