Eurorack module design: Compara4

I made another original module for my synthesizer! It’s called Compara4 and it’s a quad comparator / logic in 6hp for the Eurorack format. So far only one exists, I built it on prototyping board. I’ll outline some of the design ideas and lessons learned; maybe someone else would like to build one!

There aren’t any audio/video demos yet, need to figure out a workflow for that…

Compara4 synthesizer module standing upright. An aluminium panel is labelled with 9 input/output jacks, a switch and a large control knob. A circuit board is seen extending behind the panel, with colourful wires and black chips


While Llama Llama Duck is designed as several simple independent sections chained together, Compara4 is the opposite: a more tangled set of functions which can reduce to simpler purposes by leaving some inputs/outputs unused. So this fairly compact module can be a comparator, a gate-combiner, an inverter… or an interesting combination of the above, which will turn multiple modulation inputs into streams of gates.

Block diagram: four inputs are compared with a common threshold before processing to provide four different logic outputs.

The OR output is high when any input is positive, while XOR is high when an odd number of inputs are positive. Complementary NOR/XNOR outputs are provided, and for an additional variation the fourth comparator output can be inverted.

The concept was partly inspired by my need for a gate combiner; I also didn’t have a comparator, which seems a useful building-block in general. Further encouragement came from the realisation that comparators are basically “free”: most Eurorack inputs use some kind of op-amp buffer to set the input impedance and avoid unexpected interactions between modules. The input buffer can be converted to comparator simply by moving resistors around; a cheap TL074 chip provides four comparators. Modular synth electronics should be voltage-controllable where possible to allow automatic modulation. Some circuits (e.g. filters) are tricky to modify for voltage control, replacing resistors with inconsistent optical elements or redesigning to allow current-control with an OTA (probably at lower signal voltages). But comparators are easy; the threshold is set by high-impedance voltage input.


The schematics were drawn up with KiCad and are available on Github. Here’s a PDF version. It’s really quite similar to the block diagram, but a few implementation details are worth discussing.

Extract from electronic schematic. Lots of resistors, diodes, op-amps and XOR logic.
Compara4 schematic extract, showing comparators, NOT, OR and XOR sections.

The TL074 comparator section runs on +/- 12V. A quirk of the TL07x series means that this still isn’t quite able to handle the full range of possible input voltage; these ICs handle extreme negative voltages poorly, so 47k resistor pairs act to a) set a ~100K input impedance b) halve the voltages. The threshold is also divided this way (on the other sheet) so the comparison is consistent, but a bit of error will be accumulated from component tolerances.

The following CMOS logic chips run on 0-12V, so a set of diodes and pulldown resistors limit the comparator output voltages to a safe range. The OR logic is then achieved by a set of parallel diodes; if any channel is high, this voltage will pass the diodes without contaminating other “low” channels. The 4-way XOR is achieved with a CD4070 chip, which is a quad 2-way-XOR package. Three of these are cascaded to give a 4-input XOR; the remaining XOR is used to implement a switchable NOT for the fourth channel. (Logic is pretty neat, apparently you can build anything with enough NAND gates. Should try that some time…)

Finally, another CMOS chip is used for the outputs: a CD4041 “quad complementary logic buffer”. Each section takes one input, and outputs one “high” and one “low”, which switch places depending on the input state. As well as deriving our NOR/XNOR outputs, these make quite elegant bipolar LED drivers. This is illustrated with a pair of LEDs, but Compara4 uses a single bipolar LED package which encapsulates such a pair in one bulb. I had a useful discussion with some Modwiggler users about the safety of exposing the CMOS outputs to Eurorack without another buffer stage; we concluded that it’s probably ok, but… uh… use at your own risk. Protection with diodes/transistors is possible but adds complexity and may be unnecessary. It was also suggested that maybe circuits like this one could operate at mostly 5V for energy efficiency. Something to play with in future?

Complementary buffers as bipolar LED drivers

Layout and finishing

A lesson learned from Llama Llama Duck was to try planning the layout for designs of similar or greater complexity. Also, while I enjoyed using the Sourcery board I wanted to allow a bit more space and get some experience with traditional hole-per-pad “perfboard”. This helpful article shows how the KiCad PCB design features can be used to figure out a stripboard layout; just stick to the appropriate grid, use wide tracks and keep to some rules about spacing and directions of connections. I adapted the idea to develop a perfboard layout; non-vertical jumpers on the upper side and non-horizontal connections on the lower side are now permitted, but straight lines are still preferred where possible to avoid clutter and make good use of component-lead connections. Even so, the resulting layout is a bit intimidating and I’m very glad it was done with CAD; KiCad indicates which parts should be connected and can run an error report from the schematic, pointing out missing or inappropriate connections. Still, having done this once for perfboard I’m feeling less sceptical about using stripboard for a future project; you can get a lot done with jumpers and it would cut down on fiddly soldering.

Wiring layout with KiCad 6. Both panel and main board are drawn in the same document, for ease of understanding and lining things up. Blue lines indicate copper-side wiring, red lines are jumpers on component-side.

Mostly things get crowded around the three chips, which is understandable as each has four sections, taking inputs from a common direction and sending outputs in a common direction. Typical pin layouts do not facilitate this, so a bit of crossing-over is inevitable! But in KiCad this became quite a satisfying jigsaw puzzle; I can see how PCB design becomes a long refinement process.

The front panel was worked out on paper and refined by plugging components into perfboard, before making a drilling template and transparency graphics in Inkscape. The end result looks pretty professional, but there is supposed to be a shaded rectangle grouping In 4 with the NOT switch and this is very faint. On Llama Llama Duck the shading was a touch dark. More experimentation needed!


