CD vs FLAC. Which is better?

[Dr.Bass]

The transmission of data over spdif is digital data.

Now you cannot hear the music from that sequence of 1 or 0. Transmitting that sequence of 1 and 0 over a cable does not make it analog.


The cable is probably not where you would want to throw your money at. I will spend on a DAC

If you want to insist that it is analogue, and base further discussion on that assumption, okay I concede your point. Maybe you should elaborate further on analog processing of the analog data that is transmitted (note: no quotes or rolling eyes). Another question to ask is what about streaming services like Tidal ? If transmission over cables caused things to go horribly and uncorrectably bad that should be impossible, right ?

I have never said data being transmitted is analogue. It is too elementary to even think like that. Data being conveyed is of digital domain but the transmission, which is in the form of electric charge in the SPDIF cable or a light wave in a optical cable is "analogue". Electricity and light is analog, I mean. So, if there is a error/distortion during transmission due to factors like the wrong impedance or the length of the cable, this error is an analog domain error. The receiver at the end of the cable is going to get a distorted signal and now has to interpret this into a digital data which is different from what was fed at the source. So it is an erroneous digital data in the end. The question is, what is the nature of these errors and what is the impact of these errors to the final sound we hear ?

The priorities on how much one should spend on transport - DAC - cable is a different subject. But lets be clear that no DAC is going to fix the loss happened in the transport or in the cable.

jls001 wrote: @Dr Bass, from transmission line theory, we know that matching the characteristic impedance of a transmission medium/channel (which an SPDIF cable is) to the source or the load maximises the energy transferred, and also avoids reflections. If one uses a 25 ohm cable, it creates an impedance mismatch with the 75 ohm source. It also is a mismatch to the 75 ohm load/destination. The cable will reflect a part of the energy sent by the source, back to the source. So a new waveform is created and will exist and interact with the original waveform. These waveforms will interact and inter modulate each other, thus giving rise to see third waveform. Whatever signal that manages to reach the destination is no longer the original, and to make things worse it will undergo further distortion.

Are any bits lost ?
Same question, what is the impact on the final sound ?

 

[mbhangui]

The priorities on how much one should spend on transport - DAC - cable is a different subject. But lets be clear that no DAC is going to fix the loss happened in the transport or in the cable.

Are any bits lost ?
Same question, what is the impact on the final sound ?

So there will be some error correction involved and any error correction will add some delay. For file transfers, this will not matter. But for audio signal, the waveform will get stretched (if you view it simplistically), and hence you will not have the original waveform OR we will have a portion of the audio signal lost. This will definitely cause the sound to change IMHO.

 

[jls001]

Are any bits lost ?

Yes.
If there are error correction mechanisms in place, the lost bits can be rebuilt, provided the loss isn't too bad. But beyond a point the error correction will be helpless.

Same question, what is the impact on the final sound ?

I don't know enough about SPDIF transmission protocol to comment. But I can unequivocally state that one must use a line of correct characteristic impedance to avoid the maximum power, and to achieve correct VSWR (zero reflection loses).

 

[Dr.Bass]

So there will be some error correction involved and any error correction will add some delay. For file transfers, this will not matter. But for audio signal, the waveform will get stretched (if you view it simplistically), and hence you will not have the original waveform OR we will have a portion of the audio signal lost. This will definitely cause the sound to change IMHO.

Agreed. So, music can be played even with some incorrect bits! The same is not true for a data file. Which was exactly my point.

Now let us talk about quality.
IME, cheap DACs have never been as demanding of a quality transport (CDP or Computer) as a good expensive DAC. A typical $5k sounds like too unforgiving with a DVD player as a transport, even though the DVD player in isolation (as a complete player) is still listenable. It all boils down to the resolution, which is a double edged sword.

 

[sound_cycle]

I have never said data being transmitted is analogue. It is too elementary to even think like that. Data being conveyed is of digital domain but the transmission, which is in the form of electric charge in the SPDIF cable or a light wave in a optical cable is "analogue". Electricity and light is analog, I mean. So, if there is a error/distortion during transmission due to factors like the wrong impedance or the length of the cable, this error is an analog domain error. The receiver at the end of the cable is going to get a distorted signal and now has to interpret this into a digital data which is different from what was fed at the source. So it is an erroneous digital data in the end. The question is, what is the nature of these errors and what is the impact of these errors to the final sound we hear ?

