Interesting topic

[rickcr42]

One not much mentioned here and to be honest one I pretty much walked away from years ago it being about the most pain in the ass DIY Audio project you can conveive of-improving the computer power supply for audio use

We all know just how nasty RFI is yet most never contemplate that ALL SMPS's and ALL digital circuits are RF Generators (why here in the states they must meet a certain level of radiation controlled by the FCC which controls all aspects of

-COMMUNICAtIONS TRANSMISSION-


Radio,Amatuer Radio,TV,Microwave,etc.

so it is a given armed with that knowledge that our computers are transmitting stations but because of the laws low level transmitting stations with radiation measured in mere inches-feet instead of miles but what about the analog circuits inside the computer ? Are they not directly in the transmitting path ?

and when is the last time you actually LOOKED at the board structure and layout inside of a PC,a machine never inteneded to be a high fidelity music source but rather a source or data manipulation ?

This is one reason so many try and get the music "out of the box" by first via the SPDIF connection to an external DAC and later Firewire then more recently USB Audio but even then,unless you either use an optical connection or galvanic isolation you STILL end up with a damn lot of crud on the lines simply due to the way the ground bus structure of a motherboard/plug in boards computer is designed.

So it would seem on the face that simply getting the "DAC" and "Analog Stage" outside the box would be enough but the truth is,just like when you take those sections out of a CD player and use it as a transport to an external DAC an entirely new set of problems crops up-Jitter

So as usual,no free rides and you choose your poisen and make the best of a bad situation by attempting to optimize what you have (either internal or external)

The second major problem for computer audio is the power source.Not only is it usually about the WORST POSSIBLE method for audio,the SMPS (switch mode power supply) but will get far worse before it gets any better in these days of "greening" the world where efficiency takes precedence over actual performance or reliability because unless you have been lving in a vacuum it is clearly "seen" even to a blind person that our electronics are increasingly less reliable and it can ALL be layed at the feet of less heat-higher efficiency-more in the box-smaller box

Another reaon why the "external" option looks better and better jitter increase and all because NOW you have externally powered as well.....................um sometimes.USB DACs mostly use bus power until you step way up in price class but here at least you CAN add some additional filtration to the USB buss on the input side (then galvanic iusolation on the output side) and "improve" the feed to a level good enough for most.

So where this is going is as I mentioned earlier,the typically most difficult DIY Audio Mod-the computer power supply and what options are out there for even one with limited time or limited skills to implement with good expectation of improving on the shit sandwich we have been served.

OPTION 1-The "plug 'N Play" option would be to drop in an BETTER lower ripple SMPS,close the box and call it a day www.antec.com/Believe_it/product.php?id=NjY=

zalman.co.kr/ENG/product/Product_Read.asp?idx=196

OPTION 2-The "I can do this" option is more improving on what you have rather than wholesale replacement and should be within the capabilities of anyone who can handle a soldering iron plus is more "hands on" for those of yopu who like to get dirty

www.audioasylum.com/cgi/t.mpl?f=pcaudio&m=42455

OPTION 3-This is interesting because it takes some and it adds some leaving the "players" to do what they do best for each durty so SMPS powering the digital data circuits,a place where efficiency is a real plus when you consider just how many circuits are located inside even a small laptop,and the far less efficient Linear Supply powering the "music sensitive" circuits-the ADC/DAC and analog sections.A damn lot of work and wouldbe a bitch to pull off unless you have the time and a good PLAN but doable for those who satisfy the requirements


www.audioasylum.com/cgi/t.mpl?f=pcaudio&m=47156

www.audioasylum.com/cgi/t.mpl?f=pcaudio&m=48848

OPTION 4-The ultimate ! Ultimate in time,ultimate in cost,ultimate in potential but man,not for the squeemish becasue THIS is not simple plug and play mod and if you computer has "timed powering" and some do (where one section is powered/started before another to prevent lockups) you NEED to follow that protocol precisely or your computer mau not even turn on !

www.audioasylum.com/cgi/t.mpl?f=pcaudio&m=51188

www.audioasylum.com/cgi/t.mpl?f=pcaudio&m=53854

But get it right and you are home free-the LINEAR PS FOR EVERYTHING

www.audioasylum.com/cgi/t.mpl?f=pcaudio&m=53854

[Will]

Rick, you are right, a very interesting topic.

