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Does the quality of a digital signal matter?

I recently heard a demonstration where a CD player was played with and without being supported with three Nordost Sort Kones. The difference was audible to me, but did not blow me away.

I was discussing the Sort Kones with a friend of mine that is an electrical engineer and also a musical audio guy. It was his opinion that these items could certain make an improvement in an analogue signal, but shouldn't do anything for a digital signal. He said that as long as the component receiving the digital signal can recognize a 1 or 0 then the signal is successful. It's a pass/fail situation and doesn't rely on levels of quality.

An example that he gave me was that we think nothing of using a cheap CDRW drive to duplicate a CD with no worry about the quality being reduced. If the signal isn't read in full an error is reported so we know that the entire signal has been sent.

I believe he said that it's possible to show that a more expensive digital cable is better than another, but the end product doesn't change.

There was a test done with HDMI cables that tested cables of different prices. The only difference in picture quality was noted when a cable was defective and there was an obvious problem on the display.

I realize that the most use analogue signals, but for those of us that use a receiver for our D/A, does the CD players quality matter? Any thoughts?
mceljo
paulsax
275 posts
 
let me ask a related but slightly different question. I read often of a player being colored. THere is a thread right now about a music hall player being slightly "forward" and "bright". All things equal and in a world where jitter is the dominate error (or am I misunderstanding the tone of this thread?) how does a "color" creep in? Jitter seems like a strictly time domain issue and the coloration of music would seem like a level vs frequency issue? If so that may imply that the DAC or perhaps some outside electronics issue outside of bit reading is at play. Is that a reasonable assessment?

Sorry about the dumb questions. I'm your boy for mechanical engineering / physics / material science but I'm just about the "bang the rocks together" stage with digital electronics!
mapman's avatar
mapman
22,341 posts
 
Expect different DACs to have different tonality for sure.
kijanki's avatar
kijanki
4,428 posts
 
Paulsax - IMHO everything plays role. In addition to sound of jitter that was described in mentioned Stereophile article there is digital signal processing (oversampling, non-oversampling, upsampling) and filtering algorithm, type of DAC (traditional or sigma-delta, voltage or current output, single or dual differential etc.), particular DAC selected (sound differently) and chosen update rate, type of current to voltage conversion (transformer, tube, op-amp), analog electronics (tubes, op-amps, discrete), type of op-amp or tubes, quality of components and PCB, quality of power supply. It is endless list. Even something trivial like "mute" circuit can be responsible for loss of sound quality.

At the end sound in your system is the only thing that matters.
almarg's avatar
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almarg
9,670 posts
 
Paul, I believe the thread you are referring to is dealing with a one-box cd player (a Music Hall CD25.2).

Although it has a digital output and can be used as a transport in conjunction with a separate dac, presumably the discussion pertains to its analog outputs, which are generated by its own internal dac, and processed through its analog circuitry. Given that, as Mapman indicated, tonality and color can certainly be affected by the design and quality of the dac and the analog circuitry in the player.

Jitter is the predominant consideration just in the digital parts of the signal path, up to and including the dac chip. And it becomes a MUCH more critical consideration when the transport and dac are in separate components, because of the impedance matching, reflection, noise, clock recovery, and other interface-related issues that have been discussed above.

Best regards,
-- Al
musicnoise
377 posts
 
Paulsax: Once the digital signal is converted back to an analog signal there can be any amount of additional amplification, filtering, etc within the CDP prior to feeding the analog signal to the preamplifier. The effect of this additional signal processing is what is important and would certainly affect the sound,and indeed would be likely to have been designed for just that purpose. It is this post conversion processing that colors the sound, not the completeley insignificant effect of jitter.
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