Welcome, Guest. Please Login or Register
Decware Audio Forums
07/24/14 at 03:33:53


Pages: 1 2 3 
Send Topic Print
Computer vs Transport discusion and information (Read 11662 times)
will
Seasoned Member
****




Posts: 1138
Computer vs Transport discusion and information
04/29/11 at 00:20:01
 
There is a lot of discussion about Computer/DAC setups and Computer/DAC versus Transport/DAC as separates or as CD players, including sidelines in threads on this forum. I find it a compelling discussion, and since we have the ZDAC, the choice is there for Decware users. It seems like a subject that could use its own thread, so I am starting this one. In fact the following is basically a fleshed out response to a side discussion in the Zen Ultra thread of the Decware News
http://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1301477558/58#58
….please join in with your experiences and opinions.

Here is my simple (haha) take on the question of relevance of computer/DAC versus transport/DAC.

Wink


No matter what circuits or transport mechanism we use to decode and convey CD data, in the beginning, it is just that....data. Our most common choices for turning the data to music with the least compromise seem to be CD players (combined transport and DAC in one box), separate transports and DACS (offering mix and match potential that CD players don't offer), and Computer/DAC combinations. Each individual or combined setup is all about converting the data and making it sound good according to the tastes of the designers and users.

As far as I have been able to tell, the main technical differences between properly done error corrected, uncompressed Computer data taken from a CD, versus CD data through a Transport are as follows. All transport/DACs bring with them the issues are error correction and jitter, issues inherent to transports and the CDs themselves. So the technical difficulty for transports is extracting and conveying the data with as little error and jitter as possible. Then the DAC stuff happens, trying to correct or mask inherent errors and jitter, while converting the data into listenable analog music. Then comes the output section with its technical and sound choices. Choosing circuits and circuit paths brings a designers preferred tonal attributes to the stuff that shows up at the output jacks.

Properly done, with a good computer, error correction software (for extracting and correcting the CD data), and an optimized setup for transparent computer to DAC music serving, the issues of errors and jitter are virtually eliminated. This solves a bunch of the challenge transports bring to the picture. In this we theoretically have as good a beginning as is presently possible to get the CD data ready for the data-to-music conversion. As far as I know there is no technical question here. I can't conceive of any problems with the efficacy of eliminating (for the most part) the errors and jitter, thus simplifying the work of the DAC, and at the same time simplifying the circuit path.

Whether we get good sound or not is dependent on the proper data, equipment design, optimized systems components, system setup, and finally synergy. These are where the technology blends with tastes, both for design and listening.

To make this happen requires allowing our technological biases to shift to an open mind in order to deal elegantly with the details and issues of turning music into data, and then data to music. As with the transition from LPs to CDs, we are a recalcitrant lot, and once we find something we like, we tend to believe it is the end-all, so the digital transition is still not as refined as it should be. A big part of the problem was that we had pretty good sound, especially in the most refined systems with great tables. And most of the rest of the problem was that gear was designed so that tape and LPs sounded at their best.

So when the 44k CD data hit the scene, poorly derived from tape, and played on gear designed for tape and LP, it sounded awful. All the gear from mics to mixers, compressors, monitors, reverbs, and the rest in the studio, as well as what we listened with at home, was made to deal with the triumphs and deficiencies of the original mediums. Tape and LPs have native "warmth"  and compression, but also, they have a seemingly infinite "bit rate," a very particular set of criteria when recorded and reproduced.

CDs are mostly limited to 44K, not enough bits for it to sound like music, and are made and played from a deficient and still developing knowledge base......bizarrely, we still argue over how to work well with 1s and 0s. And our original digital recordings are also put down in bits, usually more than 44k now, but also very, very clean with no inherent compression and relatively noiseless.... This is a very different thing than tape and LP, and requires very different approaches to make it come out like beautiful music. Our heritage of many decades of tape/LP based gear development does not make shifting to digital an invalid pursuit though....As a medium to efficiently capture and convey music as accurately as possible it has great potential.

