Whether you’re a sound engineer, producer, consultant, installer, or musician, you’ve just added a powerful new weapon to your audio armory.

The DPR-901ii is a new class of audio equalizer. Both subtle and powerful, it builds on the established problem-solving capabilities of parametric equalizers.

Its uses range from processing and sweetening speech, instruments, and composite music, through SPL control, to loudspeaker system and room tuning. The DPR-901ii refines the EQ process, makes it more specific—and expands it too. For the first time, changes in EQ and signal dynamics at the EQ’d frequency can be created, which are triggered either above or below the individual threshold levels in four adjustable frequency bands. The changes in tonality can range from the subtle and highly specific to the extremes of instrument effects. Either way, the DPR-901ii’s unique subtractive process coupled with state-variable equalization ensures uncolored, low distortion sound. Group delay in particular is low and uniform, maintaining vital accuracy in the time/transient domain that is lacking in the majority of conventional equalizers with ‘Bell’ response envelopes.

The DPR-901ii is a four-band parametric equalizer which varies the degree of equalization dynamically, as the program level changes. The process can be thought of as frequency-selective compression and/or expansion, but it is fundamentally different from simple ‘frequency-conscious’ dynamics processing as used for noise gating, de-essing, and the like. It is also very different from the growing family of ‘sliding filter’ techniques used in single-ended noise reduction processors. A split facility allows the unit to be used as two separate two-band units, and a side chain listen button allows monitoring of the filter setup.

Frequency-selective compression is equivalent to applying CUT on a normal equalizer, while frequency-selective expansion is like applying BOOST. However, the DPR-901ii can be more subtle as the process is dynamic: it will only occur above (or below) the threshold you have set.

Some possible uses for the DPR-901ii technology can be:

• To selectively compress and/or expand, broad or narrow-band segments of program.
• To de-ess and de-pop.
• To add dynamic loudness control (e.g., bass boost at low SPLs).
• To control SPL in a dynamic and frequency-conscious manner.
• To enhance or ‘sweeten’ mixed program.
• To improve voice intelligibility (without risking howlround or feedback).
• To enhance low-level vocals.
• To correct for and/or guard against bad microphone technique (by unskilled performers).
• Friendly rotary control knobs for all parameter adjustments.
• Excellent low-level resolution to maintain subtle musical detail.
• Minimum phase and low group delay for any EQ setting.
• High headroom >+ 20dBu.
• Conservative drive capability into low impedances (down to 600 ohms) and long, highly capacitive cables.
• Automatic relay-controlled signal bypass if mains power is disconnected or fails.

Altogether, the DPR-901ii will not degrade a conventional high-quality analogue signal processing chain, even when two units are inserted in line with the composite stereo mix.