Introduction
The 620 pickup is a high‑output humbucking pickup designed for electric guitars and basses. It first appeared in the early 1970s and quickly gained a reputation for its powerful tone, durability, and versatility. The model was produced by the American company St. Paul Manufacturing, which specialized in pickups for professional musicians. Over the decades, the 620 pickup has been used by a range of artists across multiple genres, including rock, blues, metal, and jazz fusion. The design of the 620 pickup incorporates a unique coil winding technique and a proprietary magnetic alloy that distinguishes it from other pickups of its era.
Although the 620 pickup is no longer in mass production, it remains popular among vintage and custom guitar builders. Its distinct sonic character is often sought after for its blend of clarity and sustain, making it a valuable component in both stage and studio settings. The pickup's legacy is reflected in the continued reissues and aftermarket versions that seek to capture the original performance characteristics.
History and Development
Origins
St. Paul Manufacturing was founded in 1967 in Springfield, Illinois, by a group of musicians and engineers who were dissatisfied with the tonal limitations of existing pickups. The company focused on creating pickups that offered greater dynamic range and reliability. The 620 model emerged from this research as a response to the growing demand for high‑output pickups that could compete with the emerging super‑humbuckers used in hard‑rock and heavy‑metal recordings.
The initial concept for the 620 pickup involved a coil design that minimized the typical hum associated with single‑coil pickups while preserving a bright, articulate tone. Early prototypes were tested on custom guitars built for touring musicians in the Chicago music scene.
Development Process
The development of the 620 involved collaboration between St. Paul's in‑house engineers and a small cadre of seasoned guitarists. Feedback from these musicians guided the tuning of magnetic flux density and the optimization of coil gauge. The final design settled on a 9‑turn coil winding using 22 AWG wire, wrapped around a laminated ferrite core.
A key innovation was the use of a proprietary magnetic alloy composed of neodymium, iron, and a small percentage of cobalt. This alloy provided higher magnetic flux density without increasing weight, enabling the pickup to produce greater output while maintaining a manageable overall weight of approximately 200 g per unit. The design also incorporated a double‑coil configuration, with the two coils wired in series but reversed in polarity to cancel out electromagnetic interference.
Commercial Release
The 620 pickup was released commercially in 1974 under the St. Paul brand. The initial launch was limited to 5,000 units, marketed primarily to touring musicians and studio engineers. Distribution channels included specialty guitar stores and direct sales to custom builders. The 620 quickly gained a cult following, with many players praising its ability to sustain notes in high‑gain settings.
Throughout the late 1970s, St. Paul expanded its production capabilities and introduced a revised version of the pickup, the 620‑R, featuring a modified coil winding pattern that further increased output. By the mid‑1980s, the pickup had become a standard feature on several models of custom guitars produced by independent luthiers.
Design and Construction
Mechanical Architecture
The 620 pickup is a rectangular plate mounted in the bridge position of an electric guitar or bass. The main mechanical components consist of:
- A laminated ferrite core that serves as the magnetic pole pieces.
- A pair of copper coils wound with 22 AWG wire.
- A plastic housing that holds the coils in precise alignment.
- Four mounting screws that secure the pickup to the guitar body.
The core's laminated construction reduces eddy current losses, contributing to a clearer signal. The coils are positioned on either side of the core, with the magnetic flux lines passing through the strings in a pattern that captures both the string vibrations and the tonal nuances of the instrument.
Electromagnetic Principles
Each coil in the 620 pickup functions as an induction sensor. As a string vibrates, it moves within the magnetic field produced by the cores, inducing a voltage proportional to the vibration's amplitude and frequency. The two coils are wired in series but with reversed polarity; this arrangement reduces electromagnetic hum while doubling the output voltage.
The use of a neodymium‑iron‑cobalt alloy increases the magnetic field strength, which, in turn, allows the pickup to respond to subtler string vibrations. The result is a high‑output signal that retains the clarity of a single‑coil design while delivering the power of a humbucker.
Materials and Quality Control
St. Paul implemented rigorous quality control procedures during the production of the 620 pickup. Each unit underwent the following tests:
- Magnetic field strength measurement to ensure consistency across batches.
- Electrical impedance testing to confirm the expected series resistance.
- Vibration analysis to verify that the pickup accurately reproduced a wide frequency range.
- Durability assessment, including repeated mounting and dismounting cycles.
All pickups that failed any of these tests were discarded or returned for rework. The result was a product that maintained a high level of reliability, even after years of use on touring rigs.
Technical Specifications
- Output: 18 kΩ (typical)
- Impedance: 18 kΩ
- Weight: 200 g (per pickup)
- Dimensions: 110 mm × 70 mm × 30 mm
- Core Material: Laminated Neodymium‑Iron‑Cobalt alloy
- Coil Wire: 22 AWG copper
- Coils: Two (reverse‑wired series)
- Mounting Type: Standard 4‑screw
Variants and Models
620 Original
The original 620 pickup was the first iteration, featuring a 9‑turn coil winding and a double‑coil design. It provided a balanced output that could drive amplifiers and effects pedals without excessive distortion.
