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Does a jittery stream affect quality if reclocked?

Mat

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I bought a Wiim Pro to compare Airplay streaming against my Airport Express and I need a little objectivity because A/B testing is getting neurotic and I'm not sure if perceived differences are in my head.

The Airport Express has enough jitter that a cheaper DAC I tested can't lock the signal without skipping like a CD discman. It also has some noise injected in the signal that I only discovered thanks to this thread, but would otherwise not have noticed. The Wiim on the other hand is clean and measures great here.

The thing is, my DAC has an internal buffer and reclocks the signal. This results in no skipping/locking issues I found with the other DAC. I've been using the Airport as a streamer for the past year and thought it was great.

My question is: Would reclocking make both streamers equal in the end, or is giving the dac a signal with less jitter to reclock going to affect sound quality for the better in any way?
 

onlyoneme

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From my experience reclocking itself will not make both streamers equal as it depends on the ability of the DAC to handle the incoming jitter. In case of ASRC DAC which doesn't lock to the incoming clock, a jitter will affect the stream before reclocking happens.
 
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Mat

Mat

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From my experience reclocking itself will not make both streamers equal as it depends on the ability of the DAC to handle the incoming jitter. In case of ASRC DAC which doesn't lock to the incoming clock, a jitter will affect the stream before reclocking happens.
can this be reflected in an audible difference? or is it just a matter of locking on
 

Blumlein 88

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If the data is correctly transferred, yes reclocking would likely make them equal. In fact ASRC is one method of creating very low jitter like in the case of RME devices. A buffer that reclocks is another. You'll likely not hear a difference.
 

onlyoneme

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can this be reflected in an audible difference? or is it just a matter of locking on
I think it will depend on the implementation. If a DAC doesn't lock to the signal, any deviations will affect and degrade the audio stream. As a result the signal which leaves the reclocking engine and goes to the DA conversion will be "jitter-free", but with internally degraded quality.
 

Blumlein 88

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I think it will depend on the implementation. If a DAC doesn't lock to the signal, any deviations will affect and degrade the audio stream. As a result the signal which leaves the reclocking engine and goes to the DA conversion will be "jitter-free", but with internally degraded quality.
Does not work that way. If the data is read, you'll need no skipping from whatever reclocking is being used, then the output will be of sufficiently low jitter not to be a problem.
 

NiagaraPete

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onlyoneme

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Posting from a phone I'll say more later.
Let's say I have an ASRC DAC which gives different looking FFT graphs of source 12k sine signal coming from different streamers, I mean a digital domain here. What would be the explanation?
 

Tangband

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From my experience reclocking itself will not make both streamers equal as it depends on the ability of the DAC to handle the incoming jitter. In case of ASRC DAC which doesn't lock to the incoming clock, a jitter will affect the stream before reclocking happens.
In certain cases a good reclocked signal will sound better than a jittery signal, even if an ASRC is used before the dac. A bad implemented ASRC can destroy the original digital signal forever so it cant be restored.

 
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NiagaraPete

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NTK

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In certain cases a good reclocked signal will sound better than a jittery signal, even if an ASRC is used before the dac. A bad implemented ASRC can destroy the original digital signal forever so it cant be restored.
How does jitter reduction help with a "bad implemented ASRC"?
 

Tangband

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How does jitter reduction help with a "bad implemented ASRC"?
A bad ASRC is not a good thing, true - worse than without.
 
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Mat

Mat

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Well if you’re using it as a DAC it could but the specs are pretty good.


honestly jitter on apple streamers is probably its own thread just comparing the different generations

Measurements: First and Second Generation Apple AirPort Express - Reviews - Audiophile Style

An example of jitter measurements NOT real numbers.
On the digital out of the Second Generation AirPort Express there is 1 nanosecond low frequency jitter (20 Hz to 200 Hz) and 1 nanosecond higher frequency jitter (over 50 kHz). A measurement will show in total 1.4 nanosecond jitter (square root out of 1 +1). When converting into analog the 50 kHz jitter will be suppressed by the receiver (every receiver has a low pass filter), but the 20 Hz jitter not and will still be 1 nanosecond at the analog out.

An example of jitter measurements NOT real numbers.
On the digital out of the First Generation AirPort Express there is 10 picosecond low frequency jitter and about 2 nanoseconds higher frequency jitter. A measurement at the digital out will tell you 2 nanoseconds jitter and appear worse to the layperson. When converted this signal into the audio band, only the 10 ps bass jitter will remain and as a result will sound much better even though the digital out itself looks worse.

but i digress
 

NTK

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A bad ASRC is not a good thing, true - worse than without.
Many DAC's already have ASRC built into them.

DAC.png
 

Tangband

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Here is an interesting thread:
 
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