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.

PotD - The Organ Grinder

Featuring the Plan B Model 23 Analog Shift Register.



The Organ Grinder plays his merry tune. All is well until monkey and Schnapps get the better of him:

PotD - The Organ Grinder  by  navs

In this patch the M23 was used to shift a quantized sequence to a pair of detuned VCOs, the 'both' input of a Bananalogue/ Serge VCS and the CV input of a VC-LFO. The sequence was transposed by the stepped output of a Wogglebug. A sequential switch was used to alternate between a 'regular' and voltage controlled clock. The switch was triggered by a comparator reading the output of a second random source.

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UPDATE: Patch details

I tried to keep the patch description as simple as possible, but for those of you who want to try this here is a patch chart.

The A-147 VC-LFO acts as the master clock and feeds the SQ8, which sends a gate to the VCS (or Maths).

The envelope generated by the VCS is patched to the output VCA. In my patch I fed the two VCOs to a separate mixer (VCA-4MX) before the final VCA (VCA-2P), but for simplicity I've shown an A-131 in this chart.

The sequence generated by the SQ8 goes to an A-156 quantizer, the CV goes to the ASR and the trigger output of the A-156 clocks the ASR. From there, output one goes to VCO1, output 2 to VCO2, output 3 to the second input of an A-151 switch and the last output feeds the 'both' input of the VCS.

The random elements:

the 'step1' output of the SQ8 clocks the Wogglebug. In turn, its clock output steps the S&H/ noise.

The Wogglebug's stepped out feeds the transpose input of the quantizer. At the beginning of the patch I kept the randomness to about 9 o'clock, towards the end I swept it up manually and then back to zero.

The SH-NZ output feeds an A-119, which I've used as a comparator. Depending on the gain & threshold settings you can generate an amplitude-dependent gate. As the A-151 feeds the CV-in of the VC-LFO, the gate toggles the switch between 'regular' and VC-clock. As an alternative, you could use a VCA to alter the amount of VC-clock or, indeed, alter the CV amount manually. If you don't have a comparator or A-119, you could use the burst output of the Wogglebug. I sometimes find this too frenetic, so I send the burst gate to a clock divider to calm it down a bit!

Patch Tips #14 - Sub-Harmonic Division

Using Maths or the VCS to generate sub-harmonic variation.



Today's Patch Tip is cribbed from Seth Nemec's Bananalogue/ Serge VCS demos and the 'Undertone Generator' patch in Rich Gold's Serge book:

"Sub-Harmonic Generator: If a series of triggers are applied to the VCS faster than the total rise and fall times, the module will divide the incoming signal by a whole number. In the audio range the output will be the sub-harmonic series."

The VCS has the benefit of an AC-coupled output, but I feel Maths offers finer control over the settings. As this patch relies on the rise time, Math's EOR pulse can be used to provide an even beefier sub signal.

The technique simply involves patching a mult of your principal oscillator to Maths' trigger input and mixing either the envelope or EOR with the main VCO in a filter etc. Set the response to linear, fall to fully CCW and then gradually increase the rise time. Additionally altering the fall time will give you more control over the timing and hence sub-divisions.

Here's what it can sound like: subharmonix.mp3

The patch relies on the envelope's inability to respond to a second trigger until it has completed its cycle, meaning it will 'skip' pulses and thus generate a lower frequency. You can try this patch with other trigger-able envelopes like the Plan B Model 10, Cwejman CTG-VC or Doepfer A-143-1, bearing in mind that the minimum possible cycle time and trigger response will affect the possible sub-divisions.

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!

Doeper/ Serge VCS Expander Schematic

A description of the method I used to add Hold, Burst and EOR functions to the Doepfer A-171-2. An update to this post. The module is a licenced version of the Serge/ CGS DUSG/ VCS, so these mods will work on them too, although the pins may be different.

You can download the schematics and Fritzing file here. I wish I had done this at the time in spring as I've had to retrace my thoughts from incomplete notes. It's been fun but I might have some things wrong and I’m sure some aspects could be done better. So, please continue the discussion and post corrections and improvements to this circuit in this forum thread. I will update this post accordingly.

