What is stereo?

There are now two system of high fidelity, monophonic (monaural) and stereophonic. Monophonic is a system that starts from one microphone and is fed through a single high fidelity set. Stereophonic is a double system. Two separate microphones are placed at different sides of the orchestra and two different systems are used to keep the two signals or channels separated. Two separate speakers are used, placed on different sides of you room. Stereo is much like 3-D photography, two slightly different sound reach your ears giving you a new dimension in sound.

H.H. Scott '59

QUAD 33 (1969)

The external design continues the Quad tradition of practical simplicity, which has won prizes and worldwide acclaim. The internal appearance is unmistakably Quad and reflects cocnern with quality of manufacture and ease of service.

The Quad 33 select and controls the radio tuners, gramophone pickup and tape recorder connected to it and feeds the loudspeakers via the power amplifier, providing for stereo or mono on either or both channels, from all inputs, plus monitoring and track selection facilites for tape.

Quad units may be used either free-standing or mounted in a cabinet, with plenty of scope for individual preference in layout design.

The standard Quad system of mounting is used, requiring only a rectangular cut-out for whiche a template is provided.


The controls are comprehensive but simple and are logically grouped to facilitate selection and control of the programme.


The filter is essential with modern good quality speakers and helpful at any time. It removes surface noise, tracing distortion and similar shortcomings in the upper frequency range of the recording or broadcast, and the two control filter system achieves this to a very fine degree without intruding unnecessarily into the harmonic range so essential for realistic reproduction.

Another fixed, built-in filter cuts out (without affecting the normal low frequency response of the equipment) unwanted signals at frequencies below 20 Hz, due to mechanical causes in motors and turntable mechanisms.

Bass and treble

Entirely separate from the filters are the bass and treble controls which provide independent adjustment of tonal balance when required. This operations is symmetrical and smooth without any unpleasant 'steps' in the response.

Every pickup correctly matched

To change the pickup matching merely remove the Disc Adaptor and plug it in again with another edge leading; four matching circuits on one board with provision to accomodate any future development in pickup design simply by changing the board. The input load is purely resistive over the entire audio bandwidth.


Any signal passing through the Quad 33 may be recorded without affecting normal reproduction on monitored off the tape (AB monitoring) as desired. The plug-in tape adaptor carries independent pre-set adjustments of signal level for both recording and replay on each channel, to suit the tape recorder in use. Again since this is a plug-in board, any future or special requirements can be met merely by replacing the board, thus adding further to the versatility of the Quad 33.

The Quad 33 control unit is designed to give maximum flexibility to the whole audio system combined with ease of operation. The unit features a simple and novel method of matching pick-up inputs, using a square printed circuit adapter board: each side of the board carries one circuit which can be plugged into the rear of the unit, so that the four sides offer four alternative circuits; tape recorder inputs are matched with a similar plug-in board. The controls are arranged in logical sequence suiting the importance of their function. While it is possible to adjust and correct for every eventuality required by the avid enthusiast, the design is such that once the minor controls are correctly set,

day by day operation becomes extremely simple. Two switched mains outlets at the rear of the unit supply the amplifier and radio tuner.


Distortion: All controls level, 0.5V rms output, with any input 0.2%; any control settings and any level within overload ratings <0.1%; both at 30 - 10 kHz

Residual Noise: 0 - 30 phon weighting 15.7 kHz bandwidth: <-90 dB controls level or cancel

Frequency Response: Any input, any output, RIAA or flat as appropriate: ±0.5 dB, 30 Hz - 20 kHz

Tone Controls: ±1 dB of curves shown opposite

Filters: To curves shown opposite at 5 kHz, 7 kHz and 10 kHz ±5%

Interchannel Balance: Within 1 dB with volume control varied from maximum to -45 dB

Balance Control Range: 9 dB either way

Crosstalk: Dependent on input sourec impedences. Replay/record typically better than 70 dB; interchannel typically better than 40 dB: both at 30 Hz - 10 kHz

Power input: 100 - 130 or 200 - 260 V, 50/60 Hz, 1.5 watts

Dimensions: Width 260 mm, Height 92 mmfree-standing, 83 mm panel only. Depth 165 mm free-standing, 140 mm behind cabinet panel when mounted.

Weight: 3 kg

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