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Radial Engineering


Radial Q4 State-variable EQ 500 Series Module


The Radial Q4 is a unique equalizer that combines the warmth and detail of a pure class-A circuit with the character of true 100% discrete state-variable filters. In other words, no integrated circuits are employed whatsoever. Each full size through-hole part is carefully inserted by hand and then wave soldered to ensure optimal signal flow. This produces a level of sonic warmth and musicality that excels above the others.


      • Four band semi-parametric equalizer
      • 100% discrete class-A state-variable filters
      • Sounds exceptionally warm and natural
      • Fits all standard 500 series power racks

      Unlike most EQs that employ high-gain, low-noise chips to convey a sense of clinical accuracy, the Radial Q4 is all about adding analog character to the signal path. This is achieved using 100% discrete parts throughout to produce the unique class-A circuit architecture. With this approach, you will encounter a slightly higher noise floor, a little bit more distortion and of course, overdriving the Q4 will occur more rapidly as you push it beyond it's intended working range. But these are the very characteristics that one looks for when recording with vintage audio devices. Yet even with this in mind, the Radial Q4 still manages to deliver less than 0.01% distortion and better than 90dB signal-to-noise. This is truly impressive given the nature of this unique EQ design.
      Specifications are subject to change without notice.
      Circuit type: Discrete state variable class-A
      Frequency response: 20Hz ~ 20kHz
      THD+N: 0.03% @ +4dB
      Maximum input level: +21dBu
      Maximum output level: +18dBu
      Gain: +/-12dB for each band
      Dynamic range: >95dB
      Equivalent input noise: -95dBu
      Common mode rejection ratio: >64dB @ 55Hz
      Intermodulation distortion: 0.07%
      Input impedance: 20K Ohms
      Output impedance: 150 Ohms
      Controls: Hi & low frequency shelving
        Hi mid & low mid semi parametric EQ
      Switches: Wide & Narrow Q
      EQ bypass
      Omniport: Configured as TRS in out connection
      Power requirement: 80mA
      Compliance: Yes - with API 500 series VPR aliance* 
        Yes - with Radial WHOS-Doc specification
      Size: Standard 500 series rack format
      Weight: 1.5 lbs. (0.7 kg)
      Shipping Size (L x W x H) : 9" x 6.5" x 2"
      Shipping Weight: TBA
      Conditions: For use in dry locations only between 5°C and 40°C
      Warranty: Radial 3-year, transferable
      *Radial is not a member of the VPR Aliance

      Requires 500 Series Rack that meets power requirements
Need more info on the Radial Q4? Click HERE for the Radial website >>>