The UREI 545 Parametric Equaliser is a fully featured professional equaliser designed for precise creative and corrective signal shaping in recording studios, broadcast facilities, sound reinforcement systems, motion picture and television production, and live performance environments. Released in 1979, the UREI 545 was engineered as a true parametric equaliser, with all critical filter parameters continuously variable, offering a level of control and flexibility that was advanced for its time.
At the centre of the UREI 545 design are four independent parametric equalisation sections. Three of these sections cover overlapping frequency ranges from 24 Hz to 12.5 kHz, while the fourth section incorporates a multiplier range switch, allowing it to span the entire audio spectrum from 15 Hz to 20 kHz. Each parametric section provides continuously variable control over frequency, bandwidth, and boost or cut, with perfectly reciprocal characteristics. Boost and cut are adjustable between plus and minus 15 dB, while bandwidth is continuously variable from one quarter of an octave to two octaves, enabling both surgical correction and broad tonal shaping.
In addition to the parametric sections, the UREI 545 includes dedicated low cut and high cut filters for bandwidth restriction and system optimisation. These end cut filters are of the Butterworth type, providing a smooth and predictable response with an attenuation slope of 12 dB per octave beyond the minus 3 dB points. The low cut filter is continuously tunable from 16 Hz to 800 Hz, while the high cut filter is adjustable from 500 Hz to 25 kHz, allowing effective control of low frequency rumble and high frequency noise or harshness.
Although each filter section is independently adjustable, the filters are designed to combine smoothly when tuned to similar or identical frequencies. This behaviour is particularly useful when extreme filter characteristics are required, as it avoids unwanted ripple or irregular response. The front panel layout features large concentric controls with clear markings and accurate calibration, making filter selection and recall straightforward. The uncluttered and logical control layout contributes to the ease of operation that characterised UREI’s professional signal processing equipment.
The UREI 545 incorporates a multi point overload detection circuit that monitors signal levels throughout the unit. If any stage approaches overload, a front panel LED flashes to alert the user. A front panel bypass switch allows the equaliser section to be removed from the signal path entirely, restoring a flat frequency response for instant comparison. Balanced or unbalanced bridging inputs are provided, along with floating, transformer isolated outputs, ensuring compatibility with a wide range of professional audio systems and maintaining excellent noise rejection.
Power is supplied by an internal regulated power supply, selectable for operation on either 100 to 125 volt or 200 to 250 volt AC mains at 50 or 60 Hz. The UREI 545 is housed in a standard 19 inch rackmount chassis, with a brushed black anodised aluminium front panel and a cadmium plated steel chassis, reflecting the robust construction expected of professional equipment from this era.
Features
- Four fully parametric equalisation sections
- Continuously variable frequency, bandwidth, and boost or cut
- Boost and cut range of ±15 dB per band
- Bandwidth adjustable from one quarter to two octaves
- Wide frequency coverage from 15 Hz to 20 kHz
- Dedicated low cut and high cut Butterworth filters
- Multi point overload detection with front panel LED
- Balanced or unbalanced bridging input
- Transformer isolated floating output
- Internal regulated power supply for worldwide operation