The priorities on how much one should spend on transport - DAC - cable is a different subject. But lets be clear that no DAC is going to fix the loss happened in the transport or in the cable.



Are any bits lost ?
Same question, what is the impact on the final sound ?

Ummmm, No Dr Bass. In my understanding the cable's job is to deliver a bitperfect stream. It delivers that. This is ofc testable and demonstrable.

I can't remember where I read this but the USB spec has a transit time spec which ensures that the reflection/ impedance type issues do not affect anything. Not aware of what the spdif specifies

To my mind, audio data is just another digital data type, and will not behave any differently as long as it remains digital.

We have talked of errors, jitter mostly, but also bit errors and electrical related errors. The DAC is there to take care of the first. Using optical SP/DIF takes care of the last, bit errors, what are they, missing data ? it is missing data.

What other errors should we consider ?

I have no experience, knowledge, requisite hearing acuity or necessary equipment to judge for myself whether any of these errors and their correction matters to the sound.

(I have just said above in clear clear text that in my current understanding, cables and the device responsible for providing a data stream cannot make a difference to sound. So let me hasten to add, that I don't want to be drawn into, cannot, have not and will not debate these issues)

ciao
gr

 

[Dr.Bass]

Ummmm, No Dr Bass. In my understanding the cable's job is to deliver a bitperfect stream. It delivers that. This is ofc testable and demonstrable.

I can't remember where I read this but the USB spec has a transit time spec which ensures that the reflection/ impedance type issues do not affect anything. Not aware of what the spdif specifies

To my mind, audio data is just another digital data type, and will not behave any differently as long as it remains digital.

We have talked of errors, jitter mostly, but also bit errors and electrical related errors. The DAC is there to take care of the first. Using optical SP/DIF takes care of the last, bit errors, what are they, missing data ? it is missing data.

What other errors should we consider ?

I have no experience, knowledge, requisite hearing acuity or necessary equipment to judge for myself whether any of these errors and their correction matters to the sound.

(I have just said above in clear clear text that in my current understanding, cables and the device responsible for providing a data stream cannot make a difference to sound. So let me hasten to add, that I don't want to be drawn into, cannot, have not and will not debate these issues)

ciao
gr

If you look at all my posts on this thread, barring a few, most of them would contain my real experience with these products. Today I am actually in the market for a digital playback system. I could buy a seriously good DAC but my past experience tells me I would need an equally serious digital transport and cables to make the whole thing sound unobjectionable, hence I am looking for a one box solution.

Back to the subject, according to Gordon Rankin (a guru in computer audio), USB cables needed for satisfactory audio signal transfer is rare and hence all USB cables have a different presentation (what you hear is their limitation). Same is true for SPDIF cables too, every cable sounds different. What happens to the missing bits I do not know, but it cannot be irrelevant to music reproduction.

 

[jls001]

If you want a true 75 ohms coaxial cable, just buy a Belden 1855A. It is rated for a throughput of 4 Gbps. If correctly terminated, it won't be the weak link in the chain. BTW, I use one pair between a tonearm to phono stage for its very low capacitance, and it sounds as good, if not better than any cable I've tried in this application. Cost is just 90 rupees a meter.

 

[jls001]

to avoid the maximum power

Correction: the above must read "to achieve maximum power transfer"

 

[keith_correa]

Slightly OT but not by very much. Can someone who uses a PC and Windows try this and report back if it has an effect on audio? A friend of mine living in the US says that it has a noticeable effect. https://bitsum.com/

 

[arj]

Since everyone on this thread is talking about jitter.
How does it sound like?

You know, like I know how low and high bit rate sounds like, how high and low noise floor sounds like, how high and low sampling rate sounds like etc.
But how does this low jitter vs high jitter sound like?

It's funny but jitter can make the sound more pleasing or discordant or both

In the end it is a distortion due to data being read wrong and it could go both ways. Either way it will not be "neutral"

 

[keith_correa]

Slightly OT but not by very much. Can someone who uses a PC and Windows try this and report back if it has an effect on audio? A friend of mine living in the US says that it has a noticeable effect. https://bitsum.com/

Sorry! Forgot to mention that "Process Lasso" is the software that my friend said made a difference.

 

[sound_cycle]

To me external power makes a noticeable improvement

My PC is connected to DAC/ amp via optical S/PDIF.

