Reclockers: I don't understand. Are they Snake Oil?

[DerBryGuy]

Hello:

I am new to the forum, but not new to the youtube channel. I'd like to ask a question about something I saw online that just doesn't make sense.

My background is in electrical engineering, and I have worked for years in IP network operations. Which is to say I have enough of a technical background to understand the difference between Toslink/SPDIF being synchronous and USB operating asynchronously.

Recently I have come across claims on youtube that inserting a reclocker device can improve perceived sound quality in digital systems. Specifically, the claim is inserting a reclocker after a Wiim Ultra but before a DAC will improve Jitter. The reviews used subjective words that are red flags for me (blacker background, instrument smearing, stereo separation, galvanic isolation et al). The discussions seem to focus on Jitter being a/the problem.

From my background, I have seen jitter, in the form of irregular IP Inter-packet delay, cause visual artifacts in a Multicast/Mpeg 4 video stream. But the primary causes were inconsistent network latency and congestion, which caused Set Top Boxes to excessively buffer or discard packets. Video packets arriving late, errored or out of order introduce video artifacts such as image freezing, pixelization, or black bars (missing data). Even still, we were successfully able to transmit Mpeg 4 video over IP/Multicast virtually across the country without introducing artifacts if the network latency was consistent and no individual network element caused packets to arrive out of order.

If I translate this to audio which as a bitrate of orders of magnitude lower, digital audio transmission should have a much wider margins for error. I don't understand how those could be exceeded in a transmission line of reasonable (<5m) length.

To my mind, if I translate my video experience to audio, audio frames transmitted over the Toslink/SPDIF connection that arrived late, errored or out of order would cause obvious audio glitching. I should hear that. But if they arrive in order, un-errored, I am at a loss to understand how reclocking could impact digital audio quality.

If I am using Toslink/SPDIF between a Wiim Ultra and a DAC on the same AV equipment stand, the connection is relatively short and point to point. There is no possibility of 'network congestion'. If there was excessive buffering here one of the products is faulty. If the data arrives errored, the cable is damaged.

Further, the DAC's recommended in the video do not have an external clock input. IE: They must have a pre-existing internal clock. Nothing we do to clocking external to the DAC overrides the internal clock of the DAC

So to sum up, what I do not understand is how a reclocker could affect any audible difference in this simple digital signal chain. It is not bypassing the clock in the DAC. I can see it only adding latency before the audio started to play. It seems to me adding digital elements can only increase the possibility of bit errors each time they are processed.

Are reclockers really just snake oil?

Thanks!

 

[Thighsofsteel]

Are reclockers really just snake oil?

Thanks!

Yes.

 

[kemmler3D]

Further, the DAC's recommended in the video do not have an external clock input. IE: They must have a pre-existing internal clock. Nothing we do to clocking external to the DAC overrides the internal clock of the DAC

So to sum up, what I do not understand is how a reclocker could affect any audible difference in this simple digital signal chain. It is not bypassing the clock in the DAC. I can see it only adding latency before the audio started to play. It seems to me adding digital elements can only increase the possibility of bit errors each time they are processed.

You're not the crazy one. There's nothing they know that you don't, in this case.

The long and short of it is that devices that don't measurably affect output can still all improve sound quality through cognitive effects / "placebo effect".

The ecosystem of snake oil brands and reviewers who appear to buy their claims is sustained by this. Some of them truly believe the claims, others cynically exploit the universal tendency to hear something change every time the gear changes.

But as you note, there's nothing special about audio bits vs. other kinds of bits.

 

[Roland68]

Hello:

I am new to the forum, but not new to the youtube channel. I'd like to ask a question about something I saw online that just doesn't make sense.

My background is in electrical engineering, and I have worked for years in IP network operations. Which is to say I have enough of a technical background to understand the difference between Toslink/SPDIF being synchronous and USB operating asynchronously.

Recently I have come across claims on youtube that inserting a reclocker device can improve perceived sound quality in digital systems. Specifically, the claim is inserting a reclocker after a Wiim Ultra but before a DAC will improve Jitter. The reviews used subjective words that are red flags for me (blacker background, instrument smearing, stereo separation, galvanic isolation et al). The discussions seem to focus on Jitter being a/the problem.

