One meter is a length that will often not be optimal. See this paper. While the paper recommends 1.5 meters, IMO a very short length (e.g., 6 inches or so, or perhaps as much as 12 inches) may also be a good choice, if that is physically practicable. There will be exceptions to these guidelines, of course, depending on various technical characteristics of the components that are being connected. Regards, -- Al |
Listen to Al. Go with 1.5 meter. As for suggestions, one good choice is DH Labs Silver Sonic D-75. It's well shielded, reasonably flexible, and sounds good. And at $90 for 1.5m, it's less than half your budget. Bryon |
Have/Canare
Black Cat Veloce
Grover Huffman
I agree on the 1.5M length being optimum in most cases. |
Listen to Al. Either go very short to avoid reflections on impedance boundaries or go 1.5m with typical transport transition time that is about 25ns. Assuming threshold in the half of that reflection from the end of the cable (started by the beginning of the transition) has to come later than 12.5ns. Assuming 2/3 of the speed of light signal travels thru 1.5m forth and back (total of 3m) in 15ns just missing threshold point. 1m cable would be much worse bringing reflection in about 10ns - just before signal crossing the threshold. Any disturbance of transition at the threshold will convert to time jitter (equivalent to noise in frequency domain).
Digital cable behaves like transmission line (reflections) when one way propagation time to point of first possible reflection (end of cable) is shorter than 1/8 of transition time (rule of thumb) - about 3ns in our case making for 0.6m. 0.5m cable should be safe but I would go no longer than 12" (as Al stated) since driver is in few inch distance from the connector. |
Kijanki:
Would that also apply for a word clock cable. I have a Esoteric player that accepts a 10mhz signal and I'm running a 3m length BNC-BNC 75ohm digital cable from the external word clock?.
Thanks. |
What happens when you have reflections? What do you hear? Ideal length for me would be maybe 0.7m I think, but need to measure. I have a 1m cheap cable currently working. |
1.5 will work ok, but i will have to coil it up at one end. So what to buy and from where? $200 or so, good quality and sound, flexible and well shielded from RF. |
06-13-12: Mike60
What happens when you have reflections? What do you hear? There would be an increase in jitter. See this paper for further background on jitter. The degree to which the jitter would have audible consequences is dependent on the particular components. In some cases there may be little or no consequence, depending on the jitter rejection capability of the DAC and other factors. Typically, though, there would be a general loss of clarity and focus, its exact character depending on the spectral characteristics (frequency content) of the jitter, which in turn are dependent in unpredictable ways on the particular components and setup. 06-13-12: Flashunlock
Would that also apply for a word clock cable. I have a Esoteric player that accepts a 10mhz signal and I'm running a 3m length BNC-BNC 75ohm digital cable from the external word clock?. I suspect that the risetime and falltime of the 10 MHz signal that is being sent out by whatever is generating your word clock are significantly faster than the risetime and falltime of the S/PDIF output of a typical transport or other S/PDIF source, so it is a fundamentally different situation. Also, the problem that can occur for S/PDIF with a 1 meter length will be avoided by lengths that are longer than 1.5 meters, as long as the length is not so long that reflections corresponding to one signal edge arrive near the mid-point of the NEXT signal edge, or some other subsequent edge. 3 meters is too short to cause a problem on the "next" edge of a 10 MHz square wave, and is very unlikely to affect subsequent edges, in part because those edges would only be affected by reflections making multiple round-trips (i.e., reflecting and re-reflecting multiple times between the two components), which would cause them to be very small in amplitude. That said, when possible it is preferable to avoid longer lengths like that, because it will reduce the possibility that jitter may occur as a result of ground loop-related noise or rfi/emi pickup. Regards, -- Al |
Mike60, Get 1.5m Reflections come from change in characteristic impedance that for higher frequencies can be defined as SQRT(L/C) and depends on geometry of the cable or connector (for given dielectric type). When you have absolutely perfect cables there would be no reflections but in practice it is almost impossible. Reflections contaminate straight transition edge of digital signal changing time when threshold is crossed (level recognized) making signal to jitter in time. This jitter is a form of modulation and as such makes two sidebands in frequency domain. These sidebands are very small but audible because not harmonically related to root frequency. With complex signal containing many frequencies (music) it creates many sidebands that together become hash/noise. This noise amplitude is proportional to signal amplitude and is zero when music is not playing - difficult to detect. It appears as lack of clarity and affects even imaging. Some of this jitter comes from noise (ambient or system) and is correlated but some is random. Using impedance matched and well shielded cables plus providing clean power reduces jitter effects.
Noisy system modulates amplitude of transmitted signal but also makes threshold (level recognition point) on receiver side not steady causing jitter.
