Femto clocks ,every unit should have one

The term Femto clock is actually a registered trademark for IDT for a MEMS type oscillator, but i suspect this is not what we are talking about here. W4S are talking about Femto grade clock. I contemplate they are referring to jitter performance in the femtosecond range. Did anybody check out if this jitter is specified for the Audio range, or the industry standard 'Sonet range' of 12 kHz - 20 MHz? (In which case the low jitter spec is pretty much useless).

Yes actually it does deal in the audio range,there are a lot of variables,the clock is very capable of the 82 Femto second mark, the precision of the
Dac will determine how close it will hold to this standard . Even at it's
Worst it is still much more accurate then Any pico second clock.
Up to 75% if you do the math,maybe not at all frequencies, but a good
Part of the spectrum.I spoke with both Clock Mfg,and Wyred and
On both accounts the clock is most accurate in class Guaranteed,and
Wyred 4sound DSD-SE model has parts quality in several areas better then Any dac even at the $10k level. Such as the precision regulators, and resisters
Which are 10 x more accurate then the typical very good 1% variety.
In digital every small improvement is cumulative , and audible .i am not stating it is better then any $10k, I am stating that at it's price point and against anything up to $5k it is a very involving music maker.

Don't believe the hype. In the real world ALL so-called Femto clocks are just marketing BS when applied to audio.

This specifically applies to clocks intended for SONET applications (Read internet backbones), which need to have very low phase noise (jitter) above 12KHz, but care zero about phase noise below 12KHz. Which is why clock jitter for these clocks is specified usually as RMS 12KHz - 1MHz (or higher) and a very low level of phase noise / jitter at these frequencies is essential. This is why this specification recently became important and specified (many vendors simply adjusted their datasheets for what is the part that previously was a "picoclock")

Now here is the killer. it is practically impossible to make a crystal oscillator that is fixed frequency and does not measure at the max. a few 100 Femtoseconds RMS phase noise/jitter under the tests conditions. The cheapest clock you find in China will do that.

For Audio use what matters most is audioband (20Hz-20KHz) jitter. In this case a really basic "Tent-clock" rated at 3pS P-P Jitter RMS IIRC from a commonly available source with a cheapo 3-Pin chip regulator will beat the pants of ANY Femtoclock most designers are aware of.

None of them provide even 50pS peak-Peak jitter 10Hz-20KHz.

The GMT System, which uses a programmable clock that was not optimised for SONET, but for an application that needs low audio band phase noise levels., when measured it "Femto Clock" style, shows around 200 Femto Seconds RMS phase noise.

Most any clock in audio (1 rung above lo-fi) use if measured "Femto Clock Style" is a Femto Clock .

Finally, jitter is NOT the end-all be-all of good sound in digital.

Audioengr, Implementing a Femto clock will have little effect on your designs in my opinion. Kind of like a cop out :-) I have researched your designs as best I could and they are brilliant. One of the best there is and I don't know you from Adam just your work. Obviously Silver is a better conductor than Copper but seriously no way you or anyone will hear the difference in your well designed products. But if you want to hear a difference you will. Stick to what you do don't pander.

I agree with most of what Wisnon just said. I wouldn't claim that every chinese CPU clock can beat any femtosecond clock, but maybe some of them.
These canned clock's are usually made with a logic gate as the active element, in a Pierce coupling. Such as the 74HCU04 The equivalent input noise is relatively high. I don't think anyone would use 74HCU04 as a RIAA amplifier?
Noise on the input of the active gate, transfers directly to jitter in the clock signal.
Also the input level is half that of the Vsupply. So half of the noise on the supply rail is transferred to the input. That's why the regulator is of great importance.
Much better is the Colpitts oscillator, built with discrete transistors. Here you can get somewhat better noise (jitter) performance.
I agree with Wisnon also that jitter is not necessarily a make or break factor, the problem is when the music signal is transferred to the clock, over the 5V supply lines. That is going to kill depth perspective, and sound stage. And strangely if you have a jitter instrument, you will find this in many CD players or DAC's. Random jitter is far less intrusive, and like low order distortion in tube amplifiers, it can mask other distortion / jitter.