Although i am a supporter of equal-tension bass sets as a big improvement over traditional bass sets, there are in fact many advantages to having a tension that falls gradually and consistently from low to high strings (traditional bass sets have tension rising from low to high strings). Here i quote from my post at sevenstring.org where i'm talking about designing an all-fifths set for 6 string bass:
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I designed the set by feel, by trial and error, and calculated the tensions afterward to see what tension 'profile' i like. To my surprise the tension falls gradually and consistently from low to high strings. The highest string was at 2/3rds the tension of the lowest.
This falling tension i now consider optimum for many reasons ...
The lower strings are more massive and therefore more prone to flop, they need more tension to keep their vibration tight, with good tone. Higher strings are lighter and do not need so much tension for good tone. The minimum practical tension for a string therefore falls as the string gets thinner.
The pitch response to string bending falls as a string gets thinner, therefore for an even pitch response the tension must fall from low to high strings.
Thinner strings 'feel' tighter even when at the same tension as a fat string. So a falling tension creates a more even feel.
Thin roundwounds and thin plain strings are more prone to breakage, the larger the range of an instrument the more necessary it is to reduce the tension of the higher strings to avoid breakage.
Tapping becomes increasingly difficult on higher strings, a falling tension evens out the response to tapping. If you analyse the string sets for Chapman Stick you'll see they also have falling tension.
Thinner strings are naturally brighter, fatter strings naturally darker in tone. Tightening the fat strings brightens their tone, loosening the thin strings mellows their tone, resulting in a more even tone across the set.
The plain string problem. Plain strings can be rather harsh and bright in a set, a step down in tension from wound to plain mellows their tone for a better blend.
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Heavy bottom / light top guitar sets (9-46) are a step in the right direction. However
traditional bass sets are the very opposite of what i consider optimum.
I'm very familiar with the D'Addario tension chart, is there anything specific that confuses you? I'm happy to explain it
