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Frequncy standard use in audio equipment

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tkamiya:
I'm asking because I'm genuinely curious....

I have been seeing reference oscillators of all kinds, including Rb, OCXO, and GPSDO for audo use.  Some report says they can "clearly hear the difference."  I'm thinking for syncing digital recording, etc, regular crystal or maybe TCXO is sufficient and that human ear can't possibly distinguish the difference in phase and frequency stability. 

Is this yet another case of snake oil?  Some of those goes for $4KUS or so. 

james_s:
It's no different than fancy expensive speaker cables and other audiophool nonsense. The placebo effect is real, if you believe some gadget will make your audio sound better then it will sound better to you. A reference oscillator would have to be REALLY bad to have any sort of audible effect though, and it's unlikely the oscillators in the gear used to record and master the audio were anything exotic either.

Gyro:
Master clocks and distribution are used in recording studios for equipment synchronisation I believe. I don't know to what accuracy though.

For consumer audio, the reference oscillators you mentioned are total snake oil. What does matter is noise and jitter. Better quality gear tends to have better internal clock oscillators - starting from the basic on-chip inverter oscillator through to better quality canned ones and those using discrete components. These (all things being equal) do seem to improve sound quality - Different DACs have different jitter rejection, likewise clock recovery in things like S-PDIF receiver ICs.

Absolute frequency accuracy is totally inaudible though, even with the cheapest and most basic crystal oscillator.

ataradov:
Clearly hearing the difference is not enough. Can you measure it with measurement equipment? If not, then you are full on audiophool. 

And for most audio application $1 crystal is sufficient.

SiliconWizard:

--- Quote from: Gyro on May 11, 2021, 07:52:55 pm ---Master clocks and distribution are used in recording studios for equipment synchronisation I believe. I don't know to what accuracy though.

--- End quote ---

Yes, but synchronizing several digital sources and the frequency stability of a single source are two completely different things.

The typical use case for an end-user is just a single source. So there's usually nothing to synchronize.

Of course, as said above, for a single source, jitter matters much more than absolute frequency. We'd need to know if those shit expensive oscillators have at least much better jitter figures than modest ones. We can suppose so, but that's really the main point to consider.

Now whether the typical jitter of even a modest crystal-based oscillator (as long as it's not pure crap) has any measurable impact on distortion (harmonic/phase), that remains to be seen. That may be measurable if you directly measure the ouput of a DAC with a very clean output stage, but once it goes through some kind of amplifier and speakers (or headphones), all bets are almost certainly off. The latter will have a much more severe effect on phase and harmonic distortion than the digital clock.

And, now even when it's actually measurable, which as said above is likely not the case with a typical audio system, whether it can actually be "heard" by our normal ears, it's yet another question. The most sensible answer to this is probably, not at all.

But as we say on a regular basis, as long as said equipment has measurable technical benefits, even if it makes no difference to the ears, then it's just a matter of luxury IMO. If you want luxury equipment, that's your call. Now OTOH, if there is absolutely NO measurable technical difference, then it's snake oil, and a different category, although certainly some people won't be able to tell the difference. But I like the "luxury" argument. If you're buying a $20k watch made with very good engineering and great materials, that may not give you much more accurate time than a $20 watch (or so), but it IS luxury. Now if you're buying a $20k that is actually really a rebranded $20, that is just rip-off.

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