Hubbry Logo
Deacy AmpDeacy AmpMain
Open search
Deacy Amp
Community hub
Deacy Amp
logo
7 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Deacy Amp
Deacy Amp
Deacy Amp
View on Wikipedia
from Wikipedia

The Deacy Amp (pronounced "Deeky" /ˈdiːki/) is an electric guitar amplifier created in 1972[1] by Queen's bassist John Deacon, who is an electronics engineer by training. The amplifier circuit board from a Supersonic PR80 portable radio found in a builder's skip was fitted into a speaker cabinet and powered by a 9-volt battery. The amplifier had no volume or tone controls and for most of its history it was never broken and thus never repaired. It was used along with Queen lead guitarist Brian May's Red Special electric guitar and treble booster to produce sounds reminiscent of various orchestral instruments, such as violin, cello, trombone, clarinet, or even vocals, starting from the songs "Mad The Swine" (an unreleased song from the 1973 album Queen) and "Procession" from the 1974 album Queen II.[2]

KAT Deacy Amp replica

[edit]

In 1998, Greg Fryer undertook the job of trying to make three copies of the Deacy Amp with May's full backing with the help of UK amplifier specialist Dave Petersen. These amplifiers produced a similar compressed and saturated sound but lacked the tonal characteristics that were so crucial to the unique Deacy sound. In 2003, Nigel Knight became involved in the amplifier's development. Several prototype amplifiers were built that were continually edging closer to the sound of the original but all fell short of the mark when compared side by side with the real amplifier. It was only in 2008 when Knight was given permission to take the original Deacy Amp apart and test and analyse each individual component that he finally began to understand the intricate workings.[2]

With this new information in hand, Knight called on speaker manufacturers Celestion, who developed and produced nearly 30 prototypes for testing and analysis over a two-year period. Custom transformers were produced to exact winding and laminate specs, obsolete components were sourced and made RoHS compliant and bespoke cabinets were constructed from Sapele veneered chipboard, exactly as the original.

In 2010, some 12 years after the project commenced, The Brian May Deacy Amp replica was given the official approval and blessing of both Brian May and John Deacon.

The first production run of KAT Deacy Amp replicas were shipped in March 2011 and sold out within one month. Production of the KAT Deacy Amp was later discontinued.[1]

Vox VBM-1 Brian May Special Amplifier

[edit]

In 2003, Vox released the VBM-1 Brian May Special amplifier.[3] This mains-powered unit combined a treble booster with the sound of the Deacy amp circuit with a 10W amplifier pushing an integrated 1 × 6.5" twin cone speaker.

Brian May had allowed the Vox engineers to study the original Deacy amp to enable them to develop the circuitry required to accurately reproduce the original sound.

The amp featured a unique white vinyl covering on a traditional-looking Vox amplifier design with a Brian May 'Back to the Light' star logo in the lower right corner of the grille cloth.

The top-mounted controls from left to right are:

  • 1/4" input jack socket
  • Gain knob
  • Booster input
  • Gain (high/low) push switch
  • Tone knob
  • Volume knob
  • 1/4" recording/headphone output jack socket
  • 1/4" external speaker output jack socket

The three knobs were of a 'chickenhead' design.

Vox discontinued the VBM-1 amp in 2005.

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Deacy Amp

View on Grokipedia
from Grokipedia
The Deacy Amp is a custom-built, low-wattage solid-state , approximately 1.5 watts in output, constructed by , the bassist and electrical engineering student of the rock band Queen, in 1971 or 1972 using components salvaged from a discarded Conquest Supersonic PR80 found in a skip. Originally intended as a portable practice for Deacon's guitar playing—alongside his bass and keyboard work—the device features a simple four-transistor circuit with AC128 transistors in a Class B , a 6.5-inch twin-cone speaker, transformer-coupled input and output, and power from a standard 9-volt PP9 battery, with no volume control after modifications for streamlined use. Housed in a compact wooden derived from an old bookshelf speaker, the amp's asymmetric clipping produces a warm, harmonically rich that became integral to Queen's studio sound when Brian May adopted it in the early 1970s, pairing it with his handmade guitar and for multi-layered, symphonic guitar harmonies rather than live performances. Its distinctive tone contributed to iconic tracks across Queen's discography, including the instrumental intro to "Procession" and rhythm guitar on "Killer Queen" from Queen II and Sheer Heart Attack (1974), acoustic-like parts in "Love of My Life" and "Good Company," the orchestral swell in "God Save the Queen," as well as May's solo album Another World (1998). The original amp remained unopened until 1998, when audio engineer Greg Fryer examined it during Another World sessions, leading to authorized replicas by Fryer and starting that year and later by Knight Audio Technologies, which replicate its germanium-based circuit and unique for enthusiasts seeking to recreate Queen's signature sound.

