Verbos Bark Filter at NAMM 2017 & Unusual frequency scaling

Already announced before NAMM (but the video below) is from NAMM 2017 here’s the Bark Filter from Verbos Electronics. It’s named the Bark Filter due to the scaling of the frequency bands used which come from the Bark scale. I’m sure (as with every other Verbos module I’ve used) that this will be killer and you can hear it in the Analogue Zone video below but I wanted to delve into the Bark Scale and using non standard spacings for filter banks and EQs.

I first came across an unusual (or rather uncommon) frequency spacing in the Serge Resonant EQ. Without having an original I jumped at the chance to get one in eurorack format from Low-Gain, Clark and Manhattan Analog with the module pictured to the left. It’s frequency aren’t split like a  normal EQ that may have the bands 55Hz, 110Hz, 220Hz, 440Hz, 880Hz and so on. The reason in the case of the Serge EQ is that normal EQs reinforce a musical scale or key. In the numbers listed above those frequencies are all the note A with the frequencies split at octaves all reinforcing the same scale or note. There’s some great blurb for the Serge EQ on the Thonk store page for the DIY kit (not available at the minute) … erm … that page isn’t around anymore and I can’t find it. Which is gutting as it was a good read about the scale. But you do get the idea from the random*source Res EQ module blurb quoted below.

Except for the top and bottom frequency bands, the bands are spaced at an interval of a major seventh. The Resonant Equalizer is designed to produce formant peaks and valleys similar to those in acoustic insstruments.

Until the Verbos module came to life I’d not heard of the Bark scale so doing some digging (god I love the learning that the modular world continues to invite you delve into) and here’s a summary. The Bark Scale was first proposed in 1961 by Eberhard Zwicker (not a Mr. Bark as you may think) however it is named the Bark scale as it was named after Heinrich Barkhausen who proposed the first subjective loudness measurements. Above 500Hz the scale is very similar to a logarithmic curve but below and increasingly becomes more and more linear. The scale has 24 bands that correspond to the 24 critical bands of hearing. The idea of these critical bands was introduced to audiology and psychoacoustics by Harvey Fletcher  invention of the in 1933 before it was refined in 1940. Interestingly Harvey Fletcher is known as the father of stereophonic sound and credited with an early electronic hearing aid and alongside Wilden A. Munson they determined the Fletcher-Munson curves … which is something I imagine some of you have heard of. But back to the critical bands … The critical bands describe the frequency bandwidth of the “auditory filter” created by the cochlea which is an organ within the inner ear. Each of the 24 critical bands has a varying bandwidth but a rounded version (so the quote below to see why these are rounded) of the center frequencies is as follows. 60Hz, 150Hz, 250Hz, 350Hz, 450Hz, 570Hz, 700Hz, 840Hz, 1000Hz, 1170Hz,1370Hz, 1600Hz, 1850Hz, 2150Hz, 2500Hz, 2900Hz, 3400Hz, 4000Hz, 4800Hz, 5800Hz, 7000Hz, 8500Hz, 10500Hz and 13500Hz.

In his letter “Subdivision of the Audible Frequency Range into Critical Bands”, Zwicker states:

“These bands have been directly measured in experiments on the threshold for complex sounds, on masking, on the perception of phase, and most often on the loudness of complex sounds. In all these phenomena, the critical band seems to play an important role. It must be pointed out that the measurements taken so far indicate that the critical bands have a certain width, but that their position on the frequency scale is not fixed; rather, the position can be changed continuously, perhaps by the ear itself.”

Thus the important attribute of the Bark scale is the width of the critical band at any given frequency, not the exact values of the edges or centers of any band.

The Verbos Bark Filter doesn’t work with varying the bandwidth but uses the idea of these rounded/approximated center frequencies to form the 12 band fixed filter that the module is. The filters used here are steep 6th order band pass filters and you get a huge range of control and data out of the module. Bands are split into even and odd where you can take in one signal and split the output into the odd and even bands or you can even use two different inputs into the odd and even bands. There’s an envelope follower per band (awesome for extracted CV data out of dynamic and broad band sources such as a drum kit or even a full patch) and also a CV over each band. You can control the decay of the envelope followers and also shift and tilt the EQ in the same way as you can control the first 8 harmonics on the Verbos Harmonic Oscillator. As I said above every bit of Verbos kit I’ve touched is awesome, super high build quality and amazing sound quality. One trick mentioned by Mark Verbos and also brought up regarding the 4ms SMR (although that’s only 6 bands in total, but a very different module I should add) is that you can do basic vocoding with the module. A vocoder is simply an analysis system for extracting information and a processor for applying that to something else. So using the odd input as analyzers you can then use the envelope follower outputs to control the amplitude through the CV inputs of the even bands. There’s even switching to do this on the module which will save a mound of cable spaghetti. I’m excited to check out the module in person hopefully sometime soon and also to see Mark Verbos again at Superbooth in April. It was great to meet him and chat about ideas and his work in person and even better to get him on the Modular Podcast show to talk about origins and applications of Random which I’ve linked below too.

I should add that quotes are from Wikipedia and are all linked through. Like most my digging involved google, Wikipedia, clicking on and checking sources etc. I hope that inspires some digging and a bit of your own research too. 

