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Digital transport brawler

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Strictly Stereo

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Jan 29, 2018
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Andrewjvt said:
Then surely a photo would not print correctly Or a video on Netflix would make mistakes? It's all data at the end of the day?

Are music files so complex/temperamental that they need special treatment.

What else in industry/science etc suffers the same problems as music files?

As it's all data surely there will be other examples.

If it's only music files then we need to ask, why?
We need to distinguish between files and streams.

Files (FLAC, WAV, XLS etc) can be reliably moved from one place to another using commonplace technologies which detect and also correct errors. So when you transfer a file across your home network, the file is split into packets and the TCP protocol ensures that all of the packets arrive at the receiving end or an error is reported. USB has a mode which works in a similar manner, so when you save your spreadsheet to a USB drive, you can be confident that either the data will be successfully saved or you will receive an error message.

Streaming music from services like TIDAL works in much the same way as transferring files. When TCP is used and a packet is lost in transit, the streamer will ask the server to retransmit that packet. Obviously, if this happens part way through a song, the streamer and server have a limited time window in which to correct the error. Most streamers and software players use a buffer to cope with such eventualities. If the buffer empties completely, the output will normally be muted until some more data arrives.

A digital transport will typically output audio streams such as PCM or DSD sent via S/PDIF, AES and USB audio for conversion by a DAC. This is markedly different from transferring a file or streaming from an Internet service. These streams do not include error correction. Reconstructing the original analogue waveform from these streams depends on more than just having the bits arrive in the right order. The timing of the bits is crucial too. These streams are essentially just a continuous series of samples. The timing of the samples is determined by the rate at which they arrive. Variations in the timing (aka jitter) lead to corresponding variations in the analogue waveform. In modern systems there are various schemes employed to minimise jitter or recover an accurately timed signal from a jittery input signal, but every DAC I know of will have an easier time working on a low jitter input signal.

There are probably other variables in play too. Digital signals are ultimately transmitted between and within devices as voltage changes. The speed with which devices can switch voltage and conceivably also any noise present in these essentially analogue waveforms, might affect the ability of the receiving end to accurately recover the original digital signal and timing. There is quite a good primer here...

http://www.thewelltemperedcomputer.com/KB/BitPerfectJitter.htm
 

Andrewjvt

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Jun 18, 2014
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Strictly Stereo said:
Andrewjvt said:
 

Then surely a photo would not print correctly Or a video on Netflix would make mistakes? It's all data at the end of the day?

Are music files so complex/temperamental that they need special treatment.

What else in industry/science etc suffers the same problems as music files?

As it's all data surely there will be other examples.

If it's only music files then we need to ask, why?
We need to distinguish between files and streams.

Files (FLAC, WAV, XLS etc) can be reliably moved from one place to another using commonplace technologies which detect and also correct errors. So when you transfer a file across your home network, the file is split into packets and the TCP protocol ensures that all of the packets arrive at the receiving end or an error is reported. USB has a mode which works in a similar manner, so when you save your spreadsheet to a USB drive, you can be confident that either the data will be successfully saved or you will receive an error message.

Streaming music from services like TIDAL works in much the same way as transferring files. When TCP is used and a packet is lost in transit, the streamer will ask the server to retransmit that packet. Obviously, if this happens part way through a song, the streamer and server have a limited time window in which to correct the error. Most streamers and software players use a buffer to cope with such eventualities. If the buffer empties completely, the output will normally be muted until some more data arrives. 

A digital transport will typically output audio streams such as PCM or DSD sent via S/PDIF, AES and USB audio for conversion by a DAC. This is markedly different from transferring a file or streaming from an Internet service. These streams do not include error correction. Reconstructing the original analogue waveform from these streams depends on more than just having the bits arrive in the right order. The timing of the bits is crucial too. These streams are essentially just a continuous series of samples. The timing of the samples is determined by the rate at which they arrive. Variations in the timing (aka jitter) lead to corresponding variations in the analogue waveform. In modern systems there are various schemes employed to minimise jitter or recover an accurately timed signal from a jittery input signal, but every DAC I know of will have an easier time working on a low jitter input signal. 

