Why do my CD's still sound better than flac files?

I'm not disagreeing, but to be clear, I was specifically talking about converting FLAC files to WAV files (for subsequent playback), rather than playback of FLAC files directly. Lest there be any confusion.

 

Anyone want to bring interconnects in to this discussion for the trifecta?

 

Another can of worms.

 

I enjoy flac and lossless rips in my system more than the CD versions. This statement has an number of equipment, software and limited knowledge variables that will not match most other peoples situation, but it is true for me. My ignorance is bliss, so listen to what sounds good to you.

 

Now power cables are involved, didn't see that coming. Course I agree, but that's besides the point.

 

Any software that plays FLAC files will decode them to PCM bits and place the bits into a buffer that is then accessed by the D/A converter. Placing 300Kb per second of data in a buffer is basically something that any audio digital equipment of today can do in 1/10000 of its processing power.

There is no on-the-fly decoding, there is no jitter reaching the D/A converter TODAY because the D/A takes so little data at a time even for a 192/24 stream that when you play a FLAC file your computer is sleeping 99.999% of the time just waiting for the D/A to do its work.

Jitter was in the picture when the first CD players entered the market and they could barely process the data to send to the D/A converter. That was a time when computers took 3 minutes to write 1.4 MB of data to a floppy disk. Today a computer can process 1.4 GB in a fraction of a second while the amount of data sent to the D/A converter is the same as it was 30 years ago when the CD was invented.

Do you remember when they introduced anti-shake portable CD players? You could shake the player and the laser would lose the track on the disc, however playback would continue uninterrupted? How did they do that? Was it magic? Or perhaps it was because the data to the D/A converter was not coming straight from the disc but via a large buffer?

So bottom line: jitter is influencing your playback? You have faulty equipment. FLAC playback produces different data for the D/A converter? You have faulty equipment. Full stop.

 

You are talking more about advancements in error correction here. Jitter is never eliminated, it has just gotten smaller and smaller in magnitude.

 

Unless I'm missing something, the referenced post has nothing to do with error correction.

 

No I am not talking about advancement in error correction. I am talking about the fact that jitter does not exist when playing digital files, whatever their format, unless we are talking about jitter in the D/A converter.

 

Jitter exists in the transport of bit from files/music server to a DAC. There have been improvements but some timing error exists.

 

Sorry but I have never seen digital information altered because of jitter. If you were right then potentially when you open a Word document you could see characters altered because of jitter. Does it happen?

There are two sources of jitter in digital music playback:

- CD seek jitter... this problem has been totally eliminated years ago. But in case you experience CD read jitter this will manifest itself through samples being read twice or skipped and that means clicks and pops in the playback, not a continuous alteration of the sound. If you are playing files this type of jitter does not exist.

- D/A converter jitter: in theory this jitter still exists however the accuracy of clocks in modern equipment is many degrees of magnitude higher than what is required to perform jitter-free D/A conversion for an audio stream that tops at 20KHz.

 

You cannot compare digital playback to viewing a Word document. That's a very different animal. A Word document has no timecode like a digital stream.

 

A digital audio stream has no time element (timecode???) anywhere in the chain before it reaches the D/A converter!

 

Read this: http://www.positive-feedback.com/Issue43/jitter.htm

Playback jitter originates from a large number of contributors, which are usually additive. These range from the master clock, which has its own jitter, to logic devices, to mechanical systems for spinning a CD. One digital cable can even add more jitter than another. Each contributor adds more jitter to the signal as it makes its way to the D/A converter. This summation of this jitter is the system jitter.

Here is a lengthy, but probably not complete list of jitter contributors, including how each of these can or might add jitter to a digital audio system:

1. Master Clock Jitter

This is the source clock for all of the data streaming timing, usually a quartz-crystal-controlled oscillator at a very high frequency. It may be a 11.2896MHz clock in a CD player for data sampled at 44.1kHz, or in computer audio systems, a clock that is software generated from an even higher frequency CPU clock. The jitter of these clocks is intrinsic to the crystal device, but also depends on the design of the oscillator circuit. In the case of the master clock being software generated, the jitter can also be dependent on the program code.

2. Servo-system/rotational jitter

This is the system in the CD player/Transport that determines the spin-rate of the CD. It is an electromechanical system. Even though most modern CD players have buffering of the data to create some tolerance to this jitter, there is usually a PLL (Phase-locked-loop) involved, which is usually still somewhat susceptible to jitter. For newer players that completely buffer the data at high-speed from a CDROM reader to a memory buffer, this jitter is not an issue.

3. Jitter from the pits on a CD

These are the pits in the CD media that represent the recorded data. Variation in the spacing of these pits result in jitter when reading the data. Commercially CD's created from a glass-master generally have more variation in the locations of the pits than a CD-R written at 1X speed on a good CD-R writer. Even though most modern CD players have buffering of the data to create some tolerance to this jitter, there is usually a PLL (Phase-locked-loop) involved, which is still somewhat susceptible to jitter. To determine if your player is susceptible, it is a simple experiment to re-write or "clone" a CD and then listen for playback differences from the commercial version. For newer players that completely buffer the data at high-speed from a CDROM reader to a memory buffer, this jitter is not an issue.