I’m really happy with the form factor: 6hp with a big knob and LEDs tucked between two columns of jacks. It’s comfortable to use without much wasted space. It does the intended job as a modulation/logic processor but in practice is also a lot of fun at audio-rate, creating variable-width pulse outputs from sources other than oscillators. (Detuned groups of oscillators make good drones!)

Finished module making some drone music

I got into modular synthesizers, sorry

I’ve been fascinated by modular synthesizers since I was a teenager and saw pictures of Moog, Macbeth and systems. Huge electronic instruments that are patched with cables to create unusual new sounds; looks fun! A few drawbacks though:

  • horribly large
  • horribly expensive
  • most of the sound examples I could hear from e.g. ELP records were not actually that hard to match with a modern digital synthesizer?

A little later I realised that some of the crazy electronic sequences on my favourite Nine Inch Nails records were not practical to produce by sampling many short sounds from conventional electronic instruments; they were curated machine-generated monstrosities. Ghosts I-IV came out and was rather more open about the creative process, consisting of simpler musical sketches and decorated with pictures of studio equipment. This kind of electronic musicianship is more driven by the “West Coast” world of Buchla and Serge instruments, favouring rich and inharmonic timbres driven by exotic controllers, sequencers and modulators. Compared to the Moog systems, the Buchla stuff is a lot more compact but still ruinously expensive. The approach is illustrated well by this wonderful performance:

Alessandro Cortini performs with a Buchla system

So, fast-forward a few years and some things have changed:

  • The dominant format is now “Eurorack”, which is significantly more compact; modules are 3U tall compared to 4U (e.g. Buchla) and 5U (e.g. Moog) and many modules are just 10mm wide. There’s a very competitive market, making things a bit more affordable.
  • There’s a very competitive market of ideas as well: some designers prioritising features/inch, some prioritising ergonomics, some favouring clean industrial design and modern components, some using bizarre symbols and reclaimed soviet parts. There are people creating exact clones of classic synth subsections (so you can e.g. combine the oscillator of a minimoog with the filter of a Juno) and then there’s this Aussie genius who’s put out 15 chaos generators.
  • There are DIY options. Actually there has been a modular DIY scene all along, but it wasn’t very visible outside electronic music circles.

So, after ten years of interest I had a bit of disposable income and bought a few modules. And built some DIY kits. Then graduated to buying circuit boards and front panels, sourcing other parts. Then started making my own front panels. It was inevitable the day would come…

I started designing my own modules.

Eurorack module design: LlamaLlamaDuck, a CD4049-based distortion envelope thing

I started designing my own modular synthesiser components. I wrote a few words here about how that fits into my life. This is my first original module design.

Well, I say original, but let’s give credit where it’s due: this is mostly based on stuff I’ve learned by looking at schematics from Nonlinearcircuits and Mutable Instruments, blog posts by Northern Lights Modular and hanging out on the Modwiggler forum. This particular design is also heavily influenced by some classic guitar pedals.

Llama Llama Duck assembled prototype module. The module is resting on its side and has an aluminium panel with labelled jacks and control knobs. Behind that are circuit boards with various components.


Here is a block diagram of the module. This makes it clear that there are essentially three independent functions, but default “normalled” connections link them together to provide a combined function. This structure is inspired by “Serge” design conventions, in which complementary units are brought together in a single panel, dividing up a regular grid layout of controls and jacks. However while Serge systems use “banana” jacks (which have the advantage of easily stacking to split one output to many inputs), Eurorack uses smaller and more complex 3.5mm jacks which include a “switching” feature to pass a default signal when disconnected.

Block diagram of module:

AC in runs through DC block and soft clipping to AC out.

"DC in 1" and "DC in 2" are summed, run through soft clipping to DC out.

Gate in runs through comparator to release envelope, then Env Out.

Normalled connections are shown with grey dashed lines: AC out is connected to DC in 1, the Release envelope is connected to DC in 2 and a +12V voltage is connected to the Gate In.


So, what’s the deal with the AC/DC clipping stages? Well, I like the idea of the Tube Sound Fuzz, Red Llama and similar guitar distortion circuits, which abuse a CMOS logic chip to create a “tube-like” (soft and asymmetric) distorted gain stage. But guitar pedals have to make a few design compromises; although the input/output signal range is bipolar around 0V, they use a “single-sided” power supply between 0 and 9V (to support the use of convenient batteries). The processing needs to happen about some non-zero reference voltage, with a “bias” shift at the input and output. There’s an easy way of doing this: “AC-couple” the circuit with series capacitors. In the process we filter out the lowest frequencies; a non-issue for electric guitar. In a modular synthesizer this is sometimes a useful side-effect, getting a bit of headroom for unipolar input signals and avoiding excessively asymmetric clipping. The first section of Llama Llama Duck follows this scheme. The manual gain control can be used to dial things back into a kind of AC-coupled buffer, or push into pleasant distortion.

Circuit diagram 1
Section 1 schematic: an AC-coupled distortion section, similar to CD4049-based guitar pedals, is set between inverting opamp buffers which establish typical impedances for a Eurorack system.

Each inverter stage acts as an inverting amplifier when setup in this negative-feedback configuration. The principle is the same as an inverting opamp, making use of a linear region in the middle of the voltage range. There is heavy soft-clipping on one side of the transfer curve; to get something remotely symmetric we use two stages. The chip has six inverters on it, so we may as well use some more…

The joy of modular, for me, comes in the presence of generic processes that make sense for both control-voltage (CV) and audio signals. It should be possible to use distortion to reshape CV, and manipulate audio distortion by injecting interesting modulation sources. The above AC-coupling approach blocks DC and prevents such shenanigans. But the CD4049 can’t handle the full +/-12V Eurorack power supply; either it has to run “single-sided” or we need to regulate e.g. +/-6V rails within the module. I took the approach of dialling in bias voltages with a trimpot. Original experiments used two trimpots, but it turns out that one will do; as long as the output lines up properly (i.e. return 0V for 0V input) it doesn’t matter if the 4049 inputs are slightly off-centre.