There are probably other variables in play too. Digital signals are ultimately transmitted between and within devices as voltage changes. The speed with which devices can switch voltage and conceivably also any noise present in these essentially analogue waveforms, might affect the ability of the receiving end to accurately recover the original digital signal and timing. There is quite a good primer here...

http://www.thewelltemperedcomputer.com/KB/BitPerfectJitter.htm
So I needed to be clearer.
This topic has nothing to do with music streaming services or tidal/Spotify etc.

Just to be clear we are talking about digital transport of local stored music files and to keep it even more simple all in original resolution.

Let's also presume we all own the same dac.

So having said all that how can a digital transport change the sound quality by going up the range?

I've used the innous products as an example.
 

Andrewjvt

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From David: the data(bits) need to be preserved.

My question
What would be the audio result of degraded data?

From s strereo
The speed in which the voltages can switch on and off will effect the timing of the signal

My question
What the hell is the DACs job?

You also mentioned for local file transfer from hhd there should be no issue from the transport

Please confirm

From Ellis:
Room acoustics is most important.

Yes I agree on acoustics
But you've been saying how large the difference is in same room/speaker/amp combo with the transport.
But no technical reasons as to why this can be.

Cno:
Yes I agree in testing products over a time to fully understand a product..
In fact I've been demoing the same brand of speakers now in lots of different scenarios over the last 2 years.

But what's triggered me is all these quick demos and the night and day clear winner comments.
 

Strictly Stereo

Well-known member
Jan 29, 2018
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Andrewjvt said:
From David: the data(bits) need to be preserved.

My question What would be the audio result of degraded data?

From s strereo The speed in which the voltages can switch on and off will effect the timing of the signal

My question What the hell is the DACs job?

You also mentioned for local file transfer from hhd there should be no issue from the transport

Please confirm

From Ellis: Room acoustics is most important.

Yes I agree on acoustics But you've been saying how large the difference is in same room/speaker/amp combo with the transport. But no technical reasons as to why this can be.

Cno: Yes I agree in testing products over a time to fully understand a product.. In fact I've been demoing the same brand of speakers now in lots of different scenarios over the last 2 years.

But what's triggered me is all these quick demos and the night and day clear winner comments.
Respectfully, that is not what I wrote.
 

Strictly Stereo

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Jan 29, 2018
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Andrewjvt said:
So I needed to be clearer. This topic has nothing to do with music streaming services or tidal/Spotify etc.

Just to be clear we are talking about digital transport of local stored music files and to keep it even more simple all in original resolution.

Let's also presume we all own the same dac.

So having said all that how can a digital transport change the sound quality by going up the range?

I've used the innous products as an example.
DACs typically deal with streams rather than files. See my original answer for an explanation of the difference and the dependancy this places on the clocking of the bits. An Innuos transport connected to a DAC via USB is sending a stream rather than files. This stream is a series of samples in a precise order at precise intervals. It is the combination of both the bits (the samples) and the timing (the sample rate) which allows the DAC to accurately reconstruct the original analogue waveform.

In the case of the Innuos products, whilst the software is the same on all models, you get a variety of hardware enhancements and quality improvements as you move up the range. You can find the specs at Innuos or on my website.
 

Andrewjvt

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insider9 said:
Have you watched the YouTube vid I linked?
I've seen loads of his videos

He starts off talking sense then goes on a tangent.

But his main point I agree with in that the sound quality will depend on the quality of the dac.

So now we all have the best dac in the world how can the transport effect the sound of the dac is arranging the conversion with no audible jitter.
How can a transport improve the sound.
 

Andrewjvt

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Nothing is more revealing than a good set of headphones and a top class dac.

No-one needs a £45000 system to notice these changes
 

Andrewjvt

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Jun 18, 2014
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Strictly Stereo said:
Andrewjvt said:
So I needed to be clearer. This topic has nothing to do with music streaming services or tidal/Spotify etc.

Just to be clear we are talking about digital transport of local stored music files and to keep it even more simple all in original resolution.

Let's also presume we all own the same dac.

