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In Reply to: RE: Minimum of 1.5 meters has been discussed many times. nt posted by Elizabeth on April 07, 2014 at 11:45:48
Great, thanks you for the advice.....
........I was a vegetarian for 15 minutes... until the main course.
Follow Ups:
It is not just a matter of, a minimum of 1.5 meters.
Rather, 3 feet/1m and their multiples and fractions are to be avoided.
So, 1.5 meters or 3 meters, but NOT 2 meters.
What is important is not the length, but the time of the arrival of reflections from the far end.
If components are close, there is no reason I can see that .75m should not work, but nobody makes those as a stock item. Cardas will chop and re-terminate a 1m digital cable for a surcharge over the 1m cable.
Hope that helps.
JM
When this topic came about a few years ago I asked some of the heavy hitters in cable design, serious players, as well as pro mastering and recording engineers and overwhelming consensus was this theory about cable length is total and utter BS. I concur.With a gun to your head you could not pick out a .5m, 1m, or 1.5 cable in use.
FYI, Audioquest sells .75M stock digital cables
Edits: 04/09/14
concept came from Bob Fulton. He claimed that one meter was the length of your car antenna so 1 meter cables made perfect antennas for a lot of RF. Of course he built analog cables, so I am not sure of the applicability of his ideas for digital.
Borrowing his idea though, remember those stubby antennas for early cell phones? Pretty short: I seem to remember just three or four inches.
FWIW
That's an interesting notion, unclestu. But cable reflections are a result of improper impedance of cable terminations (and/or the cable itself) that actually cause the reflections in the first place, while the ideal cable length manipulates the timing of the reflections, which mitigates the aspect of reflections that actually affect the digital I/Os.
That said, the RF observation is an still interesting idea about the topic ;-)
is a tool, a reflectometer or perhaps it has some other name which shoots an impulse signal down the cable and then measures the reflections. I've seen it in use ( military test lab) and its pretty cool. It will tell how far down the cable length where the reflections are being propagated.
It will do it for coax as well as CAT 5/6 cables, where often times a mere pinching of the cable bundle can cause issues. I see them every so often in Military surplus auctions but never won one yet.
The machine was being used on board a Sub to check out the recently installed wiring harnesses.
The tool was interesting because it points out other possible issues which may cause unwanted reflections
In my scenarios using a digital cable I had a 1/2 meter Vampire that I first used with a transport. Switching to the Silflex per your rec was a huge improvement. When I then switched the source to a SB III with the same DAC (Trivista SACD w/dead transport) I felt the Silflex too bright and tried the Vampire again and it was great no longer suffering from the grungy-ness present when using it with the transport.
Out of curiosity I'd like to try a different digital cable at some point but don't have any disposable income right now.
ET
What model is your particular 0.5m Vampire digital coaxial cable?
Its a modified RG 226.
Got it from a surplus satellite uplink for our local phone company. Heavily silver plated, and with silver plated shielding braid.
What is unusual is that the center conductor is in a plastic tube (not teflon) and there is a strand of polyethlene or something similar wound around the center conductor to center it in the tube.
Sounds very good: Similar to the Illuminati D-60. With 75 ohm ends sounds the equivalent if not better (IMHO).
Had it tested once and it was flat out to 2 Ghz. Never seen it listed in any catalog, but the original had mini BNC's stamped with a KS part umber which I assume was WE.
I'd try it out if you'll set me a foot and a half.
ET
I can't remember, it's from the early 2000's has a thick blue cable and RCA's that unscrew somehow. By tomorrow I will take a pic of it and post. Thanks.
ET
Excellent, Awe-d-o-file. I might be able to steer you towards a fine sounding DIY build that's likely affordable.
Cheers, Duster
Here is the old Vampire-ET
That's actually a classic UP-OCC digital coaxial cable made by Neotech. Vampire terminated the cable with entry level brass Vampire Tiffany style rca connectors and marketed it as the Vampire DI-1 digital cable.
A version was previously available (now discontinued) as a Neotech ND021090 cable from Take Five Audio with upgraded copper Vampire Tiffany style rca connectors:
http://www.takefiveaudio.com/mall/shopexd.asp?id=1058
The same version is still available from another seller, but priced substantially higher than Take Five Audio:
http://www.douglasconnection.com/Neotech-Digital-Interconnect-and-Vampire-Wire-9X-CB-NVDIC.htm
You had mentioned you might have a DIY I may want to try. Now that you know what I have do you still think I should try it? Thanks in advance.
ET
Great,I'd like to try that. I'll get the pic up later today.
ET
I kindly thank you and the others for your response and knowledge of the subject matter.I don't mind spending money, but I hate to spend it foolishly.
After reading your response I was brought back several decades (the 70's) to when I was a young kid. I can remember my uncles fooling around with cb radios and how they were always concerned with keeping the antenna cable to multiples of 3 feet (3,6,9,12 etc....). I do not know or not if it's similar here or not.I was perusing the Dh Labs site and came across their D-750 cable with diy instructions for termination; So I think I will give it a go.
Thanks again.
........I was a vegetarian for 15 minutes... until the main course.
Edits: 04/10/14
It tends to depend on what make/model cable/connector, and/or what make/model components (both transport and DAC) the digital coaxial cable is placed between (synergy tends to be the key).
The prevailing wisdom as being a safe bet is 1.5m, while a 0.5m length tends to be less of an issue than a 1m length.
Equally important is the type of connector and termination method involved in a digital coaxial cable build in order to mitigate cable reflections rather than just rely on an ideal length to address the matter.
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