HOLD



The idea behind the Hold circuit is simple: interrupt the integrator. If you wanted to go no further and keep this mod passive, all you would need to do is cut one trace and hook up a switch. On the A-171-2, I found a convenient place between pin 7 of the TL084 quad opamp and the 8k2 resistor (R39).

If we want to automate this, we need an analogue switch. Transistors can be fiddly and the common CD4066 won’t process all signals, so I used a DG201. This switch is ‘normally closed’, so with no gate on the command input, drain and source are connected and the integrator’s loop is closed. Pulsing it breaks the connection.

EOR

Referring to Tim Stinchcombe’s VCS analysis and comparing with the Doepfer layout, pin 4 of the LM3900 is high during the attack phase. The ‘not attack’ gate, which will become part of our EOR gate, can be found on pin 5 of the LM3900. If you observe this output with an oscilloscope you’ll notice we need to process it as the ‘not attack’ gate remains high until the next attack phase is initiated. This can have its uses, but it’s not what we’re after if we want an EOR/ variable length gate that can be used to ping filters etc.



This is where we have to get creative and ‘patch with ICs’: we use another switch on the DG201 to operate a logical AND function. The signal which chops our ‘not attack’ gate down to the right length is the EOC gate. We can tap this signal from the End Out jack on the A-171-2. As the EOC gate is ‘high’ at the wrong time, we want to flip its activity.

The need for a logic inverter conveniently also answers the question of how to buffer the inputs for this mod. I used an HCF4049UBC Hex Inverter. As the supply voltage also determines the logic threshold for this chip (lower voltage = lower threshold/ faster response), I chose to run it off 5V, supplied by a 78L05A regulator. I sent the new EOR signal from pin 15 of the switch to a jack and an LED.

BURST

Now that we have the means to process logic, the burst function is relatively simple. It’s a circuit adaptation of the classic Maths Trills patch where we used a logic gate to interrupt the loopback of the EOC signal to the trigger input. As with the EOR gate, we use a switch to function as a logical AND gate. The DG201 is ’normally closed’, so we need to keep the switch open when there is no burst command present. To do this, we use a spare inverter to flip the activity of the burst input. Looking at the schematic on Ken Stone’s site, the trigger and cycle inputs are OR-combined by diodes, so the VCS can be triggered and burst/ cycled at the same time.



The DG201 is powered from +/- 12V. Filter the supply as usual and add 0.1uF bypass caps for the ICs. The burst and hold inputs were conditioned by cutting negative voltages. The schematic says 4001, but I used 4148 diodes.  I added a manual gate by tapping 5V and sending it via an ON-ON switch to either the burst or hold jack’s switching contact.

It sounds more complicated than it is. Once I’d thought it through, I built it on stripboard on the fly, without the need for a detailed schematic. Lesson learned on that score! I hope these notes help and look forward to your comments and improvements.

Thanks to Dieter Doepfer and Chrisi & Erik at Koma Elektronik for their help on the subject of switches.

The usual DIY disclaimer: do this at your own risk, take care and have fun.

Doepfer A-156 Dual Quantizer Demo

It's one of Doepfer's oldest modules and not something I really thought I needed. But, having spent a weekend playing with the A-156, I've got to ask myself 'Why the hell didn't I get one of these years ago?'.

Doepfer A-156 Quantizer Demo by navs

Patch Notes:

1) SEQUENCE FROM ENVELOPE. Plan B Model 10 loops, envelope to A-156, End Out to Wogglebug clock. A-156 Trigger to VCS. Wogglebug stepped output to A-156 transpose, M10 VC-Timebase and VCS VC Fall.

2) GLISSANDO 1. Pitch CV slewed by VCS, then to A-156. Trigger out to A-143-1.

3) GLISSANDO 2. Kenton Pro 2000 II provides auto-portamento. CV to A-156.