Circuit diagram 2
Section 2 schematic: again CD4049-based distortion sits between op-amp buffers. This time there are no AC-coupling capacitors, and a trimpot sets the bias voltage for input and output.

A couple of other details are worth mentioning: a secondary input and clipping diode. Adding DC bias creates all sorts of nice fuzz effects, so an extra input is provided with a level potentiometer. (This works nicely with Section 3, as we shall see.) The diode is a precaution to prevent the U2C input node from being exposed to negative voltages if an unusually low input voltage is supplied. The inverting configuration keeps the node at ~6V but would need a lot of current in such a case. This shows up as a bit of hard-clipping in the output but isn’t really noticeable for sensible inputs.

The gain levels are fixed but fairly useful; a bit over +6dB of gain, and peak levels clipped to around +/-5.5V. This plays well with typical Eurorack oscillator signals which are 10V peak-to-peak. For more gain, consider pre-processing with section 1. For less gain, use the attenuating input.

Release envelope

Section 3 is a simple envelope generator with a fast attack stage, fixed sustain and variable release speed. I came up with it messing around on solderless breadboard but I doubt there’s anything unusual or clever going on: it’s just a comparator and slew limiter.

Circuit diagram 3
Section 3: Envelope generator with fast attack and variable release

An LED indicator is driven by the comparator rather than the output; not really clear if that was a good idea. The timing control uses a 1M linear pot in parallel with a 1M resistor to approximate a 500k logarithmic taper.

Why include a release envelope on a distortion unit, anyway? Well, it’s “normalled” to the DC In 2. If you send a clock to it, this will “fuzz” the audio running through that section’s other input by smashing the signal into one side of the clipping so hard it gets quieter. The result is something a bit like the classic dance music pumping / ducking effect. But weirder and noiser! That’s why this is the “duck” section. And when I realised that would mean the module could be named Llama Llama Duck, well…


After testing with solderless breadboards the circuit was built “freestyle” from the schematic on a Sourcery protoboard. The board was really nice to work with, having a neat power-bus system that allows IC power to be routed by soldering across a few pads. The control board was done with a few bits of regular perfboard, soldering wires and tracks to a header strip. In hindsight this would have gone more easily with a bit more planning; there was a lot of checking back-and-forth between the header strips, and mistakes were awkward to fix where leads crossed over.

Prototype module, side-view showing top of prototype board with components. One of the ICs is a small surface-mount component soldered to an adaptor board. A few jumper cables criss-cross around the board, but generally the layout is dense and tidy.
Prototype circuit on Sourcery Proto board.

The front panel was created as an inkjet waterslide on a drilled Doepfer blank panel. The drilling template and graphics were done with Inkscape. The knob/jack choices partly follow existing conventions in my modular system; I use chunky Bananuts to indicate outputs and knurled nuts for inputs. White knobs are attenuators, black knobs are offsets or direct controls. The waterslide colours ran slightly, turning grey into pink. I don’t really mind, but will try to refine that process a bit… I really like the on-grid section divisions of Serge-style panels and the consistent, informative design of Intellijel panels. I expect my approach will evolve, but for now the principles are: indicate independent sections; indicate normalisation; keep it playable. The ergonomics of knob/jack access are easily overlooked and many modules feel over-crowded.

Finished prototype installed in my modular synthesizer

Apologies if this post made absolutely no sense, it’s more of a DIY build log really. Hopefully there are more to come ūüėÄ

Curve matching: Waves Renaissance EQ, emo-Q4 and the TB Equalizer

TLDR: the Waves EMO-Q4 has the same resonant shelves and bell boosts as Renaissance EQ, but not the same cutting behaviour. The filters aren’t adjustable and EMO-Q4 still uses more CPU. It has a better GUI but everything else is worse. Toneboosters equalizer has very similar curves to RenEQ and may be a better option for those looking for a bigger GUI.

In the last year I’ve moved my music-making to a Windows 10 dual-boot setup (I’m still using Linux for most other things.) This was mostly motivated by a sense that I wasn’t getting the low-latency performance that my i7 CPU should be capable of when running nice audio effects. Much as I’d prefer not to support the Windows monopoly, I’m really excited about some of the music production tools that have been released in the past few years by developers like Klanghelm and Tokyo Dawn. Apple consumer hardware remaining impractical (more USB ports and HDD bays please!), it seems like Win 10 is the least terrible option for this task at the current time. (It’s pretty awful though. Your computer/OS is a professional appliance and you should not have to dedicate time to turning off advertising.)

Deep breath

So, this article. One “benefit” of using a proprietary operating system is the chance to take a few more risks with DRM-encumbered software. Some of the older “industry-standard” stuff is now available at fairly reasonable prices, so I took a punt on a few things including Waves Gold.

Waves digital EQs

Waves Gold includes quite a few equalizer (EQ) plug-ins. These are used to re-balance the frequency content of audio. EQ is probably the single most important tool in the mixing process after basic level control, so producers tend to a) have lots of equalizers and b) have strong opinions about them. “Clean” digital EQ is actually quite well-defined mathematically so in principle there shouldn’t be much of a “quality” difference between digital EQs. What distinguishes them is the curves, generally controlled with frequency, gain and “Q” (the narrowness of the filter). How easy is it to make the frequency response graph that you want?

Waves have been making digital equalizers for a long time. Did you know they made Q10, the first digital EQ plugin, in 1993? You do if you’ve read the Renaissance EQ manual, which is a recommended read for computer music nerds. The manual makes it clear that a lot of thought went into the design of its slopes. There are two key features that remain somewhat distinctive; the “resonant shelf filters” which add a small cut near a boost or vice-versa, and the “asymmetric bells” which have narrower cuts than boosts.

Here’s the thing about Renaissance EQ (RenEQ); people really like it. It’s pretty old, but if you poke around online there’s not a lot of criticism, and plenty of people seem to be using it over newer and shinier alternatives. The main downside is the tiny, dated GUI. Waves Gold also comes with a much newer EQ called “emo Q4”, developed for live sound applications. It has a big pretty GUI, and there’s barely any info about it online; not many technical details, not much discussion. Given that “RenEQ with a better GUI” should be an absolute hit, it seems worth investigating those curves…


The screenshot above shows four plug-ins. On the left is the emo-Q4 and above is the RenEq. On the right is a noise generator, and at the bottom is a spectrum analyser (SPAN). Each EQ is working on the left or right channel only (REAPER makes this kind of thing really easy!) and SPAN is set up to show two spectra, one for each side. You can only see one here, because the curves match exactly! I’m using two resonant shelves, a bell boost and the high-pass filter. But there’s a trick – the emo-Q4 filter is not adjustable, so I had to adjust the RenEQ filter to match. The emo-Q4 does have a wider parameter range on the shelf filters though, so it can make some curves that RenEQ can’t.

Let’s look at an 8dB bell cut:


Now we see two curves in the analyzer! The RenEQ is narrower on cut. I can actually adjust the emo-Q4 Q to match it, from 0.80 to about 1.96. This Q is no longer correct if we change the gain, so the RenEQ cut width is gain-dependent. This makes a big difference to the workflow and so won’t help win over RenEQ users.

Finally, some quick and unscientific testing with REAPER’s performance meter suggests that the emo-Q4 has a slightly higher CPU usage, although both are pretty low at less than 0.1 CPU%. Final verdict; I like the layout of the emo-Q4 and the shelves are great, but some different design decisions were made from the popular RenEQ.

Toneboosters EQ

As an afterthought, I pulled up the demo version of the very affordable Toneboosters EQ. This has quite a few different bell types. The “digital bell 2” and low/high “shelf 2” options seem to follow some of the philosophy from the RenEQ manual so I thought they might be worth a look!


With a slight reduction in the Q value, I was able to get a great match from this low shelf and high-mids cut using identical frequency and gain values. The narrow default cut value was promising so I tried boosting…


Boom! The gain/Q relationship seems to be very close.

Closing remarks

There are other factors in EQ choice than the curves and gain/Q behaviour. The Toneboosters EQ has a bigger graph than RenEQ and the text is more readable; however personally I prefer being able to see all the parameters at once rather than the one-band-at-a-time approach of TB-EQ, ReaEQ or TDR Nova. I also find the overlapping coloured bands display of TB-EQ a bit distracting even if it is pretty. There are other features to consider; TB-EQ’s “gain effect %” parameter makes it very appealing for automating mid-mix. My current workhorse for mixing is the SlickEQ GE, which demands more CPU but has a great interface and some pleasant saturation options.

I mostly wrote this up because I was frustrated by the lack of online discussion of emo-Q4. If you’ve got something useful to say about any of these EQs, do use the comments section below!

Gig review: TesseracT, Contortionist, Nordic Giants

¬†O2 Academy Oxford ‚Äď 10/02/2016

This post was written on the train the day after the gig, and believed to be lost due to iPad/Dropbox/Editorial nonsense. However, I have since found the file, so here it is…

It’s hard to explain what makes the Oxford O2 Academy such a dissatisfying venue. From a practical point of view it’s fine, with enough room to move, decent access to toilets and bar, a cloakroom, good view of the stage, reasonable acoustics… The bar is expensive at a touch under ¬£5 a pint, but there is a good ale (St Austell Tribute) available at the same price so you don’t have to feel a complete chump. The best explanation I can give is that the stage is too high to feel “intimate”, while the capacity is too low to feel “epic”. Both of those things have their downsides, but would compensate for the utter lack of romance.

Double-act Nordic Giants are a band who take their live visuals seriously, and the music itself can be seen as a simple accompaniment to their video show, which cleverly places a portrait screen in the centre of the stage so those closest can see the main action, as well as adding some layered effects √° la Nine Inch Nails. Most of the songs were set to short films and animations by filmmakers, but the highlight of this effect was the addition of a virtual singer, in appropriate costume, for one song. Their arrangements are excellent, sounding well-mixed in this case but also easy-to-mix in general, using the main instruments (piano and drums) well and layering synths, bowed guitar and other surprises over reasonably restrained backing tracks. The fatal flaw in their schtick is the approach to composition, with most songs having a single theme built in a predictable quiet-LOUD-quiet-LOUD-(awkward stop) structure. Their closing song “pencilled” was by far the best, having a reasonable payoff in the form of a section of new material at the end. Even then, there was little sense that they are truly in control of their chord progressions. Why are post-rock bands so bad at using cadences?

The Contortionist followed, with their brand of somewhat-accessible-but-still-occasionally-shouty progressive metal. The simplest description I have is “like Between the Buried and Me but slower”, which is really no bad thing. The main themes of their songs felt very musical although not especially technical, and occasionally gave way to chugging breakdowns with more screaming. These breakdowns will always be a matter of taste: for the record, I think the Contortionist use them well to create meaningful passages. Vocalist Mike Lessard also knew when to step back, with some percussion on stage to play with while the audience could enjoy a more extended instrumental passage. A good band.

