QUAD 303
QUAD 303
- Overview
- Specifications
- Downloads
- Reviews
Avforums Editor's Choice
"Best Mid-Priced Stereo Amplifier"
HIFIANDMUSICSOURCE
"QUAD have hit the bullseye for me. I’d have a 33 and two 303’s in a heartbeat if I wasn’t already happy with my setup, but any reader out there who is thinking of changing or upgrading should give the QUADs a listen."
QUAD 33/303: The Future is Now!
“…when I went back to the 303 it was just so much more transparent. I could hear the Acoustics of the church that this session was recorded in, it just sounded more ‘you are there’ with the 303”
Pearl Acoustics
"... it's got a lovely sound, it's a little sweetness in the mid-range, not overly colored, dynamic, a good sound stage...
it does deserve to be there alongside companies like Luxman, MacIntosh and these really top quality brands.. And the beauty is, because QUAD have the production in China, the quality of the finish is like the iPhone quality... it's beautiful you couldn't criticise it at all. You get all of that for a very very realistic price!"
Quad 33 & 303 and Quad Revela 2 – preamplifier / power amplifier combo and floorstanding loudspeaker
The Quad 303 is a Class AB power amplifier that combines its retro aesthetic with modern performance and stability. Thanks to the triples output stage, it delivers a clean, precise and musically warm reproduction that impresses at both low and high volumes. The controlled bass reproduction, clear mids and detailed highs create a balanced sound. With its robust construction and low heat generation, the Quad 303 is highly reliable even during long periods of operation.
Best of 2024 - STAND OUT HIFI PRODUCT
I really enjoyed having this QUAD setup here in my home; it was a pleasure to live with. The Quad 33 and 303, wins a Pursuit Perfect System Standout Award for 2024, and I think it is very well deserved.
A British Audiophile
The 33 preamp and 303 power amp deliver a warm, rich audio experience, maintaining the classic sound signature and output stage of their predecessors.... Overall, I highly recommend the QUAD 33 preamp and 303 power amp for their admirable blend of modernity and tradition.
Pursuit Perfect System (UK)
I just like having the Quad 33 preamplifier in the system; it’s easy to live with... Most people will likely use the Quad 33 with the 303 power amplifier, creating a setup that’s easy to live with—hardly any heat generated and very enjoyable sound... The real appeal lies in the overall package—its look, feel, and easygoing sound that works fantastically with the Super Linton speakers.
AREA DVD
With the new edition of the legendary Quad components, consisting of the 33 stereo preamplifier and the 303 power amplifier, the British company has achieved a great success...
Acoustically, the Quad 33 and Quad 303 shine with an enormous degree of sonic culture and acoustic harmony. Shrill, harsh sounds are foreign to the duo, even at high volume. Powerful bass and a dense spatiality complete our listening impressions.
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.
A dream team of Rob Flain & Paul McConville (the world’s most experienced QUAD service engineers), Jan Ertner (30 years of experience in QUAD design), Peter Comeau (the acoustic director behind some of QUAD’s most successful loudspeakers) and David McNeill (the industrial designer responsible for two decades of QUAD innovations) were all a part of this labour of love, making no compromise in the demand for a product that could bear the name of 33 and 303.
The QUAD 303 power amplifier was intended for normal domestic use with loudspeakers of moderate efficiency, but was also used by broadcasting and recording studios, worldwide, who appreciate its excellent performance and dependability. The ethos hasn’t deviated.
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.
The QUAD 303 power amplifier was intended for normal domestic use with moderately efficient loudspeakers, but it was also used by broadcasting and recording studios worldwide, who appreciated its excellent performance and dependability.
The ethos hasn’t deviated. The original 33 and its partnering 303 were awarded with a ‘Council ofIndustrial Design Award in 1969’. Even today, the original design is celebrated and confirmed by its presence at the Museum of Modern Art in New York. The new 33 and 303 have been industrially engineered to surpass those original standards, with a truly modern appearance and functionality.
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!
Such a level is, of course, completely inaudible no matter how refined the test.
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.
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. 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 | 15k ohms (Line) 22k ohms (XLR) |
| 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) | 120 x 176 x 325 |
| Carton Size (mm) (W x H x D) | 226 x 312 x 462 |
| 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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