Video - Navs live at Powwow

I had a lovely time playing at Powwow last week. If you missed the stream, here is the full video.



The line-up was Navs, Uchi, Wilted Woman, Goldwiener + Luma/Chroma and Hainbach. It was the first Berlin Powwow to be held at Patch Point’s new store in Neukölln and in stereo.

My 6U case contained the usual suspects - Cwejman, Mungo, Makenoise, Toppobrillo - with the new additon of a Harvestman Piston Honda MkI. It's a wavetable oscillator, packed with timbres and glitchy surprises - an oldie but goldie.

Thanks to Darrin and Stefan for organising the evening and setting the stage, to Uchi and Wilted Woman for their wonderful sets, Luma/Chroma for her mesmerising visuals, to Paul for his excellent camera work and Wouter for that suit!

Powwow - thanks …

… to our hosts, Hainbach & Goldwiener and to Luma //Chroma for the mesmerising visuals! The launch of Powwow Berlin was loads of fun and I’m looking forward to doing it again.



Here is a video teaser of my set:



And here is a proper recording which you can also buy from my Bandcamp:



I patched a 6U case live, with back-up provided by a Clavia Micromodular and EHX SMMH as delay and looper. Given the short set-up and play time, this was a good selection which provided enough options. It was nice to get back to basics after a couple of virtual modular gigs and I think there’s enough play in this caseful of modules for another outing.

A-171-2 VCS Expander

Adding gated hold & burst functions and an End of Rise output to Doepfer’s Serge VCS. An update to this post.



A recent forum thread about the Serge 1973 envelope got me thinking about whether it would be possible to add its hold function to the VCS. Once I’d understood what was needed, a burst and EOR pulse were obvious additions.

Both Burst and Hold can be activated manually or by an external signal. Hold freezes the envelope in its tracks. It’s different to patching via a S&H as the envelope continues where it left off. Burst simply cycles the envelope at will.

Audio examples: Hold (cycling VCS FMs a VCO, button pressed to hold), Burst (first manual, then activated by 2nd row of sequencer).



The EOR is needed for quadrature functions with two envelopes (the other fires at the End of Cycle). Conditioning the pulse required some creative thinking, a case of patching with ICs! Its width can be varied, so it can be used to ping filters or delays.

These modifications are simple to implement with switches and logic inversion (schematic to follow). The additions borrow from my favourite envelopes and make the A-171-2 close to ideal. Yes, I could have just bought a Function but it wouldn’t have been as fun or educational!

Serge VCS Modification

Modifying the Doepfer A-171-2 Serge VCS for more extreme non-linear curves and more manual control over rise and fall times.



The Serge Voltage Controlled Slope is a classic design and an integral part of many modular musicians’ systems. The Doepfer A-171-2 is a faithful recreation of the original circuit. It works just like the Bananalogue VCS that has been in my case since pre-Maths times. That’s good, and bad.

The VCS easily allows one to set different contours for its rise and fall phases. But its non-linear curves are not as extreme as those possible with Maths. Setting times on the VCS is harder, as the useful range is limited to about 20% of the potentiometer’s throw. It’s these differences between these two similar function generators that this modification tackles.

The feedback that generates non-linear shapes is pre-wired on both the VCS and Maths. Calibrating the VCS output voltage from 5V to 8V has only a marginal effect. But if one patches the VCS envelope output to its ‘Both CV’ input with VC Rise + Fall set to linear, the Serge yields the desired curves. This suggests the internal CV feedback loop is capped.

Indeed, if we look at the left of the schematic, at switches SWF & SWR we find 330K resistors limiting the amount of feedback to the CV mixer to about 30%. If we lower this resistance we’ll get more feedback. I desoldered and replaced the 330K resistors with 200K but you could also try soldering another value in parallel e.g. 150K (= ca. 100K, 100%) or 470K (=ca. 200K, 50%).

This part of the modification helped clear up an oddity about the VCS: namely, why making the curves more exponential actually increases the overall envelope time. Negative feedback should make it shorter, and vice versa.

If we study the same part of the schematic again, we can see -12V across a 1M resistor feeding the summing points. Given the gain ratio set by the 100K resistor, this offsets the rise and fall rates by +/-1.2 volts. I find this counter-intuitive, so I removed both 1M resistors.