620‑R (Revision)
Released in 1981, the 620‑R incorporated a modified coil winding of 11 turns, increasing output to approximately 20 kΩ. The revision also included a redesigned magnetic core that further reduced internal noise.
620‑S (Semi‑Humbucker)
The 620‑S variant was introduced in 1985 as a hybrid between a single‑coil and a humbucker. It employed a single coil with a magnetic flux configuration that minimized hum while preserving the brightness typical of single‑coil pickups.
620‑V (Vintage Reissue)
In 2000, St. Paul launched the 620‑V, a limited reissue that aimed to replicate the original 1974 production quality. The reissue used the same core material and coil winding but employed updated manufacturing processes to improve consistency.
Applications
Electric Guitars
Musicians in rock and blues often use the 620 pickup in the bridge position to achieve a cutting, high‑gain sound suitable for solos. Its high output allows for aggressive distortion without losing note definition.
Bass Guitars
Though originally designed for six‑string guitars, the 620 pickup was adapted for bass guitars. The increased output provides a robust low‑frequency response, making it popular in funk and jazz fusion contexts.
Steel Guitars
Lap steel and pedal steel players have used the 620 pickup to add sustain and clarity to their melodic lines. The pickup’s high‑output capability helps sustain long, lyrical notes that are characteristic of steel guitar playing.
Custom Builders
Custom guitar builders frequently incorporate the 620 pickup into boutique instruments. The pickup’s versatility allows builders to craft guitars with a wide range of tonal palettes, from bright single‑coil sounds to thick, overdriven humbucking tones.
Performance Characteristics
Tone
The 620 pickup delivers a bright, articulate tone with a pronounced midrange presence. Its high output facilitates strong distortion when paired with high‑gain amplifiers, yet it retains note separation even at maximum volume.
Sustain
Due to its robust magnetic flux, the 620 pickup can sustain notes for longer durations. This sustain is particularly evident when playing single notes or chord arpeggios, as the pickup continues to capture string vibrations with minimal decay.
Dynamic Range
Dynamic response is a hallmark of the 620 pickup. It accurately reproduces subtle variations in picking intensity, allowing expressive playing. The pickup's coil design ensures that quiet passages are not lost while still producing powerful high‑gain tones.
Noise
The reversed‑coil configuration effectively reduces electromagnetic hum. Users report minimal background noise, even when the pickup is placed close to the bridge or used with long cable runs.
Legacy and Influence
The 620 pickup has influenced subsequent pickup designs by demonstrating the viability of high‑output pickups that maintain clarity. Many modern manufacturers have incorporated elements of the 620's coil winding technique into their own models.
Prominent musicians who have employed the 620 pickup include:
- Steve Miller – noted for using the pickup in live performances during the 1980s.
- Peter Green – utilized the pickup for its sustain in blues solos.
- Jimmie Vaughan – incorporated the pickup into his signature guitar models.
- John Mayer – favored the pickup for its clarity in acoustic‑electric hybrid setups.
These artists' adoption of the 620 pickup helped cement its reputation as a reliable, high‑performance component in professional music production.
Reissues and Aftermarket Variants
The demand for vintage gear has spurred a number of reissue projects. Companies such as Vintage Gear Ltd. and Retro Tone Inc. have released pickups modeled after the original 620, using modern materials to improve reliability. These aftermarket versions often feature slightly higher output and improved shielding, appealing to both collectors and contemporary musicians.
Collectibility
Original 1970s production units of the 620 pickup are considered valuable collectibles. They are often found in auctions for vintage guitars, with prices reflecting their condition and provenance. The limited production numbers and the pickup's historical significance contribute to its desirability among collectors.
Production and Availability
Original Production
St. Paul Manufacturing ceased production of the 620 pickup in 1995 due to a shift in company focus towards digital audio equipment. During its production lifespan, approximately 25,000 units were manufactured, with the majority sold to custom guitar builders and professional musicians.
Current Market
Today, the 620 pickup is available primarily through aftermarket suppliers and reissue projects. Many suppliers provide detailed specifications and installation guides to assist luthiers in integrating the pickup into modern instruments.
Installation Guide
Installation typically follows these steps:
- Remove the existing pickup or prepare the guitar body for a new pickup.
- Align the 620 pickup's mounting screws with the guitar's mounting points.
- Screw the pickup into place using a torque wrench set to 5 Nm.
- Connect the pickup's wiring harness to the guitar's output jack.
- Test the pickup using a multimeter to verify impedance.
Following these guidelines ensures proper alignment and signal integrity.
Warranty and Support
Aftermarket suppliers typically offer a 90‑day warranty on reissue pickups. The warranty covers manufacturing defects and provides replacement services if the pickup fails within the warranty period.
Conclusion
The St. Paul 620 pickup stands as a testament to innovative pickup design. Its high‑output capability, clarity, and sustain make it a sought‑after component in both vintage and modern musical contexts. While production has ceased, the pickup's influence continues to resonate across the guitar manufacturing and performance communities.
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