Quad 33 Preamplifier A compact analog preamplifier with balanced XLR input and output, MM/MC phonostage, current-feedback headphone amp, remote control, and Quad’s signature Tilt control The Quad 33 is a modern return to one of the most recognizable preamplifiers in British hi-fi. Designed to partner with the Quad 303 power amplifier, the 33 keeps the practical simplicity and unmistakable visual language of the original while adding modern functionality, improved build quality, balanced connectivity, remote control, and a newly developed MM/MC phonostage. Supported by digital microprocessor control but otherwise faithful to a classic analog preamplifier layout, the Quad 33 is built around a short, direct signal path, analog volume control, and Quad’s long-running approach to subtle system tuning. The result is a compact control center for analog systems, with line-level RCA inputs, fully balanced XLR input and output, dedicated preamp outputs, headphone output, and 12 V trigger outputs. Classic Quad Design The Quad 33 carries forward the practical, understated design language of the original 33 and 303 combination. Its machined and anodized front panel, all-metal chassis, backlit LCD screen, and illuminated push buttons give the preamplifier a familiar Quad identity while improving durability, visibility, and day-to-day usability. The display relays settings, adjustments, and values, while illumination settings for the buttons and LCD screen allow brightness and contrast adjustment, as well as a simple on/off setting to suit the room. Analog Control The master volume control is a fully analog, precision motorized ALPS potentiometer selected for long-life and low-noise performance. It remains tactile and precise when used by hand, while its motorized operation allows the knob to rotate automatically when volume is adjusted from the remote control. Alongside the main volume control, three endless rotary encoders provide immediate control over Quad’s bass adjustment, Tilt control, and balance control. These fine-tuning features are designed for subtle system adjustment rather than heavy-handed equalization. Balanced and Single-Ended Connectivity The Quad 33 includes both single-ended RCA and balanced XLR connectivity. Inputs include three RCA line inputs, one balanced XLR input, and one switchable MM/MC phono input. Outputs include RCA aux, RCA pre out, XLR pre out, headphone output, and two 12 V trigger outputs. The balanced XLR input and output set the new 33 apart from the original model, making it easier to integrate into modern preamp and power amplifier systems while preserving the compact analog simplicity of the 33 concept. MM/MC Phonostage The Quad 33 includes a new low-noise phonostage compatible with both moving magnet and moving coil cartridges. MM and MC operation can be selected directly, with no board upgrades or modifications required. The phono input stage uses ultra-low-noise audio op-amps, while the RIAA processing circuit uses a dual Bipolar/JFET audio operational amplifier. The JFET portion of the input stage supports high slew rates to help keep distortion low even when larger output swings are required. Bass and Tilt Controls The bass control allows adjustment from -3 dB to +3 dB, useful for adding a little body to leaner recordings or reducing excess bass in rooms where low frequencies become overblown. Quad’s Tilt control adjusts both ends of the frequency spectrum together, either lifting the bass while attenuating the treble or attenuating the bass while lifting the treble. Operating in 1 dB steps around a 700 Hz axis, Tilt changes the overall tonal balance toward warmer or cooler without simply acting like a conventional tone control. Power Supply and Signal Path The Quad 33 uses a custom-specified low-noise toroidal transformer, numerous reservoir and smoothing capacitors, and five regulated supply rails. Multiple ultra-low-noise regulators are used with measures designed to prevent contamination and cross-coupling between supply sections. Following traditional Quad practice, the core signal path is short and direct to preserve signal purity, while volume is adjusted purely in the analog domain under microprocessor control. About Quad Founded in London in 1936 by Peter Walker, Quad has built its reputation on disciplined engineering, practical design, and the enduring goal Walker described as “the closest approach to the original sound.” Originally focused on amplifiers and public-address equipment, the company moved to Huntingdon, Cambridgeshire, in 1941, where Quad’s British engineering, service, and development remain centered today. Quad’s history includes some of the most important products in British hi-fi, from the Quad II amplifier and the 33/303 preamp and power amplifier combination to the 405 current-dumping amplifier. In 1957, Quad introduced the world’s first production full-range electrostatic loudspeaker, establishing a loudspeaker lineage that continues through generations of ESL designs. Today, Quad continues to balance heritage and renewal, developing electronics and loudspeakers that respect the company’s classic design values while addressing modern listening habits. Across its amplifiers, digital components, and loudspeakers, Quad remains defined by clarity, restraint, and engineering purpose. Features Modern version of the classic Quad 33 preamplifier Designed to partner with the Quad 303 power amplifier Analog preamplifier with digital microprocessor control Short, direct signal path Fully analog precision motorized ALPS volume potentiometer Three RCA line-level inputs Balanced XLR input Balanced XLR preamp output RCA preamp output RCA aux output Dedicated current-feedback headphone amplifier Switchable MM/MC phonostage MM phono gain of 46 dB MC phono gain of 63.5 dB Ultra-low-noise audio op-amps in the phono input stage Dual Bipolar/JFET audio operational amplifier for RIAA processing Classic Quad Tilt control with 1 dB steps around a 700 Hz axis Bass adjustment from -3 dB to +3 dB Balance control Backlit LCD screen Illuminated push buttons Adjustable button and display brightness Premium machined and anodized front panel All-metal chassis Custom-specified low-noise toroidal transformer Five regulated power supply rails Multiple ultra-low-noise regulators Two 12 V trigger outputs Remote control functionality Included Accessories Power cord Remote control User manual Specifications General Description: Preamplifier Design Philosophy and Core Technology: Illuminated LCD screen, dedicated high-performance low-noise MM/MC phonostage, classic Quad Tilt adjustment, classic Quad tone controls, dedicated current-feedback headphone amplifier Inputs: 3 RCA, 1 balanced XLR pair, 1 phono MM/MC switchable Outputs: 1 RCA aux, 1 XLR, 1 RCA pre out, 1 headphone, 2 12 V trigger out Preamplifier Gain (Line/XLR, Phono MM, Phono MC): 0 dB, 46 dB, 63.5 dB Preamplifier Input Sensitivity (Line/XLR, Phono MM, Phono MC): 695 mV, 3.2 mV, 460 µV Preamplifier Input Impedance (Line/XLR, Phono MM, Phono MC): 10 kohms, 47 kohms/100 pF, 100 ohms/1.7 nF Preamplifier Signal-To-Noise Ratio (Line/XLR, Phono MM, Phono MC): >108 dB, >82 dB, >74 dB Preamplifier Output Impedance: 120 ohms Headphone Output Impedance: 2.35 ohms Headphone Load Impedance: 20–600 ohms Standby Power Consumption:
