Spira SR-420-WH Electric Guitar Shred Machine – White – Locking Tremolo

The Spira SR-420 (SKU: SR-420-WH) is a double-cutaway hard rock and metal guitar built around a specification that prioritises fast playing and aggressive tone: 24 jumbo frets on a flat 14-inch radius Ebony Tech fretboard, Spira's Villain high-output ceramic humbuckers in HH configuration, a Sung-il locking tremolo for divebombs and whammy work, and a locking nut that keeps the whole system in tune under heavy use. The roasted poplar body and Canadian Roasted Maple neck with Modern D profile are matched to a stripped-back 1 Volume / 1 Tone control layout that keeps the player's attention on the instrument rather than the controls. Finished in Gloss White with black hardware throughout, the SR-420 carries the visual directness of its '80s metal influences in a package built to current performance standards.

Roasted Poplar Body

The SR-420 body is roasted poplar — poplar that has been subjected to a controlled heat-treatment process (torrefaction) before the instrument is built. Roasting drives off residual moisture and volatile compounds from the wood fibres, producing a material that is more dimensionally stable than standard poplar — less reactive to changes in humidity and temperature — and slightly lighter in weight than untreated stock. The tonal character is a balanced response: the low end is tight rather than loose, the midrange has definition and punch, and the high end is clear. This tonal balance is well suited to high-gain playing, where a bass-heavy or midrange-congested body character can make already-dense distorted tones harder to cut through a mix.

Canadian Roasted Maple Neck — Modern D Profile

The SR-420's neck is Canadian Roasted Maple, heat-treated through the same torrefaction process as the body wood. Roasting produces a neck that is more resistant to warping and movement in changing conditions than standard maple — a meaningful practical advantage for an instrument used on stage, where temperature and humidity vary widely from venue to venue. The surface of roasted maple has a slightly open, matte texture that many players find pleasant under the hand during extended playing.

The Modern D profile is a slightly flatter, more angular cross-section than the round Modern C shape. Where a C profile has a consistent oval curve that is comfortable for most playing styles, the D profile provides a flatter back that suits a thumb-over-the-neck grip and fast single-note runs across the upper strings — techniques common in rock and metal lead playing. Scale length is the standard 25.5 inches, providing clear string definition and consistent feel.

Ebony Tech Fretboard — 14-Inch Radius, 24 Jumbo Frets

The SR-420's fretboard is described by Spira as Hi-Graded Ebony Tech — an engineered synthetic fretboard material designed to replicate the playing characteristics of ebony. Synthetic fretboard materials are increasingly used in quality instruments: they offer consistent hardness and surface smoothness, are unaffected by humidity changes that can cause natural wood fretboards to swell or shrink, and avoid the supply and sustainability constraints that have affected natural ebony availability. The playing surface is hard, smooth, and fast — functionally similar to what a quality ebony fingerboard would provide.

The 14-inch radius is the most immediately significant specification on this fretboard. Most Stratocaster-style guitars use a 9.5-inch or 10-inch radius; Gibson-style guitars typically use 12 inches. A 14-inch radius is considerably flatter — the fretboard curves less across its width. The practical result: when you bend strings in the upper positions, the strings track closer to the fretboard surface rather than pressing into it, which eliminates or substantially reduces the tendency to fret out — where a bent string goes sharp and then abruptly cuts out by fretting against a higher fret. For lead playing at the top of the neck, a flat radius is a technical advantage.

Twenty-four jumbo frets extend the guitar's range by two frets compared to the 22-fret standard — placing the highest notes available two semitones higher, which matters for extended-range licks and phrases in higher positions.

Locking Tremolo System — Sung-il, Made in Korea

The SR-420's locking tremolo is manufactured by Sung-il, a Korean hardware producer with an established record in quality OEM guitar hardware. The bridge is a locking tremolo design — a two-point pivot bridge with individual saddles for intonation adjustment, a tremolo arm, and a locking mechanism at the bridge plate that clamps the strings at the saddle rather than relying on string tension alone to keep them in position.