From my background, I have seen jitter, in the form of irregular IP Inter-packet delay, cause visual artifacts in a Multicast/Mpeg 4 video stream. But the primary causes were inconsistent network latency and congestion, which caused Set Top Boxes to excessively buffer or discard packets. Video packets arriving late, errored or out of order introduce video artifacts such as image freezing, pixelization, or black bars (missing data). Even still, we were successfully able to transmit Mpeg 4 video over IP/Multicast virtually across the country without introducing artifacts if the network latency was consistent and no individual network element caused packets to arrive out of order.

If I translate this to audio which as a bitrate of orders of magnitude lower, digital audio transmission should have a much wider margins for error. I don't understand how those could be exceeded in a transmission line of reasonable (<5m) length.

To my mind, if I translate my video experience to audio, audio frames transmitted over the Toslink/SPDIF connection that arrived late, errored or out of order would cause obvious audio glitching. I should hear that. But if they arrive in order, un-errored, I am at a loss to understand how reclocking could impact digital audio quality.

If I am using Toslink/SPDIF between a Wiim Ultra and a DAC on the same AV equipment stand, the connection is relatively short and point to point. There is no possibility of 'network congestion'. If there was excessive buffering here one of the products is faulty. If the data arrives errored, the cable is damaged.

Further, the DAC's recommended in the video do not have an external clock input. IE: They must have a pre-existing internal clock. Nothing we do to clocking external to the DAC overrides the internal clock of the DAC

So to sum up, what I do not understand is how a reclocker could affect any audible difference in this simple digital signal chain. It is not bypassing the clock in the DAC. I can see it only adding latency before the audio started to play. It seems to me adding digital elements can only increase the possibility of bit errors each time they are processed.

Are reclockers really just snake oil?

Thanks!

They are nowadays.
There was a time when USB was really bad for audio, and poor-quality or dirty USB ports on the host device also had a detrimental effect.
But since XMOS and Amanero USB interfaces came onto the market, that's essentially history. Today, USB is among the best digital audio interfaces.

In addition to USB, the SPDIF signals in modern DACs are also completely processed, and any existing jitter is drastically reduced. So good, in fact, that no further improvement is possible with external devices, or at best a very slight improvement in the measured values, which is far from being audible.

Just take a look at the SMSL DACs D1 and SU-1.
Both have three crystals, a jitter reduction circuit, and a sophisticated power supply filtering system for the USB connection, all for €79. You'd be hard-pressed to find an audible improvement, even at €1000.

Yes, there was a time when reclockers, DDCs, and external clocks could actually improve things, but the differences weren't night and day; they were more subtle, even barely audible, and that was well over 10 years ago. Since then, it's all just milking a dead cow, and as my father always said, a fool is born every morning....

 

[john61ct]

There is nothing wrong with Wiim's USB output.

Note it is subject to all the internal DSP'ing, takes some hoops to get "bit perfect" pass through.

HOWEVER there are target devices with lousy USB inputs downstream, or none, S/PDIF only.

Or maybe you want multiple outputs concurrently?

Topping D10S acts not only as a DAC but as a DDC as well, allowing you to convert the USB input from the WiiM to analog plus digital Coaxial plus Optical, all three simultaneous outputs.

Wiim Ultra + Topping D10S to help with DSP and bass management

Wiim Ultra makes not only a great preamp + streamer / network player, but has got basic DSP functionality. For overall system PEQ, using REW + other filter creation tools even an automated room compensation EQ "Autofit". Its bass management is for me too basic, as I need midbass couplers and...

www.audiosciencereview.com

Note I am not saying its function as a "reclocker" is needed AT ALL.

 

[Descartes]

My grandfather used to reclock all the time

 

[JSmith]

My grandfather used to reclock all the time

Mine was too large for the shelf, so it spent 90 years on the floor.


JSmith

 

[solderdude]

Hello:

I am new to the forum, but not new to the youtube channel. I'd like to ask a question about something I saw online that just doesn't make sense.

My background is in electrical engineering, and I have worked for years in IP network operations. Which is to say I have enough of a technical background to understand the difference between Toslink/SPDIF being synchronous and USB operating asynchronously.

