Pro Audio Files

Interview with Nir Averbuch of Sound Radix

Sound Radix is a small company with big ideas.

While many software companies have sought to reproduce the quality of analog hardware, Sound Radix has focused on exploring the full potential of the digital world.

Their flagship products include: Auto-Align, Pi, and Surfer EQ.

Each takes full advantage of digital capabilities and the results are quite profound.

Let’s start with a bit of history. How did your company come into being?

I’ve always loved music technology. After dropping from classical piano training in my teens (I just had it too rough…), the thing that brought me back to playing was this Yamaha toy synth I stumbled upon in a local music shop. I was immediately captivated by its ability to create new sounds and even though it was fairly limited, and it inspired me to play again and revive my passion for music. Since then, I was living on the edge of new music technologies, coming from the pure analog world through the digital revolution.

To make a long story short… for quite some time I’ve had ideas for new tools that I wanted to have for my work.

At the time, I felt that the majority of plug-in developers were focusing on vintage and analog gear emulation, which I love and use daily, but I also thought that we’ve got this powerful machine that can be harnessed to do some magic that analog gear cannot. I also wondered what if we looked at problems we’ve been solving with early 20th century technology, from a new, radical perspective, now that we have such powerful machines?

In 2010 a mutual friend introduced me to Yair Chuchem, who is a true genius, an algorithm artists and a true radical ; )

Soon after, we were joined by yet another genius developer, Dan Raviv, to found Sound Radix, Ltd.

What kind of music production background do you have?

I’ve been arranging and producing everything from world music to death metal for major and indie local artists since the early 90’s, as well as arranging and composing music for film and TV.

I think Pi is one of the most exceptional tools on the market. It’s one of those things that changes nothing but changes everything. Like someone just flipped the better button. What exactly, in technical terms, is Pi doing?

Thanks for the kinds words. Pi is the brainchild of Yair.

The idea is: What if channels in the mix could be “aware” of other channels and get their phase state optimized individually and automatically so when they’re summed into a mix bus, they’ll have minimal cancellations from overlapping frequencies (and therefore phatter sound).

Pi is a multi-channel aware, dynamic phase rotator. Pi has a central background mixing engine, that receives the audio streams from the individual tracks, calculates their optimal phase state for the mix, and sends the phase degree rotation instructions back to the individual Pi instances and groups.

And maybe in more laymen’s terms, what does Pi do?

Pi makes the mix sound better by significantly minimizing phase cancellations in the mix.

Pi has ended up on pretty much every mix since I purchased it about half a year ago. While I’ve gotten a feel for it, I still wonder how best to deal with situations where I’m bussing multiple tracks to a subgroup, and then processing that subgroup with EQ or compression. Is this counteracting some of the effects of Pi, or is there perhaps a way to set Pi to make this kind of thing work optimally?

Great question. Because processing groups with EQ and compression can alter their phase, it is possible that processing a bus will somewhat diminish PI’s optimization.

Having said that, assuming the tracks arriving at the subgroup are already Pi optimized, any phase changes that occur due to processing will impact all the tracks in the group equally and will retain most of Pi’s effect.

Now, I have read the manual, but I think it bears repeating — could you explain the ‘weight’ knob and why it’s so important? And when do you recommend using the Full Range mode vs. the Low Frequency mode?

Weight control allows us to give higher phase state priority to certain instruments. Depending on a channel’s weight settings, Pi will rotate tracks in the mix with lower Weight more to match tracks with higher Weight value.

This helps to reduce any artifacts that may be caused by some bass heavy instruments on other tracks in the mix.

For most use cases we recommend using the Full Range mode.

In cases where mostly low frequencies phase interactions is an issue we recommend using the Low Frequency mode.

Any chance of implementing that FR/LF to work outside of global controls, so that it could function within the group mix? In other words, if I wanted to have all my low end stuff (basses, kicks) working under an internal group mix only, I could have it functioning in LF mode, while everything else functions in FR mode? Just wishful thinking…

We could do that of course. Although in this specific example because most of the low end stuff is naturally low frequency heavy, and because Pi looks for an overall phase correlation improvement, Pi will naturally optimize the low frequencies of the low end instruments if they’re grouped within Pi.

Ok, let’s talk SurferEQ. First, for the reader, what exactly is this EQ?

Simply put, SurferEQ is a pitch-tracking equalizer.

While static EQ’s are in fact changing the harmonic balance of an instrument for every note played, SurferEQ retains the natural harmonic balance of solo instruments by pitch-tracking their notes and adjusting each EQ band frequency accordingly in real-time.

There’s certain situations where Surfer EQ is a no-brainer. Crafting a perfect sound from a monophonic instrument, it’s quick to re-shape the harmonics exactly as need be. But what about more complex chordal instrumentation like, say, Piano? Do you find certain uses for the “Surf” mode even on the polyphonic stuff?

Absolutely. We’ve incorporated a MIDI control functionality in SurferEQ so the fundamental frequencies of a song can be programmed into the project and then set any SurferEQ instance to reference that MIDI track. This allows for a decrease in the bass-prominent frequencies from the Piano track to avoid a cluttered mix while avoiding broad low end cuts which may cause the piano to sound like a lifeless dry bone ; )

Something I’d like to be able to get from SurferEQ that I don’t quite have under my belt: Sometimes an instrument/voice will produce annoying resonances that move relative to pitch. Any tips for taming down that kind of thing with SurferEQ?

A “surfing” EQ band can be swept just like standard EQ in real time. Dialing in a 6 dB boost of a narrow surfing band and sweeping the inner-freq knob of the EQ band (harmony) can help you hone in on the rogue resonance.

Auto-Align is very cool. It significantly reduces the comb-filter in a multi-microphone recording setup. Why is that so important?

Summing a recording of a single sound source with multiple microphones positioned at different distances can cause a really nasty comb-filter effect which is caused by the delay between the microphones.

A comb-filtered sound can often be described as “hollow” and “phasey” as some frequencies are getting cancelled while others are getting boosted unnaturally. Furthermore, the delay between microphones also smears the transients which are so important for drums.

Trying to fix the issue with a phase rotator can only help to some degree, because by its nature, comb-filter offsets every frequency at a different degree and it can’t help the transient smearing.

Auto-Align fundamentally fixes the issue by automatically detecting and removing the delay between the various microphones (or DI) and significantly reducing the comb-filter effect.

When using Auto-Align on drums, which contains a balance of phase-similar sound sources, how would you advise choosing a “central” element to begin aligning things?

I like to start with the top snare mic as the central reference. Its position in the space of the kit, broad frequency range and clear transients make it the perfect reference for the overheads and other distant mics. Once these are aligned to the snare, other pieces of the kit could be aligned to the overheads.

What’s next for Sound Radix?

We’ve just released Drum Leveler, which is a new beat detection-based compressor/expander. Because it processes each beat independently of others, it’s possible to improve the dynamics of drums without bringing up bleed or affecting other drum beats.

It’s an upward and downward compressor and will effortlessly increase softer beats and decrease louder beats to the target level. Ease of use was a major factor in Drum Leveler’s design.

A free fully functional trial version is available for download on our web site and here’s a little video that shows Drum Leveler in action.

Thanks so much for having us, Matthew. It’s been a pleasure!

Happy Holidays!


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Matthew Weiss

Matthew Weiss

Matthew Weiss is a Grammy nominated and Spellemann Award winning audio engineer from Philadelphia. Matthew has mixed songs for Snoop, Sonny Digital, Gorilla Zoe, Uri Caine, Dizzee Rascal, Arrested Development, 9th Wonder, !llmind & more. Get in touch:
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