Mordax DATA updates from NAMM 2017

CURVES CURVES CURVES (sing that like Girls Girls Girls by Motley Crew) … Lissajous CURVES CURVES CURVES 🙂 No I’ve not lost my mind, fallen into a glam rock state of trance or decided I need a huge bass drum for my kit a’la Tommy Lee.

I am however excited for the new firmware update in the Mordax Data scope. There’s Lissajous curves which take two inputs to create an X and Y waveform which looks killer on the DATA. It was dying for this mode from the start in my mind, synthesists love curves don’t you know!

The oscillator section now features both clipping and wavefolding. That’s right, an oscilloscope that’s also a dual oscillator that you can modulate, 1v/oct control and also modulate the amplitude with internal DCAs (digital VCAs). It also makes for a killer clock and rhythm generating source. It could already do these things but it’s worth mentioning as I’m not sure everyone has realised. For more on the DATA watch out for my article and tutorial in magazine and video with Future Music Magazine. Check out the video below to Brandon from Mordax walking through the new features with Analogue Zone.

Hexinverter Mutant Rimshot & VCNO at NAMM 2017

Stacy at Hexinverter, bright eyed and bushy tailed as always has graced the NAMM show floor with his presence (no hay bails full of screaming rubber chickens and allergic reactions a’la Knobcon this time) and brought along two new modules. The Mutant Rimshot and the VCNO.

God I love the Mutant artwork, it’s done by Hannes from Papernoise who you can find interview with right HERE (click it, go on you know you want to). The arms turn drum sticks in the design reminded me of the Squarepusher x Z Machines and the Aphex Twin and Chris Cunningham Monkey Drummer.

The Mutant Rimshot is the new 8hp (I hope we get more 8hp Mutants too) Rimshot and Clave module that features a switch to move between high and low rimshots or clave based sounds. You have a pitch control and modulation decay with can go to the on board multimode filter with an attenuverter to control the modulation. Filter modes are on a switch for LP, BP and HP and as well as trigger and accent inputs you get CV over the pitch and filter cut off as well as a separate input for the filter. As you can see in the video demo released by Hexinverter you can use other sounds and mix those with the on board percussion. The NAMM show videos again are by Analogue Zone.

Following the Mutant Rim Shot is the VCNO which is a voltage controlled noise oscillator. No-one has said it yet but it looks like an expansion / update of the vcNOIZ module from Hexinverter which was a more basic clocked noise module. The VCNO uses a pseudo random pattern of bits to generate what sounds like white noise at the highest frequency, but turning down the pitch brings in those downsampled lower clock rate noises you’ll be familiar with from explosion sounds in old Atari games. You get a screech output which is more … screechy … and then there’s the main white noise output, a tear output and the sizzle output. The sizzle is more suited to vinyl crackle kind of tones where you get an additional sizzle control as well as pitch. These sort of noise modules are perfect for a range of things within your patching. From making drum sounds, to noise beds through FX right through input for random modules and modulating oscillators and filters. You can get bacon frying sounds modulating a highly resonant filter with a high cut off and noise modulation for example. Modulating an oscillator may seem odd as full signal modulation would just be noisy and not that useful for a lot of applications but if you heavily and I mean heavily attenuate that into a linear FM input you can get some sort of jitter and movement that makes patches feel alive and full of character. Well worth checking out.

 

Make Noise Morphagene at NAMM 2017

The Morphagene is the latest collaboration module between soundhack / Tom Erbe and Make Noise and is “microsound and tape music module that’s designed to capture, regenerate and process sounds from both inside and outside your modular system”. It’s a stereo in/out module and works on the idea of tape reels. Each audio file is called a reel and multiple reels can store on SD cards. Each reel can be up to 87 seconds long, splices can be up to 87 long and it can have up to 99 slices per reel. Additionally you have genes (like the Phonogene) that can be used for small grains for granular processing.

Tony from Make Noise has been introducing the module with Time Lag Accumulator. Time Lag Accumulator literally means Time Delay Memory. This was first used by an unknown engineer on Terry Riley’s 1963 recordings for Music for Poison in Paris. It’s based on using two tape recorders for delay and feedback. Here’s a great quote about it from an interview with Terry Riley

“The accumulation technique had not been done yet. I was working in Mescaline Mix. I wanted this kind of long, repeated loop and I said, ‘can you create something like that?’ He got it by stringing the tape between two tape recorders and feeding the signal from the second machine back to the first to recycle along with the new incoming signals. By varying the intensity of the feedback you were able to form the sound into a single image without any delay. I enjoy the interplay between the two extremes. This is the first time I have been able to do this. It took me a while before I could afford to buy two good tape recorders to run this process in my own studio. “

Enough about the Time Lag Accumulator (go check that out more yourselves) and onto the Morphagene again. It looks like there’s CV over every parameter, it’s coming around March and is in manufacturing now. There’s more details from Walker Farrell (who works with Make Noise, you’ll recognise his voice from their own videos) in the second video posted below. Both videos are from Analogue Zone, who were awesome when I saw them in Budapest over summer.