QUAD 303 amplifier

The QUAD 3O3 with its QUAD 33 preamp are among the rare emblematic high-fidelity products. They have influenced several generations of music lovers and audiophiles over the last fifty years.

They still remain one of the most popular models in history and Quad, one of the most famous Hi-Fi brands in the world. The first QUAD 303 left the manufacturer's factories in 1967 and during all these years it symbolized a benchmark in terms of performance and reliability.

By revisiting the QUAD 303, the brand demonstrates its desire to reconnect with authenticity and history!

QUAD 33: Box

We find the lines and codes of the Quad 303, but it receives a slight makeover which gives it a touch that is both vintage and very contemporary. This “industrial” design of this new version is immediately recognizable. The anodized chassis is equipped with heat sinks machined with a CNC machine. The housing assembly provides a very robust and inert structure that resists both internal and external interference and vibration. 

QUAD 303 : Connections 

On the back of the device we find a pair of unbalanced inputs in RCA format and a balanced one in XLR format. A small push button allows you to choose between these two inputs.

Another allows you to put the amp in bridged mode (Mono).

The connection to the speakers is made via a very beautiful and efficient terminal block accepting banana plugs and forks.

The power cable is in IEC format and can therefore be serviced if necessary.

QUAD 303: Technology 

The exceptional performance of the QUAD 303 is still relevant today, and is largely due to the output circuit developed by QUAD and Peter Walker in 1967.

As in the original, the new QUAD 303 remains faithful to the original circuit by using the famous “symmetrical triples” diagram of the historic QUAD. 

They are used to provide a completely symmetrical output stage, significantly reducing distortion and making the quiescent current independent of the thermal drift of the output transistors.

Due to the lack of complementary transistors (NPN and PNP power transistors) in the past, the old QUAD 303 used a "quasi" complementary output stage. The new version of the QUAD 303 now uses a fully complementary output stage, thus providing better linearity, more stable static bias and improved stability under high voltage and large current conditions. This development allows designers to reduce distortion to extremely low levels without sacrificing stability and maintain this excellence in all dynamic

conditions. As the voltage is also controlled, the output transistors are completely protected and always operate within their rated values. This offers obvious advantages in reliability.

Every stage of development and every innovation has been thoroughly tested and fully agreed with QUAD's technical design and service team.

The Quad 303 can be used alone, and therefore in stereo mode, offering 8 ohm stereo power of 50 w. By using 2 Quad 303 bridged in Mono you obtain mono power at 8 ohms: 140 w and at 4 ohms, 170 w per channel!

QUAD 303: Testing and listening

When launching this project, it was decided at Quad that the new 33 and 303 combination would only see the light of day if performance would be improved compared to the original.

After 58 years since the release of the original 33 and 303, innovations and developments have been exponential, but only some have been used, and each with good reason. 

The Quad 303 is an admirable amplifier. It can be used with its long-time partner the Quad 33 but also with the majority of symmetrical preamplifiers on the market.

This amp brings rare refinement in this price range. It reproduces the music with a lot of space and breadth. The timbres are rich and full. Sometimes it feels like you're listening to a tube amplifier. It remains transparent, precise and dynamic whatever the style of music. The Quad 33 clearly favors musicality and naturalness, so much so that you can listen to it for hours (even at a high volume) without asking any questions. The high frequencies are precise enough to bring out the full mood and atmosphere of the recordings. And that extends to the bass, which is both powerful when needed and capable of revealing all the snap and resonance of a kick drum or electric bass.

The Quad 303 is very different from what can generally be found in this segment in terms of restitution. This new version goes much further in terms of definition and subtlety than its ancestor, without making any sacrifice in terms of musical pleasure. This amplifier is a real success and a bargain at this price!

Being able to use the Bridger in mono and therefore use a second Quad 33 is an additional advantage.

Our favorite!