odibrom
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Yeah, all that trouble so the singer won't have to work something out. It's just his voice that has to adapt, he won't have to buy anything... damn lazy guys... that's one of many reasons why psiorb is instrumental...Ok, I'll elaborate since it's something that happens in both of my bands and yes the 7-string comes handy for that.
Let's say that you want to play a song in E2 standard (6-string), but the singer can't reach the highest notes comfortably. The most sensible option is to adjust the tuning to the range of the singer, but now you have a problem: You don't have a low Eb2. So, you'd be forced to go one octave higher (Eb3), and we all know the chuggs don't sound that good up there, don't they?
Or... you can get down to Eb2 in several ways: A pitch-shifter FX, a differently tuned guitar, OR playing that part in the 7th string.