Wink

So even today, after several decades of digital development, if your desire is to convert to a computer beginning, the general knowledge is surprisingly immature. There are still many questions around the bit data and its conveyance. I have heard the difference between "lossless" compression files and uncompressed files. I have heard the difference between different USB cables. Both of these, some would argue, are delusional perspectives. The word on the net tends to favor the Mac Mini over other computers for a server. Many believe that using an external drive helps the sound. There is debate over output quality….USB, coax, toslink, and SPDIF….Some prefer one error correction software over others……and many more things. The point is that though data is 1s and 0s, how we move that data around and extract and convert it to music is still in relatively young state of development.

Lips Sealed

But I have found that if I dig for information, and experiment with an open mind, there is plenty of information to put together a great sounding rig. And in my experience, like with analog, there is as much need for proper setup, gear choices and the resulting synergy with Computer/DAC setups as there are for Transport/DACs… And since our recent technological legacy is relatively entrenched in making Transport/DACs sound good, the computer setup needs its own considerations and implementations to realize its potential.

And finally, it is always the tastes of the DAC designers that gives us the quality and flavor of the analog out…..the caps and resistors used, chips and clocks, the choice of NOS chips and Upsampling chips (and which ones), outputs sections, and so on. In this, the refinements and synergy of how this is all dealt with is determined by DAC makers tastes. Then, how the preferences of designers and listeners come together puts it in our court.

To me, in the question of transports reading and conveying CD data versus correctly implemented computer extraction and conveyance, there is little doubt that computers have greater potential. With it the DAC gets the best possible data, and there is for the most part, one less link in the chain. This in turn opens the door for the DAC to be designed without having to deal with the longterm issues of Transport/DAC design...jitter and errors.

But it is relatively new stuff, whereas transport design, and how they work with DACs has been refined with much attention over several decades, so it is no surprise that this arrangement can produce amazing music. But thankfully, in recent years, Computer/DAC is getting a lot more attention, and the inherent advantages of this method and ways of optimizing these advantages for making music are slowly being exploited.

And it is not all about the first stage. With a computer there is much potential to go further toward personally refining a system to taste. For example, the ability to apply Digital Signal Processing to the data pre-DAC, a refining potential that can be as clean as the DSP applied to the masters of all those CDs we have, but we can "master" our whole system with it so to speak.

Wink

So I made the leap, partially because I think this is where the cutting edge design is going, but mostly, because I prefer my Mini/ZDAC1 sound and flexibility to my Rega Apollo (a well designed CD player that retails for just a couple hundred less than my Mini/ZDAC1). But I definitely resisted the transition. And, very importantly, I only began to truly appreciate it after I tuned the system to the new sound this brought.

Are there Transport/DACs in this price range that sound this good? There may be, but I don't understand how the transport section can be better than a computer at its main job....the job of getting the CD data to the DAC. What causes quality transports to be good is more likely the refinement of the designers choices in making the problems inherent to transports relatively indiscernible to the listener.

In the end, they are two different things though, and the issues the Computer can eliminate from the matrix, creates a different starting point. So applying a computer front end to a system that had a transport will sound different and perhaps colder and too clean.....but this does not mean the computer is the problem. It more likely means that the computer system, files and cabling are not optimally implemented, or that the system has not been tuned to the source, or a combination.

This ramble is not by any means to say that this is the whole story. I am no expert. It is just the way I have been thinking today as I write this.


Cool
Any thoughts?????
Back to top
 
 

Mac mini, Tranquility DAC, modded Oppo 83, CSP3, TORII MkIV, Morrow SP-7, HR-1s...VHaudio DIY, Grover, MAC ICs...PI Audio Uberbuss...PI, VHaudio DIY, Neotech DIY, Cryoparts DIY power cables, HerbiesAudioLab feet and tube dampers
  IP Logged
Lon
Seasoned Member
****


"Love without
guts is
worthless!"
Philip K. D*ck

Posts: 7152
Re: Computer vs Transport discusion and informatio
Reply #1 - 04/29/11 at 00:42:56
 
Sounds like you're having fun, at the beginning of the exploration. And having fun is what it's all about.

