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Post by jelosno on Nov 20, 2006 21:27:14 GMT
The more I read about that DAC stuff the more I find comments - mostly from the builders of that DACs - stating that they find the sound coming from a quiet PC through USB into the DAC much 'cleaner' and 'wider' than the sound from a high quality CD transport.
Reason stated is that the files on the PCs HDD is error free to read since it has gone through the CD reading process before. There is no error correction or alignement correction, no resonance or vibration or whatsoever anymore.
Should I rather build a fanless low spec PC with a 8" touch screen and save my favourite CDs on a HDD?
Any thoughts on this? Definately not a 'sexy' solution and rather anonymous vs. handling the CD, inserting into the CDP or transport etc....
Stefan
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rickcr42
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Post by rickcr42 on Nov 21, 2006 0:52:03 GMT
Good question but one with no "this is the definitive answer" response possible.
No way any computer with any USB DAC beats even a good CDP head to head with any consistancy (pure dumb luck if anything).The "great" CD players ?
Will flat smoke the el cheapo/bottom feeder "look what I threw together" type computer system hands down every time if by "smoke" and SQ your standard is at the microdynamic level,the nuences,a stable and predictable stereo image (one that does not wander as the dBv level of the music changes)
Flip that to a computer built specifically as a multi-media computer/DAW, :
1-Lightening fast
2-Quality high speed hard drive,defragged frequently
3-As much RAM as you can squeeze in
4-Fed from a clean source of power
5-If a Windows machine k-mixer bypassed using ASIO
6-Acoustic isolation from outside influences (chassis damping etc.)
7-properly terminated/isolated digital outputs......
in effect a PC built as you would a high end CD transport then the margin is close enough to be a tough call.All you are doing then is swapping a CD Drive for an HD drive with both (some high end CDPs/computers) having the ability to to clock the signal out of RAM instead of directly off a mechanical drive where it is in a more pure data state but the end cost would likely be neck and neck so you gain no real SQ increases going from a one-box high end CDP to a one-box other than increased user flexability (the whole house data transmission/PC jukebox/upload/download/swap & share ),ease of use due to the "hit play" nature of the human/machine interface and the lessened need to store all your CDs in the same room as the player.
I use both a CD Player spdif digital and my computer usb to feed my "project" DAC which gives me the ability to compare the two due to the DAC itself being common to both sources.My findings so far are that it is a close call but the properly terminated and isolated spdif feed has an edge in the small details,the little soft parts in the recording.That this may improve if/when I take the USB side up a notch from USB/SPDIF/DAC to USB/I2S/DAC is possible though previous limited experiments say the "tricked out" CD transport still wins by a nose and that both lose out to my vinly playback system by a wider margin than the two digital sources head to head do.
bottom line is that all formats that play music should have a place in any real music lovers system and why I have everything from cassette tape to VHS-HiFi (as a pure audio recording medium),open reel tape,FM radio,vinyl,portable MP3 player as source,computer as source (both lossy compression formats and .wav files) and even my SATV box for XM radio feed for background music.
All sound good,all enjoyable.My open reel or vinyl system have the best sonics but all have a place
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xerxes
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Post by xerxes on Nov 21, 2006 2:01:50 GMT
I don't think the PC, or the hard drive need to be anything special. The whole point about PC "playback" is that it's not real time.
First you make a good copy of the CD to the hard drive using something like EAC, which if it can't read the CD will go back and try again until it gets it right. When you play back a music file from the hard drive it isn't real time either. Any newish hard drive will have a data transfer speed in excess of 50Mb per second, that's over half a CDs worth of uncompressed music every second. It reads the music file into cache and if there are any parts of the file it can't read it has plenty of time to go back and re-read them as a CD only plays at about 1.3Mb per second, so a 50Mb per second hard drive has time for about 38 re-reads. The data is then sent to the USB port and on to the DAC.
All the subsystems within a PC, hard drive, cache, memory, USB driver etc. have to be pretty much error free, if not the many megabytes, even gigabytes of data and thousands of lines of code within programs etc. would be too corrupt to be of any use and the whole lot wouldn't work.
If the sound from a CD transport via SPDIF to DAC is superior to that from USB to DAC, I would be inclined to suspect the USB to DAC interface, rather than the data retrieval at the PC end of things.
