I disagree. String tension is a function of string mass, scale length, headstock angle, tuning peg location, neck angle, how far the strings are anchored behind the bridge, bridge height and neck relief. Anyone can tell you that there's a significant difference between the string tension on a Jazz Bass with the strings anchored through the body compared to one with the strings anchored through the bridge, or a guitar with a regular inline headstock versus a reversed inline headstock. You can increase the string tension without changing the scale length.
Perhaps I don't fully understand the definition of Speaking Length, but I know that string tension is constant throughout the length of the string from where it's anchored at both ends. The nut and bridge saddle do not hold the string securely. It's free to slide over them.
The Speaking Length varies with each note played on the string without affecting tension. But then what do I know? Maybe my fingers and ears are just telling me what I want to hear.
I'm sure that experts (such as those who build Alembics) can confirm or refute this. I'm no expert.
As well, the Epiphone has Mahogany necks with a flame Maple top, the Gibson has Maple necks with no top wood. I don't know what differences lie in their pickups or any other factor (other than tailpiece location) that may affect their sounds. The Gibson costs $3500, the Epiphone cost around $900. The Gibson is made in the U.S., the Epiphone is made in Korea.
I'm not a particular fan or owner of either.
The Epiphone sounds better to me. It feels like it has greater string tension with greater sustain - in my opinion.
(Message edited by rami on March 28, 2008)