A 7-string with a bass note bolted underneath
An 8-string in F♯ standard is tuned F♯1–B1–E2–A2–D3–G3–B3–E4 — a 7-string with one more string a perfect fourth below the low B. The six upper strings are still at standard guitar pitch, so every shape you know still works, and the pattern of fourths continues unbroken down to the bottom.
The number that explains this whole instrument is 46.25 Hz. That is the low F♯ — only two semitones above the low E of a 4-string bass guitar, which reaches its E on a 34-inch scale. An 8-string is being asked for very nearly a bass note on a neck that is often 25.5 to 27 inches. Everything difficult about these guitars follows from that single mismatch.
Tune the six upper strings as a normal guitar, then B, then F♯ last. The low F♯ needs a long ring before the reading settles — read the sustain, never the attack.
Why the low F♯ misbehaves, and what actually fixes it
On a 25.5-inch scale the low F♯ is, in practice, unusable: it flutters audibly in pitch, sounds undefined rather than low, and will not intonate cleanly. The tuner will still tell you it is at F♯1 — that reading is true and beside the point. Three things genuinely change it.
Scale length is the big one. Most 8-strings ship at 27 to 28.6 inches precisely because the F♯ needs it; the same gauge at 28 inches carries far more tension than at 25.5. Gauge is next — the low F♯ typically wants something in the .070–.090 range depending on scale, far heavier than anything on a six-string. String construction matters more than players expect: a stiffer stainless core can tighten the response without forcing you up to a gauge that no longer fits the nut slot.
Fanned frets: the design that stops compromising
A single scale length cannot serve both ends of an 8-string well. Long enough for the F♯ makes the top strings stiff and awkward to bend; short enough for a comfortable high E leaves the F♯ slack. A multiscale (fanned-fret) neck refuses that trade: each string gets its own scale length — a long bass side around 27–28.6 inches for the F♯, a shorter treble side near 25.5 inches for the high E — with the frets angled between them.
The frets are not all slanted equally. Somewhere in the fan sits the perpendicular fret, the one that stays square to the strings, with the others angling progressively further in each direction from it. Where a builder puts that fret is a real design decision: placing it lower on the neck pulls the fan toward the nut and keeps open-position chords feeling normal, at the cost of a more angled upper register. None of this changes a single target pitch — a fanned-fret 8-string tunes to exactly the frequencies above — but it is why the same notes feel and intonate so differently between two 8-strings.
Tuning routine, step by step
- Tune the six upper strings first, as a normal guitar — nothing here is new, and they settle fastest.
- Then the low B, then the low F♯ last. The two heaviest strings move the neck most; tuning them first guarantees re-doing everything above them.
- Read the sustain on the F♯, never the attack. At 46 Hz the first moment of the note is the least stable part of it, and on a short-scale instrument the pitch may genuinely still be moving. Let it ring for a couple of seconds.
- Make a full second pass. Eight strings put substantially more tension on the neck than six; the first pass shifts the truss-rod balance enough to pull the earlier strings out.
- Check the F♯ fretted at the 12th against its open harmonic. A sharp fretted note means intonation, not tuning — and on the lowest string of an 8-string this is common enough that it is worth checking every time you change strings.
Frequently asked questions
Why is the low F♯ so much harder to work with than the low B on a 7-string?
Because of how low it actually is relative to the neck it sits on. F♯1 is 46.25 Hz — only two semitones above the low E of a 4-string bass guitar, which reaches that pitch on a 34-inch scale. An 8-string asks for nearly the same note on a neck that is often 25.5 to 27 inches. Physics does not bend: at that length the string needs either a very heavy gauge or a much longer scale to carry usable tension, and without one of those it flutters in pitch, sounds undefined, and will not intonate. This is not a tuning fault and no tuner can correct it.
What are fanned frets, and do I need them?
A fanned-fret (multiscale) neck gives each string its own scale length — typically a long bass side around 27 to 28.6 inches for the low F♯ and a shorter treble side near 25.5 inches for comfortable bends on the high E — with the frets angled between them. It exists because a single scale length cannot serve both ends of an 8-string well: long enough for the F♯ makes the top strings stiff and hard to bend, short enough for the high E leaves the F♯ floppy. You don’t strictly need one — plenty of straight-fret 27-inch 8-strings work fine — but it is the design that most directly solves the tension imbalance rather than compromising between the two ends.
What is Drop E on an 8-string?
Drop E lowers only the 8th string a whole step, from F♯1 down to E1 at 41.20 Hz, leaving the other seven exactly where they are — the same relationship Drop D has to standard tuning. That puts the lowest string at precisely the pitch of a 4-string bass guitar low E, which is worth knowing before you reach for it: whatever tension problem you already had on the F♯ gets meaningfully worse, and a gauge that was marginal at F♯ will be genuinely slack at E.
Do my normal chord shapes still work on an 8-string?
Yes — F♯ standard keeps all six upper strings at exactly standard guitar pitch, with a low B and a low F♯ added underneath in the same pattern of fourths. Everything you play on a six-string transfers with nothing relearned, and everything you play on a 7-string transfers too, since a 7-string in B standard is just this tuning without the eighth string. The additions are at the bottom of the range only.