24 bit, high-res
Copyright 2012 © Troels Gravesen

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I'm a newbie to 24 bit high-res, but as a few visitors have asked for links and info here's a few lines on my experiences. I'm in no way competent in recommending any gear or software, so comments are welcome, questions are not! This is what I've picked up "with a little help from my friends" - not least Frederico from Italy who was so kind lending me a spare Stello U3 + power supply (King Rex U-Power (battery)).
Little did I know of S/PDIF and the like. The Stello U3 is a DDC, Direct Digital Control unit - or a 24 bit/192 kHz sampling rate USB link, making sure that what comes from our PC hits our DAC in perfect condition.
From the Stello add: USB Audio Class 2.0 compliant Asynchronous synchronization mode High Speed Bit Perfect Audio Data  Stream up to 192kHz sampling rates Master clock. Super low jitter 2 external clocks Sampling Frequency 22.5792mHz/24.576mHz for multiples of 44.1kHz/48kHz sampling rates. Resolution Standard sample rates 44.1, 88.2, 176.4, 48, 96, 192kHz/24bits. So far, so good.

One of the reasons I bought the Shanling 2.1 CD player was it can be used as a "transport" or as a DAC alone. Maybe I'd some day start listening to "computer" music along with my LPs and CDs. And I did.
Being an LP aficionado I only use my CD player when I cannot get the music I want from vinyl. However, a visitor brought in his MAC/ext. harddisk/DAC for audition and some 24 bit stuff didn't sound bad at all. So, I have started buying high-res downloads and played it via the Shanling 2.1 DAC. Not bad at all either. I obviously had to download Jazz at the Pawnshop giving me the ability to compare 24 bit to fresh 180 gram vinyl. Quite rewarding. Adding the Stello U3 was a further step up the latter.

To cut a long story short: The 24 bit may actually be more fidelity in the true sense of the word where vinyl has that reach-out presence we sometimes miss from digital media. 24 bit has more transparency and it has less distortion, which is so easy to hear from the applause from live recordings. Here vinyls simply fall short although 45 rpm applause comes close. For good classical recordings 24 bit is a dream come true. Try Mahler's Fifth from here. Playing the Pawnshop, vinyl vs. 24, most visitors preferred the vinyl has to be said despite 24 bit having more depth. With all its imperfections, vinyl has its virtues.

I do think this Shanling DAC, modified with proper coupling caps, has exceptional performance. Only thing I can recommend is to have a check at your coupling caps in your state of the art DAC. If you find some stack-foils, some electrolytic caps, etc., I dare say may not have heard it yet. These vital components are unlikely to be seen in even the most expensive gear as e.g four silver/gold super caps will set you back some 3-400 USD. I think I should start calling these caps "high-res caps". Most likely you can do with two caps in a DAC separate. 

If you think setting up a turntable is trouble, getting lost in VTA, azimuth and the like, try high-res downloads! A turntable is a piece of cake comparatively.  
The Stello U3:
Asynchronous synchronization mode High Speed Bit Perfect Audio Data Stream up to 192kHz sampling rates. Master clock Super low jitter.  2 external clocks. Sampling Frequency 22.5792mHz/24.576mHz for multiples of 44.1kHz/48kHz sampling rates. Resolution Standard sample rates 44.1, 88.2, 176.4, 48, 96, 192kHz/24bits. Audio Input 1 USB 2.0, Type B connector. Outputs Galvanic Isolated, Up to 192kHz sampling rates. 1 COAX 75 Ohms, Gold Plated RCA Connector. 1 AES/EBU 110 Ohms, Neutrik XLR Gold plated contacts.
This is a copy/paste from the Stello U3 website. Before you know it you're flooded with numerous abbreviations you didn't even know existed. AprilMusic simply tells us this is best DDC ever made. So, what's a DDC? We go to FAQ and search for DDC. No hits on DDC. So, we google "DDC" and find Wikipedia (bless Wikipedia) and find "Direct Digital Control". OK! "Direct Digital Control (DDC) is the automated control of a condition or process by a digital device (computer)". Honestly, I'm still confused about what the Stello does although I feel certain it provides an improved transmission of data from my computer to the DAC. So it solves a problem I didn't know existed. Have we heard that one before? Well, at the end of the day this Stello DDC works. It's does improve the sound considerably. I use my Shanling 2.1, TRAM line stage, Jungson power amp and Jenzen D speakers. The diamond tweeters will for sure tell you this Stello thing works.

