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Description:

The Boss PQ-3B is a specialized three-band parametric equalizer pedal produced between 1991 and 1995, specifically engineered for bass guitars and other low-frequency instruments. Unlike standard graphic equalizers with fixed frequencies, the PQ-3B offers "surgical precision" by allowing users to sweep across a wide frequency range (25Hz to 16kHz) to find and adjust specific tonal areas. Key Features & ControlsThe pedal features a dual-concentric knob layout for each of its three bands, providing control over both the Frequency (the specific tone you want to target) and the Level (how much you want to boost or cut it). 

• Three-Band EQ Sections:
• • Low Band: Ranges from 25Hz to 400Hz, ideal for adding "body" or removing "room boom".
  • Middle Band: Covers 160Hz to 2.5kHz, useful for defining the "growl" of a bass or removing "mud" from the mix.
  • High Band: Ranges from 1kHz to 16kHz, perfect for adding "snap," clarity, or crisp articulation.
• Massive Boost/Cut: Each band provides a variable range of ±18dB, which is the highest boost/cut value found in any Boss EQ pedal.
• Master Level Control: A dedicated volume knob (also ±18dB) is placed before the filters. It helps balance the volume between the effect and your clean sound or can be used as a clean preamp boost. 

Technical Specifications

• Circuitry: Fully analog design.
• Input Impedance: 1 MΩ.
• Output Impedance: 1 kΩ.
• Residual Noise: -98 dBm or less (extremely quiet with all controls centered).
• Power: 9V battery or a Boss PSA Series AC Adaptor.
• Current Draw: 25 mA.
• Weight: 410g (15 oz.). 

Why it's Highly RegardedProfessionals often consider the PQ-3B a "preamp shaper" rather than just a simple EQ. It is favored for live performances to fix room-specific acoustic problems like standing waves. While designed for bass, it is also highly effective for extended-range guitars and synth basses to carve out a distinct presence in a dense mix.