Tone that serves the song

Why it matters

A second melody has to be heard. If notes die or vanish into mud, the line turns back into roots.
tetsuya picks a different instrument and sound for different songs. What he listens for: a clear, snappy attack, a wide range from soft to loud, every string as strong as the others.
He also says you only know a bass’s sound when it’s played loud, in a room or with the band. Bedroom volume lies.

Passive pickups: no battery. Volume and a tone knob that only cuts treble. Warm, dynamic, simple.
Active electronics: an onboard preamp on a battery (usually 9 V), with boost and cut for bass and treble, sometimes mids. Hotter, clearer signal; dead battery, no sound (some switch to passive).
Pickup blend: neck pickup round and deep, bridge pickup tight and focused. Melodic lines often sit nearer the bridge so they cut through.
Strings: roundwounds are bright and sustain (good for slides); flatwounds thump and fade fast. Old strings lose both.
Attack: a pick gives a defined front edge that cuts through guitars; fingers give a rounder note. Where you pluck matters too: near the bridge is tighter.
Compression: a compressor or limiter evens out volume so hammered and pulled notes match plucked ones.

Extra strings change the whole instrument, not just the range. tetsuya prefers a four-string’s balance and tunes a four-string down when he needs a low note in the studio. Check that your low B (and high C) match the middle four in volume and clarity.

Same tests: even strings, no dead spots, wide dynamics.
Doubling a bass line an octave up: neck pickup, tone rolled back, less gain, so it supports rather than competes.
Lead-style counter-lines: bridge pickup and a little compression keep legato notes as loud as picked ones.

Seven strings: check the low B for balance and floppiness; heavier gauge or a longer scale tightens it.

Sawari: the buzz of the ichi no ito that makes open strings and their related pitches ring. Too little and the instrument sounds dry; some necks have an adjustable mechanism (azuma-sawari).
Koma: the bridge’s material and weight change tone and volume; players swap koma for the piece and the room.
Skin and bachi: the skin’s tension, the bachi’s weight and edge, and where the bachi lands all shape the attack.
Tsubo: a slightly missed tsubo kills sawari’s ring on that note. Check them with the tuner.

Sweep: every fret on every string, same pluck, same volume. Note any that die early or jump out.
Plan around dead spots: play that pitch on another string or in another position.
Learn your controls: set everything flat, then change one thing at a time (a knob; on shamisen, the koma or bachi) and say what changed.
Two takes: record the groove from exercise 2 twice, changing one thing (pick or fingers, pickup, tone, where you pluck). Mid-volume, not whisper-quiet.
Listen back: which take lets the slides and hammer-ons be heard? Tell your tutor.

Tune before each take; the tuner also checks single notes (and shamisen tsubo):