Getting all this up and running was easier than it may sound like. Once you get into your computer settings (Win7, "change sound card settings") and the JRiver settings, you're flying. I can very well understand people buying a squeezebox handling all this compared to computers, external hard discs, power supplies and meters and meters of cable. It quickly becomes a mess and the touch-screen/all-in-one solution is appealing. 
One key issue is storage of data as your high-res downloads may represent a significant amount of money and hard discs crash over time - or a burglar may drop by and put your entire record collection into his pocket. Things to consider! Back-up becomes a key issue.

The software I use for handling the music files comes from JRiver:
http://jriver.com/audio.html

Here's a thorough review of the software, a must read:
http://www.computeraudiophile.com/content/436-jriver-media-center-17-detail/
I'm not overly enthusiastic about the performance of this software. File handling appears a bit awkward and it doesn't always remember your settings. But the more you use it you learn to live with its shortcomings. These "shortcomings" may actually be that it can do much more than I need it to do, but it doesn't have that "Apple" intuitively user friendly interface.

I started downloading from this site:
https://www.hdtracks.com/index.php
This site works really well and with a PayPal account you can quickly spend a lot of money!

http://www.harbeth.co.uk/usergroup/showthread.php?527-High-Res-Downloads
This Harbeth site lists a number of high-res download sites.

http://www.highresaudio.com/index.php
This site works crap, but if you need the Keith Jarrett Köln concert, you better live with it. The sound was a bit disappointing, a little hard, but the level of transparency by far supersedes my LP(s). I have several copies of this concert.  

http://www.troelsgravesen.dk/shanling-cd-2.1.htm
This is my Shanling CD/DAC machine. Give it four silver-gold output coupling caps and you're running.

http://www.6moons.com/audio reviews/aprilmusic8/4.html
6moons review of Stello U3 and other stuff. Now, there are bits and - bits. Federico told me I should try this Stello U3 thing to "smooth" the bit-stream and I have to admit it does its thing. More clarity and transparency in upper registers. 

http://www.aprilmusic.com/eng/main/sub02_03_05.html
Stello U3 website.

http://www.diy-audio-guide.com/kingrex-ud384-dac.html
This power supply runs the Stello U3 by battery!


Just a few hours after having released this page, I had the following responses, and I think this may be of interest to others.

From Sweden:

I read your post about high rez downloads. Good to see that you are playing high rez music, too J

I have been doing this for many years, and I know feel that setting up a turntable is much harder than getting high rez bit perfect etc. etc. is far easier J I just sent my Delos cartridge in for service, and I have a Denon  Dl103 but I do not want to touch my settings in the Thorens/SME tonearm so I will not install the Denon! Rather wait 6 weeks for the Delos and not touch anything!

My music collection is now 2,5TB. Backup is a bit of a problem but I use a 3TB USB hard drive for that purpose.
All my CDs have been ripped (pfui, that is a loooot of work!)I have used USB to SPDIF feeding a Buffalo II DAC with special power supplies and have tried several IV converters with this setup.

I also designed my own IV converter together with Erno Borbely and we have an article in the Linear Audio magazine.
http://www.linearaudio.net/index.php?option=com_content&view=category&layout=blog&id=69&Itemid=113

The Buffalo 2 (and now 3) is a DIY audio kit from Twisted Pear. Excellent quality and sonics! It uses the ESS9018 DAc chip which today is the best there is. It has a sort of analog sonical imprint. Today, this chip is all over the place among more expensive DAcs. http://www.audiostream.com/category/dac-reviews
I started to use I2S signal transmission a few  years back, and will never return to SPIDF!  SPDIF is a mess of difficult matching problems, coaxial cables sound differences, etc etc. USB also has its drawbacks but with galvanic isolation for the USB wires, INCL the ground connection!, solves some issues. But then we have USB cable differences and other things like the computer´s internal noise levels. SPDI is also limited to 24bits and 192kHz but I play higher than that today.