So having said all that how can a digital transport change the sound quality by going up the range?

I've used the innous products as an example.
DACs typically deal with streams rather than files. See my original answer for an explanation of the difference and the dependancy this places on the clocking of the bits. An Innuos transport connected to a DAC via USB is sending a stream rather than files. This stream is a series of samples in a precise order at precise intervals. It is the combination of both the bits (the samples) and the timing (the sample rate) which allows the DAC to accurately reconstruct the original analogue waveform.

In the case of the Innuos products, whilst the software is the same on all models, you get a variety of hardware enhancements and quality improvements as you move up the range. You can find the specs at Innuos or on my website.
So if your dac is very good at doing its job and has no audible jitter from a cheap laptop
What would be the sound quality upgrade from a mini to a zennith statement top of the range

Please describe what the listener will start to experience as he climbs up the innous ladder?
 

Strictly Stereo

Well-known member
Jan 29, 2018
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Andrewjvt said:
Strictly Stereo said:
Andrewjvt said:
So I needed to be clearer. This topic has nothing to do with music streaming services or tidal/Spotify etc.

Just to be clear we are talking about digital transport of local stored music files and to keep it even more simple all in original resolution.

Let's also presume we all own the same dac.

So having said all that how can a digital transport change the sound quality by going up the range?

I've used the innous products as an example.
DACs typically deal with streams rather than files. See my original answer for an explanation of the difference and the dependancy this places on the clocking of the bits. An Innuos transport connected to a DAC via USB is sending a stream rather than files. This stream is a series of samples in a precise order at precise intervals. It is the combination of both the bits (the samples) and the timing (the sample rate) which allows the DAC to accurately reconstruct the original analogue waveform.

In the case of the Innuos products, whilst the software is the same on all models, you get a variety of hardware enhancements and quality improvements as you move up the range. You can find the specs at Innuos or on my website.
So if your dac is very good at doing its job and has no audible jitter from a cheap laptop What would be the sound quality upgrade from a mini to a zennith statement top of the range

Please describe what the listener will start to experience as he climbs up the innous ladder?
That rather depends on the DAC and how its USB input operates. What DAC are we discussing here?

What makes you think that your laptop has no audible jitter? It may not be obvious, except by comparing it to a low jitter source. Even then, other limitations in the system might conceal the differences. Jitter in a digital bitstream leads to tiny inaccuracies in the reconstructed analogue waveform, which is essentially a form of distortion. This would translate as qualitative differences like tonal accuracy or naturalness, rather than something obvious like hum, hiss or breaks in playback. You can certainly measure jitter. A typical laptop will have much higher levels of jitter than an Innuos Zenith and the Zenith Statement promises even better performance, but the only way to tell if the differences are audible is to listen to them.

Other variables might also impact how effectively a DAC can handle the input signal, but I picked out jitter specifically because it cuts across the "bits are bits" argument and the science is thoroughly understood. It underpins PCM and DSD sampling theory.
 

Andrewjvt

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Jun 18, 2014
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Strictly Stereo said:
Andrewjvt said:
Strictly Stereo said:
Andrewjvt said:
So I needed to be clearer. This topic has nothing to do with music streaming services or tidal/Spotify etc.

Just to be clear we are talking about digital transport of local stored music files and to keep it even more simple all in original resolution.

Let's also presume we all own the same dac.

So having said all that how can a digital transport change the sound quality by going up the range?

I've used the innous products as an example.
DACs typically deal with streams rather than files. See my original answer for an explanation of the difference and the dependancy this places on the clocking of the bits. An Innuos transport connected to a DAC via USB is sending a stream rather than files. This stream is a series of samples in a precise order at precise intervals. It is the combination of both the bits (the samples) and the timing (the sample rate) which allows the DAC to accurately reconstruct the original analogue waveform.

In the case of the Innuos products, whilst the software is the same on all models, you get a variety of hardware enhancements and quality improvements as you move up the range. You can find the specs at Innuos or on my website.
So if your dac is very good at doing its job and has no audible jitter from a cheap laptop What would be the sound quality upgrade from a mini to a zennith statement top of the range

Please describe what the listener will start to experience as he climbs up the innous ladder?
That rather depends on the DAC and how its USB input operates. What DAC are we discussing here?

