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Deco Audio Shop
Quad 303 Power amplifier - New Edition
Quad 303 Power amplifier - New Edition
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£1,199.95 GBP
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£1,199.95 GBP
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The iconic Quad 303 power amplifier is a design classic. It was Quads first transistor design and was radical in both the circuit and the physical design. The chassis, with the heatsinks forming a integral part of the appearance won Quad an award from the Council of Industrial Design in 1969. It's easy to forget just how radical this product was back in 1967 when it was launched. It's still a great looking product today.
So it's with great delight we will see its return in November 2024 with a new edition, that's faithful to the original in many ways with some modern touches to boot.
The new model is faithful to the original in its architecture, but just as the looks have been subtly modernised so has the circuit.
The famous QUAD ‘symmetrical triples’ output stage remains. This is employed to provide a completely symmetrical output stage, greatly reducing distortion and rendering the resting current independent of output transistor temperature.
The use of ‘triples’ permits simple and effective control of the output current and since the voltage is also controlled, the output transistors are completely protected and must always operate within their ratings with the obvious advantages of greatly improved reliability under all conditions, without the use of elaborate and expensive circuitry.
Due to the lack of complementary transistors (NPN and PNP power transistors) in earlier times, the older QUAD 303 used a quasi-complementary output stage. The new version of the QUAD 303 now uses a fully complementary output stage, providing better linearity, more stable static bias, and improved stability under high voltage and large current conditions. Using premium power transistors, the 303 offers excellent gain linearity for accurate reproduction of the input signal with greater dynamic range.
The amplifier cannot be upset even when overdriven by an asymmetrical signal or by shorting or disconnecting the loudspeakers.
A brand new 200VA, custom specified low-noise toroidal transformer has been developed for the new 303.
The output stage of the discrete power amplifier circuit employs an advanced feedback topology to ensure superior linearity and exceptional thermal stability. Through its Class AB design, the ideal current is maintained independently of the temperature of the output transistors.
The result is a compact, cool-running power amplifier that possesses the capacity to deliver dynamic power and maintain a firm hold on the music while providing rich sonic detail.
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 @ 8 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.
The use of ‘triples’ permits simple and effective control of the output current and since the voltage is also controlled, the output transistors are completely protected and must always operate within their ratings with the obvious advantages of greatly improved reliability under all conditions, without the use of elaborate and expensive circuitry.
Due to the lack of complementary transistors (NPN and PNP power transistors) in earlier times, the older QUAD 303 used a quasi-complementary output stage. The new version of the QUAD 303 now uses a fully complementary output stage, providing better linearity, more stable static bias, and improved stability under high voltage and large current conditions. Using premium power transistors, the 303 offers excellent gain linearity for accurate reproduction of the input signal with greater dynamic range.
The amplifier cannot be upset even when overdriven by an asymmetrical signal or by shorting or disconnecting the loudspeakers.
A brand new 200VA, custom specified low-noise toroidal transformer has been developed for the new 303.
The output stage of the discrete power amplifier circuit employs an advanced feedback topology to ensure superior linearity and exceptional thermal stability. Through its Class AB design, the ideal current is maintained independently of the temperature of the output transistors.
The result is a compact, cool-running power amplifier that possesses the capacity to deliver dynamic power and maintain a firm hold on the music while providing rich sonic detail.
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 @ 8 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.
What's more the amplifier can be bridged to use it as a mono amplifier which would then allow each chassis to produce a potent 1 x 140w into 8 Ohms (and 1 x 170 into 4 Ohms).
Naturally the matching 33 pre amplifier is also having similar treatment, you can see details about it here.
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
Standard accessories Power Cord, Remote Control, User Manual
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
Standard accessories Power Cord, Remote Control, User Manual
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