Digital Re-Clockers a strange thing but worth trying

[savvypaul]

For me, the interesting question is whether the Mutec (and other digital reclockers) are solving a genuine problem or simply papering over cracks elsewhere in the chain. Is a reclocker the most cost-effective way to do that?

[Fretless]

If you work from the assumption that all the bits are trundling along and in the right order, but the effect of Jitter is to interfere with the timing / synchronisation, then a reclocker will be effective in improving the playback by emsuring what arrives at the DAC is properly timed.

[CN211276]

As high resolution streaming is an emerging science it is no wonder there is divergence of opinions. For my part I am reluctant to add additional components to the digital chain which are electrical, with the exception of switches. I suspect they could be adding more nasties through the mains than they are taking away and think passive filters are the best solution.

[Geoff.R.G]

For me, the interesting question is whether the Mutec (and other digital reclockers) are solving a genuine problem or simply papering over cracks elsewhere in the chain. Is a reclocker the most cost-effective way to do that?

Digital audio, indeed all digital systems, are reliant on a clock. The clock determines such things as when samples are taken and how fast the individual bits are transmitted. There is an assumption that the clock is very stable and very regular. Usually the “clock” is a quartz crystal with an accuracy of, for example, 20ppm. Whilst this may sound good the frequency can vary under the influence of temperature, the temperature inside your computer, CD player etc. isn’t very stable so the clock frequency isn’t any more stable. I will leave it to your imagination what effect a drift in the clock frequency may have on the sound.

It is possible to make the crystal more stable by regulating it’s temperature in an “oven” at around 75C. Obviously a temperature controlled oscillator is more expensive than one left at room temperature. Given that most people don’t listen well enough or more accurately hear what they expect to hear and the errors caused by the drifting oscillator aren’t noticed. They aren’t inaudible but our brains know what they expect to hear, much of the time, and filter out anything that doesn’t fit.

Now, assume that the recording equipment has a clock that drifts at a given frequency and thus the 44.1 KHz samples vary by a few hundred Hz. That means that sometimes a peak comes early by a tiny fraction of a second and other times it is late. Combine that with a player that has a clock that drifts at a different frequency, it might bring the errors in differently from recorder. What do you think the effect might be?

A reclocker should, in theory, restores the stable, regular clock and thus minimises the errors.

[CN211276]

the frequency can vary under the influence of temperature, the temperature inside your computer, CD player etc. isn’t very stable so the clock frequency isn’t any more stable. I will leave it to your imagination what effect a drift in the clock frequency may have on the sound.

Could this be an explanation as to why my system sounds better when it has been on for a while and is warmed up?

[Bencat57]

I make no claims to know why the addition of DDE units improves sound . Above is an explanation of what using a more accurate and stable clock can do and I am sure there is something in this but i suspect it is not the full story . I do not have or use a USB DAC so the Denafrips unit while interesting is not much use to in my systems .

The other area that I think a DDE can help is that it breaks the noise chain from the network to your player being carried over through to your DSP or DAC unit . This happens when the digital stream is taken and the clock timings are stripped out and replaced by the DDE more accurate clock timings .

There may well be other reasons and i suspect there is because of all things DDE units sound different I picked up the Audio GD unit because the then owner tried a Mutec and was convinced that it was considerably better . I am very happy because I can get a DDE of good quality in my system for not a huge amount of money and probably get 95% of the a sound advantage .

Digital and streaming are still for music a bit of an unknown , Computer Network engineers will tell you that things do not matter and there is nothing to be gained as networks are designed for much higher levels of traffic and are made immune to drop outs and the like and that for music streaming you are using very little of the bandwidth or speed so there is no problem . But it is a similar issue with DDE units they are often like the Mutec designed to solve a very different issue and then you find that they also offer advantages that were not even considered in the design . Despite what we are told listening to music via a network is not the same as sending digital information . Digital information in most cases just has to be accurate and complete you do not have any emotional content in reading a spreadsheet or sharing files they are just artifacts that you read and then use . Music on other hand has a very emotional content and you respond to it and react to it in an emotional way . If the music you play using the addition of a DDE in the chain makes your emotional response easier to get or even if it moves you more that this is a good thing and you need to keep having it in place . I would love to be able to have a simple and repeatable test that showed exactly what is happening and why I hear and react the way I do but currently no one has been able to isolate this so I have to just trust my own ears and my own reactions even if as many have said to me they false and caused by my own brain in response to bias and other stimulus .

[CN211276]

What's wrong with the clock inside a DAC? Is there not an advantage to the clock being as close as possible to the conversion?

[Bencat57]

Paul it is like everything in any product , much depends on what the clock is and how important the designer thought that item was. As noted above the cheapest and most commonly used clock is a quartz crystal and this has reasonable accuracy . Then you move up to FEMTO clocks which have huge uplift in accuracy and it these clock types often used on DDE units and also stand alone Master Clock generators . One of the reasons why better clocks are often not used in CD players made in large numbers is that it is not as simple as just changing one clock for another. Because the new clocks are so much more accurate then what is fed to them and implementation also needs to be as accurate and stable as the new clock . This is a major undertaking and needs good design and good component use which adds to cost . Small seeming costs at the design and build stage amount to huge cost uplifts for the final selling price . There is a similar thing going on with TOSLINK connections . This optical or fibre connection should be by far the best and most transparent connection for digital signals but in most cases when you listen RCA SPDIF sounds better. The issue is the send and receive chipa and transformers used which for economies of scale are mass produced at very low cost and with no real concern if they do the best job they can rather they are just about good enough and no more . If you doubt this and can find two items that use At&T optical was used on some digital equipment and sounded superb but because it was expensive to implement it was dropped before it could gain any acceptance amongst the main stream mfg companies.

There is the belief that having the clock as close to the source as possible and this is often given as the reason as to why a CD player will sound better than a transport and DAC . However the main reason is more likely that the signal between the chips and the clock is I2S and this has both right information and left information and then clock signal as part of its stream which means the same clock timings will be used throughout so making it very stable .

[CN211276]

What's wrong with the clock inside a DAC? Is there not an advantage to the clock being as close as possible to the conversion?

A very good point which brings me back to the ASR review of the Mscaler. The Mscaler measured terribly for jitter, but when it is connected to a appropriate Chord DAC with dual BNC inputs jitter does not appear to be an issue.

[Geoff.R.G]

What's wrong with the clock inside a DAC? Is there not an advantage to the clock being as close as possible to the conversion?

Unless the clock in the DAC is temperature stabilised it is no better, or worse, than the one in a CD player. Ideally there would only be one clock in a digital recording/playback system, irrespective of the number of boxes involved. If there is more than one clock the chances of the frequencies being the same is very small, even if the devices can handle the differences they are still there.