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In Reply to: What's wrong with bare copper-wire speaker connections? posted by The Wiz on April 20, 2007 at 17:54:03:

Looking at it from a simple viewpoint, it would seem that a bare copper wire tightened down inside a 5-way binding post would be the best connection. The logic of "fewer connection points" is very seductive.
However, as someone who has bothered to seriously listen to speaker wires connected in a variety of ways, and then attempted to correlate what I heard with measurements, I found that what seems eminently logical, may not really be the best way to go.
Bare wires come in two forms: solid or stranded.
The stranded can not be tightend down that well. Place it into the hole that runs through the binding post, and if you tighten down enough to start getting a good tight connection, the strands start getting cut off. If you tighten it to the point just before the strands start to cut through, then it is not really that tight, the wire can be wiggled back and forth in the post.
(Minor aside here: if you can wiggle the wire or plug in any connection, then it is not making a good speaker level, high current connection. There MUST be a tight enough fit between the connector/termination and the wire that no motion is possible within or at the connection, or in other words, if the wire can move across what it is making electrical contact with, it is not making a very good conection.)
If you try to wrap the wire around the post, and tighten down the nut, well, we have probably all experienced the inevitable squish-out of the stranded wire strands as they get squeezed out to the sides. If you do not tighten the nut enough to cause the wire to start squishing out, it just is not tight enough, it can be moved or wiggled and come loose.
Tinning the wire is not a good idea, solder is not that conductive, and adds another layer of connection, and one which can not be tightened down enough either, the tinned wire deforms and gives (more easily than solid copper), and ultimately, can be wiggled or moved, and come loose.
If we consider a solid wire, this might seem to avoid the main problems with the stranded, as you have one "big" wire to tighten down against, and this would seem to solve the problem. But no, the copper deforms as you tighten down, and you can not get the connection tight enough without deforming the copper. It might seem that smashing the wire down enought to make it flat, and thus, create a "good connection" that way would be a good way to go, but the severe deformation of the copper required to acheive this also creates a fracture boundary right where the wire goes back to being round, in essence, you have damaged the metalurgical structure of the metal, just like when you bend the paper clip back and forth, until it is almost ready to break. The smashed portion is not only physically weak, but electrically inferior due to the creation of numerous HUGE voids in the copper's crystalline structure.
I have seen such smashed wire ends break-off after very little time (exposure to the vibrations of the speakers is enough to complete the stress fracture) and fail completely, but even if they don't outright fail in such a manner, they are a lousy spot in the conductor that the signal MUST pass through.
When I listend to a properly crimped spade lug, tightend down so it could not be moved or wiggled, THAT had very little "sound of it's own", compared to bare wire, or banana's or GACK! spring loaded push-in terminals.
As a very simple definition, a proper crimp is one that has not been soldered in any way, and that the wire can not be pulled free from, with the wire itself failing first. This kind of crimp creates a "cold-weld", and has very little audible effect on the sound.
After listening and finding that bare wire connections just did not sound as good as they "should", I then took some measurements.
A well tightened proper crimp had the lowest resistance, a locking banana plug the next lowest, then bare solid wires (this was an average, since the readings varied from time to time, and from connection to connection), then a good grade of "regular" banana's, then stranded wire cobbled onto the post as best as could be done (a doubled over section stuffed into the center hole worked best for the short term), then the pins for the spring loaded push-in type terminals were way last (highest resistance).
The bare wire connections had a lot of variance in how much resistance they had, and at no time, even with contact cleaners, freshly stripped wire, etc., could I get a solid low resistance connection that was consistent and reliable over time. Only the crimped spades provided that kind of measured performance, and sounded as solid and consistent sonically.
One side benifit of using a gold plated spade with a gold plated post, is that as long as the parts are clean to begin with, once fully tightened, the connection will not oxidize or go bad over time, and the connection will remain low resistance.
So NEVER use bare stranded wire for anything but an emergency short-term connection, and strongly consider getting a decent set of spade lugs and/or matching posts for each speaker level connection point that must be disconnectable.
For more on audio cables, see:
http://www.geocities.com/jonrisch/i1.htm
AND
http://www.geocities.com/jonrisch/s1.htm
Jon Risch

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