History and Origins

Creation by John Deacon

, a trained electronics engineer, graduated with first-class honors in electronic engineering from Chelsea College, University of London, in 1972. During his university years, he cultivated a hobbyist passion for assembling audio equipment, often experimenting with salvaged components to build custom devices. In early to mid-1972, amid Queen's early formation and before their breakthrough with the 1973 debut album, created the Deacy Amp as a modest home practice . He sourced the core circuit board from a discarded Supersonic PR80 portable radio found in a skip, integrating it into a modified hi-fi bookshelf speaker cabinet for a compact, battery-powered design that emphasized portability over professional output. The build reflected 's resourceful approach, featuring a simple jack socket and minimal controls, tailored specifically for personal guitar and bass practice rather than stage or studio demands. Brian May eventually recognized the amp's distinctive warm tone and incorporated it into his setup during band rehearsals.

Early Adoption by Brian May

In 1972, after joining Queen in 1971, bassist brought his homemade practice amplifier to the band's rehearsal space in for the group to try. Designed initially as a compact practice amp powered by a , the device caught the attention of guitarist during these sessions. May quickly experimented with the amp, plugging in his handmade guitar and to explore its tonal possibilities. Despite its origins as a practice , May discovered that pushing it into overdrive produced a warm, saturated ideal for his layered guitar harmonies, marking an early shift from its intended use. This experimentation highlighted the amp's versatility in a rock context, transforming it from Deacon's personal project into a shared band tool during Queen's formative years. The amplifier earned its nickname "Deacy Amp" from Deacon's surname, reflecting his ingenuity in assembling it from scavenged parts. In the pre-fame period of the early , May incorporated it into practice sessions to refine the band's sound, valuing its ability to create cohesive, symphonic guitar textures without the need for larger rigs. These rehearsals solidified its role as an essential element in Queen's evolving musical identity before any formal recordings.

Technical Specifications

Core Components

The Deacy Amp, constructed by in the early 1970s, relies on a simple array of scavenged electronic components to achieve its low-power amplification. Central to its design are transistors, specifically one AC125, one AC126, and two AC128 models, which provide the core amplification stages using surplus parts from 1960s radios like the Supersonic PR-80. These transistors, known for their warm, vintage characteristics, were selected for their availability and performance in low-voltage circuits. The amp's audio output is delivered through a compact 6.5-inch twin-cone speaker, housed within the unit to create an intimate sound projection suitable for close-miking in studio environments. Power is supplied by a standard 9-volt PP9 battery, clipped externally for easy replacement, enabling portable, battery-operated use without the need for . The amp originally featured a dangling volume which was later removed, leaving no user controls for streamlined operation. With an output of approximately 1 watt, the Deacy Amp is engineered for quiet, nuanced performance rather than high-volume applications. Its enclosure consists of a handmade wooden box fashioned from a modified hi-fi bookshelf speaker cabinet, constructed with mahogany-veneered chipboard for durability and , maintaining portability. Deacon's background allowed him to adeptly integrate these scavenged radio components into a functional .