What makes you think that your laptop has no audible jitter? It may not be obvious, except by comparing it to a low jitter source. Even then, other limitations in the system might conceal the differences. Jitter in a digital bitstream leads to tiny inaccuracies in the reconstructed analogue waveform, which is essentially a form of distortion. This would translate as qualitative differences like tonal accuracy or naturalness, rather than something obvious like hum, hiss or breaks in playback. You can certainly measure jitter. A typical laptop will have much higher levels of jitter than an Innuos Zenith and the Zenith Statement promises even better performance, but the only way to tell if the differences are audible is to listen to them.

Other variables might also impact how effectively a DAC can handle the input signal, but I picked out jitter specifically because it cuts across the "bits are bits" argument and the science is thoroughly understood. It underpins PCM and DSD sampling theory.
Let's assume we all have the same dac and it's one of the best.
Fyi: my dac is a benchmark dac3 and when on the test bench by reviewers they concluded using a Nas drive and cd transport that there was zero jitter in the audible spectrum using that dac.

But this thread is not to be side tracked by which dac is best.

Let's assume we all have the same dac and it's the best in business.
Can a digital transport cause it to have distortion/jitter?

Could any of these differences in sound you describe be measured as proof that the better transport produces better sound?
 

nopiano

Well-known member
Feb 15, 2009
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Andrewjvt said:
Strictly Stereo said:
Andrewjvt said:
Strictly Stereo said:
Andrewjvt said:
So I needed to be clearer. This topic has nothing to do with music streaming services or tidal/Spotify etc.

Just to be clear we are talking about digital transport of local stored music files and to keep it even more simple all in original resolution.

Let's also presume we all own the same dac.

So having said all that how can a digital transport change the sound quality by going up the range?

I've used the innous products as an example.
DACs typically deal with streams rather than files. See my original answer for an explanation of the difference and the dependancy this places on the clocking of the bits. An Innuos transport connected to a DAC via USB is sending a stream rather than files. This stream is a series of samples in a precise order at precise intervals. It is the combination of both the bits (the samples) and the timing (the sample rate) which allows the DAC to accurately reconstruct the original analogue waveform.

In the case of the Innuos products, whilst the software is the same on all models, you get a variety of hardware enhancements and quality improvements as you move up the range. You can find the specs at Innuos or on my website.
So if your dac is very good at doing its job and has no audible jitter from a cheap laptop What would be the sound quality upgrade from a mini to a zennith statement top of the range

Please describe what the listener will start to experience as he climbs up the innous ladder?
That rather depends on the DAC and how its USB input operates. What DAC are we discussing here?

What makes you think that your laptop has no audible jitter? It may not be obvious, except by comparing it to a low jitter source. Even then, other limitations in the system might conceal the differences. Jitter in a digital bitstream leads to tiny inaccuracies in the reconstructed analogue waveform, which is essentially a form of distortion. This would translate as qualitative differences like tonal accuracy or naturalness, rather than something obvious like hum, hiss or breaks in playback. You can certainly measure jitter. A typical laptop will have much higher levels of jitter than an Innuos Zenith and the Zenith Statement promises even better performance, but the only way to tell if the differences are audible is to listen to them.

Other variables might also impact how effectively a DAC can handle the input signal, but I picked out jitter specifically because it cuts across the "bits are bits" argument and the science is thoroughly understood. It underpins PCM and DSD sampling theory.
Let's assume we all have the same dac and it's one of the best. Fyi: my dac is a benchmark dac3 and when on the test bench by reviewers they concluded using a Nas drive and cd transport that there was zero jitter in the audible spectrum using that dac.

But this thread is not to be side tracked by which dac is best.

Let's assume we all have the same dac and it's the best in business. Can a digital transport cause it to have distortion/jitter?