Used in combination with the locking nut at the headstock end, the complete locking system works as follows: the strings are locked at both ends of their vibrating length — at the nut and at the saddle. When the tremolo arm is used to change tension (lower for divebombs, raise for flutter effects), the string is displaced at the bridge end but held securely at both locking points. When the arm is released, the bridge returns to its resting position and the locked strings return to pitch. Fine-tuning is handled by the individual fine-tuner screws on the bridge saddles — standard tuning machines on the headstock are not used for pitch adjustment once the nut is locked.

This system makes aggressive tremolo use — divebombs to slack pitch, sustained flutter, squeals — practical on stage in a way that a non-locking tremolo cannot match. The trade-off is that string changes require loosening the locking nut and bridge saddle locks, and retuning from scratch after a string is replaced.

Spira Villain Humbuckers — Ceramic, 12K Output, HH Configuration

The SR-420 is fitted with Spira's Villain humbuckers — custom-voiced pickups with ceramic magnets and a 12,000-ohm DC resistance (12K output). Two pickups in bridge and neck positions form the HH configuration.

Ceramic magnets produce a harder, brighter magnetic field than alnico alternatives. The result in a pickup is higher output, a brighter high-end emphasis, and a more defined attack that retains note clarity under heavy gain processing. At high distortion levels, where alnico pickups can begin to soften and compress the signal, ceramic pickups maintain the separation between notes and the sharpness of pick attack — qualities that are essential for riff clarity in dense band mixes and for legible single-note lead lines through high-gain amplifiers.

At 12K output, the Villain humbuckers push the front end of a guitar amplifier harder than standard-output pickups, which tends to increase gain response, sustain, and harmonic content. For high-gain playing — distorted rhythm and lead work — this is by design.

The 1 Volume / 1 Tone control layout is minimal and deliberate. With only one pickup selector (a standard HH toggle) and one of each master control, there are no distractions. The signal path is short and direct.

Locking Nut

The locking nut clamps each string mechanically at the headstock end of the neck. In a standard nut, the string passes through a slot and is held at pitch by tuning machine tension; any movement in the string through the nut slot — from bending, tremolo use, or temperature — can cause the string to return to a slightly different position, producing tuning drift. A locking nut eliminates this: the strings are clamped in fixed position at the nut, so their speaking length is immovably set between nut and bridge saddle. In conjunction with the locking bridge saddles, this creates the complete locking system that makes extended tremolo use stay in tune.

The nut width is 43mm — a standard measurement for guitars in this style, providing a practical string spread without excessive width that would stretch a playing position.

Black Hardware Throughout

All hardware on the SR-420 — machine heads, bridge, nut, control knobs — is finished in black. Against the Gloss White body finish, black hardware creates a strong visual contrast that suits the instrument's character: direct, graphic, and stage-visible. Black hardware on white guitar bodies is a long-established visual language in rock and metal instrument design.

Who Is the SR-420 For?

The SR-420 is built for players whose primary territory is hard rock and metal — styles that demand high-gain output, tuning stability under tremolo use, and a neck geometry suited to fast lead playing without fretting out in the upper register. The flat 14-inch radius and 24 jumbo frets suit players who spend time above the 12th fret. The Sung-il locking tremolo and locking nut together mean aggressive whammy use is practical rather than decorative. The Villain ceramic humbuckers are voiced for the front end of a high-gain amplifier. The Gloss White finish with black hardware is a strong visual presence on stage. For players who want the same specification but without the tremolo, Spira's SR-400 is the fixed-bridge equivalent.

Specifications

Expert Advice at Angkor Music

At Angkor Music Melbourne we stock Spira Guitars. If you want to compare the SR-420 with the fixed-bridge SR-400, try the tremolo system in person, or get advice on strings and setup for drop tuning or high-gain playing, our team can help — and you are welcome to play the SR-420 in store before you decide.

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