According to Radial Senior Engineer Dan Fraser: "Ever since George Massenburg invented and coined the term 'parametric equalizer' in 1972, audio equipment manufacturers have followed suit by employing integrated circuit op-amps to generate the gain in equalizer circuits. This innovation did away with the finicky induction coils and expensive switches that were used in the 1950s and 1960s, bringing affordable EQ circuits to the mass market. And although this approach certainly works very well, no company has ever gone back to the purity of 100% discrete electronics to produce a true class-A state variable filter design. The Q4 is exactly that. And for the more demanding golden eared engineers, the Q4 will give them an EQ choice that has, up until now, never been commercially available."

The Q4 is a line level device designed to interface with balanced pro audio recording systems. It features four EQ bands with fixed low and high frequency shelving at 100Hz and 10kHz, plus two semi-parametric mid bands that span between 300Hz ~ 2.4kHz and 1kHz ~ 12kHz respectively. Each mid band is also equipped with choice of wide or narrow Q to open up the sweet spot or tighten it for surgical precision. All frequencies are set with up to 12dB of boost or cut. The EQ may be bypassed to compare the pre and post effect.

Fraser continues: "For years, audiophiles and engineers have been touting the sonic advantages of full sized, discrete parts over their miniaturized integrated circuit computer and cell phone counterparts. The preference of using class-A circuits over class-AB or other designs is also well documented. Couple this with the fact that 500 series users are looking for the purity of analog and you can immediately understand why the Q4 is so appealing. And once you plug it in, you can immediately hear how good it sounds! There really is nothing like it."

As with all Radial 500 series modules, the Q4 is fully encased in steel to provide durability and screening against outside electro-magnetic fields. Inside, the Q4 features a double sided circuit board with 100% discrete through-hole parts. These are hand inserted through-hole wave soldered for optimal signal flow. When mounted inside a Workhorse rack, the Omniport serves as a ¼" TRS I/O that can be interfaced with a mixer's insert point using a simple TRS connector.  The Q4 is made in Canada and guaranteed for 3 years.