Both my Doepfer and Bananalogue modules are fitted with logarithmic potentiometers to manually set the rise and fall rates. This means, when using the VCS as an envelope or slew limiter, changes in the first 50% of the pot’s throw are imperceptible. Typical envelope settings lie between about one and three o’clock. Tapering the A50K potentiometers on the A-171-2 with a 5.6K resistor between the CW/ ‘hot’ lug and the wiper solves this. The useful range now spans from nine to three o’clock.



To solder these in place, you’ll have to unscrew the jacks and remove the board from the faceplate. I tape Gaffa around the ends of my pliers to avoid scratches. While you’re there, you can measure the output between the A50K wipers and the subsequent 82K resistors to understand how the log pots choke the voltage. I did try an S-curve taper with two sets of resistors but the quasi-linearization suggested here by Daverj worked best.

So, what does it sound like? Here are two recordings:

feeback mod: exp-fall, unmodified, 0:08 modded, exp-rise, 0:16 unmodified, 0:23 modded.

pot taper mod: cycling, rise = zero, fall manually altered. Stock VCS then modded at 0:39

These simple changes have given my VCS more whip and made it easier to use. Thanks to Dieter Doepfer for helping me read his PCB layout, Ken Stone for publishing his schematic, Tim Stinchcombe and Dave Jones.

If you’d like to try this yourself, take the usual precautions to avoid damage to yourself or your module. I will not be held responsible. If in doubt, ask Doepfer or your technician to carry out the modifications for you.

Patch Tips #26 - Let's Make an Envelope

Deconstructing the AD envelope. An extravagant but enlightening exercise in understanding how triggered slopes work.



I've been looking into the circuits used in attack/ decay envelope generators and thought it might be interesting to patch one from its basic building blocks. I took my clues from a design described by Barry Klein and René Schmitz and Ray Wilson's Skew LFO to come up with the Skew-velope. Here's how it sounds (MP3).

And here's how it works:



A trigger sets a flip-flop high. Its output is slewed. When the slew signal hits a peak threshold, a comparator turns the flip-flop off and the signal starts to fall. When that voltage hits zero volts - i.e. the envelope ends - another comparator turns the flip-flop on and the process begins anew. Feedback helps shape the envelope. Here is a PDF of the patch and modules I used. Ironically, you may find yourself turning to Maths for its secondary functions in your experiments!

So, why use 8 modules to replicate something that can be done with one? It helped me understand the characteristics of these sorts of contour generators. For example, why re-triggers are ignored during the rise phase, making use as a delay/ divider possible. It also helped demystify Maths & its Serge forbears. Analogue envelopes rely on some form of logic and switching to work. These multifunction modules make some of those processes available to the user.

For more, read Tim Stinchcombe's paper on the Serge circuit.

PotD - Mutant Horse 2

A gentle gallop into Basic Electricity #5 on Friday. This is a take on the patch Tom & I played at BE#4, likened by Ian Boddy to "riding a mutant horse".



A Sport Modulator provides both timing information and CVs, driving Maths, a VCO-2RM, Triple Wave Folder, A-112 Sampler/ Delay and VCA-2P panner. The oscillators are FM'd before being gated, folded and sampled. A stepped and manual CV controls the rhythm, delay time and panning. Flipping between track- and sample-and-hold on the SM delivers the final crack of the whip.

Release: Basic Electricity #1 Live EP

For those who couldn't make it to the recent Basic Electricity event at the Auxxx in Berlin, here are the recordings of my set.





Making their debut at this gig were the Doepfer A-199 Spring Reverb, A-112 Sampler/ Wavetable Osc. & Cwejman FSH-1 Frequency Shifter. They were supported by the usual suspects: RES-4, MMF-1, Toppobrillo Triple Wave Folder & Sport Modulator, Harvestman Hertz Donut, Makenoise Wogglebug and, of course, the EHX Stereo Memory Man w/ Hazarai.

Ring-Mod Round-up

An overview of five balanced-, or ring-, modulators: the Intellijel μMod, Makenoise ModDemix, Fonitronik mh-31, Doepfer A-133 and Cwejman VCO-2RM.



RingMod Roundup by navs

These modules have a different approach, feature set and, as you can hear, sound. The Cwejman is a classic two-input, one output affair and I included it as a reference as it has good rejection and headroom.

