Cwejman VCO-2RM Dual Oscillator Review + Demo (Youtube Video)

Cwejman modules have gained the status of the holy grail of modular synthesis over the past few years. Recently I was offered to buy a VCO-2RM second hand for an OK price so jumped the opportunity and got my hands on it. I had tried some Cwejman modules before (including the VCO-2RM) at Schneiders in Berlin and was always intrigued by their classy and beautiful sound. I had read lots of good things about Cwejman stuff on the internet as well. Some critical voices tend to nitpick about the Cwejman sound being too sterile or clinical. I can understand what this criticism is about, as Cwejman really sounds very "precise" but I never saw this as a problem. If you want warm/fuzzy/overdriven sound you can still mangle your audio signal with distortion or waveshapers or whatever is available (and that's a lot!).

Briefly going through the VCO-2RM's features, it is a dual VCO with a wide frequency range (there is also an LFO mode available for both oscillators), 3 FM inputs for each oscillator (exponential FM only!), PWM, sync and a ring modulator. Since the ring modulator is  DC-coupled it can be used with CV signals, making it a VCA. Yes, you can use the VCO-2RM's ring modulator as a full-fledged audio VCA! I tried it, it works. Each VCO has 7 selectable waveforms available (everything from sine to pulse including some odd mixed waveforms). Each VCO can only output one waveform at a time. 

Cwejman VCO-2RM Dual Oscillator

So how does it sound? Well, compared to the vintage oscillators I have experience with (Moog, ARP, Octave, Roland etc.) it strikes me as being "on the spot" as opposed to "warm and organic". So, depending on what you are after it might indeed be a touch "too controllable". Obviously the components Cwejman uses for his modules are so well-selected and precise that there is hardly any room for tolerances or random fluctuations. For me the VCO-2RM really shines once you start modulating it. Feed it with CVs from various sources, amplitude-modulate these CVs with VCAs, sequence everything, well... you will see (and hear) that the VCO-2RM really begs to be modulated, and the sonic possibilities opening up are infinite. As you tweak the VCO-2RM's knobs even a tiny bit of change can make a huge difference in timbre. What I love about it is that it covers everything from classical subtractive to experimental sounds. And did I mention the VCO-2RM tracks like a champ? Tune both oscillators to a specific interval and play them across multiple octaves. Voila! Stays in tune.
For my demo video I used both VCOs and the ring modulator sequenced and modulated by Doepfer A-155 sequencer, A-145 LFO, A-143-9 VC Quadrature LFO, A-140 Envelope Generator, A-149-1 Quantized/Stored Random Voltages, A-133 Dual VC Polarizer and A-183-2 offset generator. The mixed output of the VCO-2RM runs through a STG Soundlabs Sea Devils filter and in part through a Synthrotek Echo. Enjoy!

Ladik Modules Review + Demo (Youtube Video): K-010 Utility CV Keyboard, K-011 Trigger to Keyboard and S-030 4Ch Clockworks4

Modular synthesis, especially the Eurorack format, has seen a great revival in the recent years. Frequently new companies enter the market trying to participate in the Eurorack gold rush. One of these relatively new outfits is Ladik (ladik.ladik.eu), a one-man company from the Czech Republic. I first learned about him while browsing for analog drum synths on eBay a while ago when he was offering his Synare 3 drum synth clone. Meanwhile Ladik has been busy developing literally dozens of Eurorack modules sporting everything from oscillators, modulators, filters, clock and MIDI utilities and many more useful CV processing tools. A very prolific developer indeed. 

Now since Ladik mentioned in his eBay auctions that he could make custom modules on request I got the idea to suggest creating a tool that would be damn useful but has been strangely absent in the Eurorack world:

A mini CV/Gate keyboard for the Eurorack. Sometimes I just want to play a little melody or transpose a sequence or program my old Roland CSQ-600 CV/Gate sequencer. A small 8HP module with one octave of keys and CV and gate outputs would be such a practical tool for that. Why hasn't anybody come up with this idea before? I approached Ladik with my idea early in 2015 and from then on had a very inspiring Email conversation with him. He agreed to develop the keyboard module and even came up with an idea for an extension module allowing to remote-control all keys of the CV keyboard. So yesterday, only 5 weeks after I voiced my idea, I received a package from the Czech Republic containing the Ladik K-010 CV Utility Keyboard, Ladik K-011 Trigger to Keyboard Extension and Ladik S-030 4ch Clockworks4 clock divider module. That was quick!