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rickcr42
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Post by rickcr42 on Nov 21, 2006 4:05:17 GMT
sounds good in theory but the reality is unless you have a clean slate hard drive,defrag often and have speed from hard drive you will get drop outs,blurbs,bleeps,lockups,etc. At least that has been my experience with any dual use computers I have personally owned ever actually listen to a ripped copy and compare it directly to the CD ? Even the best of them rarely sounds exactly identical which tells me the rip is changing the music. As for EAC,have had a version or another of for over five years now though recently I only use it for damaged or for whatever reason tough to rip CDs. None of my rips are exact 1:1 (in my experience anyway) so rather than fk around waiting for EAC to do the deed I go with high speed ripping and that presently is NERO 7 the better CD players also buffer the music taking the transport out of the equation (mobile players buffer the data too or bumps in the road would make the CD skip  ) again sounds good in theory but the strange thing with music SQ is it takes theory and trashes it every time.The CD was touted as "perfect" when intoduced and we all know where that has led-non stop tinkering just to get it to equal vinyl,amps with vanishing distortion specs touted as "the perfect amp" yet sounding awful in the real world,opamps with on paper killer measurements that are ear bleeders when listened too...... My take on measurements is they can verify if something has obvious flaws but only listening when something sounds right so you design on paper using the available data,run the numbers to verify the design,build the prototype then measaure it to make sure nothing is seriously amiss,tune the circuit by ear until it locks in to the "oh yes,that is what I am looking for" point,bolt down the cover and play some music Could be rabbit though I should add I have "in house" and have personally used every single USB DAC chip/USB CODEC chip worth a shit produced by Burr-Brown/TI and to be honest have not personally HEARD any improvement using USB/I2S/DAC chip with the PCM2706/7 USB DAC or PCM2907 USB CODEC over USB/Transformer coupled SPDIF out/Transformer SPDIF Coupled SPDIF In/Digital Reveiver/DAC Chip in my own system. In theory (there is that word again  ) the I2S should whip the spdif/spdif ass being a more direct connection but the reality is unless built directly into the DAC itself it is not an improvement but in fact the opposite so why not build it in ? Because then a "dual use" dac becomes way more comprimised at the spdif input (again my experience and not gospel) because it is far easier to switch between to spdif inputs at the DAC (USB_SPDIF computer feed and Straight SPDIF from the CDP) than it is to switch I2S signals properly |
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xerxes
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Post by xerxes on Nov 21, 2006 5:30:33 GMT
I agree that theory does not always translate into preactice and that best measured performance doesn't always equate to best sound. Ultimately I guess it's something I will just have to try for myself and for the most part I'm not worried which is best, there are pros and cons to either solution. If the hard drive is best it will be very convenient once everything is copied, and the ability to make play lists etc. is handy. I can also store all the CDs out of site once copied, rather than them filling shelves all around the room. However copying all my CDs in the first place will be a real chore and I'll need something like 600Gb of hard drive space to hold my entire collection.  I'll wait to see some more reviews and feedback on it, but I think I'll save my pennies for the TentLabs CD player/USB DAC. With that I reckon I'll either have a great CD player with a USB DAC for favourite albums stored on hard drive for "convenience" listening or a great USB DAC with a CD player for stuff I havent yet copied to the hard drive, or stuff I can't be bothered to copy to the hard drive.  |
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rickcr42
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Post by rickcr42 on Nov 21, 2006 7:30:06 GMT
not a bad way to go all things considered.You can at least take comfort in it being a well thought out,totally engineered product rather than some open ended never quite finished online "group build" that may start out with good intentions but more often than not end up seriously comprimised once everyone weighs in with what they think is the ultimate. Makes for a very "jack of all trades/master of none" type device that in the end is more often than not suited for anything if ultimate performance is the goal (usually the original intent) Get wrapped up in the "what is the best cap" "what is the best resistor" "what is the best chip" "what is the best method" "what is the best xxxxx" and you end up with a cob job best left on paper there being no best anything................... My personal system is presently either 100% modular or heading that way (in the middle of a total tear down/build up  ) that allows me to instantly punch in the new and compare diretly to the old or choose system parts depending on use/mood/phase of the frikkin' moon,wow factor............. Digital as above-stand alone USB interface (soon to be "hubbed" ) to a standard stand alone DAC Analog is broken down into three boxes-MC Stage/Phono Stage/Power Supply so any or all can be upgraded piece at a time Controls 100% passive-Monitor panel,recording director for four decks,insert selector for up to four external devices Monitor Control Panel then has a choice between a straight buffer,an actual gain stage or my "SE Personal Amp" that in turn is to be sent on to an almost ready to breadboard "PP Booster Stage" for high power duties Then there are the "widgets" that no system can do without (no system of mine anyway ) RCL tone control/Filter bank-passive with an outboard makeup gain stage Selector boxes,a shitload a 4x4 passive mixing/active on demand switch buss to send signals any damn where I like Totally passive headphone surround matrix Transformer isolation boxes Line drivers Line Receivers Everything separate,everything in its own little "I am invisible until you call me" world Most all power supplies external so even THEY can be upgraded or totally replaced as the mood hits ...rambling......................mind wandering..............time to take my tired ass off to bed G'night John Boy |
