DIY Interconnects 272 to 300DR

Hmm, off hand I don't know any of those.

Incidentally why specifically PTFE/FEP insulation rather then PE?

PTFE & FEP have slightly better (lower) dielectric constant (~2.1 vs ~2.3), but has 3-7 times higher dielectric loss modulus (0.0003 - 0.0007 vs 0.0001).  In my view they're much of a muchness (but PTFE has the 'bling' factor).

I'm not being that specific on dialetric,   I'll take the best,  but will not take anythng if it's a compromise.        

I think in terms of each compared to the other, both are slightly compromised, just in different ways (all dielectrics other than a vacuum are a compromise anyway  ).

In audio engineering terms I don't think it's yet really known properly which is the 'best', and indeed there may be no single universal 'best'.
(The marketeers definitely prefer PTFE because on a spec sheet it sounds more exotic than just plain old polyethylene.)

I really wish I could solder as I would love to experiment with different cables for my 282/300. I'm currently using the stock cables Din - XLR and am sure these can be improved upon. When I had my 250 I used Chord Signature Tuned Aray Din - XLR and wasn't convinced that buying another for the 300 would be the best use of system funds. 

Are there companies who will build these mogami cables (for reasonable amounts) that I can contact?

Bob the Builder posted:

I really wish I could solder as I would love to experiment with different cables for my 282/300.

Why not learn ? A decent soldering iron isn't very expensive at all and it's a good skill to have. I suspect you could probably teach yourself to be pretty proficient from youtube videos !

So long as you're sticking to relatively easy cable types (such as Mogami 2549), simple cable constructions (one wire to each pin) and relatively large connectors, it's really quite easy.

In fact so much so that, quite often, one of the trickiest parts of the operation is stripping the insulation to the right length without damaging the copper!  There are some very simple tools that can help with this as well.

Are you going to be in the area of Heathrow next Tuesday lunchtime - I know a representative of a company who will be there (OK, it's not their normal business, but they do make many of their own cables and they're very friendly).  If so I can arrange contact.

Huge - where do you get your Mogami cable from - HHB ?

Last batch was from Redco, CT, USA.

I'm also building cables for a number of other people, and the 2497 (particularly) was substantially cheaper from them.

Ah ok. Thanks Huge i'll take a look 

Huge posted:

I think in terms of each compared to the other, both are slightly compromised, just in different ways (all dielectrics other than a vacuum are a compromise anyway .     In audio engineering terms I don't think it's yet really known properly which is the 'best', and indeed there may be no single universal 'best'.
(The marketeers definitely prefer PTFE because on a spec sheet it sounds more exotic than just plain old polyethylene.)

I had a short ponder last evening & have decided to put my sensible hat on.   I'm sticking with my Mogami 2549 unless a significant better/diferent can be found,  but I'm not looking that hard.  The cable lengths I have are so short I have trouble believing any copper, silver or plastic can have much effect. 

Dialetric choice is nothing to be pedantic about,  the 2549 has XLPE (cross-linked polyethylene)  with a dielectric constant of 2.2.  This compares to Teflon/PTFE with 2.1.  Any of that group will do.  

Copper is Mogami's Neglex branded OFC,  but its still OFC.  It will probably only be improved in conductivity terms by using silver.

Capacitance;  W2549 core to screen is 76pF/m,  so my NDX to SuperNait length of 28cm has a signal path capacitance of 21pF.       Resistance over that distance has more 0. zeros than trumps brain cells. 

So I'm looking without actually trying for a miniature silver coax with one of the better dialectrics, if its not stated its not considered,  ditto for C,  it's low (sub 60pF/m) or no-go..  Then I will consider it for making into a two cable DIN-DIN harness.

Huge posted:

Last batch was from Redco, CT, USA.

The same company that I use,  rarely these days,  but when I making stage/group cables I was ordering in 100's.   Excellent service & stocks. 

Mike,

The issue with the copper isn't the conductivity as such, it's the concentration of impurities (including other metals, semiconductors, oxides, nitrides & sulphides) at the crystal boundaries as the melt / cast cools to form the bar from which the wire is drawn.  This structure is then modified by the wire drawing process (for audio use, this is best done slowly, near to the annealing temperature, and still in a non-oxidising environment, to allow the crystals to reshape without increasing the number of dislocations quite so much).

These crystal boundaries with their concentrated impurities can (and often do) have non linear electrical properties caused by the contact of dissimilar semiconducting alloys (usually because of impurities forming extrinsic semiconductors).  This problem exists in silver wire in the same way as it exists in copper (but I've not done the research to know in which metal the impurities will have a greater effect).

Have you noticed how Neglex has such a good clean bright surface showing very little visible sign of oxidation or any other impurity (I've not etched it to look at the crystal shapes and boundaries, nor do I have access to a suitable SEM or XRFM any more!)

Yes Huge,  way way back when I were a spotty student  I worked on a copper wire research project focused on marine applications & all the challenges that throws up.  I still have the doc's packed away in the attic. 

Interesting isn't it, how surface impurities act as centres for corrosion and how this then propagates into the bulk material.

And of course there's also the longer term effect on the mechanical properties when subject to vibration (less important in HiFi except maybe for speakers, but the similar effect on flex life is important for stage use), but then you have a better understanding of the metallurgical subtleties than do I!

We found oxidization propagation rates in our 'control' cable measured in numbers of metres per 24 hours in some atmospheres.      Didn't do research as such on copper hardening/annealing,  seen & suffered the effects tho',  

Wow, that's scary!  I'll never look at marine cabling in quite the same light again! 

Thats why marine cable is not just ordinary copper cable.   Also think about the chassis wiring on a truck/trailer/caravan, same problem with road salt & copper black rot is commonplace.   Tin plated wire goes a long way to slow (I did say slow, not stop) the process down as does PVC vs the rubber compounds from the old days.    Home audio cables have a remarkably easy & very long life,  provided the connections get soldered (tin plated) 

It makes you realise how reliable our own internal (neural) wiring is.

Given that the body's interstitial fluid is both kept warm and has a high salt concentration, I wonder if my trigeminal neuralgia is a corrosion effect!