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Discussion Starter #1
Hi All,


I just wanted to see how many here believe that an HTPC belongs in a highend home theater system. I have heard many praise the video quality of the HTPC. Many believe that the picture rivals that of a Faroudja processor.


But how many here think that a noisy HTPC can beat a good quality stand alone dvd player, such as a Pioneer Elite DV-09 or Theta David, or even the Sony 7000, in sound quality with movie sound tracks in either AC-3 and DTS.


I am only asking because I am considering building an HTPC but I am more concerned about the audio capabilities, more so than the video capabilities.


Currenty I have a Sony Dvp-S7000 paired with a Quadscan scaler and using a EAD Theatermaster Signature preamp/processor with a Powermaster 2000.


Any opinion and advice is appreciated.


Sincerely, Brian
 

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So long the HTPC can succcessfully pass the digtal stream to your receiver/processor, there should be no difference. But if your HTPC is decoding and sending analog signals to your R/P then you have all the problems and issues you are concerned about. Don't let anyone fool you into thinking a digital signal is as sensitive as analog signals. All you are passing are 1s and 0s. (pulse on/pulse off). If that task were affected by the inner workings of a PC none of us would be working with our PCs now.


Once while in a high end audio video store the guy tried to sell me really expensive digital cables. For kicks, I asked him which was musicaly better for digital connections, optical or coax? He told me that optical (at $300) was brighter and more sonically accurate.

It was quite amusing to see someone try and gouge my pocket by talking about something they don't understand. There is no brightness or frequency range with digital signals. Just pulse on pulse off. So long as the signal is strong enough for the receiving component to decipher on and off, you are good to go.
 

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My setup:


HTPC

NEC LT150 projector /Toshiba 32" TV

Marantz Receiver

Hafler Amp (FL, FR)

Celestion A4C center

Celestion SL6si FL, FR

NHT RL, RR

Technics DVD-A10 DVD audio/video player
 

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Sound for Video: who cares, really?? Movies are mostly dialogue plus the eventual soundtrack. Here I believe that having a good DTS and AC3 processor, 5 identical speakers and amps, is more important than the standalone DVD player or htpc. Neither one will ever be good enough for music.


For the same reasons I don't believe that someone has to buy top quality speakers and amps for video because it won't make any difference. Reserve top speakers and top amps for two ch stereo playback where you can hear the difference big time. Having one audio system for video and one audio system for music is best. GF.
 

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Loganross,


I suspect that Brian may have meant the audible noise of the fans, not electrical noise.


Brian,


With the appropriate choice of components, HTPCs can be quiet, but they have to be carefully designed so everything is kept cool. Quiet fans don't move as much air. I lost 2 dvd drives because they cooked. I don't use the PC for HT any more: the new fans are too loud.


Reasonably good multichannel analog output cards are available, but I suspect they aren't going to be as linear or have as low an intrinsic noise floor as high-end pre/pros. Computer electrical noise is up around a gigaHertz, so by itself it usually doesn't cause problems in the audible frequency range below 20 kiloHertz.


Anyhow, most people just connect a digital audio cable from the computer to a receiver or pre/pro which decodes the DVD audio tracks. Also, don't expect to see SACD or DVD-A decoder software any time soon. (In other words, it won't happen at all if the recording industry has anything to say about it.)
 

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Discussion Starter #6
Hi All,


Thanks for the input and replies so far.


I do think that having a good transport makes a difference. I am currently using a Sony Scd-777es as a transport for redbook cd's. And it is an improvement from using my EAD T-1000 transport and it is night and day difference in using Sony 7000 dvd player as a transport.


Although I do agree with Grosse Fatigue that movie sound tracks aren't as critical to me as listening to 2 channel music. I still think that good dvd transport should give you that added wow factor when watching action films.


I might have to consider an HTPC for just its video merits.


But I do disagree with loganross. Using better digital cables does make a difference, as well as a better transport.


I was using an Audio alchemy digital cable for my dvd player and decided to upgrade to my current Harmonic Technology Cyberlink platinum cable. And wow the sound with my movies is dramatically different, sound wise. It really depends if your system is revealing enough.


I did buy an M-audio sound card a few months ago but I never got around to putting together an HTPC.


I was hoping to buy a used Faroudja NR scaler but I haven't been able to find one at the price I want to buy at yet. So I am considering an HTPC route.