I'm having fun at the end of an exploration and don't feel the need to explore into a new method. I have enough material to listen to the rest of my life even if I live longer than I think I will, and I'm able to enjoy the sound of the recordings, and they inspire me to create a bit of music myself. I'm very happy with the way things are for me in playback right now. And having fun, which is what it's all about. I don't feel the need to move into this different method of playback myself.

I'm glad I've stepped away from a pursuit "of the perfect sound." I've concluded recordings and live music are two different things and no matter how much time and money and energy I throw at it, ne'er the twain will meet, which was some pipe dream of mine for some time. I know how easily I can fall into obsessions and decided it is healthier for me to obsess about how to be a better partner for the love of my life, a better son, a better friend, maybe better at executing some artistic pursuits. I really HAD been tempted to move towards a quest for even mo' better sound, but the Torii and SCD-XA5400ES have shown me a way to be happy with what I have and how to make my collection shine in playback. I'm surprised actually, and willing to be here at this point, happy.

There's my thoughts, but you knew I'd say that. Wink
Back to top
 
« Last Edit: 04/29/11 at 00:54:17 by Lon »  

Decware:ERR,HR-1,ZP3,CSP2+,Torii Mk III,PS Audio PWT+PWD MkII,PowerBases,PPP,AC-12 pcs, Denon DBP-A100, Denon DCD-A100,Rega RP3 +TTPSU,white belt+Exact2, VooDoo Cable:Evo,Ultra Linear, Iso-PodMapleshade:Double Heiix Plus.Samsonv2+v3 +4" platforms,Herbie's Iso-Cup
  IP Logged
Donnie
Seasoned Member
****


Why does it hurt
when I pee?

Posts: 654
Re: Computer vs Transport discusion and information
Reply #2 - 04/29/11 at 00:48:14
 
I'm going the 'puter route right now. I'm figuring that I can use my Ipod - Wadia for kick around the house days but my laptop for when I want to really concentrate into the music. I still haven't compleatly figured out how it will be done but I will get there somehow.
I'm open to suggestions also, what is the "right " way. I'm currently just using FLAC files played through Winamp out my USB into my ZDAC-1. Is it the best way? I doubt it. But so far it sounds pretty good to me.
Back to top
 
 

Owner of the infamous RED TORII
  IP Logged
will
Seasoned Member
****




Posts: 1138
Re: Computer vs Transport discusion and information
Reply #3 - 04/29/11 at 02:39:31
 
Lon,

I would not quite call this the beginning for me since I have played around as a music player, recorder, and listener for about 40 years! But I get your point, and as Susuki Roshi said, beginner's mind comes with each moment!

I really appreciate that your system has reached a state where you are content to apply most of your creativity in other areas important to you, admirable pursuits indeed! And your thoughts on this forum are always interesting to me, both when they make me think a lot about what I am up to (like the above ramble) and when they point me toward something I want to try in my system.

Wink


Donnie,

I have a Mac, so we would be looking at different stuff, and I could make a post about my particular setup and settings if applicable, but  for the best possible sound with a computer, I think the main things to study are these:

1) Uncompressed error corrected data with the best available software for the job. This is as close to the master as you can get so I saw no need to compromise the sound with FLAC or Apple Lossless compression. I could hear the difference between Error corrected AIFF (Apple's WAV equivalent) and error corrected Apple Lossless when I tested it on my laptop at the beginning of my computer tests, and drives are cheap these days, but a lot of folks like Lossless. You can test that yourself and make your own decisions. I think the lossless compressions cut the files about in half.

2) Next is the software player and computer settings. If you have a player set to do nothing but pass the file data to your USB port, and the rest of your computer sound settings are all off except the USB output path, and that path is set to 16 bit 44.1K (like CD data) you will get the most accurate output. I think the thing is to be sure what hits the USB cable is exactly your error corrected data without processing.

