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In Reply to: RE: I believe that that orthodoxy also holds that... posted by John Marks on April 07, 2014 at 14:15:42
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
Follow Ups:
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
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