DXD is a file format that has 24bits and 384kHz. It is what some studios use today. For ex 2L. Files are around 1GB for 10 min music. This link has free Dls fro 2L http://www.2l.no/hires/index.html. Highly recommended as they have several file formats of each song incl some DXD. No, I2S is pure and simple. There are now USB-I2S interfaces all over the place. I recommend that as the next best thing.

The device from ExaDevices is a candidate for the best USB-I2S device there is today, http://www.exadevices.com/
For the ultimate in digital playback, I use a SDcard memory player made by two Japanese people. They call it the SDTRANS384. It plays both WAV and DSD (SACD) files up to 384kHz/32bit and 11,3MHz (dsd512). It is a bit hard core like an LP player as there is no remote control and all the music has to be stored before hand. But the sound quality is just outstanding! With sync option: I also use JRiver ver 17. But also Foobar, Audacity, Wavelab, Audiogate, EAC, Flac Converter, and SONY´s DSD software.
BTW, Jazz at the Pawnshop is one of my favorite jazz albums. Regards.

To let people know more about the SDTrans384, may I ask you to add the link to the design at DIYaudio.com
http://www.diyaudio.com/forums/digital-source/142562-microsd-memory-card-transport-project.html - and to the author:
http://www.chiaki.cc/Transport/sdtrans192.html#sync-9018d

 


From Lithuania:

Hallo, I'm long time reader and a big fan of your job and site and even have Acapella Seas at home, but in the boxes. Hope finally I'm gonna build them.
I've red that you're getting in to digital world of music. (www.troelsgravesen.dk/24-bit.htm)
I would like to share with you some information regarding that. As you know, you need really hi quality USB to SPDIF converter.
I strongly recommend to look closer to those devices: http://www.johnkenny.biz/home-1/mk3-hiface
or http://www.audio-gd.com/Pro/dac/DIv2/DIv2EN.htm  (DSP version)

Those two are the best price vs performance you can find in the market! If money is not a concern, than i would strongly suggest:
http://www.empiricalaudio.com/products/off-ramp-converter (+upgrades)

Now about the DAC, i think you like analog-vinyl sound, than:
price vs performance:
http://www.audio-gd.com/Pro/dac/RE5.2/RE5.2EN.htm

money - no problem:
http://www.audio-gd.com/Master/Master-7/M7EN.htm

Both DACs have quiet decent USB decoders.

And one more great DAC:
http://www.lampizator.eu/NEWDAC/Lampizator/Lampizator_DAC.html  (its made in Poland, so you can try it at home, if you don't like it, just send it back;)

And a cable, again good price and good performance :)
http://www.wireworldcable.com/products/57.html

So this is my 2 cent, i hope it was useful and interesting for you.
Thank you, for your job in audio word! Best Regards.


From Australia

I read your update on digital sourced music.
The attached website  http://www.supratek.biz/  is from an Australian amplifier manufacturer who is serious about music quality.
His blog provides valuable insight about his digital path - also about his loudspeaker choices. Hope this is helpful. Regards


From Australia

From my experience, the best thing about going digital is that you don't need to spend a great amount of money to have a decent sound system.

My setup consists of a Mac mini, an external blu ray player to rip cds and to watch movies or live concerts, an external hard disc where I save all my cds and hi res files, a dac, a stereo amplifier, a pair of 3 way speakers, and my new plasma tv.
I use to run the music using a combination of 2 softwares.

ITunes is what I use for organising the folders, but the sound is control by a software call Pure Music(http://www.channld.com). This software processes the music in a more professional way than ITunes. Is bit perfect, and let you set a resolution (in my case it depends on the max resolution of my DAC that is 96 khz)to play your music. As I told you before, I play all my music at 96 KHz, that means that all my CD quality music is being resample and played at 96 khz. In the case of my hi res files that are 192/24, they are downsample to 96khz. This software also has a digital crossover but to make it work you will need a multichannel dac and of course a multichannel amplifier or. I think you will find very interesting another software this company developed, that is Pure vinyl. Apparently this program let you play your vinyl albums while you record them in the resolution you want, let say 192 khz.

About storing your music, I’ll recommend you to buy an external hard disc with at least 2 dics of about 1 terabyte each in a mirror setup, so in case one of your discs decided not to work anymore, you still have a copy of everything.

