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Quad 303 Power Amplifier
Quad 303 Power Amplifier
$2,299.00
Product Details
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QUAD 303 Power Amplifier at Vinyl Sound Toronto, Canada
The QUAD 303 is a stereo Class AB power amplifier from QUAD (Huntingdon, England), available at Vinyl Sound in Toronto, Canada. A modern re-engineering of the classic 303 that partnered the original QUAD 33 preamplifier, the new 303 keeps QUAD's famous symmetrical "triples" output stage while moving to a fully complementary design with a custom 200VA toroidal transformer. It delivers 2 x 50W into 8 ohms (2 x 70W into 4 ohms) with 10A of maximum output current, can be bridged to 140W into 8 ohms as a mono-block, and offers both RCA and balanced XLR inputs. The compact, cool-running 303 is designed to pair with the new QUAD 33 preamplifier.
A Design Icon Returns
The original QUAD 303 was intended for domestic use with loudspeakers of moderate efficiency, and it was also used by broadcasting and recording studios worldwide for its performance and dependability. The original 33 and 303 received a Council of Industrial Design Award in 1969, and the design is celebrated today through its presence at the Museum of Modern Art in New York. The new 303 was developed by a team including QUAD service engineers Rob Flain and Paul McConville, electronics designer Jan Ertner, acoustic director Peter Comeau, and industrial designer David McNeill.
Frequently Asked Questions
Q: What is the QUAD 303?
A: The QUAD 303 is a modern stereo Class AB power amplifier based on the classic QUAD 303. It uses QUAD's symmetrical "triples" output stage, now with a fully complementary output design, a custom 200VA low-noise toroidal transformer, RCA and balanced XLR inputs, and stereo or bridged mono operation. It is designed to partner the new QUAD 33 preamplifier.
Q: How much power does the QUAD 303 deliver?
A: The QUAD 303 is rated at 2 x 50W into 8 ohms and 2 x 70W into 4 ohms (THD under 1%), with a maximum output current of 10A. That is a little more than the original 303, which was officially rated at 45W into 8 ohms. In bridged mode it delivers 140W into 8 ohms or 170W into 4 ohms.
Q: Can the QUAD 303 be used as a mono-block?
A: Yes. The QUAD 303 offers stereo or bridged mode selection. In bridged mode it works as a mono-block power amplifier, delivering 140W into 8 ohms or 170W into 4 ohms.
Q: What are QUAD "triples"?
A: QUAD's "symmetrical triples" create a completely symmetrical output stage that greatly reduces distortion and makes the resting current independent of output transistor temperature. The triples also allow simple and effective control of output current, protecting the output transistors so they always operate within their ratings, which improves reliability. The new 303 combines this approach with a fully complementary output stage for better linearity and more stable bias.
Q: What inputs does the QUAD 303 have?
A: The QUAD 303 has one single-ended RCA line input and one balanced XLR input, plus a 12V trigger connection and high-quality speaker binding posts. Input sensitivity is 700 mV rms for the RCA input and 1.5V rms for the XLR input, with 10k ohm input impedance.
Q: Where can I buy the QUAD 303 in Toronto or Canada?
A: The QUAD 303 is available at Vinyl Sound in Toronto, Canada. Online checkout is not available for QUAD products, so please call or email us to place your order or to discuss a QUAD 33/303 pre/power system.
Key Tech Specs
The QUAD 303 brings back QUAD's symmetrical triples output stage in a compact, cool-running power amplifier with 50W per channel and bridged mono capability.
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In Depth
QUAD Symmetrical Triples Output Stage
Faithful to the original, the new QUAD 303 employs QUAD's famous symmetrical triples, which provide a completely symmetrical output stage, greatly reduce distortion, and make the resting current independent of output transistor temperature. The triples also allow simple and effective control of output current, so the output transistors always operate within their ratings, improving reliability without elaborate circuitry. Rated THD is below 0.002% at 1 kHz.
Fully Complementary Class AB Design and 200VA Toroidal Transformer
Where the original 303 used a quasi-complementary output stage due to the limited availability of complementary transistors at the time, the new 303 uses a fully complementary output stage with premium power transistors for better linearity, more stable static bias, and improved stability under high voltage and large current conditions. A new custom-specified 200VA low-noise toroidal transformer and an advanced feedback topology deliver 2 x 50W into 8 ohms, 2 x 70W into 4 ohms, and up to 10A of output current.
Stereo or Bridged Mono with Balanced Inputs
The QUAD 303 accepts single-ended RCA and balanced XLR inputs, with a 12V trigger and high-quality speaker binding posts. A stereo/bridge mode selector lets it operate as a mono-block delivering 140W into 8 ohms or 170W into 4 ohms. The anodised chassis with CNC-routed heat sinks on either side and a rugged housing that resists external vibration keep the classic QUAD look, finished in Classic QUAD Grey.
The Vinyl Sound Review
Council of Industrial Design Award | Awarded to the original QUAD 33 and 303 in 1969 Museum of Modern Art, New York | The original QUAD 33 and 303 design is part of the museum's presence, celebrating its industrial design
Technical Specifications
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