Ladik K-010 CV Keyboard

Let me give you a tour of the K-010 CV Keyboard module. We have one octave range of keys from C to C. When you press a key, the corresponding CV is output at the CV out jack. Additionally, a gate signal is present at the Gate Out jack as long as you press the key. When you release the key, the gate turns off but the CV is still present at the CV output. Each note key has its own LED which lights up fully when pressed. When the key is released the LED becomes half-lit. This way you can still tell which key was pressed last and likewise which CV you are still outputting. Very practical! A pair of octave up / down switches allows for a range of 5 octaves. The octave LEDs give you visual feedback about which octave you are in. LED off means: You are in the center octave. Octave up LED half lit means: One octave up. LED fully lit: Two octaves up. Same with octave down respectively. Now since I didn't want the octave switch to transpose my CV immediately upon button press, I requested a mode where the octave change becomes active only after you press the next key. So Ladik implemented this option for me and it works like a charm! You can even skip several octaves before pressing the next note key and it still works like it should. Nice! Alternatively you can have the octave buttons act immediately when you press them. Another mode is called "Octave Temp" and means that when pressing the octave key the transposition takes place immediately AND when releasing the octave key it instantly jumps back to the middle octave. In this mode however you only have 3 octaves at your disposal. 

Furthermore you can select high or low note priority which determines which key takes precedence if more than one key is pressed simultaneously.

There are 2 trimpots on the K-010 allowing you to set the V/oct scaling and offset of the module. It took me about 1 minute to calibrate my K-010 to my liking. Piece of cake!

Ladik S-030 4Ch Clockworks4, Ladik K-010 CV Keyboard and Ladik K-011 Trigger to Keyboard Eurorack modules

Now for the K-011 Trigger to Keyboard extension module. This is basically a remote control for all the buttons on the K-010, even the octave up / down keys! It is connected to the K-010 via two ribbon cables and draws its power from the K-010 as well. You can mount both modules in whatever order you like, the ribbon cables are long enough both ways. It accepts trigger or gate signals, activating the corresponding notes (CV and gate) on the K-010 CV Keyboard module as long as the trigger / gate input is high.

Now what do we get out of this combo? Well, first of all we have a freakin' mini CV keyboard in our Eurorack which is absolutely amazing! Second, we can use the K-011 extension to sequence the keyboard on "note level" via trigger signals, divided clocks, random gates or whatever you choose to throw at it. The results you are getting can be very musical and possibly ever-evolving and never repeating if you please. 
As you can see (and hear) in my demo video, you can get really creative and come up with very simple but charming little melodies. Possibilities are endless!

Ladik S-030 4Ch Clockworks4

The Ladik S-030 4Ch Clockworks4 is a 4 channel clock divider with adjustable division ratio and trigger length per channel. We have have two pairs of channels. Each pair is clocked by a common input. Both inputs are normalled so you only have to connect one clock signal if you want all 4 channels to receive the same clock. Alternatively you can feed both pairs of channels with individual clock signals. You can even feed the output of one channel to the input of another channel to receive even greater division ratios. Speaking of division ratios: Each channel has 2 knobs. The first knob selects the ratio you wish the incoming clock signal to be divided by. Available factors are 1 to 12. You can tweak the division knob on the fly, changing the division ratio as you go. This of course makes it tricky to "hit the spot" when trying to align your divided signal with the original signal the way you want. But on the upside this gives you complete freedom over where "in time" your divided trigger signal is. The second knob adjusts the length of the resulting trigger signal. That's very handy since you now have complete control over the "pulse widht" of the resulting trigger or gate signal. This is especially useful when you are working with ADSR envelope generators since these want a longer trigger in order to reach their sustain stage.

Now what if you set the channel's trigger length parameter to a length greater than the incoming clock intervals? Well, in that case all incoming triggers are skipped until the end of your channel's trigger has been reached. This way you can use the trigger length parameter as an additional clock divider if you like.

The S-030 Clockworks4 is an extremely useful, feature-packed tool that I am sure will be essential for my clocking duties in the future. Build quality is great by the way. Knobs are firm and smooth, jacks are firm enough and easy to operate. And I really like the design which is utilitarian but very pretty.

It is a strange thing that Ladik, given his wide range of over 60 (!!!) cleverly designed and useful modules, has not achieved more popularity. I hope that anyone interested in modular synthesis reads this review, watches this demo and goes about discovering the colorful world of Ladik Eurorack modules!