I'm in the planning stages of a Audio PC, which will be this winters project rockgrotto.proboards.com/index.cgi?board=talk&action=display&thread=4179

I had been thinking about the PSU, and Pagan mentioned it too. Lets face it, the best way to go is Linear PSU. I'd started looking at regulators, for the various lines, after finding the current draw on the lines in a Via motherboard manual, which was handy. Biggest draw was 4.3A on the 5VDC line, under heavy calcs. Rest of the lines (12/3.3 VDC) peak at 2A-ish. The PC would boot from a CF drive (pretty cheap these days), and hard-drive would be fed from it's own supply. All good apart from the sequencing

Anyway, these articles are very timely, and will give some very useful info over the next few weeks, as I figure out exactly what I want to do.

[clint]

Through all these years of digital age i tried harder to hear the what so called jitter but, until now and i have to be honest, i can't hear jitter. I'm sure jitter is real, but is it audible?

[clausdk]

I am with Clint on this, I am not sure I have heard jitter, I have heard different sounding, better or worse digital players, but is the betterness due to less jitter ??

How does jitter sound ?? and how does one tell jitter apart from other distorsions ??

I have always proclaimed that jitter was nonsens, but earlier this year I visited "Densen" and saw how they messured the jitter, they explained to me that "a jitter" was when one of the 44.000 signals per second was a little bit late or early, I understood it like it was a picture with high pixels and one of the pixels was a little bit "out of place", not something that would be noticed but if the event occurs right in a split between black and white it would be visible..

So now I have the illusion that I know What jitter is, but I still do not know how it sounds ??

44.000 impulses a second is also a lot for the brain to handle so I guess if the jitter is low nobody could hear it, maybe it will be noticed subconsiuos ?

[pagan]

clint & clausdk
This might explain jitter a bit.
photos.imageevent.com/cics/cmpjitter/Jitter7.pdf

[rickcr42]

{quote] I'm sure jitter is real, but is it audible?[/img]

Probably not if you grew up with it,and most under thirty somethings probably have (all digital sources beginning with el cheapo CD players or less than optimal computer as source) but if you come from an analog source past I think maybe you are more prone to find it objectionable because it is one of the mechanisms along with the "cold hearted sterile bitch" that we hear and just say "nope,something is not right here folks,close but wrong" and anything we/I can do to recreate the original ANALOG signal (we humans ARE analog beings afterall as our most of our instruments) is just getting us closer to what we/our brains know is "right" from years and years of listening before the changeover to all digital.

In this particular case,jitter,is a timing error.Unlike the anti-aliasing filters that cause top end anomolies or th loss of bit depth during silent passages that needs dither noise added to regain any resolution JITTER is an across the board full spectrum error so will in effect have influence on the ENTIRETY of the signal.

Ever when you were very young get scolded for yelling into a spinning fan because you,being a child with no purpose in life other than to have fun all day every day,thought it sounded really cool when your voice became all choppy,rising and falling in volume and becoming something "new" as the fan blades turned ?

That is jitter,albeit on a much smaller scale.

Another analogy ?

A mistuned carberator ("pre-fuel injection" for you youngins ) where set too low the car engine struggles to stay running so it spuuters a bit then ramps up in RPM,ramps down,sputters,ramps up.

This is not a blatant in your face thing but when compared to a jitter FREE source day and night.

For me it is also music dependant so for instance high volume high level high energy pieces seems to mask the effect nicely but if the perfromance is a delicate one,one where you are more prone to LISTEN rather than HEAR it is more obtrusive.

That there is more "black" between the notes with digital in such pieces is less relevant for me than the fact that such pieces seem to have the life sucked out of them and rather than having a natural "flow" seem forced at me as if struggling to break out.This "straining" causes me the listener to also strain,leaning forward wanting to yell " C'MON BITCH ! BREAK FREE DAMMIT !LET 'ER RIP !" but it never happens and I get a freakin' headache from the straining and leaning forward ratherthan laying back and relaxing.

again,these things are NOT in your face blatant but an overall perception that something is amiss and enough to many times,if I am in the "mood" to just fire up the vinyl system and play spinning black discs which flaws and all seem to let the music out in a way that is easy rather than forced or shouted at me.