Now the sound is quite different depending on whether I draw power through a surge strip (through which other devices PS3, STB, LC TV, DVD player - all two pinned by the way) or from by itself a grounded power socket.

http://www.cranesong.com/A_Matter_ Of_Time_The _Audibility_Of_Clock_Jitter.pdf

Noise increases as frequency goes down, thus LF jitter is the hardest to
work with. A common example is power supply noise; in clock generation, power supply noise is more critical than for mic-pres or tape-head playback electronics​

ciao
gr

 

[mbhangui]

I have never said data being transmitted is analogue. It is too elementary to even think like that. Data being conveyed is of digital domain but the transmission, which is in the form of electric charge in the SPDIF cable or a light wave in a optical cable is "analogue". Electricity and light is analog, I mean. So, if there is a error/distortion during transmission due to factors like the wrong impedance or the length of the cable, this error is an analog domain error. The receiver at the end of the cable is going to get a distorted signal and now has to interpret this into a digital data which is different from what was fed at the source. So it is an erroneous digital data in the end. The question is, what is the nature of these errors and what is the impact of these errors to the final sound we hear ?

The priorities on how much one should spend on transport - DAC - cable is a different subject. But lets be clear that no DAC is going to fix the loss happened in the transport or in the cable.

USB was designed for transferring data. Ask it to transfer data, only data and nothing but data (plus perhaps a little power) and it will be fine. Ask it to transfer timing too and you are on your own - PCs don't do timing very well anyway as they too are intended for handling data. This week I will do two experiments

1) Insert a thin plastic strip over the outer two pins inside the usb plug which goes into the PC. The plastic strip will cover the +5v and the ground pin isolating the noisy power line which comes from the pc. This will ensure that only the data lines go to the DAC.

2) Construct my own usb cable by harvesting only the plugs from a USB cable and using cat 6 cable to extend it. Will put a switch to isolate the +5v and the ground pin at the computer end and see if there is any audible difference

NOTE: The above two methods will only work for DACS which are not powered by the USB bus

I am also toying with the idea of building a USB isolator using ADuM4160 chip. The kit (DIY) is available at $33 + shipping https://www.circuitsathome.com/products-page/usb-interfaces

Project files, including Eagle schematic and board layout, as well as Gerbers, are available from downloads section. Additionally, PDF of the schematic is available in case you dont have Eagle installed. The board can be easily made at home. It was designed using SOIC IC packages and 1206 capacitors and resistors. It is routed almost entirely over top side with two ground planes at the bottom side. I also have a smd reflow station with me and wouldn't mind doing something one of the weekends. Not sure if anyone else would be interested so that one can do a group buy, build the board here and save money on shipping/custom hassles.

Here is an article about the isolator https://www.circuitsathome.com/mcu/usb/usb-isolator

 

[reignofchaos]

USB was designed for transferring data. Ask it to transfer data, only data and nothing but data (plus perhaps a little power) and it will be fine. Ask it to transfer timing too and you are on your own - PCs don't do timing very well anyway as they too are intended for handling data. This week I will do two experiments

1) Insert a thin plastic strip over the outer two pins inside the usb plug which goes into the PC. The plastic strip will cover the +5v and the ground pin isolating the noisy power line which comes from the pc. This will ensure that only the data lines go to the DAC.

2) Construct my own usb cable by harvesting only the plugs from a USB cable and using cat 6 cable to extend it. Will put a switch to isolate the +5v and the ground pin at the computer end and see if there is any audible difference

NOTE: The above two methods will only work for DACS which are not powered by the USB bus

I am also toying with the idea of building a USB isolator using ADuM4160 chip. The kit (DIY) is available at $33 + shipping https://www.circuitsathome.com/products-page/usb-interfaces

Please do be aware that ADuM4160 does not work properly with USB Audio Class 2 devices (Nearly all async DACs). It only works with Class 1 devices. Have one sitting idle. My DAC would not handshake correctly.

If your DAC can do without +5V, simply cut that cable out or use a dual head USB cable. The latter works amazingly well if your DAC does not feed from USB +5V.

 

[mbhangui]

The priorities on how much one should spend on transport - DAC - cable is a different subject. But lets be clear that no DAC is going to fix the loss happened in the transport or in the cable.

