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Old 6th January 2007, 09:13 PM   #1
gabrielbecheanu is offline gabrielbecheanu  Romania
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Default digital experiment

Hi
A few weeks ago i start an experiment. I rip a cd with excellent recordings, I resample the file at 176.4 KHz with Wavelab and after that I burn the result on a DVD with Diskwelder crome, the result a DVD audio with 16bit 176.4 kHz LPCM information.
I play the result on a budget DVD Player like Panasonic S52 an the result was fabulous. A beautiful sound on budget equipment. The sound was different more clearly, the instruments more distinctly, more natural.
The system that i have at home and listen the experiments
Amp Onkyo A 8870, DVD player Panasonic S52, CD Player Sony CDP 515, Speakers JBL ATX 60, interconnect Ixos and speaker cable Ralcable Bimetal 4mm.

Question.
Is this a good way to listen music on budget equipment? These procedures make the same thing that expansive cd players do? The result is near to a good cd player?

I want to do something else now. I want to find a decent DAC and try to listen again the result of the experiment.

If some one tries the same experiment and have some good result or knowledge to share, please type on this post.

Have a nice weekend
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Old 7th January 2007, 12:45 AM   #2
FastEddy is offline FastEddy  United States
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Well, it is a good enough way to "uncompress" the over all headroom of the compressed CD files ... 44k uncompressed to 176k ... basically "undoing" the work of the publishers' mix down engineer to some extent.

Your results will of course be determined by the level of quality of the original ... sometimes the results will be very nice indeed, sometimes not ... I would speculate that vocals and acoustic instruments would show improvements, overly compressed electrified (and possibly distorted) instruments = not.

Try it on an album of acoustic music that is obviously degraded by the mix down process ... example: Eric Clapton's "Me and Mr. Johnson" is overly compressed acoustic guitar and vocals to the point of (possibly deliberate) introduction of distorted and clipped information === maybe this CD is beyond help ... maybe not.



" a decent DAC " ... IMOP would be a DAC capable of multi-channel 24bit / 192k (or 96k x 4 channels) ... something not normally found in USB connected devices, but there are some that can do it. A bi-directional (record & playback) device like this would do it ... http://www.m-audio.com/products/en_u...Solo-main.html ... or this: http://www.m-audio.com/products/en_u...kPro-main.html ... or this: http://rolandus.com/products/product...1&ParentId=114 ... the idea here is to rip and play 24 bit audio capable of putting the DVD-Audio and DVD player scenario to its full potential.
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Old 7th January 2007, 10:46 AM   #3
Glassman is offline Glassman  Europe
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What you actually do is to substitute the oversampling filter integrated in the D/A converter chip itself with a much better one processed offline on a computer. No wonder it sounds much better. Cheap players use cheap DACs with horrible digital filters, expensive players use, well, the best DACs market has to offer with mediocre digital filters. More info here.
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Old 7th January 2007, 11:27 AM   #4
Extreme_Boky is online now Extreme_Boky
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You have introduces a lot of jitter by ripping, upsampling, burning the DVD, and playing "the original information" back on a cheap DVD Player - and you liked the sound: rounded, layed-back, "more analog-like".

A bit of jitter here and there (at correct spectrum) can do “wonders”...

Boky
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Old 7th January 2007, 11:35 AM   #5
lucpes is offline lucpes  Romania
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http://www.audiokit.ro/dac_rd2.html

And also read the http://www.hi-fi.ro/ forum

Hai noroc
__________________
We should no more let numbers define audio quality than we would let chemical analysis be the arbiter of fine wines. Measurements can provide a measure of insight, but are no substitute for human judgment. Nelson Pass
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Old 7th January 2007, 12:03 PM   #6
Glassman is offline Glassman  Europe
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Quote:
Originally posted by Extreme_Boky
You have introduces a lot of jitter by ripping, upsampling, burning the DVD, and playing "the original information" back on a cheap DVD Player - and you liked the sound: rounded, layed-back, "more analog-like".