3) Then cables. Since you are using USB, the thing I found is that USB passes power and data, and if I remember correctly, most share wire for these... Alternately, if the sound is on a separate wire, and it and the rest of the cable are protected from the power noise and other electronic interference, you will have less chance of the sequence of 1s and 0s losing anything on the way to your ZDAC. I currently like the Starlight cable from Tweekgeek, as it does this less expensively than most (100) and I heard enough difference to keep it.

3) Also, there is computer noise, and like with cables, this appears to be able to mess with the 1s and 0s as they head for the ZDAC1.

I have not tested this though. There is a lot of consensus out there that the Mac Mini does all this the best for the money, and if you are using a separate drive with the best, it is supposed to be even better, cutting more vibration and noise. Being a Mac user, having our laptop in regular use, and since they were relatively cheap, I just cut to the chase and bought a Mini. I have not tried the external drive yet, but will some day.

4) I put feet under mine too. Seems that vibration in any circuit will mess with the level of audio Decware gives us, so why risk it messing with the stream of 1s and 0s.

I know there is more, but the above has set me into some very happy listening and my contentedness slowed my research and experimentation down! Hope it is of some use.


Back to top
 
 

Mac mini, Tranquility DAC, modded Oppo 83, CSP3, TORII MkIV, Morrow SP-7, HR-1s...VHaudio DIY, Grover, MAC ICs...PI Audio Uberbuss...PI, VHaudio DIY, Neotech DIY, Cryoparts DIY power cables, HerbiesAudioLab feet and tube dampers
  IP Logged
Pale Rider
Seasoned Member
****




Posts: 1272
Re: Computer vs Transport discusion and information
Reply #4 - 04/29/11 at 16:09:07
 
Will, like you, I have a Mac rig, and here is how my office listening rig is set up:

1. Mac mini [2008 1.66gHz Intel Core Duo; 2gb RAM] dedicated to music playback running Fidelia, with iTunes as the back-end library manager.

2. WireWorld Ultraviolet USB out to Audiophileo Model 1 USB-S/PDIF bridge;

3. PS Audio Digital Link III DAC w/ Cullen Stage IV Mods

4. Decware ICs out to Taboo; Taboo to Audez'e LCD-2 cans.

At home, I have the Oppo BDP-95 for BluRay, DVD-A surround, and SACD playback, plus a server with the same files as at the office [another advantage of the server approach is the ability to mirror storage in physically disconnected locations].

I started out ripping ages ago, before I realized how destuctive lossy rips were, and then went back and cranked up to ALC, and then went back and re-ripped, as close to bit perfect as I could all discs into AIFF. For my DVD-Audio, I rip on my iMac running VMWare using DVD Audio Extractor [a really nice program, and worth the fee]. That creates WAV files. Those files, as well as hi-res WAV or FLAC files that I purchase from Linn, HD Tracks, Reference Recordings, etc., I convert to AIFF using Fidelia.

The Audiophileo has a bit perfect test mode, and so far, this setup is delivering that most of the time [I don't stare at the display, but every time I test, the chain delivers bit perfect].

This setup makes for some very sweet music. I have nothing against transports whatsoever, but I find that having 1+ terabytes of music, that a server is one way to keep me exploring it. I can set up playlists that cause me to re-doscover music that otherwise would be sitting in a jewel box. That, plus the convenience, are what drove me to the computer side.

Folks interested in server based setups should check out http://www.computeraudiophile.com . It is an excellent resource. The publisher, Chris, is very knowledgeable, and there are some great FAQs.

Greg
Back to top
 
 

Decware: Ultra | Torii MKIII [2] | SE84ZS | Taboo MkIII Sources: Synology 1812+ | Baetis Revolution | PWD DAC MKII | Lumin Network Player | Mytek 192 | Oppo 105 DSP: DEQX Mate | Emotiva Outputs: ERR [6] + Servo Subs | LCD-2 & other cans
  IP Logged
will
Seasoned Member
****




Posts: 1138
Re: Computer vs Transport discusion and information
Reply #5 - 04/29/11 at 17:38:04
 
Greg,

Excellent input! I was hoping for this sort of post in this thread....stuff that is clear and informative and doesn't assume we have all been watching the subject our whole lives! This is what has put me off about the Computer Audiophile forum in the past. Though I have always found good information there, it generally takes a lot of wading through to get near the bottom of anything. So thanks for the homepage link. I have not been there before (DUHHHH!) and I look forward to exploring the FAQs. I will also try to be more patient as I explore the forum with your recommendation.

