of the best
connections are soldered connections. The problem is only
one type of soldered connection is truly a joint, most are as the
word states, a connection. Many solders, such as the popular
60/40, are a slurried mixture of Tin and Lead. In making the
joint, the Tin/Lead mixture melts, but as it solidifies it does
so one metal at a time. It goes into a slurry state where
one metal is liquid and the other is very small solid particles.
Next, the other metal solidifies, and creates a multitude of small
connections. This type of connection is not particularly favorable
or permanent. When a phone company had to use this type of
solder on their main frames, every joint had to be reheated once
a year to insure reliability. Even then, the "cold joint"
was a common occurrence. Noisy or open joints were the main
cause of failure in early printed circuit boards and electronic
equipment until sometime in the mid-sixties or early seventies.
Then it was learned that eutectic joints were perfectly reliable.
By the mid-seventies or early eighties most electronic equipment
was being soldered with Eutectic solder (63/37). The reliability
of printed circuit boards went up nearly 1000%, and solid state
audio gear began to sound almost tolerable. Today, all printed
circuit boards use Eutectic solder. The melting point of a
Eutectic solder is lower than any of its component parts, so there
is no slurry state in these solders. They solidify as one
creating an actual solder joint. The
only wires used in high-end audio are Copper and Silver, so George
Cardas developed an ultra pure Tin/Lead/Silver/Copper eutectic or
Quad-Eutectic solder. This solder is now used in the vast
majority of all high-end cables and equipment. Properly done, Quad-Eutectic
joints reliably provide the best sound with the lowest noise and
contact resistance. (The above was taken in part and paraphrased
entirely from George Cardas' paper Soldered vs. Crimped Connections).
One pound of Cardas Quad-Eutectic solder is $68,
24 feet is $7.50. One pound of Cardas Tri-Eutectic
(Lead free) solder is $70, 24 feet is $7.