TesseracT are a major band in the onomatopoeic “Djent” genre. One might point to their extensive use of clean vocals and ethereal chiming guitars as a signature sound, but this is also a feature of peers such as Periphery. (I am reliably informed that this guitar tone is known as “Milton Cleans”.) There is something more unique in the way they use these to frame their tracks and give them identities. Really, though, it is clear what Tesseract have that their rivals don’t. Dan Tompkins. Making his return to the band after a succession of (very talented and capable) replacements, Dan is far and away the best singer I have ever heard accompanied by a guitar with more than six strings on it. His clean tenor vocals are superb (and well-balanced against the backing track or harmoniser where appropriate), his screaming is musical and there was some credible falsetto, particularly in the songs from their new album Polaris. More importantly, he was able to leap between these without obvious deterioration over the night. As for the rest of the band… there isn’t a lot that needs to be said. They are seasoned, they are tight, attention to detail seemed good especially in the drums. Perhaps a little more running around on stage and audience interaction from guitarists would be nice, but… It doesn’t quite seem necessary or appropriate most of the time. They have “it”. A+.

Festival write-up: Arctangent 2015

Arctangent is a music festival for post-rock, math-rock and noisy stuff. I had a great time at the 2014 festival, attending for two days, so this year went for the whole shebang. It would neither be feasible nor interesting to review every band I saw, so I offer here some highlights and overall thoughts. It’s a bit long so I tried to make the section headers helpful.


There is little to say about the festival organisation because it was done so well. Information was available, there were sufficient food and drink stalls at a fair price point, the toilets remained usable thoughout the festival. Silent disco lets people rock out until late while others retire to tents. My only criticism is that there was very little signage when driving to the festival site, and it could prove difficult to find in the absence of satellite navigation or a detailed map. Both the festival staff and the general atmosphere were relaxed and friendly.

The headliners

Day 1 was dedicated to previously-appearing bands, giving us LITE followed by 65daysofstatic on the main stage. Lite played loud, but often pretty, guitar-led music; they position themselves as a math rock band yet could easily be branded as post rock. Strong, but probably the least interesting headliner. 65daysofstatic were a little late due to technical problems (seemingly with their own equipment) but delivered a set of epic noisy post-rock. They’re capable of more high-tech and varied sets than the one they delivered, but it was well-judged for the festival audience and supported a good degree of mayhem at the front.

Naturally The Dillinger Escape Plan were not going to beaten when it came to energising the crowd; their set contained relatively few breaks from high-energy insanity. The festival’s organisers have commented that they hadn’t deliberately planned the headline acts to be so heavy, and were somewhat at the mercy of bands’ availability. In the end, however, the headliners all contrasted with each other, and closing each day with the most moshable band is no bad thing. While definitely “a heavy band”, sub-headliner The Fall of Troy‘s music was somewhat more intellectual than Dillinger’s while technically stunning. Frontman Thomas Erak’s guitar playing is incredible; an endless cascade of notes that form themselves into demanding yet satifying riffs.

Cult of Luna unfortunately had travel difficulties and had to play at the same time as headliner and tour-mates Deafheaven; this was probably for the benefit of the festival however as it bumped Deerhoof up to a sub-headliner slot that they clearly deserved. Deerhoof had it all; a whimsical positive energy that is somewhat lacking from the post/math/noise rock scene in general, while still able to swap instruments and bust out the most terrifying psychedelic jam of the festival. A number of people in the crowd were not familiar with Deerhoof, having come in from an interest in heavier music or at least less avante garde acts; the band’s charm and ability won them over quickly. Deafheaven‘s “blackgaze” experience was effective, and likely to win them some new fans. To paraphrase¬†the friend I dragged to see them:

I hated the first twenty minutes or so, and then it clicked. I had earplugs in because they were loud, and listened to each of the instruments. I couldn’t follow the vocals because they were just screams, the guitars didn’t seem to be doing anything interesting,the bass didn’t seem to be doing anything interesting, and the drums weren’t providing much clue to what was going on either. Then I took the earplugs out, the high-end sizzle of the guitars built up, and after a few minutes I went “oh! It’s the way they sound together!”

Smaller acts

Iran Iran were given a criminally short set. One of the more technical and avante garde acts, they do seem to struggle to attract a crowd, which probably makes promoters wary, but I am convinced they were musically one of the most interesting and capable bands at the festival. Given a captive audience and shot of confidence they might
be able to achieve a lot more. Have a listen.

That Fucking Tank were disappointing; their lack of engagement with the audience while playing and usage of a backing track are forgiveable individually, but in combination led to a sense of self-indulgence. At another festival, the quality of their music would have been more of a redeeming factor, but there was no shortage of enjoyable math rock.

Maybeshewill pulled out all the stops for their epic post-rock set, bringing backing horns and strings to double the size of the band. Possibly angling for a headline slot? They threw themselves into their set and were embraced by the crowd, but there was little to find musically that was particularly dazzling. To some extent they brought the “old-school” post-rock vibe and “Not For Want of Trying” was a festival highlight. I would recommend seeing them if they’re nearby, but it’s hard to rate them as an essential listen over conspicuously absent giants like Mogwai or Explosions in the Sky.

On loopers, sequences and backing tracks

Loopers are getting tired. A lot of bands were using loop pedals, and the restrictions they place on composition should really be quite well-known by now: they tend to lead to songs with short, repeating chord progressions; build-ups are always long, regardless of whether that is musically desired; the volume and energy level is very difficult to decrease smoothly. There are solutions to these problems, but popular loop-based acts like Mylets are not making very much effort to avoid them, leading to very predictable sets. Mylets’ Henry Kohen showed himself to be a very capable and creative guitarist, and his set was marked by suspicion that he could be doing something a lot better by playing with other musicians. Then again, his ability to structure interesting compositions was left unproven… The best attempt at working around these issues probably came from AK DK, with a two-man-two-drumkit format offering more flexibility and a very enjoyable show. Nonetheless, their outros and build-downs lacked variety compared to guitar-based bands like Toundra.