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Post by jelosno on Nov 21, 2006 19:33:45 GMT
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Post by jelosno on Nov 21, 2006 19:41:49 GMT
That whole PC USB DAC thing seems to be a) quite tricky to judge b) very much down to personal 'ears' I was thinking of a seperate 'music PC' containing a low level CPU - the highest processing power that will not require a fan - a 320 GB HDD (enough for my CD collection ) one GB RAM (should do) and a 8" LCD touch screen. Today I have received an email from one of the suppliers of the pure Philips CDPRO2 drive stating that the CDPRO2M is not available anymore but its sucessor the CDPRO2LF (LeadFree). Not to my liking since the lead free thing was discussed here some while ago. How long will a LF version last then?  Stefan, most likely on his way to upgrade the old CDP - that, as it turns out, has a simple BB 24/96 bit 8x oversampling DAC in front of the tube output stage/buffer - and building a DDDAC.  |
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rickcr42
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Post by rickcr42 on Nov 22, 2006 0:35:08 GMT
me too first "stable" trouble free hard drive since my old Windows 95 IBM that to this day was the best PC I ever owned even if it was a slow ass P1.The way IBM partitioned the drive into three drives access was to any program was INSTANT.Had voice recognition,"Whole House" wireless control,LOTUS instead of MS Office....... loved it even though I never could get the @%%^$##$ USB ports to work even WITH the final edition of '95 that was supposed to correct that  this www.asio4all.com/used with this media player www.foobar2000.org/was THE way for the longest but seems there may be a new sherrif in town www.winamp.com/with otachan.com/out_asio(exe).htmli have always like the winamp interface it being the very first REAL player i ever used way back in the dark ages of Windows 3.1  It was some would argue THE beginning of the MP3 revolution,ripping CD's and file sharing and still to this day the most intuitive interface and fits me like an old shoe.When owned by Nullsoft was cripple free sharware (no limits.nothing forcing you to pay) with a price tag of $10 that considering what you goit for $10 back then was a damn bargain (you even had to pay for a browser until MS decided to whipe out Netscape by giving IE away for free). I happily used it free for years but being THE most used piece of software on my computer and so well designed I figured the developers SHOULD be compensated so actually sent the loot in even though it changed nothing other than easing my conscience because it was the right thing to do for something I used and enjoyed so much (the old code) Skins,streaming audio,CDDB support,easy tagging,could play damn near every format and in the early stages,has gobs of secondary source support/plugins/skins.............. So always had a place in my heart and on my desktop even though better sounding along (my all time favorite player after winamp was the Liquid Music player.Loved that fk !  ) most notably being the Foobar player.I never liked the player itself but for sonic quality the best out there.......until now ! The "new" winamp has a better sound than any version since 2.3,is still the KING if options and "feel" are considered and now that there is a good ASIO plugin maybe good enough to be the "Computer to Hi-fi" USB engine.I need to do a serious head to head eval but so far in the listening i have done it is a close call If this impression of SQ holds up,even if the foobar is better in overall SQ by a slim margin I will go with the player that "Really Whipped The Llamas ASS" because like an old well broken in leather jacket it just fits so damn well it is like a second skin My feelings on all this no-pb crap are well known.I prefer to "just say no".Take my ball and go home ;D PCM1702 ? PCM1704 ? If yes a SERIOUS start to "super player" |
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rickcr42
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Post by rickcr42 on Nov 22, 2006 0:38:16 GMT
BTW Stefan,those links you provided are for ASIO drivers that are specific to the commercial devices (have no clue if they work with other software but i DO know you have to buy the product to get the drivers ) ASIO4ALL is a universal windows ASIO driver that bypasses windows kmixer and should be on EVERY computer under consideration as a source of music for a mid to high end audio system |
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rickcr42
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Post by rickcr42 on Nov 22, 2006 1:16:39 GMT
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Post by jelosno on Nov 23, 2006 12:47:46 GMT
Nope, 1716E... SORRY, was late on that end. kinda good night JimBob situation I am currently putting together the cost of a nearly no noise PC acting as a music server and then compare it to the CD-PRO drive cost including the controls, display and the wiring. Stefan |
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rickcr42
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Rest in peace my good friend.