Having said all that I listen mostly to high energy pieces and even at the "measured" high jitter levels my USB DAC produces I get music out that is enjoyable and by that I mean I am able to listen to the jam rather than the electronics.This may be my expectations being reduced or may be just pure dumb luck or maybe,just maybe because I have tried to limit whatever jitter mechanisms may be added POST USB-To-SPDIF conversion,the signal up to and at the receiver chip in my PCM DAC via the pulse transformer on the USB DAC out,the short SPDIF cable going to the PCM DAC or the cleaned up SPDIF input of the PCM DAC itself.

so it is not jitter per se that is the problem if it is all you have even known but the combination of "errors" (a word that only came into use with digital audio ) that when compared to a long history of analog listening causes one to say "nope.Not right" and why it its elimination (probably impossible) or minimizing (way possible) is a worthy pursuit

Digital is and always has been about "timing and phase" while analog "noise and distortion" so depending on where you come from will determine which is more likely to piss you off ;D

[rickcr42]

Data quality mechanisms explained

www.data-acquisition.us/DAQ-Board-Components-Digital-Fundamentals.html

jitter



The "Quick And Dirty" definition of jitter:

"jitter
A flicker or fluctuation in a transmission signal or display image. The term is used in several ways, but it always refers to some offset of time and space from the norm. For example, in a network transmission, jitter would be a bit arriving either ahead or behind a standard clock cycle or, more generally, the variable arrival of packets. In computer graphics, to "jitter a pixel" means to place it off side of its normal placement by some random amount in order to achieve a more natural antialiasing effect."

www.voiptroubleshooter.com/indepth/jittersources.html

[rickcr42]

www.avguide.com/forums/jitter-audibility

[clint]

So, where's digital there's jitter and where's analogue there's noise?
The thing is, i can ear noise but i can't ear jitter.
In analogue we can limit noise with a quieter TT motor a better arm, cartridge and cables, with better records or tapes or even with noise gates and after all these upgrades we can certainly ear some sound differences.
What in your opinion is worth doing to improve something that some of us if not the most part of us, can't ear? Do you think jitter matters or is it just marketing?
Tanx.

[rickcr42]

Thing is,we can't reliably hear noise below the -60dB threshold,somethielling pointsng easily accomplished in just about any anlog source yet the -100dB or better noise floor of digital was one of the main selling points in the beginning,the beginning also i think of "spec whoreing" where the on paper data meant more than actual listening experience because the truth is as power amplifier designers of the past discovered,the pursuit of better specs more often than not led to a decrease in actual listening pleasure (class AB over class A,negative feedback vs no overall feedback,etc) creating a situation where Amp "A" having a distortion spec of O.1% would wipe the floor with one having a spec of 0.001% which tells me that test plots can tell you if something is amiss but NOT how a thing will sound and why choosing a direction solely based on the data is a wrong direction for something as much art as it is technical

[clausdk]

Jun 9, 2009 16:20:47 GMT rickcr42 said:

(we humans ARE analog beings afterall as our most of our instruments)

One could argue that our brain is digital, the neurons either send or do not send i.e. binary.

We just have way better DACs or rather ADC, if we could skid the hole analog part and send the digital signal directly to our brain, then we would all enjoy music the best way possible..

[insomniac]

A mistuned carberator ("pre-fuel injection" for you youngins ) where set too low the car engine struggles to stay running so it spuuters a bit then ramps up in RPM,ramps down,sputters,ramps up.

Funny Rick, I was just thinking that myself. We used to say the engine was "running lumpy" to describe that.... not a very technical term but everyone seemed to know what it meant.

Anyone remember the old BMW adverts where they sat a glass of water on the cylinder head of the running engine and the camera zoomed in to the glass to show the water was perfectly calm?

[insomniac]

Jun 9, 2009 19:22:07 GMT @clausdk said:

Jun 9, 2009 16:20:47 GMT rickcr42 said:

(we humans ARE analog beings afterall as our most of our instruments)

One could argue that our brain is digital, the neurons either send or do not send i.e. binary.

We just have way better DACs or rather ADC, if we could skid the hole analog part and send the digital signal directly to our brain, then we would all enjoy music the best way possible..

Nice idea but we would probably all end up looking like this guy..

[clausdk]

Jun 9, 2009 20:28:06 GMT insomniac said:

Nice idea but we would probably all end up looking like this guy..

I do look cool on that picture

[PinkFloyd]

Jun 9, 2009 20:42:13 GMT @clausdk said:

Jun 9, 2009 20:28:06 GMT insomniac said:

Nice idea but we would probably all end up looking like this guy..

