To properly evaluate audio equipment, you must cut the soles off your shoes, sit in a tree, and learn to play the flute.
If you are merely the designer of the equipment, your knowledge is of a trivial and meager kind 😀.
If you are merely the designer of the equipment, your knowledge is of a trivial and meager kind 😀.
dave_gerecke said:
Then there is the change under a delta mass load of constant variance that plays in and really starts to wreak havoc with the simplistic models that are applied. I went to something that makes all of that entirely irrelevant.
KBK said:
Ah yes, the old "delta mass load of constant variance". I hate it when that happens. 😀
andy_c said:
You're not going to go down in history with Galileo with that narrow minded attitude.
"Jupiter's moons won't affect an optical cable, rather try a good 75Ohm coaxial cable. With a SPDIF output, cables can have a large influence on SQ, there are more to it than sending data bits."
OK Andre, perhaps you can enlighten us. What more to it is there other than error free data ?
If I have a data pattern on a CD and that data pattern is 100% error free when read into my DAC then what is the science that makes the cable bringing the bits from CD to DAC sound different?
As far as I am aware if the bit pattern intended at the CD production is 100% the same bit pattern written into my DAC, and at the correct jitter free rate of course, then everything in the entire chain of cables and everything else - mains cables, anti vibration mats etc. is completely and utterly going to make no difference to the sound.
OK, once back in the analogue domain all bets are off, but the items with most affect are without a doubt the big mechanical ones that are least easy for an engineer to make perfect, i.e. the speakers. Oh and as for mains cables, please explain why the house wiring is acceptable if the mains cable is supposed to make such a sonic impact.
OK Andre, perhaps you can enlighten us. What more to it is there other than error free data ?
If I have a data pattern on a CD and that data pattern is 100% error free when read into my DAC then what is the science that makes the cable bringing the bits from CD to DAC sound different?
As far as I am aware if the bit pattern intended at the CD production is 100% the same bit pattern written into my DAC, and at the correct jitter free rate of course, then everything in the entire chain of cables and everything else - mains cables, anti vibration mats etc. is completely and utterly going to make no difference to the sound.
OK, once back in the analogue domain all bets are off, but the items with most affect are without a doubt the big mechanical ones that are least easy for an engineer to make perfect, i.e. the speakers. Oh and as for mains cables, please explain why the house wiring is acceptable if the mains cable is supposed to make such a sonic impact.
SY said:
Well, maybe WireWorld would be a candidate; they were strongly advocating double blind testing in regard to cables, did produce special bypass switching ciruits for doing blind tests.
And maybe Cardas would also be a possibility.
AFAIR the story Bernie Grundmann once ordered a lot of test cables from different manufacturers for doing comparisons. They send out CDs to their recording engineers, produced with different wires, and asked them to choose the best sounding CD.
After the run, Cardas cable was choosen for the new Studio planned at that time.
alansawyer said:
Unfortunately something like "free from jitter" doesn´t exist in reality. So. again it´s more a matter of bringing jitter below the audibility threshold.
The audibility of jitter is still an open question, because the number of studies on this subject is quite low, at least as i´m aware. Julian Dunn provided a very conservative threshold curve, based on theoretical considerations; a later study published in the JAES found even quite high levels of jitter inaudible, but - i know SY will hate me for this 🙂 - used questionable methods.
Second possibility for sound differences could be a coupling mechanism between the two units. For good reasons were the standards later a bit more rigouros regarding interface aspects.
Today, as a lot of more factors are known then in the beginning, it would be possible to use optical connections for this purpose, and to have receiving stages that are immun to the quite high levels of jitter introduced by transmitters via the optical outputs.
alansawyer said:
There is a significant amount of investigation that has gone into this - engineering and scientific. Since I have CRS and digital is not exactly my forte, I'm strugging to recreate in my mind a very good paper on exactly this topic.
The short version is that there are many good factual papers online regarding this topic, and they will tell you that the reconstruction of the waveform is not so simple, and merely having "all the data" is only part of the trick, actually that's the easy part as it turns out...
Ahhh...Iirc, I think the upshot is that jitter is like FMing the bits, so the reconstruction is "off" in time... those synapses are very weak, oooh so weak... I must rest now....
Someone correct me please! I have no idea what I'm yammering about.
_-_-bear
alansawyer said:
With a SPDIF signal, the data and clock signals are combined and sent over one cable, this create clock jitter already. Now add reflections and distortion from improper cable / connector impedance and the problem get worse. It is hard if not impossible to recreate the clock without jitter. The problem show itself only when the digital signal get converted to an analog level with the wrong timing intervals.
alansawyer said:
Housewiring (where I live) must be at least 2.5 sq mm to the plugs, not many power cables come close.
Further, I believe the problem is with RF on the power lines, feeding directly into the equipment enclosure, affecting the circuitry. Good power cable act as RF filters while maintaining low impedance, thus reducing RF levels inside the enclosure and still allow for 'unrestricted' current pulses to flow.
Don't know if I can enlighten you but I hope it help. 😀
André
So if you read what I wrote
then you do agree that any adequate cable will be the same and as good as any other? This is plain and relatively simple engineering. Yes maybe some do CD players do not get the same bits at the same rate but there is not magic invloved and cheap cable is as good as ridiculously expensive cable provided the data gets to the DAC correclty.
alansawyer said:
I did not experiment with SPDIF signals a lot because I believe the format is flawed. I did try three different cables on my system, a relatively cheap 75 Ohm cable that I've made myself and two other quite expensive cables. All three of them sounded different, the best one of the three made a significant improvement on all aspects of the music. I was very surprised with the test result because I also believed that cables can't influence digital signals although I dont see SPDIF as digital anymore.
As I've explained, I believe the problem is caused by added jitter.
Well said, Andre. Most people have no idea what is coming from their outlet. Bob used to use tin plated (I think) AC power cables rather than silver, so that the RF, because of skin effect, would flow through the tin. Seemed to work.
john curl said:
That is quite clever, I believe it can work. The power cables I use are about 3 sq mm with lots of fine copper strands twisted in a "rope lay" format.
Andre Visser said:
With a sufficientley large FIFO and reclocking all these problems become irrelevent.
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