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Phase Engineering LEQ-5

Phase Engineering LEQ-5

The LEQ-5 is the first module by Australian music technology designer, Phase Engineering.  I am lucky to have one of six units that exist today, but a formal release will occur in the last half of 2024.  Warren, the man behind the brand, is also the lead hardware engineer for Innerclock Systems who makes the fabulous Sync-Gen technology. 

Regarding availability you can contact Warren at Phase Engineering directly, here.   

Phase Engineering may be familiar to synth and electronic music technology users in New South Wales (Australia) in the 1980s, where Warren operated the brand as a music technology repair and modification service.  Warren was also the authorised service agent for ARP, Moog, Sequential, PPG, Korg, Yamaha, Roland, Alesis, Akai, Emu etc…  So, really just the small players yeah?
 

So, what is it?

According the the one page manual, the LEQ-5 is a “specialised, 5 band inductor equaliser crafted to enhance sweet spots across the bass spectrum”.  We will talk a bit more about inductors later on.  The module is very well built, feels heavy in the hand and oozes quality in aesthetics and tonal character.  

Module Features

  • Audio IN and OUT
  • Band 1: 70 Hz
  • Band 2: 140 Hz
  • Band 3: 280 Hz
  • Band 4: 900 Hz
  • Band 5: 1800 Hz, 1.8 kHz
  • Low shelf: 100 Hz
  • High shelf: 2200 Hz, 2.2 kHz
  • Bypass switch
  • 16hp wide and an impressive 60mm deep

Inductors - what are they and why should you care?

The LEQ-5 hosts custom wound inductors.  That must be good, right?  Let's all nod as if we know what that means.  I have to admit that I didn't know what inductors were until three days ago. Today, I have slightly more than no clue, so in true internet fashion - let me share my limited knowledge with you. 

Inductor based EQs have been used in various technologies including the Moog IIIC 69 Fixed Filter Bank (1969), the Pultec EQP-1 Program Equalizer (1951) and the legendary SVT bass amplifiers.  The tonal impact is often described as squashing saturation which introduces a tape like effect.  To my ear, this makes a lot of sense.  The EQ boost and cut is incredible clean, and dialling up does create a creamy kind of saturation at specified frequencies.  

The LEQ-5 manual says “the use of inductors in EQ circuitry has a rich history in the professional and domestic audio world.  Inductors can be found in the EQ signal path of high end recording consoles, outboard EQs, bass amps, guitar amps, wah pedals etc.”  I have never liked wah pedals, but the rest of that sounds great! 

According to Wikipedia an inductor is a passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it.  I am not going to pretend I know what that means.  And really I don't care, it sounds great.  

The Tone

I suspect inductor EQ technology is the reason Paul Gilbert dedicated an entire song to the SVT bass amplifier.  “Heavier than I can lift, you'll know when I have riffed…”  And yes, you will definitely know when you have the LEQ-5 engaged… 

Flicking to bypass and then re-engaging the LEQ-5 reminds me of when I wake up in the morning and everything is blurry until I put on my glasses.  The LEQ-5 presents a night and day difference.  Having said that, I quite like both night AND day.  One is not necessarily better than the other, so this analogy really isn't working.  Let's move on… 

Engaging the LEQ-5 is a pleasure across may signal paths.  After running my Tubbutec 6m0d6 drum module mix out through the LEQ-5 I cant imagine using it any other way.  Placing the LEQ-5 at the end of a bass voice gives you opportunity to increase the attack and hit of the note with some higher frequency boost, add presence to you low bass (sub 100 Hz), or both simultaneously.  This is a beautiful thing.  

These go up to 15…

All five EQ bands have plus/minus 15dB of gain, which is rather a lot!  I had expected grainy performance past the 6 dB mark, but if you gain stage correctly the LEQ-5 remains nice and clean all the way through.  Of course, no one is forcing you to fight clean.  There are plenty of great sounds to be found by pushing the limits, from squashed warmth to full on clipping and overdrive.

Shaping of EQ - the basics

Gain - adding gain to a frequency means adding or cutting volume at (and around) the designated frequency.  Gain addition or reduction is measured in decibels.  

Bandwidth - refers to the frequency width around the centre frequency you are manipulating.  So when you cut of boost a frequency, you are also affecting an area around the specified frequency.  

Octaves - an octave up from your centre frequency is the centre frequency times 2 (f x 2).  An octave down is your centre frequency divided by 2 (f / 2).  So, an octave up from a centre frequency of 1000 Hz is 2000 Hz, and an octave down is 500 Hz

Q factor - is the inverse of bandwidth.  Increasing bandwidth reduces Q factor, and decreasing bandwidth increases Q factor.  

The below diagram shows how adding gain to a frequency will impact frequencies around the centre.  If you are reducing gain, the graph would be upside down.  I found a guy on the Internet who explains it really well, here. 

The Q rates at each frequency of the LEQ-5 are:

  • At 70 Hz Q = 1.75
  • At 140 Hz Q = 3
  • At 280 Hz Q = 3
  • At 900 Hz Q = 5.5
  • At 1800 Hz Q = 8

As the centre frequency increases, Q increases, and the peak gets narrower.  So, if you are dialling gain at 70 Hz the peak will be wider than when you are dialling at 1800 Hz.  Understanding this wont really matter for your enjoyment of the LEQ-5 but it does give some insight into what you are doing when cutting or boosting the five fixed frequencies.

What, no CV?

The lack of CV control is due to this module being positioned as an end of chain equaliser.  The manual suggests it is focused upon bass voicing, but my testing revealed a wide range of sweet spots for many different applications.

For example, one of my sound demos below shows the LEQ-5 gracefully rolling of some top end ‘noise’ in a chord voicing via Mutable Instruments Plaits.  There are many uses beyond thumping acid bass lines…  as if that wouldn't be enough to get you aroused on it's own.   

Yes, the LEQ-5 sounds great on analog or digital bass voices, but also sounds amazing with a drum loop or complex sample as an input.  So, to be clear, this is not an end of chain mastering type of EQ.  Rather, it is a sound sculpting and enhancement tool with a lot of flexibility from what is a simple and very usable interface.  

Sound Samples - all clean then effected

I have thrown together a series of OFF then ON sound examples on my Soundcloud page.  Have a listen and see what you think. 

Conclusion

If it is not already clear, I love the LEQ-5, and I would love to see more from Phase Engineering.  The in hand quality of the unit is among the best of Eurorack and it does exactly what it is meant to do with no fuss and with excellent sound quality.  I can not see myself ever using a drum module without it, and therefore will need another for bass and synth voice duties.  

 

 

 

07/20/2024