Could any of these differences in sound you describe be measured as proof that the better transport produces better sound?
Hi Andrew

That Aurender server review I linked on Mac’s Zenith thread (repeated below) covers similar ground to S Stereo’s point. They played the same music down the same cable to the same DAC, a Chord as it happens. The CD player source wasn’t as good as the Aurender. As you noted, there are some differences in noise that were measured, but I agree it’s hard to be believe they would make the difference.

http://www.moremusic.nl/reviews/aurender/Aurender_S10_hifi_news.pdf

Quite a few folks say that FLAC and WAV files sound different, and that hard disks sound different to solid state ones. I’m pretty sure I’ve read that the activity on a ssd makes it wear out when used for music! It’s all a bit beyond my ken, I’m afraid.
 

Andrewjvt

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For a demo of laptop v cheap transport v fancy transport?

For one minute I'll agree that my asynchronous dac is dependent on a quality stream of data to perform well.
I'm up for a test of various products.
Best guy I can think of is David as he's the closest and has convert/innous and bluesound
Oh and also electro stuff.

Perhaps we can arrange this some time
I'd like to come over and check your place out anyway.
Are you up for it?

Right now I'm really enjoying my headphones and crappy laptop with my roon trial.
Funny it's the recordings that make the biggest difference to the playback enjoyment imo
 

Andrewjvt

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Jun 18, 2014
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Strictly Stereo said:
Andrewjvt said:
Let's assume we all have the same dac and it's one of the best. Fyi: my dac is a benchmark dac3 and when on the test bench by reviewers they concluded using a Nas drive and cd transport that there was zero jitter in the audible spectrum using that dac.

But this thread is not to be side tracked by which dac is best.

Let's assume we all have the same dac and it's the best in business. Can a digital transport cause it to have distortion/jitter?
Jitter can be introduced during playback by the transport or by the DAC itself. Just to throw in a curveball, you can also have jitter embedded in an audio track during production. This can be introduced at the recording or mastering stages during an AD or DA conversion. Neither the transport nor the DAC can do anything about that during playback.

If there is jitter in the input signal and the DAC is unable to correct it sufficiently then yes you will have distortion. Whether or not it is audible depends on a variety of factors, as previously discussed. I have no idea on what basis the reviewers concluded that there was no audible jitter using the Benchmark DAC 3. What CD transport were they using as a source? I expect that the reviewers used a good quality transport with a low noise, low jitter output, in order to get the best from the DAC. Certainly I would not expect a DAC of this quality to introduce significant jitter. On that basis, I would expect it to give good results with a low jitter source. However, I have no idea how effective it is at cleaning up jittery input signals. Some DACs are better at this than others.
I've never noticed any difference in sound quality regardless of source
Blu-ray digital out
TV digital out
Laptop usb

Only the level in the TV is much lower for some reason.

I'm going to do some real time demos now taking everything on board that's been said.
 

Strictly Stereo

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Jan 29, 2018
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Andrewjvt said:
Let's assume we all have the same dac and it's one of the best. Fyi: my dac is a benchmark dac3 and when on the test bench by reviewers they concluded using a Nas drive and cd transport that there was zero jitter in the audible spectrum using that dac.

But this thread is not to be side tracked by which dac is best.

Let's assume we all have the same dac and it's the best in business. Can a digital transport cause it to have distortion/jitter?
Jitter can be introduced during playback by the transport or by the DAC itself. Just to throw in a curveball, you can also have jitter embedded in an audio track during production. This can be introduced at the recording or mastering stages during an AD or DA conversion. Neither the transport nor the DAC can do anything about that during playback.

If there is jitter in the input signal and the DAC is unable to correct it sufficiently then yes you will have distortion. Whether or not it is audible depends on a variety of factors, as previously discussed. I have no idea on what basis the reviewers concluded that there was no audible jitter using the Benchmark DAC 3. What CD transport were they using as a source? I expect that the reviewers used a good quality transport with a low noise, low jitter output, in order to get the best from the DAC. Certainly I would not expect a DAC of this quality to introduce significant jitter. On that basis, I would expect it to give good results with a low jitter source. However, I have no idea how effective it is at cleaning up jittery input signals. Some DACs are better at this than others. I assume that the DAC 3 was connected to the reviewer's NAS drive via asynchronous USB, in which case the clock inside the DAC controls the flow of data from the source.
 

nopiano

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Feb 15, 2009
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Andrewjvt said:
For a demo of laptop v cheap transport v fancy transport?

