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Opening an old can of worms/cd transports
I know most of you embrace the theory that there is no audible difference between one cd transport and another. Well explain this to me.
I recently bought a Conrad Johnson DA-3 DAC. To hear it at it's best I placed it in my Krell system. I used the coaxial output of my Krell cd player. Sound was great. I unplugged the coaxial digital cable from the Krell and placed in the digital output of a TDK cd recorder. All things the same except using the TDK transport instead of the Krell. The drop in sound quality was huge. So one can only assume it makes an audible difference in how the digital information is handled or transmitted by the transports. Maybe you all couldn't hear differences between similar player's transport. I know there are two hardened schools of thought here but you would have to be deaf not to hear the difference between the two I tried. I know that these two transports are at opposite ends of the audio spectrum but no difference is no difference, right?
To be fair, my friend who sold me the DAC said he tried various transports without hearing any difference.
I thought I would throw this experience out to see if anyone has an idea as to what is causing this difference. Or, any one else have a similar experience.
As time permits I plan to take the DAC and the TDK into another system to see how the TDK compares to an upper end Denon transport. I'll post my findings here.
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A lot of people know they make a difference -- a lot of other people site faulty tests such as DBT's. If you're in the latter camp then they make no audible difference -- you have buffer arguments etc.
I can't see in your example that there would be a change in level - butsome tube dacs are higher output which can swing a listening test to their favour - so Hi-Fi Choice made a note that with on AN Dac that one should be careful to level match --- they level match and they listen in blind panels...it is not a test environment because differences are assumed --- which takes a lot of stress off the listener and is pyschologivcally MORE valid than AES variants.
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A lot depends on the DAC
Strictly speaking, some audible differences between transports will depend on the quality of the DAC itself, some DACs have much better interfaces and therefore a more consistent performance from one transport to another, however some of the more elaborate transports do some exotic DSP on the digital signal coming off the disc, so some of these transports may sound different irrespective of the quality of the DAC, especially if the goal of original design was to provide a less neutral but more subjectively richer musical experience, which is not necessarily a bad idea in a domestic environment.
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Dedicated transports that aren't doctoring the data stream will produce identical results before it hit's the digital analog conversion stage. To claim otherwise simply means you don't know what the definition of digital is since the data in a digital trasnport is not subject to interpretation - and time domain issues are a 'flat earth' level rebuttal. Jitter is a function of D to A conversion and not a function of a transport.
I use an external DAC for my audio listening, and regardless of source; my computer's CDROM, or any of a half dozen DVD players and transports, as long as I use that same DAC, the music sounds the same. As soon as I start to use other DAC's, everything changes (usually for the worse), and it's an obvious, testable and verifyable difference.
If 'audiophiles' had spent more time focusing on DAC design vs illogical pursuits like bragging who had the best $1000+ transport we'd be 10 years ahead of the curve. DAC's are the key to good digital playback - not transports.
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Quote:
Originally Posted by abstracta
Dedicated transports that aren't doctoring the data stream will produce identical results before it hit's the digital analog conversion stage. To claim otherwise simply means you don't know what the definition of digital is since the data in a digital trasnport is not subject to interpretation - and time domain issues are a 'flat earth' level rebuttal. Jitter is a function of D to A conversion and not a function of a transport.
If you look at the detailed design of many elaborate dedicated transports, they do exactly that i.e. 'doctor' the data, 'doctor' being a highly appropriate word on this occasion, hence the reason for my original comments in the first place, a dedicated transport can do anything it see fit to the data before it hits the output interface, the problem with too many folks in this discussions is that their arguments presume perfection, i.e. perfect clock, prefect data on disk, data read by laser perfectly, perfectly transferred to a perfect digital output interface and received perfectly by a DAC with a perfect receiver interface, afterall it is digital and only one and zeros so it must be perfect, If only. Jitter is catch all term for various kinds of timing errors of which the sampling jitter that occurs at the D-A or A-D is just one type. Interface jitter which is itself a catch all phrase is addressed at the transport and the DAC receiver interface.
The quality of transports can and do make a difference and my experience does not mirror yours, I can hear audible differences between some of my transports as well as diffferences between different digital interfaces suggesting that some interfaces are more robust than others.
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Originally Posted by theaudiohobby
The quality of transports can and do make a difference and my experience does not mirror yours, I can hear audible differences between some of my transports as well as diffferences between different digital interfaces suggesting that some interfaces are more robust than others.
Ditto. My experience supports the notion that we have not as yet fully figured out everything responsible for audible differences in the digital domain.
rw
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Quote:
Originally Posted by theaudiohobby
..., a dedicated transport can do anything it see fit to the data before it hits the output interface, the problem with too many folks in this discussions is that their arguments presume perfection, i.e. perfect clock, prefect data on disk, data read by laser perfectly, perfectly transferred to a perfect digital output interface and received perfectly by a DAC with a perfect receiver interface, afterall it is digital and only one and zeros so it must be perfect,
The quality of transports can and do make a difference and my experience does not mirror yours, I can hear audible differences between some of my transports as well as diffferences between different digital interfaces suggesting that some interfaces are more robust than others.
Absolutely nobody is assuming perfection in anything, that is a straw man (once again).