I bought mine http://www.wdc.com/en/products/products.aspx?id=210 for about 300 american dollars.

My dac is a maverick audio dac (http://www.mav-audio.com/), and I tell you is hard to find such a great sounding dac with valve option for only 230 dollars. I’ve heard a few top ones costing 3 to 7 thousand dollars and this beauty sounded as good as them.

It is a great entry level dac and is hard to beat on sound quality and price.


From US


I noticed your recent post in regard to 24bit audio. I believe a healthy dose of skepticism in regard to 24bit/192kHz audio is necessary; many people will pay for expensive high resolution audio that will have zero discernible impact on audio quality.

It's no surprise that many people lack a basic understanding of signal theory and the sampling theorem. A basic understanding of psycho-acoustics and the limitations of human hearing is more essential than ever. There's a LOT of disinformation out there.

Please check out this very good reference in regard to 24/192: http://people.xiph.org/~xiphmont/demo/neil-young.html
Best regards,


From Italy

I've studied quite a bit the issues related to digital/analog conversion, and beside the good advices you already received as a reply to your "24 bit, high-res" page, I'd like to share with you some info: In order to digitally represent an audio signal, we need to discretize it, so that each element can be numerically represented. Given an analog (continuous) audio signal, we have to discretize it w.r.t. time. Such operation is called sampling. A sample refers to a value a point in time.
A theoretical ideal sampler produces samples equivalent to the instantaneous value of the continuous signal at the desired points.
In digital music, the sampling frequency is normally assumed to be constant. Standard values are 44100 samples per second (music on CD, usually written 44.1 Khz) or higher (48, 88.2, 96, 176.4, 192, 352.8 Khz)
Signal sampling representation. The continuous signal is represented with a green colored line while the discrete samples are indicated by the blue vertical linesMoreover the amplitude of each sample has to be measured and discretized.
The process of approximating a continuous range of values (i.e. the amplitude of a sample) by an integer values is called quantization.
Accurancy of quantization depends on the number of bits adopted to encode the audio sample.
Music on CD adopts 16 bits (so it can represents at most 65536 values)
24 bits music usually adopts 24 bits, which can represents about 16 millions different values, so it could be 256 times more accurate than CD music.
Music encoded with this approach is named PCM (pulse code modulation)
Sampling and quantization of a signal (red) for 4-bit PCM.

Reproducing PCM digital music means producing analogue sample equally time spaced. If we are not able to keep the exact time spacing, we introduce an alteration called jitter. If we are not able to reproduce the exact sample amplitude, we introduce an alteration called non linearity. So ingredients for high quality digital music are high linearity and low jitter.

Standard way of transferring digital music is via SPDIF (or AES/EBU which is the balanced version of SPDIF). Unfortunately SPDIF merges clock and numeric representation of a sample, so a DAC has first to split the two informations, and then can go ahead converting to analog. Clock extracted from SPDIF has usually an high jitter. Some top DAC (such as MSB tech) do not rely completely on the clock extracted from SPDIF: they measure the sampling rate of the extracted clock, trow it away and use an internal crystal to produce a stable clock with roughly the same frequency (this pose some synchronisation issues)
Moreover, a single crystal is not enough, in fact standard frequencies for sampling music can be divided in two families:
44.1, 88.2, 176.4 and 352.8 Khz is the first family (all frequencies are multiple of CD frequency)
the second family is composed by: 48, 96 and 192 Khz.
Each family requires its own crystal.
Computer music do not encode the clock, and give the responsibility of producing a stable clock (with low jitter) to the DAC, so USB DAC and digital streamer can theoretically perform much better in term of jitter
Stello U3 is a component that receives digital music from the PC, buffer it, and send it to the audio DAC with a low jitter clock. Unfortunately it still adopts SPDIF.
An alternative to SPDIF is I2S. In I2S the digital representation of audio samples and the clock are kept separated. This is the standard protocol accepted by DAC chips, but unfortunately only a few manufacturers decided to offer direct connection to the I2S bus, so DAC accepting I2S are quite uncommon (the connector is usually an RJ-45).
The exaDevices exaU2I (and rigisystem USBPAL) are interfaces from USB to I2S, supporting extremely high sampling rates.
Their behaviour is similar to stello U3, beside the fact that output is on I2S