A bit of jitter here and there (at correct spectrum) can do “wonders”...

Boky
jitter is an analog phenomenon, it does not exist in the data itself.. ripping or copying from one digital media to another cannot introduce any jitter.. synchronous digital processing also cannot introduce any jitter.. asynchronous resampling using nowadays popular ASRC chips integrates the jitter into the resulting digital data, however there is no talk about ASRC in this thread, only synchronous processing is being applied.. burning data onto a CD or DVD also does not directly influence the conversion clock jitter.. only indirectly via coupling of servo action current spikes into another supplies of the player, including the DAC, oscillator and analog stage supplies.. it would be very easy to test this influence by burning the original 16/44.1 track next to the upsampled one on the same DVD-A.. I can guarantee you the result will be the same as with the original CD vs. upsampled DVD-A..

you are right though that the spectrum of the jitter is very important to the percieved sound, jitter amplitude in time domain doesn't tell much about it..
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Old 7th January 2007, 12:19 PM   #7
fixerfrasse is offline fixerfrasse  Sweden
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Quote:
Originally posted by Extreme_Boky
You have introduces a lot of jitter by ripping, upsampling, burning the DVD, and playing "the original information" back on a cheap DVD Player - and you liked the sound: rounded, layed-back, "more analog-like".

A bit of jitter here and there (at correct spectrum) can do “wonders”...

Boky
Sorry if I seem ignorant, I'm quite new to this but I have a couple of questions about this.

First, I really really wonder how it comes that ripping a CD to wav introduces jitter. If i had a 650 MB textfile on a CD and copied that textfile onto my hard drive I expect all letters in that textfile to be 100% correct on the HD. Why is this different when ripping a Audio CD? In my knowledge there shouldn't be any jitter introduced in this procedure.

Then I wonder how upsampling would introduce jitter, what it actually does is what Glassman sugests, the jobb that the oversampler actually has. However since this isn't done in realtime the quality can be greatly improved.

As far as I understand, this is a great way to improve the experience of listening to your favourite CDs.
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Old 8th January 2007, 08:24 PM   #8
soundcheck is offline soundcheck  Germany
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Hi folks.

Jitter effects on audio quality is a realtime issue only.
If you run a non realtime bit perfect application, such as ripping to file,
or transfering files, you won't have any issues, unless your Laser can't read a bit
properly. But that's not jitter.

Ripping to file doesn't introduce jitter. Writing to CD introduces jitter though.
The pits are written to CD with a certain Jitter by getting different distances to each other.
This of course causes jitter immediatly by the time the data are read-out,
converted and played in realtime from CD.

This is one of the reasons why the data should stay IMO on the harddisc.

If that is no option, there are just a few CDROMs out there, such as
Plextor Premium 2, which introduce very low jitter when writing CDs.
Many people report good results with these drives. With gold CDs and a premium drive you have a good chance to end up with better sound as before, since the pits are much better written to the gold surface then on the original. This is causing less jitter when reading-out again it realtime.

I would not call jitter an analog issue as pointed out by glassmann.
The digital data are getting inhomogenous before they become converted to analog. It is a purely digital cause for jitter. Analog jitter what's that supposed to be!
Jitter is getting appearant though, by the time the jittery stream is realtime converted to analog! You can also increase the jitter in the stream by doing
upsampling here and downsampling there, poor clocking, poor and noisy power supply of the crystal, converting from USB to SPDIF - you name it.


I do offline upsampling from 44,1 to 48khz with "Voxengo R8brain Pro" by myself.
The offline conversion is giving me great improvements, even when compared to Shibatch realtime SRC. Shibatch is most probably a great algorithm introducing no phaseshifts whatsoever. But doing it realtime will have certain effects on the jitter induced to the stream.


Cheers
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Old 8th January 2007, 09:02 PM   #9
Glassman is offline Glassman  Europe
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Quote:
Jitter effects on audio quality is a realtime issue only.
If you run a non realtime bit perfect application, such as ripping to file,
or transfering files, you won't have any issues, unless your Laser can't read a bit
properly. But that's not jitter.
agreed.. in fact laser quite often misreads a bit, but thats why there is EFM and two layers of CIRC so in the end we obtain correct data..

