The Wolff Audio FREQ 500 is an exceptionally flexible 500 Series equalizer that handles both delicate tone polishing and surgical problem-solving with equal finesse. Designed by one of modern audio's most celebrated circuit engineers, it provides high-headroom transformer punch, intuitive proportional-Q response, and indispensable secondary filter modes in a single slot.

The Wolff Audio FREQ is a sweepable, 4-band proportional-Q parametric equalizer designed by industry legend Paul Wolff for the 500 Series format. Engineered to offer intuitive, musical control with ultra-low distortion and high-headroom clarity, the FREQ combines classic console-style tone shaping with modern utility. Its flexible layout allows engineers to make fast, broad-stroke tonal moves or precise surgical cuts across any tracking, mixing, or mastering application.

At the core of the FREQ's architecture is a custom Cinemag nickel and steel output transformer, carefully chosen to deliver high headroom (clipping onset above $+28\text{ dBu}$) and pristine signal transparency with subtle, musically rich low-end harmonic weight. Each of the four sweepable frequency bands provides $\pm 15\text{ dB}$ of boost or cut with a proportional-Q response—where the bandwidth automatically narrows as gain is increased or decreased—ensuring natural, phase-coherent adjustments.

To expand its operational versatility, the FREQ features secondary modes on every band. The High-Frequency (HF) and Low-Frequency (LF) bands include dedicated Wide mode switches that shift the response into a gentle 3-octave fixed curve for broad shelving and air/sub adjustments. Meanwhile, the Low-Mid (LM) and High-Mid (HM) bands offer a 1/3 Octave mode, overriding the proportional-Q behavior to lock the filter into a narrow, predictable bandwidth for surgical notch filtering and resonance cleanup. Complete with sealed relay switches, color-coded backlit status indicators, and a true hardwire bypass, the FREQ delivers versatile 500 Series equalization built for decades of reliable performance.

Key Features

• 4 Sweepable Proportional-Q Bands: Four fully parametric bands ($\pm 15\text{ dB}$ boost/cut) with overlapping ranges for total spectral control:

  • HF Band:$2\text{ kHz to } 20\text{ kHz}$ (with Wide 3-octave mode)

  • HM Band:$350\text{ Hz to } 10\text{ kHz}$ (with 1/3 Octave mode)

  • LM Band:$75\text{ Hz to } 2.2\text{ kHz}$ (with 1/3 Octave mode)

  • LF Band:$25\text{ Hz to } 700\text{ Hz}$ (with Wide 3-octave mode)

• Custom Cinemag Output Transformer: Nickel and steel core blend delivers ultra-low distortion ($<0.03\%$) and transparent performance with subtle low-end harmonic enhancement.

• Wide & 1/3-Octave Secondary Curves: Selectable modes convert high/low bands into smooth broad-stroke shelves, and mid bands into tight 1/3-octave surgical notch filters.

• Massive Analog Headroom: High-voltage design provides pristine dynamic performance with clipping onset occurring above $+28\text{ dBu}$.

• Hardwire Relay Bypass: Sealed gold-contact relays ensure completely uncolored signal pass-through when bypassed, along with noise-free mode switching.

• Single-Slot 500 Series Design: High-density control layout with backlit LED push-buttons and continuous potentiometers fits into any standard 500 Series enclosure.