On the face of it, the additional features offered by each manufacturer set these modules apart. However, given that the basic concept is the same, these differences might not be that wide. The μMod's 'Q' function, for example, seems to be a bipolar offset, something that could be patched externally with the Cwejman or by increasing the manual gain on the A-133. Similarly, the auto-AM/ pseudo-SSB modulation offered by the ModDemix's normalizing could also be covered by a dual module like the Doepfer. Incidentally, it's a shame neither of these dual modules can be used as a mixer out of the box. Pre-patching a signal to one of Maths' attenuverters and using the uni-polar OR output as modulator would yield a function similar to the μMod's rectification switches. The mh-31 utilizes rectification as part of its 'RM' process which might explain its characteristic sound.

Two technical points to note: when used as a VCA, the μMod I tested displayed a small amount of carrier bleed (audible in the example above), but I'm sure this can be corrected by calibration of the 'Q'/ offset. The A-133 suffers bleed too, but this is understandable due to its lack of centre-indent pots. At low 'strength' amounts, the ModDemix displays an unusual response - the processed waveform seemed more typical of AM than the 'attenuated' RM I'm used to from the A-133. Both the Makenoise and Doepfer are DC-coupled, so I wonder if this difference is down to the circuit employed.

In terms of sound and function, I saw the closest parallels between the VCO-2RM & μMod one the one hand, and the Doepfer & Makenoise ModDemix on the other. The mh-31 is the most unorthodox design and doesn't easily fit in either camp.

To my ears, the Cwejman and Intellijel have the cleanest tone, with the Makenoise and Fonitronik well-suited to more abrasive timbres. While not as transparent as the VCO-2RM or μMod, the A-133 can be both clean or driven to distortion.

Thanks to Schneidersbuero for the loan of the Intellijel & Makenoise modules.

Release: Trans Europa Exzess

Studio version of my set at the Schneidersbuero Superbooth event at the Saasfee Pavillion last week.


I took a 6U system to Frankfurt, which was the same rig I used for the above recording: 4MS RCD + breakout, Analogue Solutions MX224 & SH-NZ, Cwejman RES-4, MMF-1 & VCA-4MX, Doepfer A-133, Makenoise Wogglebug & Maths, Plan B M15 & M12, Toppobrillo Sport Modulator & Triple Wavefolder and, of course, the EHX Stereo Memory Man w/ Hazarai.



This was the first time I received the full security check the airport, involving a visit to a special room and swab test on the case. A tip for modular travelers: when asked whether you are a DJ and your equipment is a mixer, answer 'yes' to both questions.

Thanks to Andreas and all involved - it was a great evening!

Patch Tips #15 - Non-Linear Distortion

I recently stumbled across the Nord Modular's exponential shaper module while looking for something to bend a signal. The ShpExp works with transfer functions to generate non-linear distortion. This can give a sound edge, without totally shredding it. Of course, my next thought was whether it would be possible to patch something similar with my system. As usual, Rob Hordijk had the answer.



The trick involves generating a signal at twice the frequency of the source, which will then be used to modulate the amplifier. The easiest way to do this is to patch multiples of the source to both inputs of a ring modulator, effectively multiplying the signal by itself. This performs full wave rectification and, in the case of sine waves, frequency doubling. Patched to a linear VCA, a sine wave is bent like this:



Here's how it sounds:


Mono- then Duo-phonic signal. Clean Cwejman signal path (MMF-1 sine, VCO-2RM RM, VCA-2P)


Mono- then Duo-phonic signal. Dirty Doepfer signal path for added crunch (MMF-1 sine, A-133 as RM, A132-1 VCA)

Feeding the rectified, frequency-doubled signal back to the source, rather than the VCA, will bend the sine into a triangle, albeit with a different pitch. Try varying the FM-CV amount, other VCO waveforms or even polyphonic signals for seriously warped shapes.

I used the VCO-2RM and A-133 which, being dual, allows one to cascade and further multiply the modulator. Frequency doubling or rectification can also be achieved by feeding +ve & -ve signals to a min/max analogue logic module like the A-172 & Maths' OR processor or Doepfer's A-119 ext. input module, as per this Patch Tip. Like the A-133, Fonitronik's forthcoming mh31 and Makenoise's modDemix provide one-stop solutions.