STG Soundlabs Sea Devils Filter Demo

Play MP3 clip: STG_Sea_Devils_Filter_Demo.mp3

During my last visit to Schneidersladen in Berlin I scored a very nice module from the bargain bin: An STG Soundlabs Sea Devils Filter. It is a three pole (18dB slope) diode ladder lowpass filter with signal input, ouput, 3 filter CV inputs (one with attenuator) and resonance CV. While testing this module at Schneiders I was really impressed by its character. It is both fat and vintage sounding as well as really precise in its response to external CV modulation. It reacts gorgeously to sequencer lines, envelopes and LFOs. It does however get quite growly with audio-rate filter CV modulation. Anyway, with low resonance you get a monolithic, huge sounding bottom end. Cranking up the resonance results in wonderfully "plucky" sounds, and as soon as resonance reaches self-oscillation you end up in creamy & bubbly acidic musical territory. This filter has so many sweet spots it's a real pleasure to use. Build quality is excellent. The knobs are large and sturdy and have a firm yet smooth action. I can say I am really happy I got this module.

STG Soundlabs Sea Devils Filter

For this demo I took my trusted MFB Kraftzwerg's 3 VCOs, tuned them two octaves apart and pitch-modulated them with MFB Megazwerg's 4-step CV sequencer. This sequence is getting some random transposition via Doepfer A-149-1. The 3 VCOs were then fed into the Sea Devils' input. To modulate the Sea Devils' filter cutoff frequency I used a mix of different CV sources: Electro Harmonix 8-Step Sequencer, Doepfer A-140 ADSR Envelope, Doepfer A-171-2 VC Slew Processor plus some manual tweaking. The Sea Devils' output was then fed through the MFB Megazwerg's delay. No other FX or EQ'ing was used.
In the beginning resonance ("response") is set to zero. I gradually turn up the resonance until the filter starts self oscillating at the end of the demo.

Modular EBM Drum Patch (Doepfer + MFB)

Play MP3 clip: Modular_EBM_(Doepfer_+_MFB).mp3

Recently I asked myself if you could use a A-149-1 Quantized/Stored Random Voltages module as a noise source for audio. Answer: Yes, you can! But wait, what do random voltages have to do with noise? Well, noise is nothing but random sonic events spread out over the audible range. The A-149-1 spits out random CVs in sync with an external clock that can be way up in the audio range. However, at a certain point when the clock signal gets too fast the A-149-1 stops operating. But still it is fast enough to create some nice lofi-ish digital noise timbres. I used the lower "stored random voltages" section since here the distribution of values is more wide-spread than in the upper half. So, what can you do with noise? Make a snare drum for example. I quickly came up with a snare drum patch sounding pretty much sick & destroyed, using only an MFB Megazwerg AHDSR Envelope and a Doepfer A-133 Dual VC Polarizer serving as VCA.

Doepfer A-149-1 + A-149-2

Now that we have a snare drum, why not make a bass drum as well? For this I used a Doepfer A-143-9 VC Quadrature LFO as a sine oscillator providing the body of the kick. To achieve the clicking attack sound I layered two envelopes modulating the snare drum's VCA: Doepfer A-171-2 VC Slew generator provides a decay while a Doepfer A-140 Envelope acts as a bread-and-butter ADSR. Now to add some more spice I utilized a Doepfer A-149-2 Digital Random Gate module to randomly open up the VCA in addition to the envelope. The A-149-2 is an expansion to the A-149-1 described above. It outputs random high and low voltage states synced to the upper half of the A-149-1. A great combo by the way! The result is a sine sub-bass that comes in randomly between the bass drum hits. I also added some random pitch changes to the sine wave via the Doepfer-A149-1's upper half which provides voltages that are quantized to semitones. Very handy.

MFB Drum-07 Hihat / Cymbal module

For hihats and cymbals I used the MFB Drum-07 module which is the modular version of the MFB-522's hihat and cymbal section with some slight changes plus CV-able parameters. It has been discontinued and I highly recommend you pick one up if you can find it as it makes some wonderful sounds. I treated the hihat with some Doepfer A-114 ring modulation and the cymbals with bandpass filtering using MFB Megazwerg's multimode filter. 

MFB Kraftzwerg

Chiming in later we have some delay via MFB Megazwerg with CVed delay time and random freezes. Last not least you'll hear a bassline coming out of good ol' MFB Kraftzwerg. Nothing like a rough EBM bassline going along with your modular drumset. Enjoy!