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Post by rickcr42 on Nov 23, 2006 18:13:09 GMT
for the "Quick and Dirty" El Cheapo maybe try a CDROM as CD Player solution.Never tried it personally even though I always meant to and maybe will by the time I am 65 at this rate..... ;D That it can be a high quality transport is a definate "yes". considering this uses a CDROM as the transport mechanism www.hometheaterhifi.com/volume_8_1/images/ces-2001-day-2-meridian-588-cd-player.jpgmany DIY articles for the conversion though most seem to miss the "make it heavy/isolate that bitch from ALL mechanical vibration" part,easily corrected so no biggy. The computer seems to me better suited for "ripping to" then playing off the hard drive with the dedicated CD Player platform better for actual disc playing so in essence more you neeed to consider both rather than an either/or.always a good idea to use the best tool for the job which in my experience means specialised not "multitool" You you can do small repairs,open a bottle of wine or do some limited cutting with a swiss army knife but when the job needs a man sized tool those whimpy ass screwdrivers dont cut it,the scissors will give a you fkn blister and that after you swear at it for being so damn fumbly to grip ,and the knife some limited cutting but dude,what would you rather have in a dark alley surrounded by predators ? A swiss Army Knife with a two inch blade that will fold back on your fingers when you least suspect "Stand back Mutha Effer ! I got a knife and I know how to use it !" or a Gerber Guardian with a 6" inch low luster double edged slash and stick blade |
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Post by jelosno on Nov 23, 2006 20:05:49 GMT
Well I am planning to go multiple ways with specialized equipment. Frist of all I do have a CDP. A pretty good one. I would rate it definately above average. Last WE I took it apart and had searched the inet for the part numbers of all the internals. It has 8x oversampling and yaddayadda then a tube buffer that sounds really nice. In addition I wanted to build a 'clean' system containing a CDPRO2M transport the necessary PSUs, controls and display and use the I2S output to go into a DAC that is also - specs wise - very clean. Having not discovered a source for the good old lead containing Philips CDPRO2M I might stick with my CDP for a while. Expect some questions on what to replace with what in that CDP. Watch this place! The clock will most likely get a replacement. Some Tentlabs XO thing. I have to ask Guido Tent whether it makes sense to replace both clocks, the one fro the transport that should - I think - be the one that also defines the SPDIF timing and the much higher frequency clock for the integrated 8xOS DAC. Then comes the new DAC. I might order the DDDAC soon. I just find it so interesting. It uses a 12V battery power supply and today I got an offer for a PC UPS with exact the right battery in it for ZAR 250 which is something like 28 Euros. I will use the 12V battery and its charger and leave the 230V part of it alone. The 'music server' will be a complete stand alone thing. Motherboard with onboard graphics and LAN, CPU (where is that recently replaced AMD 3000+ chip?) with fanless cooler (Scythe Ninja or Thermalright Sonic Tower?) 1GB RAM (I do have that somewhere) custom box fanless PSU and a screen to be defined. Not even a CD or DVD drive no nothing. OK, it will have a fan that will start up in case everything gets just too hot which I don't think will happen. The CD ripping will be done on my system I am sitting in front of now. The first big junk might get copied over to the music server with a extra HDD I take from work and connect internally first in the 'ripping machine' and then in the 'music server'. Music updates can be later transferred by LAN or an external HDD orCD or DVD drive if a cheap one comes along. Enough tools to do THEIR thing for my taste. And for the knifes. I'll take my Goldhamster kitchen knifes. Not available anymore under that brand name but one of the best items from Solingen that received their finishing cut and polish and whathaveyounot by an expert knifemaker who has a degree in making surgical instruments as well. He is from an old family of knife makers. If I see what they do in my kitchen I would not like to see them do things somewhere else. And the longest blade is 26cm (slightly more than 10 inches) which should just do the job Stefan - with enough projects on hand, one being Max the ten week old nervewrecker PS there might be a shipment on its way containing three USB DACs with integrated headphone amp as well.... ;D PPS the fourth one should go to some place in CT, USA... |
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rickcr42
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Post by rickcr42 on Nov 23, 2006 21:22:25 GMT