4) RANDOM. Wogglebug woggle out to A-156, trigger to Borg filter in LPG mode.

5) KINETIC GATES. Pitch bend via MIDI joystick to A-156 (chromatic mode) and VCO. Trigger to Borg (LPG).

6) SEQUENCE. LFO to A-152 Voltage Addressed T&H/ Switch. Digital outs to mixer, four stage sequence to A-156. Trigger out multed to main envelope and A-160/ 1clock divider/ sequencer to fire kick, high hat & bass.

7) DUAL Q. LFO clock to Q1 & Q2 trigger inputs and A-160/ 1 CLK DIV/ SEQ. /2 > EG1, /16 > EG2.

All patches feature manual toggling of the A-156's mode switches and, maybe a bit too much, EHX SMMH delay.

While not as stable or versatile as my Kenton Pro 2000 II/ Sequentix P3 combo, the A-156's ability to generate sequences from LFOs, envelopes, joystick sweeps and random sources, coupled with the fact that it outputs a trigger on each quantization, makes this a very useful and musically inspiring module.

Maths Test

This module needs little by way of introduction - shortly after it was announced, it sold out in the US and Europe. So what makes Make Noise's Maths so special that it prompted the largest used-envelope sell-off in Euro format history?

Have a listen for yourself:

Maths Test Taster  by  navs

Maths packs a pair of voltage controllable slope generators, much like the Bananalogue/ Serge VCS or Plan B Model 10, plus two channels of 'attenu-version'. It's this 'package' that is probably the key to its success. It's a compact, complete system. Most patch 'problems' can be solved without resorting to other modules and, like the Wogglebug, it's fun and inspiring.

In use, I found the envelopes clean and spike-free. Setting rise and fall times was far easier than on my VCS or Model 10. As the manual states, the contours have a dramatic effect on timing. Like the VCS, filtering audio is not one of its strengths but when used to slew CVs it is precise.

The only two things I missed were a single-shot trigger button and, more importantly, voltage control over the polarizers. The latter would, for example, allow VC contours and greatly enhance the mathematical possibilities!

You can download the full test here (13.5MB)

Update: here's a short clip demonstrating Math's slew/ portamento capabilities.

TTA Z8000 Matrix Sequencer

Funny how things come in waves. The last breaker brought us envelopes, the next threatens to flood us with sequencers, programmers and control devices.

Det3 and Sequentix both have standalone sequencers in the works, STG Labs and Malekko/ Wiard plan to release slider-based programmers. The two possibly most closely-related and awaited products this year are Make Noise's René and Tip Top Audio's recently released Z8000, which is the subject of today's mini-review:



The Z8000 is billed as a matrix sequencer/ programmer and offers ten independently-clockable lines of CVs. Given its price and relatively compact size, it is a remarkably flexible and affordable package. You can find out more on how the Z8000 works here.

First up is a brief run-through using four 4-note sequences:

TTA Z8000  by  navs

Rows 1, 3 & 4 were clocked by an LFO and subdivisions generated by a Doepfer A-160/ 1 combo. I used a Bananalogue/ Serge VCS to delay the gate for row 2 to provide some syncopation. A manual gate was used to change direction and reset individual rows.


Lost in the Matrix.

The first example is relatively straight forward, something one could achieve with multiple analogue sequencers or a digital multi-track sequencer like the P3. The remarkable feature of the Z8000 is the fact that all outputs 'share' the same pot values. This takes some re-thinking on the part of the user. My initial attempt at tapping one of the aggregate lines resulted, somewhat comically, in disaster:


Z8K Matrix Hell

As I say, it takes some getting your head around! The reason this is relevant should be apparent: any change you make to an individual sequencer row/ column will have repercussions in the matrix, so beware.

Naturally, this can also be musically beneficial as you can hear in this longer take:


Z8K Live Jam (6 mins)

Four VCOs, tuned to the same root note. At about the 3 minute mark, I introduce a fifth voice taking its CV from one of the aggregate outs. I then change my mind and try the other out! As you can hear, the Z8000 is very hands on, certainly this jam was made by the fact that all pots were directly accessible, unlike the P3.