Recently I have come across claims on youtube that inserting a reclocker device can improve perceived sound quality in digital systems. Specifically, the claim is inserting a reclocker after a Wiim Ultra but before a DAC will improve Jitter. The reviews used subjective words that are red flags for me (blacker background, instrument smearing, stereo separation, galvanic isolation et al). The discussions seem to focus on Jitter being a/the problem.

Further, the DAC's recommended in the video do not have an external clock input. IE: They must have a pre-existing internal clock. Nothing we do to clocking external to the DAC overrides the internal clock of the DAC

So to sum up, what I do not understand is how a reclocker could affect any audible difference in this simple digital signal chain. It is not bypassing the clock in the DAC. I can see it only adding latency before the audio started to play. It seems to me adding digital elements can only increase the possibility of bit errors each time they are processed.

Are reclockers really just snake oil?

Thanks!

It's a bit more nuanced than just being snake-oil in the case of SPDIF/Toslink.

There are no packets being lost or arriving late in this case. Especially with Toslink there are possibilities of the digital signal becoming 'distorted' at the transmit and or receiving side which can potentially 'fool' the PLL (or whatever other method being used).
The internal clock of the DAC is not affected of course but in the case of SPDIF/Toslink the clocks of output device and DAC need to synchronize.
That's where potentially things can go wrong. Especiallly in the early days, nowadays the vast majority of DAC designs has fine SPDIF receivers,

The potential problems can be caused by:

• instability of the source's clock.
• Poor execution of an output circuit/transformer on the source side (which is not optimized for audio)
• Poor LED on the Toslink side.
• Poor POF cable on the Toslink side with too much attenuation/broken inside.
• Poor response of the Toslink receiver.
• Limited bandwidth of the Toslink receiver.
• Poor execution of an SPIDF receiver (transformer or otherwise).

This can lead to the dreaded 'jitter' in the DAC SPDIF receiver signal (Toslink is just an optical transport of the SPDIF signal).
The second issue how the DAC synchronizes its internal clock to the incoming clock.
The clock signal is embedded in the data signal and can simply be pulled apart again so one ends up with data and clock.
That clock can be jittery for one or more of the reasons mentioned above, so can the data timing be.
DAC's purpose is to ignore the jitter. Fairly easy for the data (one can sample the data halfway in the bit rate)

That incoming clock has a different (average) frequency than the one in the DAC.
In order to prevent buffer under- or over-run there is a nifty circuit called PLL.
What it does is match a 'free running' oscillator by comparing the phase of that oscillator with that of the retrieved clock.
This new clock is then used to clock the DAC chip.
That clock can have remnants of certain types of jitter due to the speed with which the PLL reacts and how that circuit is built.
In the early days this was not done as good as can be done today.

This is where a reclocker could (potentially) make a difference. That is when one of the conditions above degraded the signal enough to create audible (and very measurable) issues in the clock regeneration/speed matching process that governs the DAC chip clocking.

No such issues with UAC2 (UAC1 has other potential issues with clocking).

A reclocker could improve the signal quality of the incoming clock/data stream in such a way that the PLL of the DAC has better performance and less of the jitter passes through the PLL improving the signal.

But is only an issue with certain DAC's/connections/sources and could potentially improve the final result (stable clock of the DAC chip).

Nowadays this is not so much of an issue with the vast majority of devices out there. At least it should not be. Designers can still do stupid things.

Short answer is ... mostly nonsense but in rare cases it actually might help.... And that's where the hardcore audio-phool/phile comes in. They don't trust anything and 'everything matters'. These folks will use one anyway and buy them... just to be safe or because they 'hear' things.
That's good news for manufacturers of re-clockers. They have a potential market to sell (expensive) devices. They 'work' because psycho-acoustic phenomena always work.
regardless of how well TOSLINK, SPDIF, AES/EBU, I2S 'works' in the DAC and does not need a 'very good quality' signal.

This explains why re-clockers exist and sell these days. Mostly not because they are actually beneficial but rather to 'set' the mind at ease of the 'highly discriminate' audiophile listener that 'knows' the digital signal is polished as well as their shiny speakers.