The legendary Quad 303 returns in a stunning 2024 edition. This iconic British power amplifier features Quad's renowned 'triples' Class AB output stage delivering 50W per channel (70W @ 4Ω) or 140W in bridged mono mode. With custom 200VA toroidal transformer, balanced XLR connectivity, 10A current delivery, and distinctive vertical tower design with front-facing heatsinks - the 303 remains true to its heritage while embracing modern performance.
The Quad 303 power amplifier needs little introduction. Between 1967 and 1985, over 94,000 units were sold, making it one of the most successful and beloved power amplifiers in hi-fi history. Designed by founder Peter Walker, the 303 became standard equipment not only in homes but also in broadcasting and recording studios worldwide, earning a permanent place in the Museum of Modern Art's collection for its innovative industrial design.
Now, after decades of requests from audiophiles globally, Quad has reimagined this icon for the 21st century while staying faithful to the design philosophy and sonic signature that made the original legendary.
Iconic Vertical Tower Design:
Very few hi-fi components are as instantly recognizable as the Quad 303. The 2024 edition honors Peter Walker's revolutionary vertical orientation - a space-saving tower format that positions the substantial heatsinks at the front rather than hidden on the sides or rear.
The new version retains this distinctive silhouette while incorporating thoughtful refinements. The original's taupe finish gives way to matte silver anodized aluminum. The heatsink fin count increases from eight to ten, with squared-off fins providing more efficient thermal dissipation. The standby button is now illuminated with LED backlighting, providing clear operational status.
At just 120mm wide, 176mm tall, and 325mm deep, the 303's compact footprint belies its substantial 8.4kg weight and robust construction. The vertical orientation allows multiple units to be placed side-by-side for bi-amping or bridged mono configurations without consuming excessive shelf space.
Advanced Feedback Triples Output Stage:
At the heart of the 303 lies Peter Walker's legendary "triples" output topology - an advanced feedback design that employs three pairs of output transistors per channel arranged in a complementary symmetrical configuration. This circuit architecture, considered ahead of its time in 1967, delivers exceptional linearity and thermal stability that remains competitive with modern designs.
The Class AB operation maintains optimal bias current independently of the output transistors' temperature, ensuring consistent performance from cold start-up through extended high-power operation. The result is a power amplifier that sounds as musical and composed during the first few minutes as it does hours later, with no thermal compression or tonal shifts as it warms up.
Custom 200VA Toroidal Transformer:
Powering the output stage is a brand-new custom-specified 200VA ultra-low noise toroidal transformer developed specifically for the 2024 edition. This substantial component provides ample current reserves and rock-solid voltage regulation, ensuring the 303 maintains its composure during demanding musical passages.
The toroidal design offers superior efficiency, reduced stray magnetic fields, and lower mechanical hum compared to traditional EI-core transformers. Combined with high-capacity filter capacitors, this power supply delivers the instantaneous current required for dynamic musical peaks while maintaining vanishingly low noise during quiet passages.
Power Output and Current Delivery:
The original Quad 303 was conservatively rated at 45W per channel into 8 ohms - a modest but honest specification that understated its real-world performance. The 2024 edition increases this to 50W per channel into 8 ohms and 70W into 4 ohms, with maximum current delivery of 10 amperes per channel.
These specifications tell only part of the story. The 303's "venerability is in the finesse of the performance, not just the raw power." The amplifier's superior current delivery and damping factor provide exceptional control over speaker drivers, particularly in the bass region where precise damping is critical for tight, articulate low frequencies.
The original 303 was known to have issues with lower-impedance loads. The 2024 edition has no such trouble, effortlessly driving even demanding 4-ohm speakers including Quad's own electrostatic designs. Many users report the 303 sounds as powerful and controlled as amplifiers rated at 100W, though with greater finesse and musical refinement.
Bridged Mono Operation:
A key enhancement over the original is the ability to operate two 303 amplifiers in bridged mono mode. At the touch of a rear-panel button, each amplifier combines its two stereo channels into a single high-power mono channel capable of delivering 140W into 8 ohms or 170W into 4 ohms.
This configuration nearly triples the power output while maintaining the 303's sonic signature. The bridged mono setup is ideal for:
- Driving demanding full-range speakers requiring more power and current
- Bi-amping configurations where each 303 drives a single speaker
- Large rooms requiring higher sound pressure levels
- Audiophiles seeking maximum dynamic headroom and bass control
The 12V trigger link output allows one 303 to control the power state of a second unit, enabling synchronized on/off operation for bridged mono or bi-amp systems.