I have not gone as deeply as you in computer serving, working only from CDs.

I have the Mini only at this point and it is the model just before the latest model design shift, so I have an external power supply that is considerably distanced from the gear.

I am using XLD software, ripping from the Mini disk drive into AIFF error corrected files stored and played from the Mini hard drive. I like to listen to albums, so send and store the rips in a Ripped Music Folder. This folder is designated in the XLD preferences as where to put rips and in the iTunes preferences as my iTunes Media Folder. I make sub-folders named as the albums and drag the fresh rips into them. Then, from an open Finder window, I drag the newly ripped album folder onto the "Playlist" title in the bar in iTunes, installing it as an album playlist there.

The Mini is set up with everything off except the USB to my ZDAC1 via a Wireworld Starlight USB cable. In the Audio Midi setup Utility, the Audio is muted in all ins and outs except the USB going to the ZDAC1, and that is set to 44.1K, 16 bit, 2 channel to match the CD data and ZDAC input. Then I play from iTunes with all of its EQ and the enhancement stuff off.

Pretty simple, and with the ZDAC1 followed by the ZSTAGE, very satisfying!
Back to top
 
« Last Edit: 04/29/11 at 17:38:36 by will »  

Mac mini, Tranquility DAC, modded Oppo 83, CSP3, TORII MkIV, Morrow SP-7, HR-1s...VHaudio DIY, Grover, MAC ICs...PI Audio Uberbuss...PI, VHaudio DIY, Neotech DIY, Cryoparts DIY power cables, HerbiesAudioLab feet and tube dampers
  IP Logged
Pale Rider
Seasoned Member
****




Posts: 1272
Re: Computer vs Transport discusion and information
Reply #6 - 04/29/11 at 19:51:45
 
Will, you have a nice setup and workflow. So, are you playing out of iTunes? Looks to me like you are all set for some even higher-res stuff, and I suspect you would enjoy it. The HDTracks and iTrax sites are great sources. The new Stones hi -res releases are very revealing. The ZDAC can certainly handle it.

P.S. Nice USB cable you have there.
Back to top
 
 

Decware: Ultra | Torii MKIII [2] | SE84ZS | Taboo MkIII Sources: Synology 1812+ | Baetis Revolution | PWD DAC MKII | Lumin Network Player | Mytek 192 | Oppo 105 DSP: DEQX Mate | Emotiva Outputs: ERR [6] + Servo Subs | LCD-2 & other cans
  IP Logged
will
Seasoned Member
****




Posts: 1138
Re: Computer vs Transport discusion and information
Reply #7 - 04/29/11 at 20:39:16
 
Greg, thanks, and yes.....

I play out of iTunes.

Also, I think I would love high res stuff, but we are in the sticks and using a Verizon mobile modem, have limited bandwidth. I bet those files can be very smooth!

Back to top
 
 

Mac mini, Tranquility DAC, modded Oppo 83, CSP3, TORII MkIV, Morrow SP-7, HR-1s...VHaudio DIY, Grover, MAC ICs...PI Audio Uberbuss...PI, VHaudio DIY, Neotech DIY, Cryoparts DIY power cables, HerbiesAudioLab feet and tube dampers
  IP Logged
Pale Rider
Seasoned Member
****




Posts: 1272
Re: Computer vs Transport discusion and information
Reply #8 - 04/30/11 at 03:41:47
 
You should give a listen to Fidelia. I have Amarra, Pure Music, and Fidelia. Each has its advantages, but I prefer Fidelia overall, and it is easily the cheapest.
Back to top
 
 