Quote:
Ripping to file doesn't introduce jitter. Writing to CD introduces jitter though.
The pits are written to CD with a certain Jitter by getting different distances to each other.
This of course causes jitter immediatly by the time the data are read-out,
converted and played in realtime from CD.
not true! pit/land jitter is indeed present on every CD to lesser or greater extent, but this is not the reference signal by which the D/A converters are clocked.. signal from pickup has to undergo various processing and is buffered before being output to DAC.. the output as well as DAC is clocked by a free running usually crystal clock reference, which is not directly influenced by the pit/land jitter of the particular disk.. it's actually the other way around - the disk readout ie. spinning is adjusted to the free running crystal reference by the servo processor.. the only way how pit/land jitter or physical disk quality in general can influence the jitter at D/A convertion is via coupling of servoamp current spikes through the supplies of the player or even through RF radiation it generates.. so it is an indirect cause due to a faulty circuit design, not a direct cause!

Quote:
This is one of the reasons why the data should stay IMO on the harddisc.
if the disk drive generates less interference to the rest of the audio system than it's better indeed..

Quote:
If that is no option, there are just a few CDROMs out there, such as
Plextor Premium 2, which introduce very low jitter when writing CDs.
Many people report good results with these drives. With gold CDs and a premium drive you have a good chance to end up with better sound as before, since the pits are much better written to the gold surface then on the original. This is causing less jitter when reading-out again it realtime.
if you start with a physically perfect and regular disk, the servo will likely run smoother without abrupt actions and hence generate less interference, so yes, this can improve sound on badly designed CD players..

Quote:
I would not call jitter an analog issue as pointed out by glassmann.
The digital data are getting inhomogenous before they become converted to analog. It is a purely digital cause for jitter. Analog jitter what's that supposed to be!
Jitter is getting appearant though, by the time the jittery stream is realtime converted to analog!
depends on your point of view.. i consider it an analog every time something doesn't work in a simple '1s are 1s and 0s are 0s' way, which is precisely the instant at which we convert data from digital to analog.. the clock is an analog signal and jitter is an analog issue, becouse otherwise one would say that digital clock is nothing but 1010101010101010 sequence and is always perfect in which case jitter does not exist..

Quote:
You can also increase the jitter in the stream by doing upsampling here and downsampling there
tell me how..

Quote:
poor clocking, poor and noisy power supply of the crystal, converting from USB to SPDIF - you name it.
of course, anything that makes the conversion clock worse is affecting the end result..

Quote:
I do offline upsampling from 44,1 to 48khz with "Voxengo R8brain Pro" by myself.
The offline conversion is giving me great improvements, even when compared to Shibatch realtime SRC. Shibatch is most probably a great algorithm introducing no phaseshifts whatsoever. But doing it realtime will have certain effects on the jitter induced to the stream.
the Voxengo algorithm could just as well run in realtime with the same results, just like SSRC can work offline with the same results.. nearly all digital filters have completely linear phase response, with the exception of R8brain Pro in MinPhase mode, which is an IIR filter and introduces great amount of phaseshift..
again, you don't introduce any jitter via digital signal processing, only if the interference generated inside the computer would change dramatically under load caused by realtime processing, which to me is not quite probable..
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Old 8th January 2007, 09:19 PM   #10
BlackCatSound is offline BlackCatSound  United Kingdom
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Jitter has no effect when you are just in the digital domain.

1+1 = 2
2+2 = 4
3+3 = 6

It doesn't matter if you do those sums exactly 1 micro-second apart, 1 second apart, 1 year apart, or do 1 then get bored and go away for half an hour for a cup of tea and then come back to do the last 2. The answers will always come out exactly the same.

So long as the data is in the right order and bit correct the actual timing has no effect on the results.

Also something to note about pit/land jitter, remember the data on a CD is not stored in linear order. The data is interleaved.
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