Circuit Design and Operation

The Deacy Amp features a simple single-stage followed by a transformer-coupled push-pull output stage, utilizing four to achieve its characteristic amplification. The preamp section employs an AC125 and AC126 for initial signal gain, while the output stage uses two AC128 in a mismatched , driven via a phase-splitting . This design, derived intuitively by from salvaged components of a Supersonic PR-80 radio, lacks a formal volume control and operates at full gain, contributing to its raw responsiveness. Powered by a 9-volt PP9 battery, the amp functions as a Class B amplifier with asymmetric gains due to the germanium transistors' inherent variations, which minimize through natural leakage currents. The signal path processes guitar input through the high-gain preamp, where germanium devices introduce soft clipping early in the chain, producing warm, fuzzy even at low volumes without requiring external pedals. coupling between stages enhances this by allowing controlled overload, resulting in harmonically rich compression that sustains notes smoothly. The circuit's high sensitivity to guitar pickups stems from the low-power output (approximately 750 mW RMS undistorted) and the transistors' temperature-dependent behavior, which amplifies subtle dynamics into a layered, orchestral quality ideal for multi-tracking. When multiple guitar layers are recorded through the amp, the natural overdrive creates a "symphonic" tone with prominent resonance around 600-650 Hz, evoking string ensemble effects. No official existed for the original unit until modern replicas reverse-engineered it based on measurements and component analysis.

Role in Queen's Recordings

Studio Usage Techniques

In Queen's studio sessions, Brian May frequently employed multi-tracking techniques with the Deacy Amp to create dense harmonic layers, recording multiple guitar passes through the to build symphonic textures that blended seamlessly in the mix. This approach involved individual lines or notes progressively, leveraging the amp's unique tonal characteristics to emulate orchestral elements without additional instruments. Often, May utilized the phase-switching capabilities of his guitar during these sessions to introduce subtle variations in and spatial positioning among the layered tracks, enhancing the overall depth and complexity of the guitar arrangements. For optimal capture in the studio, the Deacy Amp was typically set up with close-miking of its small speaker using a dynamic microphone such as the positioned directly against the grille cloth, centered on a marked point for consistent tone. This intimate placement minimized room ambience and emphasized the amp's intimate, focused output, which was sometimes augmented with effects like delay to add spatial depth and movement to the recordings. The setup relied on direct connection from May's guitar via a , with the amp's volume control set to maximum and powered by a simple , ensuring a straightforward signal path that preserved the Deacy's distinctive midrange presence. The Deacy Amp's low output power, approximately 1.5 watts, proved advantageous for quiet overdub sessions, allowing May to record at manageable volumes without microphone bleed from other instruments or excessive studio . was primarily generated through the amp's circuitry saturation when driven hard, rather than relying on external pedals, yielding a smooth, organic breakup that integrated well with multi-tracked layers. However, its limited power and fragile construction made it unsuitable for live amplification, confining its use to controlled studio environments where precision and layering were paramount.

Key Songs and Albums

The Deacy Amp first appeared in Queen's discography on the tracks "" and "" from the 1974 album , with prominent use on "" from the later 1974 album , where utilized it to produce layered guitar tones resembling acoustic instruments, contributing to the song's intricate and polished sound. This debut marked the beginning of the amp's role in enhancing May's signature multi-tracked guitar arrangements, often blended with his for depth. Its usage expanded significantly on A Night at the Opera (1975), featuring in key tracks such as "Good Company," in which May layered recordings via the amp and a to emulate brass instruments like trumpets and trombones, as well as "Love of My Life" and "God Save the Queen." The amp's warm, compressed proved ideal for these experimental textures, influencing the album's groundbreaking production. This extensive application continued on subsequent releases, including A Day at the Races (1976) and (1977), where it supported similar harmonic guitar layers across multiple songs. Beyond Queen's core output, incorporated the Deacy Amp into his 1998 solo album Another World. Overall, the amp appeared on nearly every Queen album from 1974's through to 1991's , underscoring its enduring impact on the band's studio sound.