The purpose of a transport is to read and deliver bits to the converter. In a digital world they are either good enough or they aren't (i.e., it ain't analog). If the transport "did something" to the bits, the DA converter would not be able to convert them and you would get a gross audible error (including mistracking). One can simply look at the bits comming off a known encoded CD to see if they are good enough (I presume the Q/A department of the transport makers do exactly that). And, of course we can simply measure the bitstream or analog output at any point in the system and see the error or distortion present. Jitter (which, as was pointed out, does not come from the transport--you are simply wrong) would show up in THD distortion measurements. What is preventing high end seprate transport makers from telling us how much better their transports are at reading and delivering bits (with specs, not marketing text)?
(In the computer biz, CD drive makers can then proceed to tell us that their optical drives read data much more accurately than their competitors--spinning many times faster than audio CDs.)
Now, why should we throw logic out the window because a few people who don't seem to understand what is going on report hearing differences or say that transports and can do make a difference? Prove it, or at least provide some information other than you think you hear a difference, otherwise you are part of the problem. I can think of other reasons that a more likely explanations for any differences "heard"--starting with listener bias. Why should you be allowed to simply ignore those possible sources of differences?
As I have previously stated, uncontrolled listening reports from "audiophiles" have been demonstrated as being highly unreliable. No offense, but your report is an uncontrolled listening report.
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Take it or leave it
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Originally Posted by RobotCzar
Prove it, or at least provide some information other than you think you hear a difference, otherwise you are part of the problem. I can think of other reasons that a more likely explanations for any differences "heard"--starting with listener bias. Why should you be allowed to simply ignore those possible sources of differences?
Take it or leave it, the uninformed comments of a naysayer (you), however well meaning if they are, take nothing away from the facts that transports and digital interfaces can and do make a difference to digital audio quality.
Another round of fruitless circular arguments, nope not this time around, if you are not satisfied with my comments then so be it, your scepticism does not invalidate my observations nor any respectable publications on the subject If you are interested, educate yourself.
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Quote:
Originally Posted by theaudiohobby
The quality of transports can and do make a difference and my experience does not mirror yours, I can hear audible differences between some of my transports
Knew this guy who swore to every religion on earth he could hear differences when he used those CD demagnetizers/conditioners.
Basically if your $1,000 transport isn't processing data with fidelity and dumping it into the digital stream as it should be on disk, then perhaps it's time to go to Best Buy and get yourself a $25 48x CD ROM that has orders of magnitude more data through-put and error correction capability than your over priced disk spinner.
Had a discussion with an Engineer from Burr-Brown a few years ago. You know, the same Burr-Brown that builds the DAC's in the first place. He claimed as part of their testing procedures they place malformed clocks in front of the data stream to their testing DAC's and run data timing errors 10,000 more severe than is typically encountered in a home stereo. Still, you guys go our and buy those fancy digital cables, and put clocks in front of a digital stream that's going to be re-clocked at the DAC anyhow - yeah, that's intelligent. No offense, but if you are hearing sonic differences in CD transports and not DACs, then the transport is altering the actual word content and it gives us all the more reason to move away from the entire H-Fi industry. Last thing I want is a random number generator on the transport altering the digital stream, and it justifes why I rip everything to WAV, use a decent external DAC, and throw my CD's in a box. Perhaps you can tell the sonic differences between 8 and 64k clusters on a hard drive, and DDR 2100 vs 2700.
Honestly, I ran across this site the other day that sold a $3000 transport and DAC, and clamied their 'Proprietary' processing was good down to 15 Picoseconds. Last I checked a picosecond dealt with timing on the order of sub atomic reactions. If I sum this entire discussion up, it basically claims the human race can't quite handle reading a simple audio CD at a relative snails pace, and deliver that information in correct form to a lowly IC based DAC in a timely fashion. Yet, your average home computer has processors and memory in it than is a million times more sensitive to latency and handles infinitley more bandwidth. Sorry, I'll take the side of the Burr-Brown engineer.
Hey, you can cliam all you want in the analog domain, but digital processing and transmissions isn't subject to this kind of religion.
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Quote:
Originally Posted by abstracta
Knew this guy who swore to every religion on earth he could hear differences when he used those CD demagnetizers/conditioners.
Basically if your $1,000 transport isn't processing data with fidelity and dumping it into the digital stream as it should be on disk, then perhaps it's time to go to Best Buy and get yourself a $25 48x CD ROM that has orders of magnitude more data through-put and error correction capability than your over priced disk spinner.
Had a discussion with an Engineer from Burr-Brown a few years ago. You know, the same Burr-Brown that builds the DAC's in the first place. He claimed as part of their testing procedures they place malformed clocks in front of the data stream to their testing DAC's and run data timing errors 10,000 more severe than is typically encountered in a home stereo. Still, you guys go our and buy those fancy digital cables, and put clocks in front of a digital stream that's going to be re-clocked at the DAC anyhow - yeah, that's intelligent. No offense, but if you are hearing sonic differences in CD transports and not DACs.
I do not know the precise details of your conversation with the said Burr Brown engineer but your assessment of digital audio performance is grossly misinformed. I have included a link that shows the adopted AES standard for transmitting digital audio, compare it your SPDIF link. Simply put transports matter, doubly so for SPDIF interfaces, with audible differences. There are more than a number of credible documents that attest to this fact to the extent that a new standard was proposed and widely adopted in the professional world to address the negative effects of transport induced jitter.
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