I have one DAC that uses an 18 bit AD1865 that is a Non-OS type,very expensive,big heavy prick,and one that is a "cob job" using the old Audio Alchemy DAC In The Box engine which has a 16 bit AD1851,has 8x OS and to tell you the truth both sound damn fine once i got the anlog section/power supply bypassing/digital interface right and could live with either as my only DAC without feeling I am somehow missing out. The "heavy prick" is all transformer coupled triode in the analog section (copied from Yuri's "Retro DAC") so expensive as hell The "cob Job' is a tiny ass 6x6x1.5 (approx.) that I totally disconnected the analog section in,cut the pcb traces to get access to the DAC ouput pins so I could use a resistor IV stage that in turn goes to an external "piggyback" sotwter dac transformer box (a woody naturally ),cleaned up ther power supply feeds to the digital chips plus added a pulse transformer to the spdif input for a toal cost including the second hand ebay DAC of maybe $200 or so.The above around $700 just for friggin' parts and to be honest I think if iItook the DITB analog section up a notch it would equal the above even though using 8X OS ! If I ever get the time/motivation I may just socket the digital filter chip so i can then remove it,whip up "No-OS" plug in adapter and see if it matters on the SQ or not and if no then re-think my preconceptions of what makes a good sounding DAC.Is it topology ? Is it implematation ? Just pure dumb luck ? combination of all the above ? Mated with my train wreck of a USB DAC the "Cobble DAC" (more affectionately known as my DAC Sandwich) see more system use than any other single part being that it is used for Computer Adio/CD Play/DVD Player PCM stream multi-use nature. 1-Coaxial SPDIF for CD PLay 2-Optical SPDIF for DVD PLay 3-USB-to-SPDIF to SPDIF A/B switch (USB/CD) for computer audio Hardly state of the art,hardly using the "bestist parts in the known universe" and hardly impressive to look at but plays music and all i care about The CDPRO is very tasty looking though i wonder if when everything is said and done,all the parts gathered,a chassis that works on both the platter stability AND looks level is made and a proper layout realised if in the end the CD Player kit turns out to be a real bargain. Ordering parts,trying to make modules from various sellers work in unison,powering headaches,layout ditto then trying to get it to all look good can be a very long process.why i have so damn many projects on the work bench in varying stages of assembly and to the point now where with limited time I feel overwhelmed so walk away entirely (haven't built shit for months ) fire away dude ! Hopefully it begins with a good "engine" and is a DAC chip with some room to play.the rest just comes down to optimising power busses and such + using proper parts for digital (think RF range instead of AF range ) Each XO clock is actually application specific so once you I.D. what frequency your current clock XL is should be a simple plug in. If an external DAc yes,if all in one box transport/dac then no You will need to add some capacitors to the battery output to lower the impedance,maybe use a V-Reg too cool,good plan hate to meet the guy that it would not stop well that one has me totally baffled dude and being no easy task you should be commended.........or something |
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Post by jelosno on Nov 24, 2006 17:43:44 GMT
OK. ...thinkin' RF now.....hold on.....hmmmmm. No. nothing... whatsitmean? I know. Should I use this 5V PSU for the clock or is there a schematic to build a good one for less? What makes me think here is that the transport has 8.4672Mhz clock - and I think that caters also for the SPDIF line since there is no other clock to be seen in that path - and the internal DAC has a 12.0000Mhz clock. As far as I can tell it the SPDIF labeled on the PCB 'D0' is not connected in any way to the circuit that comes close to the 12.0000Mhz clock. Let´s see what the external DAC will look like and then go from there. Maybe the DAC's power in will feature the caps. V-Reg = Voltager Regulation? !! These are empty PCBs with the DAC chip on them !! Sorry. No completed units. I hope they are on their way. Haven't heard after I paid for them ;D Otherwise, no comment. HELL! My wife just fired up one of those baby soothing CDs we got from someone. Where's my EAR+?? Stefan |
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rickcr42
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Post by rickcr42 on Nov 24, 2006 19:12:36 GMT