For one minute I'll agree that my asynchronous dac is dependent on a quality stream of data to perform well. I'm up for a test of various products. Best guy I can think of is David as he's the closest and has convert/innous and bluesound Oh and also electro stuff.

Perhaps we can arrange this some time I'd like to come over and check your place out anyway. Are you up for it?

Right now I'm really enjoying my headphones and crappy laptop with my roon trial. Funny it's the recordings that make the biggest difference to the playback enjoyment imo
I am, and I could make it to Brum.

(And I’ve got to decide if my streamed digits from Qobuz sound better on my newly acquired Sneaky DS than on the Chromecast that cost a fraction of the price!)
 

Strictly Stereo

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Andrewjvt said:
I've never noticed any difference in sound quality regardless of source Blu-ray digital out TV digital out Laptop usb

Only the level in the TV is much lower for some reason.

I'm going to do some real time demos now taking everything on board that's been said.
You are welcome to come and try some alternatives here.
 

Gazzip

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Andrewjvt said:
davidf said:
I don’t know, I’ve never researched that, as I presume manufacturers have done all that when designing the products they do. I just go by my experiences,
Then surely a photo would not print correctly Or a video on Netflix would make mistakes? It's all data at the end of the day?

Are music files so complex/temperamental that they need special treatment.

What else in industry/science etc suffers the same problems as music files?

As it's all data surely there will be other examples.

If it's only music files then we need to ask, why?
I was watching Netflix yesterday (Breaking Bad. I know I’m a bit behind) and the signal broke up, leaving pixelation across the screen. Still perfectly watchable, but not the full, perfect picture I would have expected, and I obviously didn’t see everything I was supposed to. However I still understood and enjoyed it. How so different for Audio?
 

andyjm

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Andrewjvt said:
So I'll start

How on earth do we turn 1s and 0s into super audiophile music files.

Before you stick a video with music playing on a very good system as proof I'll just say now that when I watch these videos with the change of equipment prompt and the explaining of what to listen for I also hear a difference.

When I listen blind I can't.
Things that matter for digital audio playback:

1. The right sample

2. Moving to the next sample at the right time

3. Turning the samples into an analogue voltage

4. Filtering the series of analogue voltages to produce the correct waveform

5. Buffering the analogue waveform to drive the next device in the chain

The miracle of modern digital electronics (and it is a miracle) is that you don't have to worry about (1). You can send billions of bits around the world in no time and have no errors at all. Whether because of error correction or error free links, I know of no DAC that stuffs-up the underlying sample data.

Timing is more of an issue (2). The right sample at the wrong time is just as bad as the wrong sample at the right time. Think of a piece of graphpaper, and imagine plotting the audio samples to display the waveform. The Y coordinates are the samples, but the X coordinates are assumed - the regular ticking of the clock. If the X scale on the graphpaper was irregular, then the plotted waveform would be distorted. The same is true of audio. You need a regular (low jitter) clock to get it right. How regular is open to question, but this is the first thing that COULD make DACs sound different.

Turning the sample into an analogue voltage of the right level (3) is clearly key, but these days the D2A converter chips are (like error free data transmission) miracles of engineering. With analogue, anything and everything makes a difference, but the specs of the market leading D2A converter chips are so good that I would be very surprised if it is possible to tell one chip from another.

Filters are a black art, and filtering the 'staircase' output (4) of the D2A chip is a key step in the chain. The original redbook spec specified a sample rate of 44.1KHz. I won't go into the maths, but if the maximum frequency in the signal to be sampled is 20KHz, then ideally you need to have a filter that is flat to 20KHz, has constant phase delay from 0Hz to 20KHz and passes no signal from 22KHz and above. This ideal filter doesn't exist, so the compromises in the design of this 'reconstitution filter' can make DACs sound different. If there was an argument for high sample rates, it is to give the designer of this filter an easier time. Modern DACs use fancy DSP tricks to get around these problems, but it is possible that these different oversampling and noise shaping techniques may be detectable.