4. S/PDIF conversion

The S/PDIF interface was created by Sony/Philips to simplify the interconnect between digital audio devices. The deficiency in this interface is that it embeds the serial clock in the serial data-stream in order to achieve one-signal cabling. A superior interface would have included both a clock and a data signal, but we don't have this, so we live with S/PDIF. The S/PDIF interface must encode the data and clock into a single signal and then at the destination recover the clock(s) from the data-stream. The process of recovering the clocks can introduce new jitter since there is usually a PLL involved.

5. Logic buffering

The digital audio data must make its way through the system over wires/traces and sometimes through buffers, such as the buffer to drive the S/PDIF cable. Each of these buffers has finite reaction times and imprecise detection of changing signal levels. What this means is that even though the signal may not have much jitter coming into the buffer, it may exit with additional jitter. This jitter is a result of the speed of the device, thermal effects on the silicon die, power delivery on the die and even transmission-line effects.

6. Power subsystem

The DC power applied to each of the devices that must process or transmit the digital audio signal is critical. If this power varies in voltage, the devices will react differently to the applied digital signals. Power "noise" as it is referred to is probably one of the largest contributors to jitter. Voltage changes or "voltage droop" can happen anywhere on a circuit board, power cabling, or even on the silicon itself. Changes in power voltage will change the speed and reaction times of digital logic that is transmitting the digital signals resulting in jitter.

7. Toslink optical conversion

Optical conversion adds another layer of buffering on both the transmitting and receiving ends of the S/PDIF interface. This additional layer in itself adds jitter, regardless of whether it is optical or not because of (5). However due to its complexity, the optical interface adds more jitter than a simple logic buffer. For that reason, it has higher jitter/lower performance than a well-designed S/PDIF coax interface.

8. Digital Cables

Cables don't actively add jitter to the signal, however they can slow the signal transitions or "edges". When the edges are slowed, the receiver or buffer at the cable destination is less likely to detect the transition at the correct time with certainty, which results in jitter.

9. Transmission-line effects

TL effects are usually more of a problem on the S/PDIF coaxial cable, but may also be present on long traces on circuit boards. These occur because the signal transition is very fast and as a result, reflections occur on the wire or trace. The signal reflections from an earlier signal transition can return to the destination and "push" or displace a later signal edge, causing jitter. TL lines must be properly terminated and impedance-matched in order to minimize reflections and the potential resulting jitter. There are steps that can be taken to minimize this effect, such as using a longer S/PDIF cable. See:

http://www.positive-feedback.com/Issue14/spdif.htm

10. Printed circuit board effects

There are at least two effects on a circuit board that can cause jitter, including signal crosstalk and ground-bounce. Crosstalk occurs when traces with high-speed signals are spaced closely. One signal induces voltage on the other signal. It is obvious how this can add to jitter. Ground-bounce occurs when the signal return current see a high-impedance on the circuit board due to ground-plane splits or long return paths. This creates a voltage drop in the ground-plane or return path. This voltage drop causes the signal to shift in voltage, which can result in jitter.

 

Wrong. The time code is embedded in the digital stream. From the article:

Uten, you need to read Ken Pohlmann's Principles of Digital Audio.

 

If I read the OP's follow-up post correctly, it's all digital in the chain until it gets to the CD player (which is the DAC). So I don't think he's using the Squeezeboxes except as conveyors, so to speak.

That said, that seems an awfully long and convoluted chain; perhaps something could go awry along the way. Personally I would look first at whether removing the wi-fi component might make a difference. I know this might cause the computer noise to be reintroduced, but perhaps you could temporarily mask it with a blanket or something in order to compare the CD sound to the FLAC sound.

Just my thoughts.

 

Basically this guy Steve Nugent is calling "jitter" any potential alteration of digital data... He could also add that if you take a hammer and you smash it on your CD player you are introducing jitter.
Does this alteration of the digital data really happen? How many bits of the original source are modified before they reach the D/A converter in a real case scenario because of all the things he mentions? Zero.

On your other comment: of course all digital equipment works with clocks. Do inaccurate clocks change the bits of digital audio while transporting it to the D/A converter? No.

Besides, your quote is wrong.. when you transfer information over USB, Firewire, etc, timing info is used in the control signals, it is not inserted in the actual data being transported. There are a lot of errors in that paper.

 

Okay Uten, it seems your mind is made up so I don't see the point in continuing.

Good day.

 

How exactly does one make jitter below the threshold of hearing? That doesn't make any sense to me.

 

Some people in this forum use "jitter" the exact same way. Take a guess why.

Thank you.

 

There are no chocolates in your boxes anymore.

 

Well so is yours. Have a good day you too.... I hope you won't have it spoiled by jitter. I know it won't spoil mine.

As a final comment: take my opinion for what is worth but that article you quoted is full of errors (by the way "digital signal processing" was in my university curriculum)

 

Especially when on one hand, you must keep a path stringently the same for an apples vs apples comparison or its not the same 1's & 0's, then this above analogy is presented. Are posters smokin crack, do they shoot up get an idea then run to the k/b. I certainly will never know all on this or other subjects, but hopefully thinking logically is not lost.

 

The mfr is minimizing timing errors via better design and parts.

 

Just to put things in perspective. The clock in your GPS receiver (cost=$3) is accurate enough to measure the delay of signals received from various satellites in the sky and on the basis of that time difference to calculate your position on the road with an error of a couple of yards.
The level of accuracy needed for a clock to avoid spoiling a stream of 300 Kbits per second containing your digital audio pales in comparison.