Doepfer A-110-2 Basic VCO Demo

Warning: This is a hardcore technical modular synth post! I recently got my hands on the first copy of a Doepfer A-110-2 Basic VCO Eurorack module that was ever sold worldwide. It showed up at Schneidersladen in Berlin and I was the lucky one, the first one!

Doepfer A-110-2 Basic VCO and friends

The A-110-2 is the follow-up to the A-110-1 which has been selling for many years now. The A-110-2's basic features: Three waveforms (saw, square and triangle), 3-way octave switch, exponential FM (with attenuator), linear FM (without attenuator), pulsewidth modulation (with attenuator), hard and soft sync. It is only 8 units wide which is really cool. I decided to make a demo showcasing the basic and raw oscillator sound as well as two more musical snippets demonstrating various features of the A-110-2. In all examples whenever all three waveforms are presented they appear with their original volume in relation to one another. Warning: The audio files are big! Format: 44.1kHz, 16 Bit mono.

Let's start with the basic waveforms. You are hearing saw, square (50% duty cycle) and triangle in a range of 7.5 octaves. For pitch I used a Doepfer A-145 LFO (triangle waveform) through a Doepfer A-156 quantizer, set to output only 5ths and octaves:

Doepfer_A-110-2_Waveforms_Saw_Square_Tri.wav

Now let's add some pulse width modulation to the square wave. PWM source is a slowly moving sine wave LFO:

Doepfer_A-110-2_PWM.wav

The A-110-2 has a nice feature: Linear FM. In this patch a Doepfer A-171-2 VC Slew Processor serves as the source for the modulation with a frequency modulated sawish triangle waveform. The result is not as dramatic as with Exp FM. Again saw, square and triangle:

Doepfer_A-110-2_LinFM_Saw_Square_Tri.wav

Now for exponential FM. Modulation source is the Doepfer A-171-2 with the same configuration as in the Linear FM patch above:

Doepfer_A-110-2_ExpFM_Saw_Square_Tri.wav

Let's take a look at hard sync. With each of the 3 waveforms (saw, square and triangle) you first hear the A-110-2 slaved to a steady-pitch master oscillator while being pitch-modulated by an EHX 8-step sequencer. After a few seconds I add some LFO modulation via the EXP FM input. You can hear the timbre of the slaved oscillator changing along with the LFO swings:

Doepfer_A-110-2_HardSync_Saw_Square_Tri.wav

Now it's soft sync. I must admit that I haven't managed to fully wrap my head around the theoretical implications of soft vs. hard sync. All I can say is that soft sync does not reset the waveform to 0 when the master oscillator finishes a cycle (unlike hard sync) so you won't get any such dramatic changes in timbre as in hard sync. Interestingly modulating the slaved oscillator's frequency does change the perceived pitch as well (again unlike hard sync). Same modulation as in the previous clip:

Doepfer_A-110-2_SoftSync_Saw_Square_Tri.wav

Now let's go "all in". I have put together two patches that are more musical than the above examples to showcase what the A-110-2 can do if you combine all those nifty features. What you hear in clip 1 is all three waveforms cycled through a Doepfer A-152 quad sequential switch (accounting for some clicking audio glitches here and there) with some random resetting. I have added PWM, Lin FM and Exp FM from various sources as well as hard sync. No filtering, just some amplitude modulation via MFB Megazwerg VCA (AHDSR modulated):

Doepfer_A-110-2_All_In_1.wav

The following patch circumvents the VCA completely. However, there is some amplitude modulation on the saw wave. Later in the clip I start tweaking some of the parameters. Again, no filtering:

Doepfer_A-110-2_All_In_2.wav

I hope I have managed to give you a good overview of the Doepfer A-110-2 basic sound and its most important features. Enjoy the demos!

Arp Axxe & Roland CSQ-600 (Youtube video)

Celebrating my freshly repaired Arp Axxe's resurrection, I hereby present to you this little demo jam. A Roland CSQ-600 sequencer is driving the Axxe with CV and gate information (a 32 note loop). Watch me manipulate the Axxe's controls as the sequencer is rolling on. Just a bit of Korg SDD-1000 delay and Roland RSP-550 chorus added to spice up things.