Decware: Ultra | Torii MKIII [2] | SE84ZS | Taboo MkIII Sources: Synology 1812+ | Baetis Revolution | PWD DAC MKII | Lumin Network Player | Mytek 192 | Oppo 105 DSP: DEQX Mate | Emotiva Outputs: ERR [6] + Servo Subs | LCD-2 & other cans
  IP Logged
will
Seasoned Member
****




Posts: 1138
Re: Computer vs Transport discusion and information
Reply #9 - 04/30/11 at 15:39:59
 
Greg, thanks for the tip. My initial impressions of Fidelia are good...very smooth. If you get time, I wonder if you could let me know your preferred settings.
Back to top
 
 

Mac mini, Tranquility DAC, modded Oppo 83, CSP3, TORII MkIV, Morrow SP-7, HR-1s...VHaudio DIY, Grover, MAC ICs...PI Audio Uberbuss...PI, VHaudio DIY, Neotech DIY, Cryoparts DIY power cables, HerbiesAudioLab feet and tube dampers
  IP Logged
Brett
Senior Member
***




Posts: 70
Re: Computer vs Transport discusion and information
Reply #10 - 04/30/11 at 21:17:29
 
I've been using a computer as transport from the beginning of my obsession with this hobby. A computer can transport all forms of digital. Having one machine do it all, and being able to store all your digital media and cue it up quickly is just awesome.

It seems the crux of the argument for 'not all digital transports are the same' is to say that digital data is merely data while it is being stored on a disc or on a computer hard drive. However, as soon as you attempt playback we are dealing with not only the accurate conveyance of digital bits (this is the easy part), but the timing through which those bits arrive. Jitter is the measurement of time related distortion and is measured in very precise increments. So the name of the game is to provide digital bits to the DAC with zero errors, but also with respect to accurate clocking (low jitter).

I'm with the camp that advocates as little manipulation to that original digital data as possible. No oversampling, no compression. Absolutely agreed that hard drive space is cheap so there's no sense in using "lossless" compression. It's important to rip data from discs with few errors so that the ripped data mirrors the data on the disc as closely as possible.

My computer is Windows based and uses Foobar for playback. Different media players have different sonic characteristics, which is rather dismaying when trying to hold onto the belief that everything digital coming out of your computer is the same. Even within Foobar as you try different output ASIOs for kernal streaming (effectively bypassing all Windows OS manipulations) it results in different sound. This, even though supposedly the ASIO (Audio Stream Input/Output) is outputting bit perfect. I prefer the DirectSound 2.0 ASIO. To me it sounds absolutely neutral and clean.

The great thing about proper USB is that the digital data packets are transported bit perfect without the necessity for clocking. This is why I have a hard time with special USB cables. A standard USB cable can transfer data without error, or else there would be total chaos in the computer world. All USB DACs have a master clock which takes the incoming USB data and then processes it with respect for timing. It is logical to conclude that it's is only after this crucial process of clocking that we need be careful with the conveyance of the digital signal.

USB from my computer is sent to an Empirical Audio Off-Ramp which then clocks the signal using an Audiocom Super Clock 4, and coverts to SPDIF digital output for my DAC to receive.

SPDIF is considered a flawed standard of digital conveyance due to it's method of converting the data bits and clock into a sort of bit clock infusion with the purpose of serving the combined signal as a single bus.

The SPDIF Receiver Chip in the DAC unit then has to receive this infusion and convert it back to the separate data bit and clock streams as it was before the SPDIF convertion. This is because DAC chips generally require that the data bits and clock be delivered through separate buses.

And all this hopefully done without altering the timing of the master clock. There is a lot of opportunity for jitter to creep in in the process of converting to and from SPDIF. The AES/EBU standard is the same process only using balanced interconnection cables. So while an improvement, it is still not ideal.

I˛S is the best means of delivering the digital signal after being clocked since it maintains separate streams for data bits and for clock timing. And it maintains this separation throughout and can be delivered directly to the DAC chip without the need for any conversion to and from SPDIF therefore bypassing at least two chips in the process. By taking out these additional manipulations you have lower jitter and fewer data errors if any.