Because the Z8000 offers independent clock, reset and direction control for each 'sequencer', Reich-isms and polyrhythms are easily achievable:


Z8K Reichism

Four VCOs, four rows each with the same pot values. The burst out of a Wogglebug and an A-151 sequential switch were used to reset the rows and thus shift their relative positions.


Z8K Polyrhythms

VCS, Maths and A-160/ 1 used to provide gate delays/ divisions.

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The Z8000 is well-built and laid out and looks fantastic. The knobs are clean and responsive and offer enough clearance for the 'large-fingered'. It packs an astonishing amount of sequencing into 28HP. So, what's not to like?

Some might bemoan the lack of gate outputs, but this can be overcome by taking a mult of the gate signal via a Stackcable or other clock sequencer. I would have liked VC step addressing and wonder whether this and the direction function couldn't have been implemented as it is in the A-152, rather than via a gate signal. I do, however, like the fact that the method used means that one row can be programmed to provide direction triggers e.g. a pot tuned fully CCW = forward, above a certain threshold = backwards.

In use, my largest frustration with a module featuring ten separate sequencers was the lack of a global reset! Ironically, I used a muxed manual gate from my A-Sol SQ-8 to solve this. If you're particular about this sort of thing, you should know that the Z8K resets to step one, meaning that the first step when clocked is actually step two. The work-around here was to use the SQ-8 to step all sequencers to position four. My last observation is actually not related to the Z8K but Doepfer's A-160/ 1: because of the way it counts, I failed to get a sequence to go forwards and backwards in equal measure, pendulum style. If you understand German, you can read more about the problem in this post at the sequencer.de forum.

As TTA's Gur has pointed out, the Z8K's open nature means you'll need a variety of other modules to get the most out of it. Clock dividers (A-160/ 1, 4MS Rotating Clock Divider or Flame Clockwork), logic, sequential switches or a multiplexer like Doepfer's A-152, not to mention a quantizer or two, would make excellent companions. Given the voltage addressing capabilities of the A-152, a random source or a joystick would also expand the patch permutations.

The wealth of possibilities on offer might seem dizzying or daunting, but if you have the head and the supporting modules, the Z8000 could be sequencer heaven.

Patch Tips#18 - ADSR 'Free-Run'

Using a gate delay and comparator to trigger 'full length' ADSR runs, achieve looping ADSRs and delayed looping of AD envelopes. As suggested in this thread.



Unlike AD envelopes, ADSRs generally need a gate signal to fully complete their cycle. The gate determines the duration of the sustain phase of the envelope's run. So, what to do if your sequencer only generates triggers?

With a gate delay like the A-162, set the delay to zero and the length to taste. If using Maths' channel 1, the rise sets the delay time and the fall the length of the gate, available at the EOR. This provides the gate that the sustain requires. This mimics the response of AD envelopes like the VCS, which complete regardless of gate duration.

If you then mult that gate to a comparator with a suitable threshold, you'll get a second gate when the first expires. I used the Sport Modulator with the multed gate fed to the bottom input and 5V as a threshold reference sent to the top input. The middle output provides the comparator function. Mix the two gates and feed them to the input of the gate delay and you've got a looping ADSR.



The A-162 is great for these sorts of tricks and can also be used with AD envelopes which have an End Out (VCS, Maths, A-143-1) to achieve the Envelator's delayed looping.

Schneiders London Testsalon Opening

Some pictures from the opening event at Rough Trade East last Sunday.









It's been a while since I've been down Brick Lane and I was amazed at the buzz on the streets. Rough Trade East is a great location for the Testsalon and I wish Andreas and the lads every success with the venture. Thanks to everyone who came along - it was great to meet you!



TOP: Cwejman RES-4, MMF-1, Toppobrillo TWF, A-132 VCA, Harvestman Hertz Donut, VCA-4MX; BOTTOM: A-147 VCLFO, A-160/1 clock divider/ sequencer, Fonitronik Attenuverting Mixer, Analogue Solutions SH-NZ, Make Noise Wogglebug & Maths, Bananalogue/ Serge VCS.

