Balanced Cables - Shielded vs. Star Quad / Roll Your Own?

[geeqner]

My guess is that the type of solder doesn’t matter as much as one would think. The copper wires make contact or nearly so, and the solder serves to FILL the joint.
Plus, there are other metals in the solder that are far better conductors, AND the metals chemically bond with the copper wire and the contact material.

I know that in many cases, Silver Solder was selected mainly for its Higher melting point when used for high-heat Applications like Power Transistors on the Output stage of Amplifiers.

Then again, a little dab of solder is relatively cheap - so if it’s a better Conductor, again Why Not tryit? (It probably can’t hurt - so long as the additional heat required to make it stick does not cause the wire jacket to melt at the Solder Joint.

[Gary Cook]

I have exclusively used Cardas Eutectic Solder for many years, never had an issue can't measure any impedance, resistance or capacitance difference before and after soldering a connection.

www.cardas.com/solder.php

Cheers
Gary

[geeqner]

Now THAT looks to be the Shiznat!

If it’s formulated by a trusted cable manufacturer, then it should be GOOD Stuff.
(Probably flows nice and whets-out on largish Solder Lugs better than stuff designed for PC-board components.)

Thanks for the heads-up - I didn’t know that Cardas made their own solder.

[geeqner]

FYI - For those who have not received any training in things such as soldering wires to connectors with Solder Lugs:

(Proper technique minimizes the amount of heating needed and can minimize melting of the cable jacket -
Also, like nearly any skill, it takes PRACTICE. Before you mess with 30-buck or more connectors, you might want to
get a few cheap single-lug devices like some solder-on pins etc and practice on THOSE.)

A.  Prep and Tin the wire end
B.  Prep and Tin the Solder Lug
C.  Place A&B together, heat the junction gently / quickly, and they should flow-together
D.  Remove the soldering iron and hold the wires in place gently until the junction cools

You'll also find that one of the things that separates "cheapo" connectors from the good or at least "decent" ones is the construction.
Specifically - the insulator material used to suspend the solder pins / sockets into the headshell:
[I learned this on Auto-Iris connectors for Video Surveillance CCTV Cameras that usually included total CRAP connectors -
  we learned to keep a stock of "real" Amp or Switchcraft ones. 
The extra few bucks saved more than that in saved time, aggravation, and improved reliability.]

- On Cheapos - it's cheap plastic that will melt if you hold heat on the pins for more than a second or two.
   If you screw-up, the pins move / tilt and then lock into a *bleep*-eyed position once the crappy plastic cools.
   You get a connector that has to be FORCED into the mating connector / socket if the SOB fits at all

- On the better ones - they use bakelite, fiberglass, or other materials that can "take the heat" of soldering.
   (But it still helps to use proper technique)

[KeithL]

I find it interesting that they phrase it that way.....  

When applied to solder, the term "eutectic" refers to the fact that the solder hardens suddenly over a very narrow range of temperatures.

And this characteristic is only true for certain alloys in certain proportions.

Many alloys actually melt and re-solidify over a certain range of temperature.

So, for example, a certain alloy may start to melt at 450 degrees but only become fully liquid at 470 degrees... and the same is true in reverse as it re-solidified (freezes).

This means that, for several seconds as it's hardening, the solder is "squishy but not fully liquid".

This doesn't sound like a problem, and it isn't a problem if what you're soldering is held absolutely still while the solder solidifies.

However, if you're hand soldering, and the joint moves a tiny bit while it's solidifying, you end up with a messy looking connection that isn't always as secure as it should be.

This makes it very difficult to make a really good looking connection when you hand-solder with non-eutectic solder.

This is why, in the days of lead/tin solder, "SN63" was the preferred alloy - because that is the eutectic alloy of lead and tin (although, since everyone knew that, it was never marked as "eutectic").

(So, yes, virtually ALL "SN63" solder was eutectic in the days of lead-containing solder... and, if you have any old-style "SN63 solder", it is almost certainly eutectic solder.)

Back in the days of lead solder, "silver content solder" was often used for high frequency (RF) connections.

This typically had 1 % silver, which supposedly improved high frequency performance a tiny bit, and also improved wetting and adhesion to silver-plated wire (which was often used in RF connections).

It also had a slightly higher melting point.

Other alloys were also sometimes used, which had a higher melting temperature, and were often somewhat stronger or harder, but were all non-eutectic ("SN60" was another common one).

The new ROHS solders usually have a higher melting point - and are much more difficult to work with.

(Some ROHS solders actually have a lower melting point. I don't know if any of them are eutectic or not.)

Note that ANY solder connection that has been done properly should look neat and should have extremely low resistance (in the milli-Ohms or micro-Ohms). 

(If you measure a solder connection with a standard digital meter, and read anything other than "zero" from the connection itself, then something is terribly wrong.)

Capacitance is a characteristic of two conductors, near each other, but insulated from each other... you should NEVER measure capacitance on a solder connection.

Jul 21, 2019 22:29:28 GMT -5 Gary Cook said:

I have exclusively used Cardas Eutectic Solder for many years, never had an issue can't measure any impedance, resistance or capacitance difference before and after soldering a connection.

www.cardas.com/solder.php

Cheers
Gary

[KeithL]

StarQuad wire is supposed to be better because of the even strand/conductor distribution.