When I was first offered my Axxe a year ago, upon first inspection it was in a somewhat pitiful state. A good friend of mine offered to repair it so I decided to buy it from its former owner for a good price and have it fixed later. All good. However, following last year's move, my Axxe started having trouble staying in tune; its pitch would fluctuate by +- 30 cents, even after hours of operation. So I handed it over to my buddy Tobi Tubbutec who repaired it by replacing its power transformer with a new one so it can now return in full splendor.

I don't want to repeat any of the Axxe's well-known specs as you can find them all over the internet. It is true that being a stripped-down 1-osc synth the Axxe cannot hold up to its older brother Odyssey's grandeur feature-wise. However, it does have THAT powerful Arp sound due to its massive oscillator and filter. Speaking of filter, this Axxe has the Timothy Smith filter mod that fixes a design flaw in the original filter circuit preventing the filter to open up completely. With this mod the filter works as intended and has improved response. Anyway, playing the Axxe is pure joy. It's so simply laid out that you can't get lost even if you try. You can build a new sound within a minute. Admittedly I am not a huge fan of the Axxe's PPC pitchbender as I have to press really hard in order to bend a semitone but it sure gets the job done. Another one of Axxe's quirks is its strange Sample and Hold feature. When turned on, pitch drops to the lowest C on the keyboard when you release the last key. Strange. Summing up, the Axxe excels at basslines and leads and actually quite a lot in between (effects, sequencer lines, percussive sounds, noise sweeps etc.). Sure I can imagine eyeballing its bigger brother, the Odyssey, but for its price I think the Axxe is a great alternative if you want that big ballsy Arp Sound.

Arp Axxe

The Roland CSQ-600 is a fun sequencer. It hails from the early 80s and has a strikingly familiar design. Sure enough it's from the same era as the TR-808 and has probably even been designed by the same person. For today's standards its 600 notes memory does not sound like much but I bet in 1980 it was a huge thing. And huge the CSQ-600 is, by all means (physically, I mean). It has great build quality, its buttons are a joy to push and it is ridiculously easy to operate, making sequencing other analog synthesizers a real breeze.

Roland CSQ-600

Sit back and enjoy this demo featuring two great vintage pieces of studio equipment and keep in mind: Never underestimate the Arp Axxe!

Korg Mono/Poly vs. EHX 8-Step Sequencer & Doepfer Modular Skiff (Youtube video)

Today I wanted to try out how I could spice up a simple 3-note arpeggio on my Korg Mono/Poly by sending some CV modulation to its filter CV input. So what you are hearing here is the Mono/Poly with its lowpass filter cutoff frequency being externally modulated by a small modular rig. I just added some delay and reverb from the Korg SDD-1000 and Dynacord DRP-20.

Running on its internal arpeggiator the Mono/Poly sends out a gate signal for every note. I took this gate signal and used it as a clock source to synchronize an Electro Harmonix 8-Step Program analog sequencer and a Pittsburgh Modular Cell 48 case with 5 Doepfer Eurorack modules.

Korg Mono/Poly

Electro Harmonix 8-Step Program Sequencer

Doepfer A-143-9, A-151, A-138m, A-133 and A-140

My latest modular acquisition is the Doepfer A-138m 4x4 matrix mixer. It really doesn't look flashy at all nor does it have a fancy name. But looks can be deceiving. This IS a highly versatile and mighty tool. What does it do? Well, the principle is simple: It has 4 inputs and 4 outputs. You can route any input (arranged in horizontal rows) to any output (arranged in vertical columns) with whatever level you like. One really useful feature is that you can set each output column to "bipolar mode", meaning you can turn each level knob to the center position for no signal or clockwise for positive and counter-clockwise for negative (inverted) signal. That's a great thing for CV signals, but you can also use it for audio signals for example in order to change the characteristics of a filter or for M/S processing of a stereo audio signal.

So here you can see (and hear) the A-138m in action. The A-143-9 VC Quadrature LFO is providing the Mono/Poly's filter with some nice audio-rate FM while the A-140 ADSR Envelope Generator modulates the amount of LFO signal going through the A-133 Dual VC Polarizer. You can clearly spot the effect of the ADSR in the youtube clip as it creates those "a-u" and "u-a" vowel sounds. The A-151 Sequential Switch is a real funky tool, too. It can be used to cycle through 4 independent signals by routing 4 inputs to 1 output or 1 input to 4 outputs at a time, making for some very interesting rhythmical modulations. You can use it both on CV and audio signals. Hey, you can even build a sequencer with it but I will go into this another time.
This skiff really is a fun little toolbox with lots of functionality in such a small space. Enjoy the demo!