Above is a picture of the 6U case I took with me. I can happily confirm that it met Easyjet's carry-on luggage regulations. There was a sharp intake of breath from the passengers behind me as I opened the case at security in Berlin - the people at Luton didn't even bat an eyelid. I asked Easyjet about taking a 9U as carry-on: unfortunately, it's too big.

Putting together a 6U performance case was a real challenge. My normal approach is to ensure that I have all eventualities covered e.g. VCAs, polarizers, mixers etc., but this time the solution was to think in terms of the set I wanted to play and populate the case accordingly. Anything I hadn't used in rehearsal (mults, logic, sound-shaping filters, complex envelopes etc.) was easily left out.

My set comprised of three sections and relied on re-patching & repurposing the modules e.g. filter as oscillator, envelope as trigger delay etc. Rather than using LFOs, a joystick or keyboard/ Pressure Points, I made all changes manually.

Section one: white noise tuned by the RES-4 to provide a pad, the MMF-1 randomly pinged by the Wogglebug (the Allen Strange 'tail-chasing' patch); section two: my faux binary zone patch (MMF-1 through TWF as bassline), RES-4 pinged by clock divider for 'Berlin-style' stabs, high-pitched waveform discontinuity sound from Hertz Donut principal as high hat, modulator as kick drum and, section three, the RES-4 excited by the VCS and run through the TWF for some distorted klonks, with the HD providing some 'stupid' accompaniment and the MMF-1 rumbling the subs.

Part workshop, part gig, this was an interesting experience - despite rehearsing, the one thing I wasn't prepared for was shaky patch-hands. On more than one occasion, I missed the jack and hit the face-plate! Self-contained instruments like Maths, the Wogglebug & Hertz Donut are perfect for small systems (although the latter's secondary CV inputs, which need to be activated, are hardly performance-friendly!). The biggest lesson, though, was to bring your own monitoring: if you can't hear your music properly, you can't respond. Next time, I'll be wearing headphones!

Patch Tips #12 - More Mixed Envelopes

Mixing envelopes for tailor-made transients. A follow-up this post.



Today's Patch Tip aims to overcome the limitations of the simple ADSR envelope when used to open a filter or VCA. I often find that in addition to controlling the time it takes for an envelope to reach it's peak value, I also want to control the level of that stage. This is especially true of the attack portion when I want more 'bite' without increasing the overall modulation depth of the D, S & R stages. Mixing an ADSR with an AD envelope solves this problem:

envmix1.mp3

Cwejman VCO-2RM (+ sub ex A-160) > Borg filter, ADSR-VC2 + Bananalogue VCS > Fonitronik polarizing mixer > Borg. Gate to both envelopes. Pitch CV > VCOs + Borg 'key in'. Makenoise Pressure Points row 1 offsets pitch of oscillator 2, row 2 > VCS VC rise.

This is a simple but effective solution without getting into the complexities of patching-up a time/ level envelope as found on the Korg Poly 800 or Roland JD-800. If you did, however, want to try this, the Maths, Brains/ Pressure Points and Doepfer A-143-1 manuals all offer examples.

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.

It's the Envelope, Stupid!

An early Easter bunny.

(Repost from Easter 2008)

I dug these old tests out of the archive in response to these (1, 2) threads at Muff Wiggler's forum.

Bear in mind that this was 2008 and that the range of modules now on offer is far greater. Given the choice today, my recommendation would be the Cwejman CTG-VC and Make Noise Maths. Nevertheless, I hope the tests are still of use!

IT'S THE ENVELOPE, STUPID!

"Common wisdom has it that the most important module for shaping your sound is the filter. I beg to differ: it's the envelope, stupid!"

Download the test (3.3MB) here. Features Doepfer A-140, A-142, A-143-1, Cwejman ADSR-VC2 (rev.1) & Bananalogue/ Serge VCS.

