On each channel there are five bands of EQ. Shelf filters give boost or cut in the bass and treble. With four corner frequencies on each control and variable degrees of boost or cut. In addition there are three tuned boost/cut filters with centre frequency adjustable over a total range of 60Hz to 16kHz. These give a maximum boost or cut of 12dB, allowing quite large response variation but without sacrificing sensitivity. Controls are laid out for maximum ease of use and can be bypassed at the flick of a switch for quick reference to the original signal.
All the equalising circuitry in the EAR825 is completely passive, with valve (tube) electronic stages providing buffering and amplification on the input and output. This valve circuitry follows designer Tim de Paravicini's philosophy of low distortion, low noise, high headroom and wide bandwidth and runs in single-ended mode with ultra-high-quality, in-house designed, coupling transformers providing balanced and floating input and output connections at studio levels. A highly filtered power supply ensures that operation is not impaired by disturbances on the electricity mains. As with all EAR professional audio products, reliability is paramount and valve life is typically 10,000 hours.