The UREI 533 Octave Graphic Equaliser is a studio quality one octave equaliser developed for precise and musical tonal control in professional recording, broadcast, sound reinforcement, and high fidelity monitoring systems. Introduced in 1986, the UREI 533 reflects the design philosophy that defined UREI Electronic Products during the mid-1980s, combining accurate filtering, high headroom, and low noise performance in a compact and robust rackmount unit.
The UREI 533 is built around ten active, minimum phase, two-pole synthesised LC filter networks. These filters are carefully engineered so that their skirts combine smoothly when multiple bands are used simultaneously, minimising ripple and maintaining a coherent phase response across the audio spectrum. Each filter operates on standard ISO one octave centre frequencies, spanning from 31.5 Hz through to 16 kHz. The equaliser provides up to 12 dB of boost or cut per band, with vertical, stepless slide controls that allow continuous adjustment and provide a clear visual representation of the overall response curve.
Overall gain on the UREI 533 is adjustable from -10 dB to +20 dB via a front panel control, allowing the unit to be optimised for a wide range of signal levels and system requirements. With a maximum input capability of +20 dBu and a maximum output capability of +24 dBm, the equaliser offers generous headroom suitable for demanding professional signal chains. Signal to noise performance exceeds 106 dB at maximum output, achieved through sophisticated active circuitry and careful component selection, resulting in clean and transparent operation even in critical applications.
The UREI 533 features balanced bridging differential inputs and floating, transformer isolated outputs, ensuring compatibility with professional balanced systems while maintaining excellent noise rejection. Input and output connections are provided via rear panel barrier strips, supporting both balanced and unbalanced operation. A front panel EQ In Out switch allows instant bypass of the equalisation circuitry for accurate A B comparison. LED indicators on the front panel provide clear status information, including power on indication and overload monitoring, with levels observed at multiple internal circuit points.
Power is supplied by an internal regulated power supply designed for international operation, supporting both 100 to 125 volt and 200 to 250 volt AC mains at 50 or 60 Hz. The UREI 533 is housed in a durable rackmount chassis featuring a brushed clear anodised aluminium front panel finished in two shades, paired with a cadmium plated steel chassis. Optional accessories included single and double rackmount kits and an XLR adapter for input and output connections. Designed for reliable operation in professional environments, the UREI 533 exemplifies the build quality and sonic precision associated with UREI products of this era.
Features
- Ten band one octave graphic equaliser using ISO standard centre frequencies
- Active minimum phase synthesised LC filter circuitry
- Up to 12 dB of boost or cut per band
- Smooth filter combining with minimal ripple and phase shift
- Overall gain adjustable from -10 dB to +20 dB
- High headroom input and output capability
- Balanced differential input and transformer isolated output
- Front panel EQ bypass for A B comparison
- LED indicators for power and overload monitoring
- Internally regulated multi voltage power supply