Later that summer, I posted the following:

SOFT BOILED EGs

"Faster is better, right? Not necessarily ..."

Download the test (1MB) here for a comparison between the Roland MC-202 and Doepfer A-140 envelopes.

Sometimes 'sluggish' is just what you want.

PotD - We All Pass Out

Using the All Pass output of one of favourite filters - Plan B's Model 12 State Variable Vactrol Filter - to create a phasing effect. Inspired by this old thread at modularsynth.net




PotD - We All Pass Out

FM'd self-oscillating Cwejman MMF-1 filter sent to both a mixer and the M12, All Pass out returned to mixer. Gated by a Bananalogue/ Serge VCS which is responsible for much of the sequence's funk due to its inability to re-trigger.

The phase cancellations are clearly audible at around the 10 second mark as I fade in the all-pass signal to the mix.

The balance between original and all-passed signal is key to getting the phasing right. The M12 is capable of some very musical distortion (more on this below) and I think I pushed the filter's input too much in the first example. To compensate for the source material's lack of harmonics and to help set a better balance, in this example I first processed the sequence with my Ken Stone Lockhart wavefolder:


M12 as Phaser

This last clip demonstrates the Model 12's characteristic 'vactrol fuzz'. An FM'd Hertz Donut is fed into the filter, Maths sweeps the cutoff while I manually adjust the filter input level. I also compensated for the increased volume at higher fuzz levels by turning down the final VCA accordingly.


M12 Vactrol Fuzz

Normally, this is just the right amount of fuzz for my liking but, if you remember this, you'll know that the M12 is capable of some truly molten sounds.

First Patch of the Year

Dusting off the cobwebs after a week on the Baltic Sea island of Rügen

Der Rasende Roland by navs

Another P3 driven track featuring four elements: VCO-2RM cross-modded and 'thwapped' by a VCS to a Model 13 LPG and gated by an A-143-1, AFG FM'd by an A-105, MMF-1 dual sine pinged & VC'd and some white noise sweeps.

Happy New Year to all!

Patch Tips #1 - Maths Slope Control

First in a new series of tips and tricks, recapping some of the ideas I've covered in Patch of the Day.

It should be fairly obvious by now that I'm an envelope junkie. Of the eight different EGs I have or have had in my system, one of my favourites remains Doepfer's A-143-1 for its natural, rounded 'sound'. It's not the fastest transient generator in my rack, but it twangs a low pass gate like no other. Part of the reason for this is its logarithmic rise and exponential fall:



The only problem with the A-143-1 is that it's large, lacks voltage control and, to be honest, I rarely gang its four envelopes to form one complex CV. I'm running out of space so I wanted to see if I could get the same response out of Make Noise's Maths which, on the surface only offers control over the contour of both rise and fall simultaneously:



With some creative patching, however, it is possible to gain independent control of Maths rise and fall curves, without the need for other modules. Much like the Bananalogue/ Serge VCS, all that's called for is a little feedback:

Set Maths' response knob to linear/ noon. Take two mults of the envelope output and patch one to Maths' channel 2, the other to channel 3. Set channel 2's output to about two o'clock (+) and patch it to the rise CV-in, set channel 3 to ca. ten o'clock (-) and patch to the fall CV. This will give you a logarithmic rise and exponential fall:



Increasing the amount of positive or negative feedback will increase the severity of the response, flipping the polarity to the CV-ins will yield an exponential rise and logarithmic fall. If you want to go really mad, use Doepfer's A-133 Dual Polarizer instead of Maths' 'attenuverters' to gain voltage control over these parameters.

Cwejman DMF-2 Dual Filter Demo

A demo of Cwejman's DMF-2 dual filter.

Drones created with the DMF-2, a VCO-2RM, Wogglebug and Bananalogue VCS.

Cwejman DMF-2 Demo by navs

This was the first time I had the opportunity to process an audio source with two, matched filters. With the cutoff frequencies offset and, fed with different CVs, this module is capable of some great sounds.