I do look cool on that picture

Oi! "I" look cool in that picture...... how DARE you pretend that is you!

[insomniac]

International Identity Theft.

Who owns this face?

[Deleted]

Jun 9, 2009 19:22:07 GMT @clausdk said:

Jun 9, 2009 16:20:47 GMT rickcr42 said:

(we humans ARE analog beings afterall as our most of our instruments)

One could argue that our brain is digital, the neurons either send or do not send i.e. binary.

We just have way better DACs or rather ADC, if we could skid the hole analog part and send the digital signal directly to our brain, then we would all enjoy music the best way possible..

clausdk
Interesting POV .I never thought of that before. Perhaps to hear music best we need to end up like Captain Jean Luc Piccard ends up after the Borg gets to him in Startrek ?
SandyK

[clausdk]

Jun 9, 2009 20:58:58 GMT PinkFloyd said:

Oi! "I" look cool in that picture...... how DARE you pretend that is you!

Erhrmmm sorry, I do not know who he is, he looks familiar, but I am not sure, is he some kind of a hero ??

In the real world I am so much prettyer

[clausdk]

Hmmmm
dvice.com/archives/2007/12/nutty-german-in.php

Krischan Schallenberger who the fck is he ??

[insomniac]

Jun 9, 2009 22:35:09 GMT @clausdk said:

Hmmmm
dvice.com/archives/2007/12/nutty-german-in.php

Krischan Schallenberger who the fck is he ??

Heheh, I think the clue is in the URL link above

Some of his photography is very good:

www.flickr.com/photos/krischall/

[pagan]

Jun 9, 2009 19:12:16 GMT clint said:

So, where's digital there's jitter and where's analogue there's noise?
The thing is, i can ear noise but i can't ear jitter.
In analogue we can limit noise with a quieter TT motor a better arm, cartridge and cables, with better records or tapes or even with noise gates and after all these upgrades we can certainly ear some sound differences.
What in your opinion is worth doing to improve something that some of us if not the most part of us, can't ear? Do you think jitter matters or is it just marketing?
Tanx.

Maybe you can hear jitter. eg
Something in that music doesn't sound right, but i cannot quite put my finger on it.

[rickcr42]

My opinion is that if Jitter was a constant,that is EVERYTHINg time shifted by a certain amount ALL THE TIME it would be zero problem (your classis "all pass" filter" which is a time shift) but because it is varying it creates a "wander" so you can not reliably nail down the what and where which makes correcting easier to accomplish (any tech will tell you it is the intermittant problem that is the most maddening to find and fix while any "this is what is broken" is a snap to find and fix because A-it is easily identified for what it is-GO/NO GO and B-The pre circuitry and post circuitry will be operating just fine thank you ) .

This "wandering clock" is in a nutshell what jitter comes down to and why the "fix" if done right is adding low jitter clock that is time stable but if it was that simple then everyone would be doing it so as you can guess it is not only the clock itself but what powers the clock,how the clock is layed out and how the clock is actually interfaced that can make or break the clock so it is not as simple as plugging it in and calling it a success.

at least that is my understanding of the topic,a topic that is so madenning for me on the technical side to understand fully that I choose to mostly walk away from it entirely,mostly because I am a

"hit it with a ferkin sledgehammer jerky ! That'll whip 'er into shape"

type when it comes to audio electronics solutions while THIS is in the PPM (parts per million) range with EACH of the above sections having a cog in the wheel and I am neither tecnically minded enough OR patient enough to sit down and weasle this out to a definitive conclusion using the available knowledge base as a starting point but it IS out there if you look (hint-don't lock yourself into AUDIO specific technical areas if you want the REAL lowdown )

[pagan]

The first part of the fix is the power supply and earthing.

No matter what Clock you put in there, If there's noise on it's power supply line, it will jitter.

[clint]

BTW, How long has it been since you looked inside your computer?

izismile.com/2009/04/09/how_long_has_it_been_since_you_looked_inside_your_computer_32_pics.html

[Deleted]

clint

Sadly, that would be too true of many people's PCs. However, it's more due to lack of education . How many PC makers stress the importance of regular internal maintenance ?
In any case the majority of users would be too frightened to open their PCs, and too "frugal" to take them to a PC repair establishment on a regular basis, if they were unable to do this preventative maintenance themselves.
SandyK