Ooops ! Sorry 'bout that AF= Audio Frequence RF= Radio Frequency don't lose sight of what is going on here Stefan. When you have a CDP player the entire digital system is self contained so there is zero need to Send the data over a long line to an external box where it is receved so a single clock controls everything,as it should to maintain proper timing. It is the CDP Transmit/External DAC Receive part that introduces the jitter and why this signal is stripped of the clock stream after being received by the DAC receiver chip,re-clocked to get rid of the jitter that has been introduced into the original clock data stream and proper timing again is maintained......in theory anyway. Nothing is perfect and that includes all the "Band-aids" we have been applying to digital audio since the introduction of this "Perfect Music forever" audio format,one that will never end in our lifetime ;D Electronic Valiums ? |
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rickcr42
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Post by rickcr42 on Nov 26, 2006 17:42:53 GMT
well,I am going to assume the package that arrived in the mail yesterday (and that I didn't see until 10:00 PM last night it being a Holiday Weekend here ) is the "some place in Connecticut,U.S.A." fourth parcel and if it is you have obviously narrowed down "someplace" to "Rick's House" which is surprising since I rarely give out my name/adress but if I am on target here then.... DAMN BRO ! 100% unexpected pleasant surprise ! And I thank you for the gesture Stefan.Very nice of you dude and i owe you one (assuming it was you that is.If not the jury needs to disregard my remarks and pretend they were never said.Won't do to have anyone think I may actually have a "nice guy" bone hidden away in my body somewhere ) NOW the fun begins (if such over my ninth grade drop out head mental gymastics can be considered such ;D ) and the process unfolds in Rick time....which means probably take eons but I mean well Sooooo without further yadda yadda yadda here is the demi-plan : ************************************************** The Analog Section Mod : Thorsten's TDA1543 analog stage with SINC rolloff correction filter using a 6N1P in place of the ECC88.Unlike every other non-compensated TDA1543 NonOS this one will be dead flat in the treble.Specs for the TL analog stage : Vout = 2V RMS for digital full scale Zout = 400 ohms ! Zload = 10K,very important THD = 0.02% (2nd harmonic dominant) Freq. Resp. = 20Hz-20Khz +/- 0.3dB (No O/S) about as good as it gets ! If I want to retain battery operation or just to keep the size and cost down the option would be Thorsten's passive IV stage,also with SINC treble rolloff correction.Being a passive network the Zout is in the high range so buffering the output a good idea,one easily implemented by using the pcb pads already inluded for the output OpAmp stage.Hell,if headphone driving is not important and the interconnects from the DAC are kept short even the buffer could be left out.Putting audio electronics on a diet is never a bad thing until you leave out critical functions and if not needed ? SEE YA BABE ! For those who need to SEE what I am talking about the schemos are available at the Yahoo Group "Thunderstone Technical" of which you have to be a member of to view so you need to sign up.Better do it quick though because Thorsten has stated he will pull all his Yahoo Group designs and shut down his Thunderstone Audiophile and Thunderstone Technical groups in the very near future due to commercial interests so get them now or never Next up,the powering. I understand the reasoning behind the DC-DC step-up and I am sure it took a damn lot of work to find the part,test it then design a section around it and tweek it for sonic quality but for me personally it is the weak point.It defeats the reasons behind the targeted DAC design which is ultimate SQ or why bother going to the obsolete TDA1543 and NonOS operation ?If only to get it to work portably why then not go to USB buss powering ? Can't be all about the "USB power is dirty power" thing because it is no worse yet a lot less complicated than the current powering method IMO. @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ Edit/Update : Obviously because the USB Power is at 5 volts DC and the chip needs to be fed 5 VDC leaving zero slack between the two for regulation even with the best LDO V-Regs so making the TDA1543 a poor choice for portable duty IMO.
It CAN be made to operate with a DC-DC converter to bump up the voltage which is then stepped down and regulated again to get the normal five volts the DAC chip needs but why go there if the very nature of switchers and digital audio is the main bottleneck to good SQ ?
Why when tossing the switching supplies in favor of a replacement linear voltage regulator is the single most common (and in my mind makes THE MOST readily audible improvement) "mod" to a CD/DVD Player,the Squeezebox before it too shit canned the DC-DC switcher in favor of linear regs,sound cards not "its in the box" and any other digital audio device known to humans ?
