George Massenburg

Vintage Massenburg EQ

Inside View of Radial Q4

Q4™ Development

Go ahead and ask: Why in the world would Radial bother building another EQ? Has this not been done time and time again? Yes of course... there are already all kinds of EQs in the market but none have ever been made quite like the Q4.

When we set about developing the Q4 the mandate was to produce an EQ that would enable the audio engineer to control various frequencies to shape the sound of a given track, while also introducing a measure of analogue character. The whole point of having analog processing is to add tone. We felt that given the limited space available in a 500 series module, the best option would be a semi-parametric EQ. This gives you instant control over the top and the bottom while letting you dial in or out the mid range frequencies to suit. The Q4 was designed to be easy to use, familiar and effective.

The first parametric EQ is attributed to George Massenburg and is documented in a paper he produced in 1972. His design did away with parts such as inductors and switches that were said to be problematic. These were replaced by op-amps, resisters and capacitors. Since then, all analog EQs have pretty much followed suit using integrated circuits to create the op-amps other than those that have replicated vintage Pultec coil EQs or some of the newer designs like the Radial Q3. Integrated circuits (ICs) are in fact a combination of miniaturized parts that together perform the function of amplifying the signal. In an EQ, this enables you to adjust the gain of a given frequency. ICs amplify the signal by a factor of thousands and use negative feedback to control the performance. Herein lies the problem: applying excessive negative feedback erodes the sonic performance.

Truth is, ICs are technical wonders! They are small, pack hundreds of miniature parts into an incredibly compact space, are generally very quiet and are amazingly inexpensive due to the huge numbers that are produced. They are used in almost every electronic device you can think of including cell phones, TVs, and computers! So why buck the trend? For years, the most demanding recording engineers and golden-ear audiophiles have unanimously proclaimed that larger parts sound better just as they tend to prefer old-school class-A circuits over newer alternatives. The amazingly high gain of IC op-amps is part of the problem. The large amount of negative feedback needed to set the operating point of an IC causes issues with the sound while removing a lot of the character. IC op-amps also employ class AB or class B output stages which can also alter sonic character. This is why so many high-end microphone preamp manufacturers employ discrete class-A circuits in their designs.

So why hasn't anyone ever made a 100% discrete class-A state-variable EQ?

There are several reasons that we can think of: Using discrete parts to create gain is expensive due to the added labor. More parts crammed into a small space increases noise – so getting the circuit to behave quietly is a challenge. This means that you have to invest a lot of time and effort into solving noise problems by moving parts around and at the end of the day; it becomes more expensive to produce. So manufacturers simply avoid the problem by reverting to the all-in-one IC solution.

The Q4 is not about compromise. It is about tone. The Q4 does not contain any IC op-amps or integrated circuits whatsoever. In other words, instead of driving the audio signal through a bunch of ICs with excessive gain that needs to be throttled back - full size discrete components are employed throughout for optimum gain at each stage. The circuit is class-A which of course further appeals to the most demanding audio fanatics. Yes, the Q4 is more expensive to build... and it probably has a bit more noise than the latest digital alternative, but these are small prices to pay given the incredible warmth and character. And in today's world of digital replicators and boring presets, isn't it nice to know that there is a unique old-school alternative that will make your tracks sound amazing?

The Radial Q4 is in a league all its own. Give it a listen. You may never EQ the same way again.