I'd like to add that straight conversion from analogue to PCM is almost impossible.
most ADC are based on extremely fast sampling rate (6 or even 24 Mhz), and low resolution quantization (5 or 6 bits, which means 32 or 64 values), and adopt a technique called DeltaSigma modulation to recover the quantization error.
Digital low pass filtering the output of a DeltaSigma ADC and decimating the number of sample, we get a standard PCM signal.
 Even DAC conversion from PCM to analogue is most of the time not trivial. Usual approach is to:
- reverse decimation (by reconstructing missing samples - this can theoretically achieved, without loss of accuracy, thanks to the Nyquist theorem)
- digitally modulate the PCM signal to a multibit Sigma delta code (usually 6 bits, at several Mhz)
- convert the DeltaSigma code to analog
- finally low pass the analog signal trough an analog Low pass filter.
For details you can refers to:
The DAC conversion can be much simpler, by adopting a 16 or 24 bit DAC like PCM 63, PCM1704, or discrete R-2R dacs like in MSB tech products. Unfortunately this approach requires extremely a accurate resistors, which are very expensive, and in any case the achievable resolution is limited to 14-16 bits.

An alternative approach to PCM music is the direct encoding of DeltaSigma representation (so high sampling rate and low resolution)
Super Audio CD (SACD) tried to follow this approach: music is encoded at 2.8 Mhz, with a single bit of resolution. Decimation and reconstruction are no longer required, but converting from 6 bit DeltaSigma to single bit DeltaSigma still requires an additional modulation step, and is prone to additional error.

PS.
I believe some of the points in http://people.xiph.org/~xiphmont/demo/neil-young.html are due to the complex process associated to PCM music production, and there is room for improvements in the digital audio mastering and reproduction chain.
SACD aims to overcome some of the issues, by simplifying the ADC-DAC chain.. but it miss the point by using resolution and sampling rate much lower than actual ADCs and DACs.


DENMARK

Jeg har samlet nogle links sammen i fortsættelse af 24 bit high-res artiklen:

http://www.dddac.com/dddac1794.html Nyt site fra Doede Douma, som konstruerede den legendariske NOS dac DDDAC 1543 mk. II Også denne gang er der tale om en NOS dac hvor chips / moduler kan parallelkobles for bedre liniaritet / lyd - nu blot med muligheden for afspilning af 192 / 24 lydfiler.

http://hifimediy.com/index.php?route=product/product&path=62&product_id=60 En billig DIY dac til både 16 og 24 bit highres. Det udsædvanlige ved den er, at den ikke har noget udgangstrin (efter Lampizators 'snipit' forbillede) og dac chippen (voltage out typen) afleverer sin spænding direkte til en forforstærker - eller evt. en effektforstærker. Forforstærkeren kunne være dette baseret på dette DIY sæt fra Lampizator http://lampizator.eu/shop/viewitem.php?productid=216 Det fås både samlet og usamlet, og i en version med balanceret drift. 

http://www.aliexpress.com/item/Free-shipping-BBP-101-enhanced-version-hifi-192K-24bit-wav-player-digital-turntable/641167285.html Blev opmærksom på denne afspiller i tråden om SDTrans384

Hvis det kun er CD / Redbook afspilning det gælder, er der denne billige løsning fra QLS hifi

http://www.qlshifi.com/en/wzcapi/qa550.htm Afspiller kun WAV filer og kun i 44.1 khz og 16 bit. Til gengæld har den udtag på printpladen for I2S så den bl.a. kan kobles direkte til DACs med denne mulighed for at gå udenom SPDIF / AES/EBU

Glemte at sige, at mr. Douma i disse dage skriver på detaljerne omkring udvikling, konstruktion, m.m. af sin nye dac. Han er p.t. kommet hertil (scroll ned til bunden af siden) i sin første gennemskrivning (kan se, at han løbende retter også på de foregående sider) http://www.dddac.com/dddac1794_sound.html
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PS: Her er i øvrigt et link til Tachyon om levering, priser m.m. på CDTrans384 afspilleren (postet af Bunpei 30. oktober 2012)http://www.tachyon.co.jp/~sichoya/SDTrans/SDTrans2.html