(A balanced connection is quieter because noise picked up by the wire from outside sources is cancelled by the balanced circuitry... this works best if the wire conductors themselves have good symmetry.)

I can't personally claim that I've seen a significant difference - but it seems like a good idea - and there are no obvious drawbacks.)

I would always stick with a reputable brand of solder....

You can still find SN63 (lead/tin eutectic) solder, by reputable brands like Kester, on eBay (it is still widely used outside the US and is still manufactured).
A one pound roll will cost you around $20 (although sometimes significantly more from US distributors).

In general, in the past, silver-content solder was used for things that operated up in the mHz range (like oscilloscopes, RF equipment, and such.

Also, do not confuse the "silver CONTENT solder" used in electrical work, which is usually 1% to 2% silver, with the actual "silver solder" used in jewelry (and sometimes in brazing).

(It only contains a tiny amount of silver - which shouldn't add much if anything to the cost.)

When I worked at Fairchild on military contracts....

- we used SN63 (eutectic) for most things

- and SN60/ (1% silver) for "high frequency applications" (it was non eutectic, so slightly more care was required to achieve a neat connection when using it)

The big thing with electrical work is that you choose solder with the proper flux core.

When you solder some of the flux core is unavoidably trapped inside the metal...

And, even if you clean your work carefully, it is very difficult to ensure that you remove all trace of flux.

For electrical soldering, most people prefer rosin core flux, which is inert at low temperatures...

There are now several rosin type fluxes which claim that they don't need to be cleaned...

There are also a few "no clean halogen type fluxes" - which are claimed to be inert at low temperature.

For electrical work, NEVER use solder with "acid core flux", which is often used for plumbing...

And NEVER use an acid-type separate liquid or paste type flux intended for plumbing...

(They will cause terrible corrosion later down the road if you miss even a tiny speck of them...)

And make sure your work is really shiny clean before you start....

(Not "it was shiny clean when I got it but it's been sitting on the table for a few weeks since then"..... )

Jul 21, 2019 16:27:56 GMT -5 Casey Leedom said:

Also note that most Oscilloscopes use Silver Solder as far as I remember. And their signal integrity and noise issues are far more rigorous than simple Audio Frequency stuff. My bet is that high quality Lead Solder would probably be fine, but I'm also guessing that there's a lot of very poor quality Lead Solder out there ...

Casey

[KeithL]

True "silver solder" of the sort used for jewelry and brazing is almost never used for electronic circuitry (except perhaps for brazing contacts onto transmitting tubes or something like that).

(And a soldering iron will never reach the temperature required to melt actual normal silver solder.)

When audio companies talk about "silver solder" what they're really talking about is lead/tin or other solder with 1% to 2% of silver added.

(In the industry this is usually referred to as "silver content solder".)

This has better performance at extreme high frequencies - in the mHz to microwave range - and also wets and adheres better to silver plated wire (often used in HF applications).

It generally has a melting point a few degrees higher than eutectic lead/tin solder (as much as 50 -100 degrees higher).

A joint that has been properly soldered should have no more than a few THOUSANDTHS of an Ohm of additional resistance.

But, then, a properly crimped or welded joint should measure about the same.

A properly done crimp should measure about the same as a weld... but crimps can loosen with age.

(And, for a variety of reasons, "bad crimps" are a lot more common than "bad welds".)

I should note that, these days, "cable welds" are most often done by using extreme pressure and ultrasonic vibration rather than by direct heat welding.

Vibration and friction heat the metal and cause it to "flow together" into essentially a single piece of metal.

Jul 21, 2019 14:35:27 GMT -5 Boomzilla said:

I believe that the use of lead solder in interconnects makes no difference. Why? Because when you're dealing with an input impedance of an amp or preamp of 10,000 ohms, an additional ohm or two caused by lead solder makes no difference. But when you're dealing with a four ohm speaker load, an additional ohm becomes really significant. For that reason, I favor welded or silver-soldered speaker wires. Once I discovered that BlueJeans welds measured exactly the same as bare wires, I found no reason to solder speaker wires at all any more. The problem with silver soldering is that you're very near brazing temperatures (if the solder is high in silver content). Those temperatures are very destructive to insulation. So the best way to silver solder a wire is to:

1. Use a heat sink between the soldering point and the insulation - Otherwise the insulation melts, stinks, and runs. It will also burn you if you let it...
2. Use a terminating insulator that prevents air from getting to the the bare wires between the soldered portion and the insulation (prevents oxidation of the bare copper)
3. Consider using a torch rather than an iron for silver soldering (heats faster)
4. Use the right flux - Unlike lead/tin alloy solder with "resin" inside as flux, most silver solder is solid and you'll need an external flux.
5. Be meticulous in removing excess flux. Really...

So in short, silver soldering can be a PITA. Maybe it's better now (I haven't done any in a couple of decades), but back in the day...

But it's all academic for interconnects. No silver needed - "standard" electronics solder works fine. No exceptionally high temperatures. It's all good!

Boom