There are plenty of DAC chip choices that are far more suited to USB powering (3.3VDC power ),even some truly good ones.To use a TDA1543 because of the SQ then go to a known weakness immediately (DC-DC operation) seems to be going in the wrong direction when
A )-a mongo battery pack to get +/- 8 VDC followed by five volt super regulators would solve the portable powering glitch or
B )-there are other chips available that will at the minimum match or beat the 1543 powered by a DC-DC converter-the newer BB Multi-segment chips that operate on 3.3 volts for example,and do it with less hassle
again,not to toss rocks,I admire any "doers" and the design is well thought out but not the way I personally would do it is all and since I have a blank slate here (bare pcb) I won't @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ Since my build will have no restraints on power source being a totally "home base" design I am free to pretty much do as I wish here limited only by the pcb itself which is really no limit at all all things considered. Here again I am thinking about a Thorsten Loesch design,his "Low Power Mega-Regulator" that I can build on a perf board,add pins to the board line up with the pads previously occupied by the current regulators and just drop it in.On paper a damn good path,the reality of things may mean changes down the road once I actually dig in to the design but the current power supply is a definate "see you later bubbba" TL MR cut and paste : "5V precision, wideband and super low noise, currentsource fed shunt regulator for low current consumption, additional decoupling included, impedance DC-30MHz <= 0.4 Ohm, < 1 Ohm @ 100MHz depending upon physical layout "Beat THAT with a stick !again only available at Thunderstone Tech or by searching diyAudio forum in the digital area.Search Term "thorsten's mega regulator" +15VDC input to an LM317 V-Reg to an LM334 series connected current regulator to the final LM431 based shunt reg-good for 7mA per V-Reg.A tad more involving than simply dropping in a three-terminal V-Reg chip but the way to go here methinks and fits in with my present external "Power Station" that currently powers all my low voltage digital with the initial DC voltage (starts @ +/- 16VDC and is regulated down at each external device.). A simple AC section RFI/EMI inlet filter,36.2 VCT 1.6 A per polarity power trafos,John Camille reverse spike snubber to the MUR4007 rectifiers to an independant CLC filter for each of the three DIN jack power distribution outlets. Best of both worlds would be: 1-Portable use-USB Power 2-Home Base-Flip the switch,TL Mega Regulator/externalwell filtered raw DC power feed. so that takes care of the clean power source and the analog section leaving what ? The digital signal is what.When I build something I like to leave it as open ended as possible.I try to see the future (yeah right) and any potential use down the road and if the addition of more features does not harm the purity of the project or degrade the SQ,does not take it way past K.I.S.S. and into way overcomplicated then I would be foolish not to plan ahead and make the changes in the beginning when those changes are easy. In this case it is the ability to send out a SPDIF stream to an external DAC so I can use a single USB interface for all things USB Playback related (have the PCM2907 CODEC for record/play sound card replacement duty.) My current USB/SPDIF interface using the PCM2704 that in turn goes to my DITB (or any other DAC I want if it has a SPDIF input ) is a tiny little thing in a teeny tiny little box but this DAC is not TOO much larger so I am thinking about pulling my own "ugly duckling" perf board construction DAC and retrofitting this one in its place.If nothing else it is not as ugly as my own Mongo-DAC franken USB cob job. The process is involves adding a switch to pin #9 (FSEL) : Low=I2s High=SPDIF and tapping the signal for the transformer coupled SPDIF feed at DOUT (pin #17) Not entirely shure how to get the I2S/SPDIF feed/switching from DOUT squared away yet but hell,I just started to get up to speed here so cut some friggin' slack ! Last is the TDA1543 reclocker.not sure where this will go yet.could be the Kwak Clock V7,could be the L-Clock (both schemas available for downloading) or maybe right to a Tent Clock.Dunno.Not real high on the priority list yet. Also have no yet decided if I will add an analog output feed from the USB chip for use with a line level device (see fig.32 "remote headphone feed") The only other possible mod I can think of would be to add in a digital receiver card for the TDA1543 making the DAC a full function "everything digital" DAC but that goes beyond where I am at presently which is gathering parts,doing the build,begin the "feed me" tweak process.Having little or know experience with the Phillips chips (I use all ADI or BB DAC and ADC work,TI for all USB) I need to get the head to head going to see which DAC stays and which goes or maybe even if i need to modify the DITB again for portable use [ I will also do out a 6N1P stage without the SINC correction which is not needed for DACs with digital filters for the 8X OS DITB/PCM2706 USB-to-SPDIF "Cobble DAC" for head to head comparing ] More later....................................... |
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Nov 26, 2006 17:46:25 GMT
oh yeah,I just happen to have the PCM2707 chip already waiting for a project so maybe this was on my list even before I conciously thought about it................... Twilight Zone shit again |