Modern Connectivity:
While maintaining its analogue heritage, the 2024 Quad 303 offers contemporary connection options:
Inputs:
- 1 x RCA stereo pair (single-ended)
- 1 x XLR stereo pair (balanced)
- 1 x 12V Trigger input
Outputs:
- Gold-plated speaker binding posts (stereo pair)
- 1 x 12V Trigger output
- 1 x 12V Trigger Link output (for controlling second 303)
The inclusion of balanced XLR inputs matches the output options on the companion Quad 33 preamplifier, allowing optimal interfacing with balanced source components while maintaining compatibility with traditional single-ended equipment. Gold-plated binding posts accept spade lugs, banana plugs, or bare wire terminations up to substantial gauge.
Exceptional Technical Performance:
The Quad 303 power amplifier delivers specifications worthy of its heritage:
- Total Harmonic Distortion: <0.002% (1kHz)
- Signal-to-Noise Ratio: >108dB (A-weighted)
- Frequency Response: 20Hz-20kHz (+/-0.3dB)
- Input Sensitivity: 700mVrms (RCA), 1.5Vrms (XLR)
- Maximum Output Current: 10A
These figures represent true high-fidelity performance, ensuring the 303 adds nothing unwanted and subtracts nothing desired from your music. The ultra-low distortion and exceptional signal-to-noise ratio create a "black" background from which musical details emerge with startling clarity and precision.
Designed and Built to Last:
Like the original, the 2024 Quad 303 is designed for decades of reliable service. The robust construction, premium components, efficient thermal management through front-mounted heatsinks, and conservative operating parameters ensure this amplifier will deliver peak performance for generations.
The vertical tower orientation promotes natural convection cooling, with heated air rising away from the internal components. The substantial heatsinks maintain safe operating temperatures even during extended high-power operation. This is audio equipment designed to become a treasured part of your system for years to come, just like the many original 303s still in service over 50 years after manufacture.
Perfect Partner: Quad 33 Preamplifier:
The Quad 303 is designed to work seamlessly with the companion Quad 33 preamplifier (sold separately), recreating the legendary pre/power combination that defined British hi-fi from 1967 to 1985. The matched pair delivers the warm, smooth, musical sound that distinguished Quad amplification from harsher-sounding transistor designs of that era - now with enhanced clarity, detail, bandwidth, and dynamic range.
The 33/303 combination at £2,398 (or $3,198 USD) represents extraordinary value. In 1967, this system sold for £98 - equivalent to £2,230 in today's money. Add 20% VAT and the new combination costs over £400 less in real terms while delivering vastly superior performance, build quality, and features.
Technical Specifications
General Description: Stereo Power Amplifier (bridgeable to mono)
Design Philosophy & Core Technology:
- Class AB Power Amplifier
- Quad 303 Triples Output Stage topology
- Custom 200VA ultra-low noise toroidal transformer
- Stereo/Bridge mode selection
- Vertical tower orientation
- Front-mounted heatsink array
Power Amplifier Section:
Gain: +29dB
Rated Power Output:
- Stereo: 2 x 50W (8 ohms, THD<1%)
- Stereo: 2 x 70W (4 ohms, THD<1%)
- Bridged: 140W (8 ohms, THD<1%)
- Bridged: 170W (4 ohms, THD<1%)
Frequency Response: 20Hz - 20kHz (+/-0.3dB)
Total Harmonic Distortion (THD): <0.002% (1kHz)
Input Impedance:
- 10kΩ (RCA Line)
- 15kΩ or 22kΩ (XLR - sources vary slightly)
Input Sensitivity:
- 700mVrms (RCA Line)
- 1.5Vrms (XLR)
Signal-to-Noise Ratio (S/N): >108dB (A-weighted)
Maximum Output Current: 10A
Inputs:
- 1 x RCA stereo pair (line-level)
- 1 x XLR stereo pair (balanced)
- 1 x 12V Trigger
Outputs:
- 1 x Stereo speaker binding posts (gold-plated, accepts spades/bananas/bare wire)
- 1 x 12V Trigger
- 1 x 12V Trigger Link (for second 303)
Physical Specifications:
Orientation: Vertical tower design
Dimensions (W x H x D): 120mm x 176mm x 325mm (4.7" x 6.9" x 12.8")
Net Weight: 8.4kg (18.5 lbs)
Gross Weight (with packaging): 9.5kg (20.9 lbs)
Carton Size: 226mm x 312mm x 462mm (8.9" x 12.3" x 18.2")
Finish: Classic Quad Grey (matte silver anodized aluminum)
Heatsinks: 10 squared-off fins (front-facing)
Standby Button: Illuminated LED
Standby Power Consumption: <0.5W
Power Requirements: 220-240V ~ 50/60Hz or 100-120V ~ 50/60Hz (region dependent)
Power Supply: Custom 200VA ultra-low noise toroidal transformer
What's Included
- Quad 303 Power Amplifier
- Power Cord (region appropriate)
- User Manual
Note: Remote control is NOT included with the 303 (it's included with the 33 preamplifier for system control)