I'm not sure if this process is in fact single-sideband modulation as the modDemix description suggests, but it's certainly closely related to Amplitude Modulation which will be the subject of the next Patch Tip.

Patch of the Day - Harmonyhertz

I twisted my knee and had to undergo an MRI scan this week. For those of you who haven't had the pleasure, this is what it sounds like:

Harmonyhertz-PotD  by  navs

Having entered the machine, you're given a pair of noise-canceling headphones. The classical music that is piped through these is supposed to calm and distract you from the grunts and buzzes generated by the scanner. Don't know which device was responsible, but the kick and hi-hat pattern was a bizarre counterpoint. Sort of like a Clockwork Orange warehouse party. Someone with a sense of humour at Siemens, the company that built the contraption, decided to call it 'Harmony'. The nurse told me that the larger unit is called 'Symphony'.

THE PATCH

The patch features four voices: kick and hi-hat, ring modulated squarewaves, FM klunk and some 'ducked' classical music. Although I managed to use up nearly all of my patch cables, it was actually fairly straightforward.

Drums: MMF-1 sine wave kick, M12-filtered-noise hat. LFO provides rhythm, VCS provides gate delay for 'swing'.

Buzz: Wogglebug stepped out provides slow pitch changes for VCO-2RM. Two square waves, with a touch of XMod and manual pitch and PWM tweaking, are output from the ring modulator. Timing is generated by the burst out of the WB which is patched to a clock divider. The /8 gate signal triggers one Maths channel. An inverse /8 gate is fed to a second Maths EG so that the klunks are timed to occur after each buzz has sounded.

Klunk: M15 & AFG lin FM plus some pitch woggle and envelope thwapping from Maths and the mix out of an A-143-1. Maths' EOC used to trigger the Doepfer, klunk gated by M13 LPG.

Classical: Borg-filtered with a bit of FM from the combined buzz & klunk CVs. Vactrol speed in evidence as the CV takes a while to fade away from it's peak.

Ducking: this was achieved by sending the classical sample to the first channel of an A-134-2 VC Xfader, the audio mix of buzz and klunk to the second and applying the combined buzz and klunk CVs to the (asymmetrical) Xfader.

Hope you enjoyed the sounds and remember to look after yourselves!

This PotD dedicated with thanks to the docs and nurses.

Borg, Boogie & the Thwap Test

I only went to Schneiders yesterday to pick up a second Doepfer mixer...



Enjoy the recordings.


Borg Low Pass. Starts in LPG mode, then manual tweaks.


Borg Modes. EG + Manual tweaks


Boogie Modes. EG + sequenced/ random CV of mix relationships (Cwejman VCA-4MX).



I also borrowed a Makenoise QMMG to run a quick 'Thwap' test.



For some, the gold standard in Euro is still the Plan B Model 13. Decide for yourself.


LPG Thwap Test. M13, Borg, QMMG.

VCO and envelope were multed to the three LPGs. The Borg, QMMG & M13 all use different vactrols with different response times, so I adjusted the modulation depth until I got a similar timbre. The M13 was used as the 'control' i.e. offset at zero, MD at full.

Thanks to Schneidersbuero for the loan of the modules.

Patch of the Day - The Wogglebug

Well, I didn't have to wait much longer - the Wogglebugs have landed in Berlin!



I'll spare you the details but, suffice to say, it's well built, a pleasure to look at and bucketloads of fun. There's plenty of information and demos on the web. If you're curious, check out the Make Noise site and Grant Richter's synth DIY pages.

In today's patch I've used the Wogglebug as a VC bit crusher. The left-hand channel is the source material (various VCOs being FM'd). I nudged the right-hand channel back by two divisions in Logic, so the bit crushed recording is heard as a delayed response.

Fish For Breakfast - Wogglebug Demo by navs

The Wogglebug is being clocked by a Plan B Model 10, which itself is having it's time-base modulated by the WB's smooth out. The random FM sequences were generated by a Sequentix P3. Looks like I might need a second bug ...

Patch of the Day - Waiting for Woggle

Waiting for the Makenoise Wogglebugs to land, I patched up a little alien welcoming committee using a Frostwave Resonator Korg MS-20 filter clone, a random source and two VCLFOs (Doepfer A-147 & Plan B Model 10).

Waiting4woggle by navs