Finally, the output buffer (5). Again, being analogue, anything and everthing can make a difference, but buffer stages have been around for ever - so while a bad design could stuff up a DAC I would be surprised if differences in the output stage of a DAC would be detectable.

Sorry for the length of the post. In summary, the most likely candidates for DACs sounding different (if indeed they do) is the stability of the clock used to drive the D2A converter chip, and the design and methodology around the reconstitution filter.

Edit: I probably should have added that stuff like clean supply rails, proper shielding and so on could effect the quality of the output, but that is true of any piece of audio equipment.
 

Andrewjvt

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andyjm said:
Andrewjvt said:
So I'll start

How on earth do we turn 1s and 0s into super audiophile music files.

Before you stick a video with music playing on a very good system as proof I'll just say now that when I watch these videos with the change of equipment prompt and the explaining of what to listen for I also hear a difference.

When I listen blind I can't.
Things that matter for digital audio playback:

1. The right sample

2. Moving to the next sample at the right time

3. Turning the samples into an analogue voltage

4. Filtering the series of analogue voltages to produce the correct waveform

5. Buffering the analogue waveform to drive the next device in the chain

The miracle of modern digital electronics (and it is a miracle) is that you don't have to worry about (1).  You can send billions of bits around the world in no time and have no errors at all. Whether because of error correction or error free links, I know of no DAC that stuffs-up the underlying sample data.

Timing is more of an issue (2).  The right sample at the wrong time is just as bad as the wrong sample at the right time. Think of a piece of graphpaper, and imagine plotting the audio samples to display the waveform.  The Y coordinates are the samples, but the X coordinates are assumed - the regular ticking of the clock.  If the X scale on the graphpaper was irregular, then the plotted waveform would be distorted.  The same is true of audio.  You need a regular (low jitter) clock to get it right. How regular is open to question, but this is the first thing that COULD make DACs sound different.

Turning the sample into an analogue voltage of the right level (3) is clearly key, but these days the D2A converter chips are (like error free data transmission) miracles of engineering. With analogue, anything and everything makes a difference, but the specs of the market leading D2A converter chips are so good that I would be very surprised if it is possible to tell one chip from another. 

Filters are a black art, and filtering the 'staircase' output (4) of the D2A chip is a key step in the chain.  The original redbook spec specified a sample rate of 44.1KHz.  I won't go into the maths, but if the maximum frequency in the signal to be sampled is 20KHz, then ideally you need to have a filter that is flat to 20KHz, has constant phase delay from 0Hz to 20KHz and passes no signal from 22KHz and above.  This ideal filter doesn't exist, so the compromises in the design of this 'reconstitution filter' can make DACs sound different.  If there was an argument for high sample rates, it is to give the designer of this filter an easier time. Modern DACs use fancy DSP tricks to get around these problems, but it is possible that these different oversampling and noise shaping techniques may be detectable.

Finally, the output buffer (5). Again, being analogue, anything and everthing can make a difference, but buffer stages have been around for ever - so while a bad design could stuff up a DAC I would be surprised if differences in the output stage of a DAC would be detectable.

Sorry for the length of the post. In summary, the most likely candidates for DACs sounding different (if indeed they do) is the stability of the clock used to drive the D2A converter chip, and the design and methodology around the reconstitution filter. 

Edit:  I probably should have added that stuff like clean supply rails, proper shielding and so on could effect the quality of the output, but that is true of any piece of audio equipment.
Thanks
So presuming we all have the same dac that is very very good

In your opinion does the digital transport (laptop, auralic, innous etc)
Effect the sound quality seems it just sends the info to the dac?
 

Andrewjvt

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Gazzip said:
Andrewjvt said:
davidf said:
I don’t know, I’ve never researched that, as I presume manufacturers have done all that when designing the products they do. I just go by my experiences, 
Then surely a photo would not print correctly Or a video on Netflix would make mistakes? It's all data at the end of the day?