Patch of the Day - Maths Trills

More Maths tips - this module continues to inspire me! Picking up on this thread over at Muff Wiggler's forum on how to attain trills and bursts from Maths, I tried Yohda's patch:

Chianti Trills

It works a treat! As per Yohda's suggestion I used a mixer/ VCA, but I think Rechner7 is right: a logic module would be better: when I lengthen the decay time in the example, you can hear some 'flamming' where the gates overlap.

The patch is simple: use channel 4 as your envelope, as it is equipped with an EOCycle rather than channel 1's EORise. An LFO clocks a sequencer and A-160/161 clk div/ seq. The main gate is sent to channel one of a VCA-4MX and the EOC to channel two. This is gated by the division output of your choice from the A-160/161 combo.

You could also replace the A-160/1 combo with a Wogglebug to VC Maths' 'both' input, transpose the sequence and use its burst output to generate random trills:

Pills, Trills & Wogglecake

Be sure to read Tony Rolando's patch tips for gated looping in that thread. And thanks to Mr White (Mr Yellow) for asking the question!

EDIT: the trills patch will also work with a Bananalogue/ Serge VCS! I also replaced the VCA-4MX in the patch with an A-134-2 VC Xfader to generate somewhat 'cleaner' trills. Using a cross-fader means the main gate is 'pushed out of the way' when you want the EOC to take priority.

Patch of the Day - Long Way Down

Something gentle for a Sunday afternoon:

PotD_longwaydown  by  navs

Live, four-voice patch with manual tweaks.

Self-oscillating Cwejman MMF-1 dual-peak sine modulated by WB smooth out. A-Sol SH-NZ noise to Plan B Model 12 HPF, VCA VC'd by Doepfer A-147 VCLFO sine, itself VC'd by the output of a A-156 Quantizer. Ring Mod output of a VCO-2RM filtered by a Malekko/ Wiard Borg, envelope from Bananalogue/ Serge VCS VC'd by Woggle out. M15 VCO (linFM) gets WB stepped, gated by M10 envelope which is triggered by WB burst and VC'd by stepped out. M10 EOC to A-142 envelope which provides the voltage which is then quantized by the A-156.

Patches. They always start out simple, don't they ...

Patch of the Day - Los Comparadores

Abusing Doepfer's A-137-2 Wave Multiplier as a quad comparator and event timer.

This had me laughing my head off: the results are just too unpredictable and the patch needs some explaining.

Have a listen first:

Los Comparadores by navs

The background:

I'm currently attempting to build a quad event timer along the lines of Plan B's Model 17 Triple Event Timer and have so far bread-boarded a working dual comparator using an LM339. This works quite nicely, but is not ideal.

Taking a break and looking for an alternative (read: quick, cheap fix. I'm lazy, right?) I realized my A-137-2 Wave Multiplier is itself a quad comparator. Happily it will accept a DC input, output triggers of a sort and the threshold levels are voltage controllable. Unfortunately it only has a mix out but I overcame this by using a sequential switch to feed a trigger to each envelope generator.

The patch in detail:

Bananalogue VCS paces the A-137-2, A-137-2 mix out to A-151 sequential switch, +5V to its common input is fed to each of the A-143-1 Complex EG's four envelope generators, individual outs to a Cwejman VCA-4MX gating four VCOs, mix out to a CGS52 Lockhart Wave Folder and on to a VCA-2P for panning which is controlled by the mix out of the A-143-1. Still with me? I then took two LFOs (positive and inverted) and patched them to the CV ins of the A-137-2 to modulate the timing of the events.

Two oddities about using the A-137-2 for this sort of application: it's totally imprecise and the input level of the pacing CV has an effect on the timing. You can hear this in the first thirty seconds, where all I am doing is changing the input level. The Lockhart really made this patch for me: when the spacing between events is tight, in effect producing a chord, the wave folder churns out a lovely clangorous noise.

While not as precise as the M17, it's close enough for Rock 'n' Roll and, if it saves me from the soldering iron, then it'll do for now!