Thanks again, Brian
 

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Quote:
Originally posted by loganross
Once while in a high end audio video store the guy tried to sell me really expensive digital cables. For kicks, I asked him which was musicaly better for digital connections, optical or coax? He told me that optical (at $300) was brighter and more sonically accurate.

It was quite amusing to see someone try and gouge my pocket by talking about something they don't understand. There is no brightness or frequency range with digital signals. Just pulse on pulse off. So long as the signal is strong enough for the receiving component to decipher on and off, you are good to go.
Over the last months, I had two chances to compare coxial VS optical (TOSLINK) sp/dif on both a Tag av32r and parasound processor.


Yesterday a parasound owner was clearly convinced that optical was much better, so we did the test.


With optical first (fed from a Pioneer elite R1 DVD player) and then switching to coaxial at moderate volumes it sounded slightly better, but dificult to tell why.


Then I tried some tracks with accoustic instrument (e.g. violin) at reference level with coax. When switching back to toslink it was easy to notice that optical sounded much more harder and agressive (even a bit compressed in the treblle to my ears).


Once this difference was known, another guy noticed the difference already in the first A/B, but didn't know how to address it or express his feelings about the difference.


Some rationale : coaxial means 2 extra format conversions in which timing errors (jitter) may occur. Most pre's are still sensitive for these errors, even my Tag av32r which already has some advanced anti jitter circuitry onboard.
 

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Hi,

first, you can find excellent silent power supplies at PC power and cooling (pcpowerandcooling.com).


second, (this is fact, not arguement :)

So long as a digital cable is sufficient to pass electric pulse on/electric pulse off, it is sufficient for the best audio possible (depending on other components).


If you were to open a PC or even the most expensive critical-use computer system in the world, You will not find "high end" cables to pass the digital signals. Why? its not necessary. Passing pulse on pulse off is simply a non-issue.


I would agree that having good speakers and amplification are an absolute necessity. Why? because thats where the sound we hear is formed. In addition, good A/D conversion is also absolute.


But, passing digital signals is simply not that difficult. If it were there would be no internet, no atm bank transactions, etc......


This is coming to you as not only a Patent Attorney, but also a computer scientist. The snobbery of high end audio (not you) is idiotic. It seems that many will say anything to keep themselves above the "commoners". The truth is, the more advanced technology gets, the more "common" A/D converters, digital sources become and the less there is to distinguish from High end audio.


Everyone has a right to spend (or waist) their money as they please. But when it comes to digital cables its only the manufacturers that are getting any benifit. And who can blame them, with every day the need for anaolog cables erodes and so does their profits. So why not create a new need? If I were in there shoes I would probably do the same thing.

Me, I would rather invest in Speakers, amps, and processors. to each his own :)
 

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Quote:

The snobbery of high end audio (not you) is idiotic. It seems that many will say anything to keep themselves above the "commoners". The truth is, the more advanced technology gets, the more "common" A/D converters, digital sources become and the less there is to distinguish from High end audio.

___________________________________________________


The snobbery is mostly in stores at the selling level, and is not perpetuated by audiophiles. It is powder dust bad and ignorant salesmen throw at newbies, alienating a majority of them. In fact I find most audiophiles more interesting, more educated in arts with a self deprecating bend and penchant for anarchy, less technical than the straitlaced and boring video crowd, in general.

GF.
 

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Quote:
Originally posted by loganross


In addition, good A/D conversion is also absolute.


But, passing digital signals is simply not that difficult. If it were there would be no internet, no atm bank transactions, etc......


This is coming to you as not only a Patent Attorney, but also a computer scientist. The snobbery of high end audio (not you) is idiotic. It seems that many will say anything to keep themselves above the "commoners".
May I point out a few flaws...


1) Its a D/A convertor, not an A/D convertor. Yes, the studios need a good A/D convertor... the consumer needs a good D/A convertor. Consumers only need an A/D convertor for video on analog sources.


2) It is actually much more difficult to pass a digital signal than you lay claim to here for audio. Its easy to send the 1's and 0's and atms have no problems with it because the timing doesn't matter. However, audio is a different story and a high jitter data stream is not only audible, it sound like garbage. Crappy transports produce a crappy high jitter signal... sure, they get the bits right but cannot send them in a clean fashion to the D/A to save their life. It sounds like a high frequency shrill that is nothing short of annoying.