Are music files so complex/temperamental that they need special treatment.

What else in industry/science etc suffers the same problems as music files?

As it's all data surely there will be other examples.

If it's only music files then we need to ask, why?
I was watching Netflix yesterday (Breaking Bad. I know I’m a bit behind) and the signal broke up, leaving pixelation across the screen. Still perfectly watchable, but not the full, perfect picture I would have expected, and I obviously didn’t see everything I was supposed to. However I still understood and enjoyed it. How so different for Audio?
We already covered this
And I don't think any of us stream music from Netflix.

We are talking about the validity or snake oil of expensive digital transports over cheap ones

We all have best dac/speakers/amp
 

nopiano

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Feb 15, 2009
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I mentioned Melco before, and their explanation of the difference their gear makes is at the bottom of the page I’ve linked here. A good little graphic.

They are the firm who got rich through computer switching, but the audiophile boss wanted something better than a PC for his Hi-Fi. So, like you do, he made it!

https://www.melco-audio.com
 

andyjm

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Andrewjvt said:
Thanks So presuming we all have the same dac that is very very good

In your opinion does the digital transport (laptop, auralic, innous etc) Effect the sound quality seems it just sends the info to the dac?
Like all things, it depends. It would be a safe assumption that the data received by the DAC will be identical no matter the transport - unless the software on the transport is messing with it (I believe both WIndows and Linux varients will do this unless properly configured).

If your DAC is extracting its clock from the input stream, then it could be subject to the quality of the clock in the transport, but frankly if this is the case you should buy another DAC. There is no reason these days to slave a DAC to the clock on the input stream, and if yours does, I don't think it belongs in the 'Audiophile' category.

It is possible that you are getting more than you bargained for from the transport. Noisy supply rails in the transport may export themselves along the common ground connection to the DAC, although any decent DAC should be able to filter this out. Toslink gets around this problem, but comes with its own catalogue of issues.

Were I in the DAC business, I would use async USB, with galvanic isolation at the DAC. In this case, I would be 100% sure that all transports (from a RasPi to a £10,000 audiophool system) would sound the same (subject to my comments about Windows /Linux).
 

Andrewjvt

New member
Jun 18, 2014
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andyjm said:
Andrewjvt said:
Thanks So presuming we all have the same dac that is very very good

In your opinion does the digital transport (laptop, auralic, innous etc) Effect the sound quality seems it just sends the info to the dac?
Like all things, it depends.  It would be a safe assumption that the data received by the DAC will be identical no matter the transport - unless the software on the transport is messing with it (I believe both WIndows and Linux varients will do this unless properly configured).

If your DAC is extracting its clock from the input stream, then it could be subject to the quality of the clock in the transport, but frankly if this is the case you should buy another DAC. There is no reason these days to slave a DAC to the clock on the input stream, and if yours does, I don't think it belongs in the 'Audiophile' category.

It is possible that you are getting more than you bargained for from the transport.  Noisy supply rails in the transport may export themselves along the common ground connection to the DAC, although any decent DAC should be able to filter this out.  Toslink gets around this problem, but comes with its own catalogue of issues.

Were I in the DAC business, I would use async USB, with galvanic isolation at the DAC.  In this case, I would be 100% sure that all transports (from a RasPi to a £10,000 audiophool system) would sound the same (subject to my comments about Windows /Linux).
Ok that's my thinking also
As these transports are getting more and more ridiculous cost.
Now they come in 3 different boxes even.

I'm still going to Do a test for myself as a doubter and also see the logic of the data stream timming but can't see how a very good separate cheap zen mini can't produce sufficient quality data stream for the dac to produce Max sound quality.
 

Andrewjvt

New member
Jun 18, 2014
99
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nopiano said:
I mentioned Melco before, and their explanation of the difference their gear makes is at the bottom of the page I’ve linked here.  A good little graphic.

They are the firm who got rich through computer switching, but the audiophile boss wanted something better than a PC for his Hi-Fi. So, like you do, he made it! 

https://www.melco-audio.com
I'll have a read later
 

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