The Off Ramp has an I˛S output so my next project is to ad a daughter board to my DAC allowing for I˛S input directly to the DAC chip. My DAC doesn't input I˛S natively so a little modification is needed.

Example here http://www.pavouk.org/hw/modulardac/en_ad1865i2s.html

Many DACs have I˛S inputs now.

http://www.empiricalaudio.com/ for Off Ramp info and using computer as transport related info.

Once the DAC does it's thing and you are dealing with an analog signal then it can be handled just as any other analog signal.

Back to top
 
« Last Edit: 05/01/11 at 04:37:33 by Brett »  
  IP Logged
will
Seasoned Member
****




Posts: 1138
Re: Computer vs Transport discusion and information
Reply #11 - 05/01/11 at 02:12:58
 
Brett, thanks for your thoughtful input.

It got me to thinking about several things, and I am glad you broached the jitter thing, though it makes my head ache. I sort of get it, but not altogether. Seems like it can come in many forms, like about anywhere in our electronic and clocking chain.....  the end result being that the data can get there altered/corrupted, or arrive with slightly off timing, ending up with smearing, introducing noise, and raising the noise floor, while causing that chilly "digital" sound. Seems like in audio transmission, errors and how jitter effects data are part of a whole in terms of their impact on our experience of music.

Also, I wonder if the sound difference in new USB cable technology isn't due, for the most part, to reduced jitter....damping and shielding, isolating power from data and whatever else they concentrate on to get the data through accurately and without adding electrical, electromagnetic or mechanical gunk. My guess is that this is the case.

And related to that, isn't computer to DAC data normally in real time, the clock of the computer syncing with the clock of the DAC? Seems different than passing data blocks to a printer or hard drive where the the timing of the 1s and 0s arrival is not so critical due to buffering in  the printer and the hard drive picking up the data and organizing it as it comes in?

Anyway, the technical details are a bit mysterious to me, and I tend to prefer the broader view with listening being the bottom line as refine the sound presentation we love......and however we resolve the issues of making digital data to music, it sure excites me when the end result is blissful absorption in the music! I have no doubt that my current sound is the best I have had and switching to the computer and ZDAC1 (and how they play together) is a notable part of that.

And where your explorations have, and are taking you, are really compelling. The concept of the Off-Ramp sounds quite sound....no pun intended. Do you find that you have solved most of the digital blues with it?
Wink


Back to top
 
 

Mac mini, Tranquility DAC, modded Oppo 83, CSP3, TORII MkIV, Morrow SP-7, HR-1s...VHaudio DIY, Grover, MAC ICs...PI Audio Uberbuss...PI, VHaudio DIY, Neotech DIY, Cryoparts DIY power cables, HerbiesAudioLab feet and tube dampers
  IP Logged
Brett
Senior Member
***




Posts: 70
Re: Computer vs Transport discusion and information
Reply #12 - 05/01/11 at 03:20:49
 
The integrity of the digital signal really is such a delicate thing. Same thing goes for a low level analog signal. For a while now I've been thinking about how amplification in an audio playback system is a lot like multiplication in optics. Each amplification stage being like a lens in a really powerful microscope. In audio it is said that the most important component is the quality of the source be it CD or Vinyl. Just as the most important lens in a microscope is the first one. If there is any distortion in the optics of the first lens, then that distortion will be magnified several times by the subsequent lenses. A small imperfection early in the system will become a major problem later on in the chain. Same is true in audio. That's not to say that subsequent stages aren't equally important, but if the first stage isn't up to snuff than you wind up magnifying distortion.

So with this in mind, when we talk about the nuts and bolts of digital data and timing and getting it to the DAC chip in the most pure form, the outcome improvements can be substantial.