3) Does being a patent attorney and a computer scientist make you informed on digital audio? Obviously not since you kept thinking it was an A/D convertor and know absolutely nothing about digital jitter.


4) I agree, there is a lot of junk kicked around in high end circles. There is also a lot of truth to it that has brought a much higher degree of quality to the recording business (if you knew the junk that goes on in a lot of studios, it is kind of scary). Once upon a time, Sony claimed the 16 bit CD was perfect sound forever. Well, it took them a while but they eventually admitted that the analog sources they tried to replace sounded better and they needed to come out with better technology. There are reasons why studios still record in analog... and doing so is far more expensive than doing it in digital.
 

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Yes being a patent attorney and a computer scientist makes me caspable to answer such questions because the transfer of a PCM data stream is the realm of physics and electrical engineering, not audio.


What makes the PCM data stream audio is how it is interpreted by the receiving D/A converter. Pulse on and Pulse off is the same for music or any other data type. And the quality (or algorithms) of the D/A converter is what determines the quality of the sound you hear (along with your pre-amp/speakers etc.).


As far as jitter is concerned, if your are referring to the audio anomolies caused where there are errors reading off the DVD (delays, scratches, etc.) I agree, but that is a problem with the drive, not the cables. The cables will forward whatever they have been given (perfect or erred) and even a $15 digital cable is more than capable of handling the amount of data forwarded by a DVD or any other audio video digital source. Remember it is a serial data stream. Bandwidth /frequency range, etc. are not issues.


The only advantage to an optical cable is in an area where there is an extremely large amount of magnetic interference. Here, the optical cable, which uses light, is basically immune. However, under such circumstances I would say that the cables are the least of your problems.


Final note, I also agree the it is most often the high end sales persons propagating the snobbery.
 

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Quote:
Originally posted by scooter_29



Its easy to send the 1's and 0's and atms have no problems with it because the timing doesn't matter.
I will have to disagree with you there. Timing IS everything here. You are talking upwards of 150 Mbps all the way up to 10 Gbps. Timing is everything. Otherwise you have packet colliosions and if you do all that speed is worthless. Also as stated by loganross remeber that digital is serial. So if we had no timing. What would prevent the other side from building the packet in an inccorect order? Again timing. Prime example is Frame relay. Timing is very critical as the signal usually never travels the same path twice but somehow it gets to the other side and is put in the correct order.
 

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Yes your are correct, but we are not talking about TCP/IP and we are speaking specifically about the role of the cables, not other components.


In this case there is no travel via multiple pathways an no reordering of packets at the destination end, as there is with tcp/ip. Just a single (serial) stream. There are no tcp/ip type collisions because there are not multiple sender devices and destination devices as on a tcp/ip network. Instead there is a single sender device (dvd player) and a single destination device (receiver/processor).


In fact even TCP generally runs on a baseband network such as ethernet, meaning one signal at a time, although the single stream can be out of order. Multiple devices can communicate on the same TCP/IP network because of collision detection and retransmission techniques such as CDMA (collision detection multiple access)


I think when you are talking about timing that you are really talking about data overruns and underruns. But this has nothing to do with the cables. This has to do with the quality of the DACs, data buffers, etc.


Also, I should mention that there could be a possible difference between audio when using optical vs coax digital cables if the component (DVD player or processor) implements one interface more poorly than the other.


I guess that what I am trying to say is that the passing of PCM data (or any data) over a digital cable (coax or optical) requires such a low threshold as far as cable type, shieldng etc. is concerned that what is considered advantageous for anaolg cables is irrelevent for digital. All the cable has o do is reach the threshold.


So I believe my premise still holds although I would welcome any corrections to mistakes I have made


This is actually a very interesting discussion.
 

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A note about coax vs. optical.


I use both. optical is better for longer runs as it consists of light pulses which go longer distances before degrading and are mostly immune to EM interference.


Neither of these is normally an issue in a home theater setup unless you have REALLY long runs (or maybe an electric generator or microwave on top of your HTPC). Most any coax cable will have sufficient shielding for short runs.


Also, there isn't any more of a conversion for optical than there is for coax. Optical uses pulses of light to represent the data bits ("1s and 0s" or "ons and offs") while coax uses pulses of electricity.


Coax: on bit = electrical pulse / off bit = no electrical pulse

Optical: on bit = light pulse / off bit = no light pulse


THAT IS ALL THAT GOES ACROSS THE CABLE.