Replicas and Legacy

Commercial Reproductions

The development of commercial reproductions of the Deacy Amp began in the late , following 's rediscovery of the original amplifier, which had been instrumental in shaping Queen's distinctive guitar tones on recordings like those from the 1970s albums. In 1998, amp technician Greg Fryer, with May's approval, disassembled the fragile original at May's Allerton Hill studio to reverse-engineer its circuit, collaborating with specialist David Petersen to construct the first three prototypes by mid-1998; this effort faced significant challenges in replicating the unique asymmetrical clipping and warm overdrive produced by the original's rare transistors (such as AC125, AC126, and AC128) and custom-wound transformers, which were prone to variation and scarcity. The project evolved through further iterations, including work with engineer Colin Bloxsom on a Mk II prototype (1998–2001) and input from Nigel Knight starting in 2003, culminating in May's endorsement of deeper analysis in 2008 to ensure tonal accuracy. The first widely available commercial replica emerged from Knight Audio Technologies (KAT), which produced hand-built Deacy Amp reproductions from approximately 2011 to 2019, with around 165 units created under the supervision of Fryer and Knight using schematics derived directly from the original. These KAT models faithfully recreated the battery-powered, low-wattage design—outputting approximately 0.75 watts undistorted—incorporating vintage-sourced germanium transistors, a transformer-coupled push-pull output stage, and a custom Celestion speaker to match the original's intimate, treble-forward sound for recording applications. In 2003, Vox introduced the VBM-1 Brian May Special Amplifier as a higher-output (10-watt) commercial variant inspired by the Deacy Amp's tone circuit, granting users a more stage-friendly volume while preserving the characteristic treble boost and overdriven harmonics; May personally endorsed the model after Vox engineers studied the original prototype. Housed in a compact combo with a 6.5-inch speaker and white vinyl covering bearing the "Brian May" logo, the VBM-1 integrated a built-in and was priced accessibly at around $149 upon release, though production ceased by 2005. In 2023, a new authorized replica was built by Manuel Angelini and delivered to , noted for its close tonal fidelity to the original. Both the KAT replicas and Vox VBM-1 were produced as limited editions, constrained by the availability of period-correct components like transistors, rendering them sought-after collector's items on secondary markets today, often fetching premium prices due to their authenticity and ties to Queen's sonic legacy.

Influence on Modern Amplifiers

The Deacy Amp's distinctive tone and humble origins have fostered a dedicated community of DIY enthusiasts since the early , who replicate it using publicly available schematics and layouts shared online. These hobbyists often construct hand-wired versions on tagboards or stripboards, drawing from detailed circuit analyses to capture the amp's warm, harmonically rich overdrive. Pioneering builder Greg Fryer developed one of the most influential replicas in the late , collaborating with Queen members to verify its fidelity to the original, and his designs remain a cornerstone for modern hobbyist projects. This movement emphasizes point-to-point wiring and vintage-style components to evoke the amp's intimate, low-volume response, popular among guitarists seeking Queen-inspired studio tones without high-wattage setups. The Deacy Amp continues to influence contemporary designs, particularly in low-wattage offerings that prioritize its signature blend of clarity and subtle compression for home and recording use. Builders and small manufacturers echo its minimalist in custom amps, such as the 9 VOG from Tone Revival Guitars, which incorporates similar germanium-based circuitry for a comparable layered texture. Additionally, the amp's circuit has inspired digital modeling efforts within modern , allowing musicians to approximate its unique response in virtual rigs for production and live applications. Commercial models like the Vox VBM-1 further nod to this legacy by adapting the Deacy's principles for broader accessibility. Culturally, the Deacy Amp has been highlighted in Queen-focused media, sustaining its relevance among fans and players. It features prominently in the 2011 documentary Queen: Days of Our Lives, which explores the band's recording innovations, and in books like Queen: The Early Years by Mark Hodkinson, detailing its role in shaping iconic sounds. The 2010s surge in Queen biopics, notably the 2018 film , reignited public fascination with the group's gear, prompting renewed discussions and builds of Deacy replicas as tributes to Brian May's tonal palette. Replicating the Deacy Amp presents notable challenges, primarily due to the scarcity and variability of its original transistors, which degrade over time and contribute to the amp's idiosyncratic warmth. Many contemporary builders turn to silicon transistor alternatives to achieve consistent performance while approximating the desired tone, often adjusting and gain stages accordingly. This adaptation allows for more accessible and durable versions, though purists note subtle differences in harmonic content compared to the germanium originals.
Add your contribution
Related Hubs
User Avatar
No comments yet.