[Seiichi Nagai] How to Recreate the Relative Theory Sound + Guitar Gear and Tone Settings [Effects & Amps]

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Introduction (Overview of Tone)

Seiichi Nagai, the guitarist of Relative Theory, is known for his unique style that blends pop and experimental sounds. His guitar tone is characterized by a clear yet distinct sound and innovative riff work.

In iconic songs like “LOVEズっきゅん” and “Miss Parallel World,” his clean tones and precise riffs highlight the pop essence of the tracks. Recently, he has actively incorporated modern equipment such as Steinberger guitars and the Quad Cortex, creating a hybrid approach that combines traditional vintage guitars with cutting-edge technology.

Nagai’s sound design balances “clear and refined clean tones” with “flexible sound creation through modeling.” His playing style emphasizes chords, arpeggios, and single-note riffs that complement the ethereal soundscape of Relative Theory.

This article will introduce the guitars, amplifiers, and effects he actually uses, detailing how his sound is constructed and how it can be recreated. Additionally, we will suggest affordable alternative gear for beginners to achieve a similar tone.

▶ Search official YouTube videos of Relative Theory

List of Amplifiers and Features

Seiichi Nagai’s amplifier setup is quite unique, as he rarely uses physical amplifiers, instead relying heavily on the amp modeling within the Neural DSP Quad Cortex. This choice enhances reproducibility in live settings and recordings while allowing for the flexible creation of “transparent clean tones” and “powerful distorted sounds” that Relative Theory’s music demands.

Among the frequently used models in his setup are the Marshall JCM800 (modeled as Brit2203) and the Fender Twin Reverb (modeled as US TWN Vibrato). The former is a staple in rock music, providing the thick distortion needed for riffs and chord play. It is particularly utilized in tracks that require a sharper edge and louder expressions, especially in performances since 2023.

On the other hand, the Fender Twin Reverb offers a wide range of tones from clean to crunch, making it ideal for Nagai’s characteristic arpeggios and cutting styles. In songs like “LOVEズっきゅん” and “Chiffon Principle,” its transparent tone plays a crucial role in creating a light and pop-like sound.

Past interviews and related materials also suggest that he may have used studio equipment such as the Marshall JMP-1 (preamp) and Marshall EL34 100/100 (power amp). These rack-mounted systems have been favored by many professional guitarists since the 1990s for their flexibility in sound creation and stability in live settings.

Overall, Nagai’s choice of amplifiers aims to accurately reproduce the texture of each song, showcasing a blend of modern modeling and classic tones. The Quad Cortex-based system excels in speed and stability for sound changes, serving as a powerful tool for the diverse musical expressions of Relative Theory.

Types of Guitars Used and Features

Seiichi Nagai’s guitar sound is characterized by a combination of vintage instruments and modern Steinberger guitars. Since the early days of Relative Theory, he has favored classic brands like Fender and Gibson, but recently he has integrated Steinberger guitars into his setup, creating a hybrid system that works well with digital processors.

The Fender Stratocaster (1962 model) features a warm and quick-responding single-coil sound, providing a clear outline for arpeggios and simple riffs. Additionally, the Fender Jaguar (1965 model, CAR) offers playability with its short scale and a unique bright tone, contributing to the pop and ethereal sound of Relative Theory.

In the realm of acoustic guitars, the Martin OOO-18 (1954 model) and Gibson J-45 (1962 model) are notable. Both possess warm and deep tones, essential for delicate expressions in recordings and acoustic arrangements. The J-45, known for its suitability among singer-songwriters, aligns well with Nagai’s playing style due to its soft midrange.

In recent live performances and recordings, the Steinberger GM-4S and GP-2S have been prominently used. The GM-4S was introduced around April 2023 and has served as the main guitar for the production of “9BIT,” known for its clear and direct sound, with the rear and center pickups being utilized according to the song’s needs. The GP-2S was added around September 2023, used for loud songs with half-step down and drop C♯ tuning, allowing for a heavier expression alongside the traditional pop elements.