Are any bits lost ?
Same question, what is the impact on the final sound ?

After lot of reading this is what I found. For audio, bits are lost forever.

"The USB audio protocols (synchronous, adaptive and asynchronous) are all in the isochronous category and do not provide for retransmission (unlike the bulk protocol used for printers and hdd). There is some errors check but no possibility to resend data."

When we compare digital audio transmission with file/data transfer, we forget timing is very very very important for audio. There is no point in doing error correction. Once the time is gone, the audio is changed forever. Hear a turntable running at a different speed. Hear skype audio with a bad network connection - The sound will not sound the same. For file transfer it does not matter if the bits 0s and 1s arrive few milli/micro seconds late. For audio it is just not the 0s and 1s, the timing plays a bloody damn important role. The only solution is that the DAC (not the computer) does some buffering. All the tweaking we do for ASIO, the buffering is on the host side.

 

[mbhangui]

Please do be aware that ADuM4160 does not work properly with USB Audio Class 2 devices (Nearly all async DACs). It only works with Class 1 devices. Have one sitting idle. My DAC would not handshake correctly.

If your DAC can do without +5V, simply cut that cable out or use a dual head USB cable. The latter works amazingly well if your DAC does not feed from USB +5V.

So ADuM4160 will be an experiment in futile. Thanks for saving few $$. I will just try isolating the +5v. Does not cost anything

 

[arj]

USB was designed for transferring data. Ask it to transfer data, only data and nothing but data (plus perhaps a little power) and it will be fine. Ask it to transfer timing too and you are on your own - PCs don't do timing very well anyway as they too are intended for handling data. This week I will do two experiments

1) Insert a thin plastic strip over the outer two pins inside the usb plug which goes into the PC. The plastic strip will cover the +5v and the ground pin isolating the noisy power line which comes from the pc. This will ensure that only the data lines go to the DAC.

2) Construct my own usb cable by harvesting only the plugs from a USB cable and using cat 6 cable to extend it. Will put a switch to isolate the +5v and the ground pin at the computer end and see if there is any audible difference

NOTE: The above two methods will only work for DACS which are not powered by the USB bus

I am also toying with the idea of building a USB isolator using ADuM4160 chip. The kit (DIY) is available at $33 + shipping https://www.circuitsathome.com/products-page/usb-interfaces

Project files, including Eagle schematic and board layout, as well as Gerbers, are available from downloads section. Additionally, PDF of the schematic is available in case you dont have Eagle installed. The board can be easily made at home. It was designed using SOIC IC packages and 1206 capacitors and resistors. It is routed almost entirely over top side with two ground planes at the bottom side. I also have a smd reflow station with me and wouldn't mind doing something one of the weekends. Not sure if anyone else would be interested so that one can do a group buy, build the board here and save money on shipping/custom hassles.

Here is an article about the isolator https://www.circuitsathome.com/mcu/usb/usb-isolator

I remember a conversation with Siva of Acoustic Portrait where he mentioned that in his experiments as well, cutting out the +5v line from the cable and giving it as a separate power gave a huge improvement in sound.

 

[shailenderb]

Sorry! Forgot to mention that "Process Lasso" is the software that my friend said made a difference.

For those interested, this is available for free for the next 22 hours or so. Try this link and follow instructions.

Giveaway of the Day - free licensed software daily. Today: Process Lasso Pro 8.1 - Process Lasso is a process priority optimization and system automation utility. It provides a ProBalance Technology, which restarts CPU hogs ...

Regds

 

[manniraj]

A new USB filter has been launched by AudioQuest company for $49.

 

[pakecc]

Saregama is selling songs in losslees format ( wav file) as well as compressed mp3 format in their web site for online download. Now the thing is, the lossless song each cost @50 rs and MP3 @ 9 Rs. And a MP3 album having 6 to 9 cost cost 50 to 75 rs only whereas you do not have the option for purchasing the full album in loseless format. In such case, say a movie with 6 songs will cost 300 rs for downloading in wav format and if the same is purchased as CD, say max at 120 Rs. This is apart from your internet data usage of say 300 mb for 6 songs)

Now what I really do not understand is why the CD itself is cost less and wav format is more when there should be no diff. in CD and WAV's SQ. Is the quality have anything to do here. I plan to purchase 2 or 3 songs in wav format and compare the same with my CD.

Regards