We’re still figuring out the rules for when a backing track is acceptable and when it isn’t. That Fucking Tank’s backing track was a big turn-off, partly because it contained bass and guitar parts. Some people did walk out of The Algorithm looking grumpy, but the sizeable and enthusiastic remaining crowd clearly appreciated that having people play the rapid and chaotic synth arpeggios by hand was not a necessary requirement for the act to work. Nobody could object to Deafheaven’s moody guitar tracks playing in-between their songs while they re-tuned, but the volume level clearly signalled that these were recorded and separate from the performance.

On post-rock culture; a hypothesis

While outsiders might perceive math/post/noise rock as a pretentious scene related to progressive rock, there is actually a general sense that things have to be very “genuine”. There are few costumes; most bands dress in jeans and T-shirts. Bands brought no scenery beyond their instruments, rack gear and amplification; even then, the majority of bands made use of the (presumably sponsor-provided) Orange amp stacks available. Guitars and basses were almost exclusively from the top two brands, reminding me of a comment by Mogwai’s John Cummings: > “I suppose it’s not so much that Fender guitars look great as that everything else just looks terrible.” Is this the post-rock philosophy? Telecasters and precision basses are fairly priced, versatile, robust and proven. There’s nothing wrong with playing another guitar, but you are making a statement by doing so. Post-rock bands don’t like making statements where they aren’t needed, which is why vocals are used so sparingly. By avoiding making any statements about fashion, futurism or their ex-girlfriends, they avoid distracting their audience from the actual music. There is no such aversion to using the latest and greatest effects pedals, because they add a novel dimension to the music.

Top moments

  • Finding Iran Iran on the “clashfinder”, having assumed they would not be appearing.
  • The Dillinger Escape Plan’s Greg Puciato diving onto the crowd from the central scaffolding; exhilarating and not too contrived. Arguably this still wasn’t as cool as the kneeling crowdsurfing guitar breakdown.
  • Any time Deerhoof spoke to the crowd.

Best band

Deerhoof. Few acts contested them when it came to musicianship, and their showmanship was also world-class.

Some other bands I liked

  • Rolo Tomassi are great performers with an effective “one-and-a-half frontman” setup.
  • Tangled Hair are one to watch, making interesting music from an accessible basement rock pallette.
  • Valerian Swing were infectiously happy to be there, fun to dance to and active in the Dillinger mosh pit. Please invite them back!
  • Downard are the ones for those of use who like the idea of the “fuzzy riffs and drums” formula but find Royal Blood to be horribly overrated.
  • USA Nails – this high-energy post-punk band were not the most obvious choice for the festival but they definitely hit the quality barrier and provided a bit of variety while providing some clues as to where the noise rock scene has its origins.

Ranty post-script: “BBC Introducing”

The small PX3 tent was hosted by “BBC Introducing” for the first day of the festival. Their attempt to record some enthusiastic crowds for a radio show did not go very well. Some pointers for next time:

  1. Don’t insult your audience. “We’re not going to broadcast any of this excellent music, we’d rather broadcast some people chanting” is not a good message. If people are at ATG, they probably think the music there is better than the vast majority of what you broadcast. Don’t rub it in.
  2. Capture an audience. An audience who can hear another band starting up in the next tent is not a captive audience; it’s an audience who actively want to leave. This could have been avoided by discussing your plans further in advance with the bands, and having them work your segment into the set.
  3. Show your understanding of the music and don’t claim credit for other people’s jokes. We are not impressed that your favourite thing about Iran Iran is their track names; the track names are hilarious but the music is pretty good too. Math rock is riff-based, but the riffs are generally mangled, drifting in and out of phase, or rapidly developed and abandoned. Singing back catchy riffs is not a natural way to respond to this music.

One-liner: Instant German techno from the command line

I’ve been doing a nostalgic re-run of the phenomenal Grand Theft Auto: San Andreas recently, which includes a fun house music radio station, “SF-UR”, hosted by the lonely German ex-pat “Hans Oberlander”. Finding myself wanting to listen to something like SF-UR while working from home I realised that in 2015 it is not exactly difficult to listen to an¬†actual German techno radio station. fits the bill nicely, with extended mixes and relatively little speech. MPlayer is pretty easy to install on Mac OSX with Homebrew and on GNU/Linux with standard package management tools; it does have a habit of spraying messages to standard output and error but this is easily solved by redirecting the output so the required command for instant techno is:

mplayer < /dev/null >&0 2>&0 &

To stop play, just killall mplayer or bring it to the foreground with fg and kill with Ctrl-c.
Setting an alias in bashrc is easy:

alias minimalradio='mplayer < /dev/null >&0 2>&0 &'

UPDATE: Last time I tried this, the Minimalradio stream wasn’t working. makes an acceptable substitute.

More fun with applescript; a play/pause button for Mixcloud

I’ve been using Mixcloud in the office lately. Progressive house mixes are quite nice for work as they are long and not very distracting. However, when something does catch my attention it’s a pain to find the tab and click on the big “pause” button. The¬†solution only took a minute or two:

#! /usr/bin/osascript
tell application "Mixcloud"
end tell

tell application "System Events"
tell process "Mixcloud"
keystroke space
end tell
end tell

This requires the Mixcloud website to be wrapped into an individual application, which is easily accomplished via Fluid. Doing this also has the advantage protecting the music from stuttering when single-threaded Safari is suffering under load.

Finally, the script is bound to shift+F4 using Quicksilver. (It needs to be saved with the “.applescript” extension for quicksilver to recognise it as an executable script.) A few other fun keybindings I use are F4 for iTunes play/pause, F3 to open a periodic table and F6 to open a de-stressing Google Image Search for fluffy kittens.

It would be an improvement if F4 could detect whether iTunes or Mixcloud is playing and start/stop them intelligently. Suggestions are welcome!

Fun with Applescript; automating obstinate programs

Applescript is a rather under-appreciated thing.