As a result there is a bit for bit forwarding of the audio data stream across the cable. There is no "lossy" (loss of data/loss of quality) conversion in the way one thinks for an analog-digital conversion.


Hope this helps.
 

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â€Coax: on bit = electrical pulse / off bit = no electrical pulseâ€


This is true for TTL signals but not for digital audio (S/PDIF) transmissions.


The S/PDIF digital signal is coded using the 'biphase-mark-code' (BMC), which is a kind of phase modulation. In this system, two zero-crossings of the signal mean a logical 1 and one zero-crossing means a logical 0.


S/PDIF biphase-mark-code has an amplitude of 500 mV (peak-to-peak), meaning it is a +250 mV / -250 mV signal in reference to the zero-crossing point, unlike TTL that has a 0-5 V peak amplitude.


The biggest mistake people make is assuming that S/PDIF transmission lines function exactly the same as TTL digital.
 

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Logan-


I agree with your analysis and apologize for the comments. Frequently, people make claims about the b.s. in the high end world and at its heart, a lot of it makes sense. The high end community has promoted technological change that has found its way over the years into a lot of the mass market equipment today which has substantially improved its quality.


One of the points I was getting at was something else you briefly mentioned... which is the implementation of the digital interface and not to blame the cable. Very frequently, toslink interfaces are not implemented very well and are jitter prone (see below). There are definitely audible differences between a toslink interface and an SPDIF interface that I don't blame on the cable. If you know what to listen for and have a decent system, the differences are readily apparent. Not only does the high-end audio community avoid toslink like the plague, so does most quality digital studio gear.


On the subject of jitter, I am not talking about scratches and dirt. I am talking about minute timing differences of the word clocks between all of the digital components in the signal path (from A/D in the recording process, D/D in the mastering and CD pressing process, to the CD transport, and then ultimately the D/A... lots of word clocks and interfaces to deal with). Most consumer gear leaves a lot to be desired when it comes to jitter. You won't find a $350 CD player doing much and you definitely won't find a $50 computer DVD player coupled to a $50 sound card doing much either.


Also, about my timing comment... it was stated out of context... yes, timing is everything in the computer world as well... just has different consequences... either my data arrives or it doesn't... but I don't have to listen to it... read the jitter article below and my comment will make more sense.


Here is an excellent article on jitter:

http://www.digido.com/jitteressay.html
 

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Interesting link about jitter. The most important paragraph is quoted below. Rather than spending big bucks on cables, spend them on a processor with good dejittering circuits that cache and reclock the ones and zeros. The lack of a cache at the receiving end is where all these timing problems come from. It shouldn't cost more than about 10 bucks extra for the preamp manufacturers to do it right. Of course, that means they will probably charge an extra thousand. :D


"Can Jitter in a Chain be Erased or Reduced?

The answer, thankfully, is "yes". Several of the advanced D to A converters now available to consumers contain jitter reduction circuits. Some of them use a frequency-controlled crystal oscillator to average the moment to moment variations in the source. In essence, the clock driving the D/A becomes a stable crystal, immune to the pico- or nano-second time-base variations of jittery sources. This is especially important to professionals, who have to evaluate the digital audio during recording, perhaps at the end of a chain of several Phase Locked Loops. Someday all D to A converters will incorporate very effective jitter-reduction circuits."
 

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and the clear winner is.......or is there one. Some will swear by the coax. I haven't heard any one swear by the optical. More like swear at it. BUT it is not the cables fault.


To kind of bring this into the forefront again. The HTPC as a dvd player is a good idea. Why? Simple. On the fly changes of resolution. HTPC you can do 480p, 540p, 720p and even 1080p if you puter can crunch that. There is a member here that did a comparison of a faroudja/crt combo vs a HTPC/crt combo. The HTPC was almost identical in PQ :eek: that sez alot. Of course you are comparing the price of a faroudja to a pc with a bit more items on it.


Feel free to correct me but the faroudja is one resolution or can it be changed also?


:) hehe
 

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Discussion Starter #20
Hi All,


This has turned into a great discussion into topics such as jitter and the merits of using different cables in their hometheater system.


But I wanted to see if people here have used HTPC's in their highend hometheater setups.


And what would interest me is the components that you all are using in your particular setup with your HTPC's. And did you notice a difference in sound between using an HTPC vs a stand alone dvd player in movie soundtrack in both AC-3 and DTS.


Thanks again everyone, Brian
 
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