About the QUAD 303 stereo power amplifier

Product Description
Very few Hi-Fi components are as instantly recognisable as the QUAD 33 and 303, and for that we make no apologies!

Still one of the most popular models in the history of one of the world’s most poignant Hi-Fi brands, the QUAD 33 and 303 are benchmarks in almost every angle of desirable audio equipment – performance, reliability, industrial design, value and musical romance. By revisiting the QUAD 33 and 303 components, QUAD demonstrates its authenticity, pedigree and excellence as a juggernaut of the British hi-fi world - past and present.

In listing the names involved in the development of this stunning iteration of an icon, you’ll find a calculation of close to 200 years of engineering experience and 100+ years of QUAD-exclusive design and service.

Function

The outstanding performance of the QUAD 303 is still celebrated to this day, and is largely due to the unique output circuit developed by QUAD. In reissuing the QUAD 303 power amplifier concept, exactly like the matching 33 preamplifer, QUAD’s incomparably experienced service team was matched with the equally adept engineering team to reinvoke the design, romance and performance in a thoroughly modern iteration of a hi-fi legend.

As with the new QUAD 33, every aspect of design and performance has been analysed and re-engineered way beyond simply modernising components and refreshing of specifications.

Circuitry

However, much like the original, the new QUAD 303 maintains its faithfulness to the original by employing the famous QUAD ‘symmetrical triples’. Employed to provide a completely symmetrical output stage, greatly reducing distortion and rendering the resting current independent of output transistor temperature. This development enables the designers to reduce distortion to emphatically low levels without sacrificing stability and to maintain this excellence under all dynamic conditions. To put this in perspective, the lowest theoretical distortion present on the very source material will still be some hundred times greater than that the QUAD 303!

Always respected for its conservative but consistent power-output, the classic QUAD 303 was officially rated at 45W @ 8 ohms. A modest but honest output, the 303’s venerability is in the finesse of the performance, not just the raw power. The new model is thoroughly the same.

However, with some tweaking and enhancements, the 303 is loaded with a little extra power – offering 50W @ ohms (70W @ 4 ohms) with a maximum current delivery of 10A into difficult loads. The original 303 was known to have issues with lower impedance loads, the new 303 has no such trouble. Perfectly suited to the more demanding requirements of the modern audiophile, it ensures any speakers – even including QUAD’s electrostatic designs – can be driven with ease. Connectivity options comprise single-ended RCA and balanced XLR inputs, a 12V trigger input and high-quality speaker binding posts. Simple, solid and thoroughly authentic, inside and out. The power output for 'bridged mode' (for use as a mono-block power amplifier) reaches 140W @ 8 ohms or 170W @ 4 ohms (bridged mono).

Specifications

Model QUAD 303
General Description Power Amplifier
Design Philosophy and Core Technology Class AB Power Amplifier
QUAD 303 Triples Output Stage
Custom 200VA Toroidal Transformer
Stereo/Bridge mode selection
Inputs 1 x Line, 1 x XLR
Outputs 1 x 12V Trigger
1 x Stereo Speaker, 1 x 12V Trigger (Link)
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 10k ohms
Input Sensitivity 700mVrms (Line)
1.5Vrms (XLR)
Signal-to-Noise Ratio (S/N) > 108dB (A - weighted)
Max. Output Current 10A
General
Standby Power Consumption <0.5W
Net Weight 8.4kg
Gross Weight 9.5kg
Dimensions (mm) (W x H x D) 325 X 176 X 120
Carton Size (mm) (W x H x D) 462 X 312 X 226
Finish Classic QUAD Grey
Power Requirements (depending on region) 220 - 240V - 50 / 60Hz
100 - 120V - 50 / 60Hz
Standard accessories Power Cord, Remote Control, User Manual

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