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Post by jelosno on Nov 27, 2006 16:34:46 GMT
Rick! Not sure what you've found in your mail but if it is a 'HPDAC v0.1b2s' PDC by Dough Savitsky then it is what should be there as far as I am concerned For the rest of your post.... I have not really a clue what you are elaborating about That is why I have bought that 'kit' thing. So I have not to come up with a own design. Simply i 'cause i can't. I also could not find 'Thunderstone Technical' on Yahoo Groups either. Never mind.... What sounds VERY interesting is that 5V power supply. I was thinking of replacing some of hte 5V supplies in my CDP anyway. Stefan |
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Post by jelosno on Nov 27, 2006 16:36:05 GMT
I did actually knew that one But what does it translate to? Complete other world regarding caps and resistors and such? Stefan |
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Nov 27, 2006 18:31:17 GMT
Yup,that would be the kitty cat but in the end likely wll bear little resemblence to the original the first "designator" being tossed being the 'HP' part of the 'HPDAC".Be more or less using the pcb as the mounting surface for the USB and Power regulator sections unless I decide to do to an on-board buffered output tech.groups.yahoo.com/group/Thunderstone_technical/?yguid=175486106an excellant design for digital chip regulation.One it seems has been copied and "modified" a bit by others so they can call it their own but best left exactly as is unless you need more current output. You also want to check ou the SINC Filter and the graphs which show the falling top end of Non OS DACs.This "rolled treble" is part of why so many like Nono DACs though getting them to admit it would be like pulling hens teeth.Adding the correction in brings the DAC back to full bandwidth operation,as it should be,while maintaining the uncanny sense of space/image of the non OS method. There are two version shown.One uses an ECC88/6J7 (or 6N1P with a single resistor change if you have the heater current available ) which can get a bit pricey when you add in high voltage power supply and passive parts,or the "El Cheapamungo" verson shown as a passive but easily followed by a AD811 CFB amp to both buffer the filter output and get enough drive to place the DAC anywhere within reason (cable drive ) In layman's terms not all passive parts sound good/respond well at AF so the analog stages need to have the passives selected totally on the SQ since ALL will pretty much measure identical. RF is an totally different animal and should be thought of just as the name suggests-a radio,and radios being what they are transmit or receive. Digital circuitry transmits RF and since it is not a signal we want can be considered a distortion so we want to isolate interference not only coming IN to the chips form either radiated or power supply riders ( the bypasses) but eliminate any RF from going BACK out then on to the power supply to mix with the signal to be used again elsewhere (decoupling/isolating). Being that these frequencies are very high any stray inductance or capacitance can act as a mini-tuner or mini-transmitter,more or less as just as these parameters are used in an actual radio (tuning cap/peaking coils-the "tuned" circuit ) so the goal is to tune out what we don't want and reduce the overall intensity and that usually by reducing impedances to allow only lower fequencies to pass combined with inductor/capacitors to "tune out" the RF band. What this has to do with part selection is plain and simple-some parts are just piss poor at RF and will do more harm than good and mainly why I cringe (though say nothing ) when I see "audio grade" parts selected because they sound good used at frequencies they have no place in-the old "color co-ordinated pcb" thing where if it looks good it IS good ;D There is a reason you see certain parts on a DAC board you would never ever see in a line level analog device (solid electrolyte OS Cons,NPO and /or stacked film,teeny tiny inductors (because it is RF,if it was AF they would be BIG MAMMA HONKERS due to response band  ),etc. Probably butchered the answer but mayube you get what i am trying to say in a kinda sorta 'roundabout "huh ?" type way. and again,I owe you one man PS-Check your in box in about ten minutes,will send the files your way |
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Nov 27, 2006 19:14:32 GMT
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rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
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Post by rickcr42 on Nov 28, 2006 5:47:37 GMT
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Post by jelosno on Nov 28, 2006 9:18:20 GMT
NOT at all! You have helped me big time already. Remember how it all started - with the decission on the headphone amp that turned out to be the EAR+  But hey, I am happy that the little kit it was a surprise Stefan |
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)
) the I2S should whip the spdif/spdif ass being a more direct connection but the reality is unless built directly into the DAC itself it is not an improvement but in fact the opposite so why not build it in ?
) that allows me to instantly punch in the new and compare diretly to the old or choose system parts depending on use/mood/phase of the frikkin' moon,wow factor.............
) most notably being the Foobar player.I never liked the player itself but for sonic quality the best out there.......until now !
),etc.