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Radial Q3 500-Series Induction Coil EQ  From Radial

The Q3 induction coil EQ... probably the most exciting equalizer ever made.

Radial Engineering


Retail:  $800.00

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What We Think

This is an unusual EQ. It’s not so strange that you’ll need to read the manual, but it is far from your typical 3 band semi-parametric. Unlike your more traditional EQ module, which would probably have knobs to boost/cut at a particular frequency, the Q3 actually has rotary switches that function like EQ presets. If you’re already confused, you’re not alone, but it gets a bit more understandable as you start to turn the knobs.

Each position on each of these switches is going to give you a different boost or cut at a different center frequency. To put it a different way, each click is not giving you more or less of a particular frequency range, but instead it’s boosting (or cutting) at a completely different point, and with a different amount of gain.

When I first patched it in on a guitar track, I had to take some time listening to each position of each switch to hear what was happening. I took some notes, and tried it on a kick drum, bass guitar and a few other guitar tracks and soon enough I had a pretty decent idea of what positions were working for me.

If you don’t have the time for an EQ with a learning curve or need something that will give you exacting control over the whole frequency spectrum, don’t get a Q3 - maybe a Phoenix DRS-EQ, Great River Harrison or Radial’s own Q4 would be a better fit. On the other hand, if you’re looking for an EQ that will impart character and vibe to your tracks then I would strongly consider the Radial Q3. It’s definitely worth a listen.

Manufacturer's Description from Radial

The Radial Q3 is a spectacular sounding induction coil EQ that has been formatted to fit the popular 500 series format and the Radial Workhorse. It is designed to accentuate the character of a voice or instrument without introducing the artifacts and phase anomalies commonly associated with typical gyrator (resistor-capacitor) equalizer circuits.

The Q3 features four easy to use controls: top-end boost, mid-range cut, low frequency bass boost and gain make-up to offset the signal loss that occurs when using passive equalization. Each of the three EQ bands employs a 12 position Grayhill switch with a different preset curve at each position. These are carefully crafted to introduce subtle accents, huge hype and warm sounding cuts that will flatter and enthral. Each EQ setting is augmented with a miniature toggle switch that enables you to attenuate the curve for more subtle effects to deliver over 10,000 combinations of tonal bliss. And because presets are employed, it's easy to recreate favourite patches by setting the dials with 'easy to remember' 3-number combinations.

Adapted for use with the Radial Workhorse and older API Lunchbox racks, the Radial Q3 is plug-and-play easy to use. Simply feed it with a balanced line level signal and you are set to go. When connected to a Workhorse, the Omniport is assigned as an effects loop to allow various processing devices to be inserted into the EQ signal chain.


  • Coil EQ based on vintage EQs from the golden age
  • A stunning combination of over 10,000 tonal variations
  • Lets you color your sound with warmth and detail
  • Works with Workhorse and all 500 series power racks
Radial Engineering

About Manufacturer

Radial Engineering is a manufacturer and distributor of professional audio equipment, building tools for the working audio and audio-video professional. Radial is located on the Fraser River, just outside Vancouver, British Columbia in the municipality of Port Coquitlam. The company began operations in the fall of 1991 as the Canadian distributor of Mogami cable and Jensen Audio Transformers. In 1992, it became a limited corporation under the JP Cabletek Electronics Ltd. banner. The Radial name was first used on house branded cables and snake systems. The Radial name and logo represents a cross section of quad cable; Radial being round. In 1996 the Radial JDI direct box was launched. This led the way to the Radial JDV and today, over 50 electronic products are now being produced under the Radial, Tonebone and Forest Audio brands. In 2001, the Primacoustic brand was launched to address the growing demand for acoustic products for the burgeoning home recording market and in 2006, the company officially changed its name to Radial Engineering Ltd.


The Q3 specifications shown below provide the engineer with basic data such as noise and distortion. To truly understand the 'functionality' of the device, one is better served by reviewing the various frequency curves that are shown on the using page. Or better yet... by actually listening the effect of the Q3 on voice, instruments and various program material. The Radial Q3 is not about clinical – it is about creatively applying the effect of a coil to add excitement to your music.


Audio circuit type: Coil/Capacitor/Resistive Boost and Cut Filters
Frequency response: 20Hz-20KHz +/- 1dB in non EQ positions
Dynamic range: 112dB
Noise floor: -90dBu filters off (-87dBu filters on)
Maximum input: +20dBu
Total harmonic distortion: 0.003% @ -0dBu @ 1kHz
Inter-modulation distortion: 0.002% (0dBu input)
Input impedance: 12k Ohms, balanced
Output impedance: 440 Ohms balanced


High pass filter: -3dB @ 150Hz
Gain: 7dB (maximum output, no filters)
XLR configuration: Balanced I/O, AES standard (pin-2 hot)


Current draw: 25mA
Shipping Size: Size: 9" x 6.25" x 2" (228 x 159 x 51mm)
Weight: 1.5lbs (0.7kg)
Compliance (API): Yes
Compliance (WHOS-Doc): Yes
Warranty: Radial 3-year, transferable





Q3 User Guide