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PostPosted: 14 Dec 2011, 07:08 
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Joined: 15 Oct 2010, 17:50
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Currently I don't have any need to construct interconnects, so anything more than a descriptive post will have to wait.

Having said that, I am looking at exploring some new types of twisted-pair cables with Mogami 2893 instead of 2534. Also, I am considering attempting to use the raw Mogami product as a convenient twisted-pair source for an unshielded construction cable (by stripping out the braid).

Although I am a believer in shielding for audio, I want to experiment and see if twisted-pair construction's ability to attenuate RF is sufficient for audio use. Certainly there is much anecdotal evidence that it is, but I am also careful to recognize that RF is very location and equipment specific ... what works for one may not work for another.

Luckily, as DIY cable constructors, one of the issues we can all easily address is cable length, which is handy since for a good antennae, all you need is a specific length of wire and an amplifying circuit ... pretty much the definition of a component-based audio system.

Adjusting your cable's length by a small amount is easy and effective if you seem to be plagued by one specific RF transmitter. In contrast to one who does not make their own cables, it's a simple matter to shorten the cable a bit and re-terminate (a "too short" antenna is less effective, which in our case is really more effective, than a "too long" one).

The change in my way of thinking has been influenced by studying the ideas and experiments of the late Allen Wright (founder of Vacuum State Electronics, Schaffhausen, Switzerland). Mr Wright is a proponent of wide bandwidth in tube-based audio pre-amplifiers ... he would insist on at least 10x the conventionally agreed upon audible limit of 20 Khz, and often preferred more if he could get it. He also wrote extensively about cable construction, and feels a shield is unnecessary given proper geometry. I found those two design philosophies from the same man interesting.

If and when I go about this, I will start a thread outlining my build and conclusions.


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PostPosted: 14 Dec 2011, 18:21 
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Why pay for expensive cable to strip out the shield (something that may be easier said than done with the Mogami). Twisted pair works. Just take 2 good quality (insulated, of course) conductors (say 20ga) and twist them together. The key is a good tight twist. I find solid conductor holds the twist better, but stranded is easier to manipulate. Also, the equipment attached to the final product makes a big difference - obviously.

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The key to a successful build is to keep the smoke IN the circuit.
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We cannot solve our problems with the same thinking we used when we created them. - Albert Einstien
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PostPosted: 15 Dec 2011, 19:53 
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Well, Les, because the cable is not expensive relative to the alternatives in small quantities. At a buck a foot you're getting 4 extremely high quality OFC copper 23 or 26ga teflon dielectric cables pre-configured in a precisely wound 4-conductor braid (a different configuration than 2-conductor twisted pair, although they both are technically the same solution to the same problem). The Canare variants are half that price. You could probably buy one or the other with a quick trip to the local music store.

The Mogami product is extremely well extruded and of known quality. I don't know what research you've done with regard to extruding wire and cable, but one of the (many) issues is the consistency of each copper strand, for example. Keeping the diameter constant over a length is not trivial and varies between factories.

There is potential for inconsistencies to affect signal integrity, although I can't say exactly how much. Suffice to say that it is not a given that each strand will be within, say, 5% of 0.1mm over any significant length. And that is just one aspect; there are issues with purity within the factory, with the hardness or softness of the copper (or other material), the quality of the PTFE (which is made worldwide now as the patents have expired and methods are known, not just by DuPont), and so on.

The best means for us mere mortals is to buy from known good suppliers, because you won't get that information from the cable manufacturer, if even that is known. For example, we don't know who makes the Canare cable, but we do know Mogami makes everything they sell at their owned factories in Japan, down to each strand of wire itself.

In my mind, eliminating possible inconsistencies is key to experimenting. So, when we have an opportunity to use a product that suits our needs, is of reasonable cost, and is made better than I myself can make it, I say take it.

Were it simple twisted pair, and if you could have a suitable single 23/26ga cable shipped to your house for 25c (or 12.5c for Canare) a foot all in, it might be different. Also, if you're buying bulk quantities, the economics might change.

I don't know how experienced you are with manually braiding cable, but it's difficult for me, at least, to get good consistency and becomes complicated with a cable length longer than about 4 or 5 feet.

I don't find it difficult to cut and remove the jacket, especially if I'm not concerned about nicking the served copper shield that Mogami prefers (despite it's higher manufacturing cost) for these two variants. Because it's not a braided shield, it's very easy to remove (just unwind it), leaving the 4-conductor braid in excellent undamaged condition for termination to your favourite RCA.

