• Account
  • View Shopping Cart

Menu Search View Shopping Cart Call Us

Radial Q4 100% Discrete State-Variable 500-Series EQ  From Radial

the Q4 is a wonderful choice for adding analog character to a voice or instrument and is excellent for enhancing music program material.

Radial Engineering


Retail:  $700.00

"Experience the Difference"

Sound Pure's 3-Year Warranty

Our Free 3-Year Warranty!
In addition to the standard included manufacturer warranty, virtually all new products carry our exclusive, industry-leading, absolutely free, Sound Pure 3-Year Warranty, which includes PARTS & LABOR. This high-value perk is our way of providing the ultimate in added value to enhance the unique personal touch our small, dedicated team contributes to each purchase.
Learn more »

Lifetime Support

Free Lifetime Technical Support!
Our small team of dedicated experts is here to help the original purchaser for the lifetime of the product. Why? Because we care about building real relationships with our customers for life and stand behind every product we sell.

Free Shipping

This Product Ships Free!
Products ship from our well-located, climate- and humidity-controlled warehouse absolutely free (inside the continental USA). Low-cost international shipping options exist for most products.
Contact us for details »
Ships Quick!
Usually ships 3 - 5 business days after order processed.
Payments as low as $52/mo.

Want a lower price?
Get Discount

Check your email inbox now!


Our best price is too low to print,
but we'll email it to you immediately!

learn more »

How to get a lower price, instantly!

Why do we do this?

Some manufacturers have a "minimum advertised price", which restricts how low of a price we can display. By requesting an e-mail quote from us, you give us the ability to offer you a lower price than anywhere else on the web. A quote on the product will be sent instantly to the e-mail address you enter, and you can add the product to your cart at the lower price displayed in the e-mail.

Manufacturer's Description from Radial

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.

Designed to fit in the Radial Workhorse and other 500 series racks, the Q4 features four frequency bands with high and low shelving at 10kHz and 100Hz and two semi-parametric mid sections that let you sweep frequencies from 300Hz to 8kHz. The two mid-bands can be further optimized by selecting either a wide or narrow Q. All frequencies may be cut or boosted by up to 12dB - affording plenty of range. A handy 'bypass' switch lets you compare the dry tone with the EQ's effect and for those equipped with a Workhorse, the Omniport is designated as an unbalanced ¼" TRS input/output connection that can be inserted into a console channel strip using a single TRS cable.

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


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.


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
Warranty: Radial 3-year, transferable






Q4 User Guide