It is very difficult to predict how reflections affect the signal because reflected signal bounces back and forth like echo between walls but there are ways of predicting how signal will get modified (Bergerone Diagrams). Read more here: http://pages.infinit.net/alcor/docs/math/TRANSMISSION%20LINE%20EFFECTS%20%20version%20L.pdf
Flashunlock, I'm not familiar with Esoteric separate clock signal but I would clock the source from the DAC, using buffered clock, on opposite edges to active clock edge (source placing bit of data on falling edge and DAC clocking it on rising edge). It is typical synchronous transmission (vs asynchronous S/Pdif) less susceptible to cable jitter but still susceptible to receiver (DAC) system noise induced jitter. I assume that Esoteric has something like that. |
Al is absolutely right stressing importance of keeping cables short. Non-magnetic shield does not stop EMI (for instance radio waves) but induced noise travels on the outside of the cable (shield) to ground because of the skin effect. Skin effect does not work at lower frequency EMI but cable is not long enough to become antenna (1/10 of wavelength) unless you make it longer than necessary. In addition, since induced noise returns thru the shield it causes voltage drops visible as signal when shield is used as one conductor (S/Pdif). Longer shield means higher impedance and bigger voltage drops. |
As usual, fantastic explanations from Al and Kijanki. 06-13-12: Mike60
What happens when you have reflections? What do you hear? As Al mentioned, it's difficult to predict the exact audible effects of jitter for any particular system, though there do seem to be some typical effects. I've had several opportunities to hear the effects of jitter in my system. A couple years ago, I added a reclocker (its raison d'être is to reduce jitter). Once or twice I reduced jitter accidentally, like when I replaced an unshielded ethernet cable with a shielded one. IME, hearing jitter is something that only happens when you REDUCE it. Anyway, here are some of its audible effects... 1. Reduced resolution 2. Shrillness in the highs 3. Fuzzy imaging 4. Unrealistic instrument timbres 5. Lack of pitch definition in the bass I'm sure there are more effects, but those are the ones I've noticed in my system that I've attributed to jitter. Taken together, reducing jitter results in a sound that is less "digital." Hope that helps. Bryon |
I bought the DH Labs D-75 a few months ago and have been very happy with it. Great cable, great company. I was using a pure silver cable before and haven't felt the need to put it back in...yet. |
I agree with the recommendation for the DH Labs Silver Sonic D-75.
An internet search will pull up several online dealers, including at least one who advertises here. You also can email DH Labs at info@silversonic.com for the nearest dealer. |
I've happily been using an Apogee Wyde Eye S/PDIF for years and most times prefer it to my Stereovox XV2 -- it's a little less crisp and more natural sounding. You can get a 0.5m cable from Musician's Friend for $50 with free shipping. Best of luck. |
Mike60, I've found the results of different coax cables to be very dependent on your gear/system - what are you connecting? And also, what connector types?
I have tried all of the following and found the basic Wireworld Starlight 6 to be best in my system (Squeezebox Touch to HK990 RCA-RCA): Supra Trico, DH Labs 75, Black Cat Silver Star |
I used a pair of the least expensive AQ cables (VDMXr or something) and although they seemed to sound fine, I upgraded to a VDM3 (1 meter) from the CD player to the DAC, and a VDM5 silver cable (.5 meter) from a Squeezebox Touch to the DAC. All work great and and the cable length seems to be irrelevant (I a/b'd them to test this) maybe due to the re-clocking ability of the DAC. The difference between the cheapest and most expensive of this group seemed minor, but it's there. Now I have an extra pair of VDMx cables languishing in my Cable Museum. |
My first choice would be HiDiamond Digital Carbon, close but not exactly in your price range. Best digital cable I've personally heard and an absolute bargain.
Second, if you need to go with a cable that already has a long standing reputation I would buy my Marigo Apparition 5.8 (RCA) from me for $300. If you're interested let me know and I'll list it. It is however not particularly flexible, but it bends and holds its shape easily and well. I wouldn't normally hawk my own stuff but the cable's rep speaks for itself and I'm selling it for a bargain price. |
Hi I recently had a convo for audio advisor and they said the length no longer matters for digital coaxial cables for any DAC built in recent times re-clocks the signal to begin with.
Is this correct I cant fine a new thread confirming this...
Any thoughts?
Kev |
My favorite reasonably priced coax is the Oyaide DR-510 (rca) and DB-510 (bnc) which is the one I've used. Comes in 0.7m and 1.3m lengths. Give it week to settle down.
Recently I've been impressed by a DH Labs D-110 balanced digital cable (under $100 new) which reinforces the recommendations above for the D-75. |
Best results for me came when I stopped messing around with RCA connections, which are woefully ill-suited for transmitting digital audio data as they are almost never a true 75ohms, and replaced my RCA digital jacks with true 75ohm BNC on both ends and replaced the fancy audio RCA cable with a simple true 75ohm BNC industrial coax cable from Digikey, of the shortest length that would reach.
Crystal clear, smooth sound. About $12.00 for two BNC jacks and $22.00 for the cable. Can you believe in better sound for $34.00?
No secret here, you don't get objectionable reflections if the impedances are matched properly, so no magical lengths or materials are required.
PS: I DO believe in good quality audio cables for analog - I prefer Zu Event in my rig. Just relating my experiences with digital. |
The best digital "coax" I've used to date is the KLEI gZero3D - but to get closer to your price point the gZero2D will also perform extremely well
I've tried them both and the 3D offers a little better imaging and a little better dynamics - but the 2D is no slouch in this respect either. Both are significantly better than anything else I've tried
There are some reviews on the KLE Innovations web site
You can order them from their web site and they generally take 4-6 days to arrive - depending on where you are.
Hope this helps. |