For a quick-and-dirty primer on shielding of cables, it's hard to beat this pdf from Belden:
http://www.belden.com/pdfs/Cable101/Shielding.pdf

I agree that sold wire construction may be the preferred configuration for audio, but then again a little experimentation comparing the shielded and unshielded varieties of the same cable has value to me. One variable at a time, so to speak.


Correction (edit 18 Dec 2011)
The Mogami cable part#'s I've mentioned use Cross-linked Polyethylene (XLPE) dielectric, not Polytetrafluoroethylene (PTFE aka Teflon(R)).

Off topic discussion moved here: PTFE and Teflon (R) :cop: 3 Jan 2012


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PostPosted: 22 Feb 2012, 22:42 
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Hi folks, we just got a short project page together showing how to construct these DIY Shielded RCA Interconnect Cables. Thanks for sharing your work Tom.
Cheers

Project Link - DIY Shielded RCA Interconnect Cables

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PostPosted: 01 Apr 2013, 14:05 
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Joined: 21 May 2010, 13:43
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I recently made a couple sets of these. All I can say is wow, I did not realize how much noise the normal interconnect cables I was using introduced into my setup. Thank you for the awesome how to and for helping me to have a more enjoyable listening experience.


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PostPosted: 01 Apr 2013, 18:17 
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Location: Australia
I must admit I haven't read every entry here but would like to re-voice my belief and practice when it comes to inter-connects. The inter-connects (cables) I am talking about connect CD player to preamp or preamp to power amp. Or even phono preamp to preamp. Not TT to phono preamp or where signal voltages fall below a volt or cables are over a meter.

Firstly I don't believe you need shielding. If you shielding against nuclear blast a thin layer of braided wire covering your hot wire probably won't have much effect. If you are shielding against EMI and RFI (in the ether around your gear) and the audio signal is coming from a CD player, around 2Vpp, will well swamp any mV or uV interference nearby. I am talking general terms here. If you cable lays across your 600W power transformer with huge magnetic flux shielding maybe required.

For a number of years now I have not used shielded cable. I have been using platted single stands of 0.7mm pure silver wire with a choked at the destination end. With the plaited arrangement or where I twist three wires I only terminate one earth at the destination end. More recently I'm only using fine wire-wrap wire. This is high quality fine copper wire with a silver plating. At all times I stay away from any form stranded wire. Even when wiring power amps and preamps I only use twisted wire-warp wire. All my speaker cables are now Cat5. The Cat5 I use is solid copper with silver plating.

Try some non-shielded, solid core cables. Use two earths at the source end but only terminate one earth at the destination end. If the cables are short leave them lose. If over 0.5m twist or plat the three wires. If really short cables just use two strands. I silver solder all my cables and hard to believe but the thinnest cheapest RCAs are the best (mine cost $1.25), but that's another story.

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PostPosted: 28 Jul 2013, 12:59 
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Hi Tom,

I take it that these shielded interconnects eliminate the need for a ground wire? Basically, I need these:

http://www.elusivedisc.com/VPI-JMW-1M-P ... /HW-JMWPC/

but am not too keen on shelling out the dough for them. I've run several sets of shielded RCA cables from my TT to my phono stage and the only ones that eliminate hum completely are grounded (borrowed from a friend). Your project is the closest and clearest how-to guide for what I need, but I'm wondering how I would go about adding ground wire - like the VPI cables in the link - if hum is still present? I'm new to DIY audio projects and any tips/advice would be greatly appreciated. Thank you.


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PostPosted: 31 Jul 2013, 20:20 
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Hi jaadaku,

On the cables you noted it looks like the grounding wire is not electrically connected to the rca signal ground. The purpose is to tie the turntable chassis ground to the chassis ground of the phono preamp. My preference is to use a separate grounding wire for this.

Cheers

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PostPosted: 03 Oct 2013, 11:23 
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If you have been waiting to try this project now maybe the time as the Mogami cable is on sale at TubeDepot.

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PostPosted: 03 Oct 2013, 11:39 
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mwhouston wrote:
I More recently I'm only using fine wire-wrap wire. This is high quality fine copper wire with a silver plating. At all times I stay away from any form stranded wire. Even when wiring power amps and preamps I only use twisted wire-warp wire.

Mark,

Is this the wire you are using? http://www.mouser.com/ds/2/14/1805%20GR005-212239.pdf
If not how about a link for reference.

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