Thus, Seiichi Nagai balances “the warmth of vintage” with “the versatility of modern” to create a unique sound world for Relative Theory. By utilizing the character of specific models for each song, he showcases a broad expressive range that transcends genres.

Effects and Pedalboard Setup

Seiichi Nagai’s effects setup is simple yet highly practical, with the main sound creation handled by the Neural DSP Quad Cortex. The Quad Cortex is a powerful processor that integrates amp modeling and effects processing, playing a central role in Relative Theory’s live performances. For a guitarist like Nagai, who needs to switch between clean and distorted sounds quickly, the precision and convenience of modeling become significant assets.

In his pedalboard configuration, the Quad Cortex is at the center, supported by auxiliary equipment. For instance, the Lehle Mono Volume S serves as a high-precision volume pedal, allowing for delicate control of dynamics within songs. Additionally, the Mission Engineering SP1-ND acts as an expression pedal, enabling real-time manipulation of parameters and effects within the Quad Cortex.

A noteworthy special effect is the MASF Pedals RAPTIO, which produces glitch-type noise effects. This pedal significantly contributes to the psychedelic and ethereal elements in Relative Theory’s music, adding new nuances to the traditional vintage guitar sound. The KORG Pitchblack XS is a reliable tuner that supports stability during live performances.

Furthermore, the Voodoo Lab Pedal Power X4 serves as the power supply, compact yet capable of stably driving multiple effects. This setup minimizes noise while maintaining a reliable environment.

Overall, Nagai’s effects board can be described as “a modern and space-efficient configuration centered around the Quad Cortex.” This approach is more rational than relying heavily on traditional pedal effects, allowing for flexible adaptation to the complex and diverse sounds of Relative Theory. The inclusion of a few unique pedals for special expressions also stands out, balancing sound creation freedom with high reproducibility.

Tone Settings, EQ, and Mixing Approaches

The most significant feature of Seiichi Nagai’s sound design is “adding necessary thickness while maintaining transparency.” The songs of Relative Theory require a balance between the lightness of pop music and the experimental nature of art rock, so the guitar sound is kept from excessive distortion, focusing on clean tones and light crunch.

For clean tones, the settings are primarily based on the Fender Twin Reverb (US TWN Vibrato modeling), typically with low Bass, slightly cut Middle, and high Treble. This balance ensures that arpeggios and cutting do not get buried when mixed with synths and vocals. This EQ is particularly effective in upbeat songs like “LOVEズっきゅん” and “Chiffon Principle.”

For distorted riffs and heavier tracks, the Marshall JCM800 (Brit2203 modeling) is employed, with Gain set around 4-5 without excessive boosting, moderate Bass, thicker Middle, and lower Treble. This setup allows the guitar sound to maintain strength and presence without overpowering the overall band ensemble. Since the introduction of the Steinberger GP-2S in 2023, there has been an increased emphasis on supporting low frequencies in drop C♯ tuning.

Within the Quad Cortex, it is also believed that a compressor and light reverb are used. The compressor smooths out the attack, ensuring that riffs and arpeggios sound uniform. The reverb is kept subtle, expanding the space while preserving the core of the sound, contributing to the “ethereal feel” of Relative Theory. Noise pedals like the MASF RAPTIO are used as accents during song transitions and breaks, adding tension and playfulness to the overall soundscape.

During the mixing phase, guitars are rarely placed in the center, often lightly panned to the left and right. This approach is conscious of the separation from synths and bass lines, resulting in a more three-dimensional sound. Additionally, EQ processing may slightly emphasize presence in the 2kHz-4kHz range to highlight the guitar’s attack, while keeping the low end below 200Hz modest to allow space for bass and kick.

Live, it is highly likely that the Mission Engineering SP1-ND expression pedal is used to adjust the reverb and delay levels in real-time within the Quad Cortex. This dynamic control of effect depth according to the song’s atmosphere is a key point in achieving a non-static sound design.