In the case of a USB DAC and also with an Off Ramp, the computer sees the component as a sound card and uses the USB cable as a bus through which to feed its data as needed. Audio files are read and data is provided to the sound card according to the time index of the audio file and so yes the rate at which the packets of data are transfered to be clocked by the sound card is probably within milliseconds of the ideal real time playback. And the signal is buffered so that a slight hiccup in data transfer will not result in an interruption of playback. However jitter is measured in picoseconds and there is one quintillion picoseconds within a millisecond. So by comparison, the job of the USB cable is really quite lax.

Another cool feature of the Off Ramp is that it takes the digital signal from the USB cable but operates on it's own power source rather than using the USB power tap. So all that dirty computer power naysayers point out is not an issue here.

Having said all that I have never tried a nice USB cable. And if it makes an audible improvement than my ears are open to it. Stranger things have happened. I'm just reluctant to pay out the money to find out.

I'm really happy with my digital playback. But I've got a long ways to go before being done. Crazy thing is how in depth you can get with it and then realize that it is just a small part of the overall system, each part needing equal attention. We go from talking about digital theory, to vacuum tube amplification theory which is a whole gamut of natural laws in practice. Audio transformers are so cool and mysterious. Then electrical signal to mechanical motion causing sound waves through speakers. And finally room acoustics which is a whole nother science in it's own right. This is why audio is the greatest hobby there is.
Back to top
 
« Last Edit: 05/01/11 at 04:25:07 by Brett »  
  IP Logged
Brett
Senior Member
***




Posts: 70
Re: Computer vs Transport discusion and information
Reply #13 - 05/01/11 at 04:56:15
 
Here's a visualization of the separate components of a digital audio signal (I˛S) as the DAC chip sees it.



Continuous Serial Clock (SCK)
Word Select (WS)
Serial Data (SD)

As you can see the clock (SCK) is referenced quite separately from the data. The DAC chip uses this clock timing to put all the pieces together with proper reference to time as experienced by the recording artist when the music was created. Each peak and dip of the square wave is like the tick and tock of a clock.

Any how thanks for starting this thread. As you can see I really enjoy pouring over this stuff.
Back to top
 
 
  IP Logged
Pale Rider
Seasoned Member
****




Posts: 1272
Re: Computer vs Transport discusion and information
Reply #14 - 05/01/11 at 16:21:03
 
When I was running my system on an Apple TV, before I got hooked on hi-res files, I considered putting an Empirical Audio Pace Car re-clocker on The ATV. Info here: http://www.empiricalaudio.com/products/pace-car-reclocker

It was impressive the difference that re-clocking, and by extension, asynchronous USB, can make. Taking the computer "out of the clocking business" is huge. In the end, I decided not to invest that kind of money—let's be honest, most high-end audio product makers are not as focused on value as Steve—in a system tied to the ATV. And I am glad I didn't. The Audiophileo is a huge improvement for me, and to my ears, reminds me of the effect I heard when I listened to a Pace Car. Detail, clarity, and air all improved.

For my next DAC, the Empirical Audio USB DAC is on the short list with the W4S, Ayre, Metric Halo and Cosecant. All are asynchronous; never going back. That's he only thing that keeps the ZDAC off the list.

One interesting thing I noticed about the Pace Car is that Empirical says that using it means you can use a cheaper USB cable, presumably because the cable is less critical. Of course, that doesn't keep Empirical from selling multi-hundred dollar USB cables. Wink I have 2WireWorld Ultraviolet cables, because I wanted a quality cable that I knew met USB spec without spending an arm and a leg. As it turns out, Audiophileo supplied the very same cable with their Model 1. I think the rub with USB cables is that, depending on their use, the role of power in the cable, and whether the cable itself meets USB spec (so many do not), and whether there is post-cable reclocking going on, the cable can make a difference.
Back to top
 
 

Decware: Ultra | Torii MKIII [2] | SE84ZS | Taboo MkIII Sources: Synology 1812+ | Baetis Revolution | PWD DAC MKII | Lumin Network Player | Mytek 192 | Oppo 105 DSP: DEQX Mate | Emotiva Outputs: ERR [6] + Servo Subs | LCD-2 & other cans
  IP Logged
Pages: 1 2 3 
Send Topic Print