I must admit I’m not fond of it’s syntax, which manages to achieve Uncanny Valley-style “natural language” while still being wholly unintuitive. Also, as someone constantly bouncing between OSX and GNU/Linux machines, it makes much more sense to learn a scripting language that I can use on any machine. Still, I have found a couple of difficult tasks recently which are elegantly solved by Applescript.

1. Home working: remote saving of applications

Like many people I use Dropbox to keep files in sync that I need to access at short notice from anywhere.

One of these files is a big LibreOffice spreadsheet, listing details of all the density functional theory calculations in my project. As this includes planned, queuing and currently-running calculations, I frequently need to access this to keep my notation and folder structure straight. One of the benefits of being a PhD student with a computational project is that it offers great flexibility in managing my schedule and working remotely. My workstation (an iMac) is on constantly, and I can log in remotely through an ssh terminal to access my files and tunnel to HPC facilities. However, there is a snag; files are only updated when I save them… There is no great incentive to save frequently when editing a simple spreadsheet on a very stable computer. It is only when I get home that realise that I now cannot edit my catalogue of calculations without running into all kinds of Dropbox conflicts and messy file merges.

Or I could just run this:

#! /usr/bin/osascript                                                                       
tell application &amp;quot;LibreOffice&amp;quot;                                                              
end tell                                                                                    
tell application &amp;quot;System Events&amp;quot;                                                            
tell process &amp;quot;LibreOffice&amp;quot;                                                                  
click menu item &amp;quot;Save&amp;quot; of menu &amp;quot;File&amp;quot; of menu bar 1                                         
end tell                                                                                    
end tell                                                                                    

Yes, that is just as filthy as it looks: remotely click “save”. Wait for Dropbox to sync. Open on local machine, get back to work.

2. Generating a lot of pretty pictures

VESTA is one of the best-looking packages out there for visualising molecule and crystal structures.
In particular it uses hardware acceleration well, draws beautiful isosurfaces and has a range of lighting options. Tragically it lacks any kind of scripting interface (as far as I am aware). For the target audience of solid-state and org chemists, this is perhaps not a huge problem. Computational guys like to think big…

Recently I’ve been looking at allotropes of sulfur. Whether and how different allotropes are bonded is quite interesting, as is the significance of spin polarisation. Having carried out hybrid-level DFT calculations, it occurred to me I had a pretty good map of the molecular orbital structure. But I was damned if I was going to open the File dialogue once for every orbital, let alone do that every time I tried a minor variation of the structure or DFT parameters. About an hour of Stack Exchange and experimentation later:

#! /usr/bin/osascript                                                                       
tell application &amp;quot;VESTA&amp;quot;                                                                    
end tell                                                                                    
tell application &amp;quot;System Events&amp;quot;                                                            
tell process &amp;quot;VESTA&amp;quot;                                                                        
click menu item &amp;quot;Export Raster Image...&amp;quot; of menu &amp;quot;File&amp;quot; of menu bar 1                       
delay 1                                                                                     
keystroke return -- Agree to default filename                                               
delay 1                                                                                     
key code 53 -- &amp;quot;Escape&amp;quot; the scaling dialogue                                                
delay 1                                                                                     
keystroke return -- Get rid of congratulatory &amp;quot;you made a file!&amp;quot; dialogue                   
delay 1                                                                                     
keystroke &amp;quot;w&amp;quot; using command down -- Close file, ready for next one                          
end tell                                                                                    
end tell

Again, absolute filth. A few tips and tricks had to be employed here: key code 53 seems to be the preferred way of sending an “escape” key message.
The 1 second delays are probably longer than necessary but leave time for the dialogue boxes to open.

Simple globbing and for loops with bash allowed me to open a stack of .cube files and paste the output images together with Imagemagick tools. The result is, I think, rather fetching (apologies for length). If you studied molecular orbital theory at school, then you should have a fair stab at interpreting this in terms of combinations of conventional sigma- and pi-bonds. Note that of the 16 combinations of valence orbitals, we have four fully-bonding, four fully-antibonding and eight mixed bonding and antibonding molecular orbitals. They aren’t necessarily in the order you might expect, however!

Valence Kohn-Sham eigenstates of rectangular S4
Kohn-Sham valence eigenstates of rectangular S4. Data from all-electron density functional theory calculation with PBE0 hybrid functional as implemented by the FHI-aims quantum chemistry code. Blue borders indicate occupation by a single electron.

Gigs: April 2013

Swans / Xiu Xiu

O2 Academy, Bristol – 6/4/13

As I understand it, Xiu Xiu has gone out with a different line-up and sound for every tour. Listening to his recent release I was expecting an elaborate electronic set-up, maybe a female vocalist and some disturbing neo-darkwave sounds. Instead, we got a man with a guitar, a few pedals (apparently all reverb) and some kind of smartphone or tablet from which he ran a few ambient loops of birdsong, wind etc. These varied over the set, building slightly in tension and running over the whole thing. The songs appeared to share a gospel music influence (the snarling “halleluiah”s a not-so-subtle pointer), presented by a conflicted, insecure character. Arcade Fire’s “Neon Bible” is an obvious peer in theme and approach, but they have rather more manpower and less fragility as a result. His voice is astonishing, very weak and warbling yet pitched exactly. Bright Eyes haters beware… If he spoke to the crowd, I don’t recall it; the set ended with the quiet genius standing up, raising a hand to the crowd, and strolling off. And then a few minutes of rapturous applause. The set was stunning; short, well-themed, structured and captivating.

Swans were really loud. That is definitely something they wanted to impress upon us. Their leader carried a level of anger and tension that wasn’t quite shared by the rest of the band, who seemed to be enjoying themselves. It felt a little artificial; if you’re making this much noise you should either be pouring energy into your guitar a la Pete Townsend or worshipping the results like Steve Vai or Gary Moore. Don’t just stand there like you’re covering rhythm guitar in a Herbie Hancock tribute band. I don’t want to beat on Swans too hard because I did enjoy their set, I did enjoy the noise and I recognise that they have been around for a while and their early influence and legacy is important.