In summary, Seiichi Nagai’s sound design embodies “naturalness without excessive crafting” and “responsiveness as needed.” By leveraging the unique tones of vintage guitars while incorporating modern flexibility through the Quad Cortex, he maintains a unique balance that supports the musicality of Relative Theory.

Affordable Alternatives to Recreate the Tone

Seiichi Nagai’s sound design features high-end equipment such as vintage guitars, Steinberger models, and the Neural DSP Quad Cortex. However, for beginners or hobbyists looking to approximate the sound of Relative Theory, budget constraints can be a challenge. Here, we will introduce commercially available models that can be purchased for a relatively low price (around $100-$500) and are easier to approach for achieving Nagai’s tone.

For guitars, to easily obtain a Fender-like sound, the “Squier by Fender Classic Vibe Stratocaster” and “Squier Jaguar” are recommended. Both are direct offshoots of Fender, offering a character close to the original tone while keeping costs down. The Jaguar, in particular, is easy to play due to its short scale and bright tone, making it easier to recreate the pop sound characteristic of Relative Theory.

Regarding amplifiers, there’s no need to gather physical models; the BOSS “Katana series” is a cost-effective option. With capabilities ranging from clean to crunch, and built-in delay and reverb, it is suitable for Nagai’s “clean to light distortion-focused sound design.” Even smaller models come with line outputs and headphone jacks, making them versatile for home practice and live performances.

For effects, multi-effects units like the BOSS “GT-1” or “Zoom G3n” are strong candidates. These include amp simulators and modulation, delay, and reverb, allowing for simplified recreation of the flexibility seen in the Quad Cortex. Additionally, pairing with a volume pedal like the BOSS “FV-30H” can provide an experience similar to the Lehle Mono Volume S.

If you’re looking to experiment with unique sounds, affordable glitch/noise pedals like the “KORG Miku Stomp” or “ZOOM MS-70CDR” can also serve as substitutes. While they may not replicate the RAPTIO’s exact behavior, they allow you to enjoy experimental sounds.

By combining these options, you can relatively affordably approach the guitar sound of Relative Theory. The key is to focus on Nagai’s philosophy of “keeping clean tones at the forefront while adding effects only as necessary.” In other words, rather than simply mimicking expensive gear, the goal should be to pursue the right tone for the music using a simple setup.

Summary and Conclusion

Looking at Seiichi Nagai’s sound design, its essence lies in the “fusion of vintage and modern.” By centering on the warm tones of historical instruments like Fender, Gibson, and Martin, he incorporates modern and practical guitars like Steinberger. Rather than relying on physical amplifiers, he constructs a flexible and reproducible sound using Neural DSP Quad Cortex modeling. This combination allows for the coexistence of “transparent pop sounds” and “experimental, avant-garde sounds” that symbolize Relative Theory’s uniqueness.

Additionally, the configuration of his effects board is distinctive. By centering around the Quad Cortex and combining only the essential auxiliary pedals (volume pedal, expression pedal, tuner, noise effect pedal), he ensures a simple yet expressive range. This reflects Nagai’s philosophy of “selecting equipment according to musical necessity without overcomplicating the setup.”

In terms of sound, the flexibility to accurately add distortion as needed while maintaining a clean foundation is crucial. EQ settings and compression are kept modest, prioritizing integration into the ensemble of the song, ensuring that the guitar does not overshadow other elements like vocals and synths. This balance harmonizes beautifully with the musicality of Relative Theory, where vocals and synths often take center stage.

For readers looking to recreate Seiichi Nagai’s sound, the focus should be on “understanding the direction and philosophy of sound design” rather than merely “mimicking expensive gear.” In essence, the approach should be to build upon clean tones while adding distortion and spatial effects as necessary, adjusting to fit the music with a simple setup. By adopting this mindset, even affordable gear can provide a taste of the transparent and ethereal sound characteristic of Relative Theory.

In summary, Seiichi Nagai’s sound design emphasizes “not relying on tools but utilizing ideas and sensibilities.” This flexibility and simplicity ultimately highlight the individuality of the band Relative Theory.