Part of the problem with drone music is that by far the hardest part is getting somebody to let you play it at the appropriate volume levels. I quickly identified a gentleman in a Sunn O))) shirt, which led me to wonder: if I had seen Swans before Sunn O))), would I have been more impressed by them and less impressed by Sunn O)))? I think Sunn O))) have a purity to their approach that is lacking in Swans; they reject rhythm rather than overwhelm it.

Swans filled the stage with some of my favourite guitars and amplifiers, extra percussion including tubular bells, trombone, clarinet… If I wrote a wish-list of instruments to form a show, this would be it. But on this night I was far more impressed and affected by one man with a guitar, a smartphone, a pile of reverb pedals, and a slightly fragile, slightly constructed and really enthralling emotional state.

And So I Watch You From Afar / Antlered Man

Thekla, Bristol – 17/4/13

Thekla is a pretty fun venue: the moored boat has an adequate performance area, decent-sized bar, upstairs balcony and, best of all, an outside deck where you can take your drink and chill out before the show starts. Arriving fairly eary, I spotted Big Jeff hanging outside the door — a good omen. I’m *fairly* convinced that some of the people at the door thought my friends were the band (leather jackets, one Irish accent), which was a touch awkward.

Although my third time of seeing ASIWYFA, I had not seen or heard of the support band Gallops, who were in turn substituted for Antlered Man. This did a great job of guaranteeing that Antlered Man would be a surprise; and what a surprise they were! Exhilarating and moody, noisy and well-constructed, they brought a kind of progressive grunge with a “Moroccan roll” flourish. Political lyrics and massive attention to detail (the bassist stepping on and and off his distortion about 50 times in the set to stop the thing humming during rests) made for a really compelling performance. The vocal melodies were both original and natural. The music was different enough from ASIWYFA to avoid any overshadowing, while close enough to engage their audience. Basically, I don’t have a bad word to say about them. The next day, I bought their record (digital download + physical in post = YES) and have been blown away by it ever since. A strong contender for my 2012 album round-up!

In a sense there is little to say about ASIWYFA’s performance; precise, powerful and sufficiently varied. If you’re not familiar with them, the music combines alternative rock sounds with the spirit of traditional (“folk”, if you must use the word) dance music. The band give a huge amount of energy on stage, likely at some cost to their health. Their new material was well-received, bringing in more electronic and synth elements, while the 1-album audience lag showed itself in the thermonuclear response to “Gangs” and “Search:Party:Animal”. It was very much a rugby scrum in that while appearing violent, the crowd was fairly considerate and friendly and I didn’t feel in any danger bending down to tie a shoelace. The greatest nuisance was one discourteous gentleman who relied on this rather too heavily, essentially trying to fall onto the floor through other people. After dispatching this twit to the edge we were treated to a close encounter with both guitarists playing in the middle of the audience. The last time I saw them do this, guitarist Rory Friers actually fainted and as such, in my position directly behind him, my thoughts were alternating between “CATCH HIM IF HE FALLS”, “DON’T MOVE OR DO ANYTHING THAT MIGHT INTERFERE WITH HIS PLAYING” and “THIS IS AWESOME”.

If I have to criticise ASIWYFA it is on a much more abstract level; while their songs are meticulously paced, the musical support for the structures is weaker. It can feel a little directionless and improvised, rather than composed; some tracks could have more “purpose”. These are fairly widespread, even intentional, aspects of the post-rock genre, and it is one of the telling things that puts ASIWYFA with the rest. But live, at 115dB or so, in front of an adoring crowd, does it matter? No. These gigs are special.

Physics House Band / Casimir / Shallows / Fixtures

The Louisiana, Bristol – 23/4/13

This was my first time in the Louisiana, a pleasant pub with an upstairs venue. The card minimum is ¬£10 and there are no cash machines nearby, so make sure to bring plenty…

Fixtures are based in Bath and I’ve seen them a few times before; they are really the city’s pre-eminent progressive/post-rock band (by which I mean they are the only one I know of that I’m not playing in) and I do genuinely think they are pretty good. There’s enough jangly pop sensibility to rope in the punters and they made a fair effort in terms of giving an energetic performance given that there were all of, oh, about fifteen people there for their set. They played some new material (again!) and seemed fairly secure; I’ve seen them play better, but they deserved more support on this occasion.

Shallows are a fairly recently-formed noisy Bristolian three-piece. Their songs were interesting and individually their playing was impressive, but on this occasion they didn’t quite gel enough to live up to their obvious potential. Plenty of practice done, but more *rehearsal* needed I think. Would happily watch them again in a month or two.

Casimir were a pleasant surprise; in many ways musically similar to Fixtures, they are a young, explosive and somewhat progressive band, with a little less pop appeal and a slightly more post-punk/noise aesthetic. Unfortunately I was not able to pick up their EP on the night owing to the aforementioned cash shortage at the venue; getting in touch and tracking this down is on my to-do list.

Physics House Band are difficult to pin down. Their music is complex, their playing technique both original and effective, their performance very precise. The drumming especially is remarkable; intricate, accurate and not too showy. Both bassist and guitarist hop on and off keyboards as appropriate, and play them with abstract tremolo or gentle stabs; they have really embraced the fact that synthesisers are not traditional keyboard instruments and each style of program demands a different playing technique. The genre would normally be identified as “math rock”, but math rock is generally much more avant-garde and noisy (see Deerhoof, for example). This is sweet, clean, grooving. Much has been made of their education and classical background but they don’t really satisfy my desire for sophisticated compositions and classical counterpoint. If you really break down the structures and chords, I think they’re playing jazz without the cliches. Nice.