Percall

Percall is a percussive oriented module that will shape four different sound sources into percussive sounds. Percall has four VCAs with dedicated decay envelopes and a mixer so that you can prepare a percussion submix.  (Source : befaco.org)

Freshly finished

As soon as Befaco introduced this module about 2 years ago, I wanted to have one.

However, at the time, available space in the suitcase and other priorities forced me to hold off.

Using my need for a new VCO and my choice of the Pony VCO, I upped my order to Befaco with a Percall kit.



This kit is qualified as "high grade", the maximum difficulty level at Befaco. And this is not misleading.  It is indeed the densest kit I have ever assembled.

Under construction

The two PCBs come grappled together.  This is unprecedented for me, and actually quite practical.
The instructions are basic and very clear. 

The PCB is dense. You have to be extra careful with the labelling, since some of the designations can be confusing if you are not paying attention. As usual, I proceeded methodically and slowly, in small sessions, highlighting the parts on the instructions as they were placed.

There were no particular issues with the soldering of the components.
 

Bob cuts components leads

 

Assembling the front panel was not as challenging as I expected.  I followed the instructions not to solder the parts before assembly, so that I could fit them precisely.  Small problem: I ended up with too few a black nut to fix the jacks.  Either I lost it or it was not in the kit.
It doesn't matter.  I used a plain old nut that was lying around in a drawer.
Did you notice it in the first picture?  I don't think so.

No empty space. The whole volume between the PCBs and the front panel seems to be occupied.

 

The boards before assembly

The edge

Here it is, mounted in the rack with its little friends. It gives me a nice envelope generation and manipulation section.

In the rack

 

Avalanche

I bought this module kit from Mammouth Boutique before the shop closed. So it's been a while.

I finally put some time into it at the end of 2022 to start building it.

Finished Avalanche

 

The kit

Avalanche is a rather imposing module with 42 HP (21 cm long). It consists of 8 oscillators with a filter, an envelope generator, an internal clock, a sample&hold and an effect processor.  The latter is based on an FV-1 SMD chip and is pre-soldered onto the board.

It's semi-modular, so you don't need any cable to produce a sound. But you can take advantage of the random generator or the envelope to play with the pitch or the cut-off frequency of the filter.

The kit is flawless like the previous ones from Mammouth Boutique.
There is a single PCB with the electronics on one side and the numerous controls on the other. The black front panel is very classy although a little cryptic.

Since I assembled it after closing the shop and the website, I had no way to download the assembly manual.  I had recourse to the designer who kindly answered me. Considering the complexity of the kit, I couldn't see myself starting the assembly without the electrical diagram in case of a problem. The future will show that I did the right thing.

The construction is done without any particular problem.  
As usual, slowly, methodically, in small sessions. The parts are well distributed in the various bags.  The sorting of resistors, capacitors and transistors required a little attention because of the quantity, but nothing too important.

Fortunately I had the manual. Details like cutting a tab off the 2N4401 or the direction of the switches would have gone over my head. The exact nomenclature of the capacitors was also welcome.

A side

B side

My synth suitcase is almost empty.  It is now used to store the modules that no longer fit in the Mantis. It will do the job well.
At the first power up, the oscillator LEDs light up correctly.  But no sound comes out. From the demo video, I knew that the clock should work.  But it doesn't.  

Crude 5V converter

A glance at the electrical diagram shows me that the audio output is connected directly from the FV-1 circuit, powered by 3.3V from the 5V power supply of the rack ... not present in my synth case: the small Doepfer power supply module bought at the time only outputs -12V and +12V.
So I decided to make the easiest and least efficient voltage converter possible.  With the components I had in my drawers and a piece of board, I made a circuit based on the LM7805 voltage regulator.  Super inefficient: more than half of the power will be transformed into heat; but ready in less than 30 minutes. Given the low power requirement, I doubt it will heat up enough.  The radiator is only there for the principle and the decoration. If you are looking for a serious solution, I suggest this innovative solution from Klavis: NoDrain.

Once this is in place at the bottom of the case, the module lights up cleanly and works the first time.  Happy.

Alive

Jay F. · Test Avalanche

New Year. New Challenge.

Ornament and Crime is one of the Eurorack modules constantly recommended in modular synthesizers forums, along with Math from Make Noise, Batumi from Xaoc or Clouds from Mutable Instruments.

If we add that it is basically an Open Source project, that it exists mainly as a kit and that there are several variations of the firmware, it goes without saying that I needed one. 

Front side

I decided on the Plum Audio version, a kit available from the Thonk online shop.   This improved version has input control in the form of attenuverters with LEDs, output voltage adjustment and a front panel USB connector.  

Let's avoid the financially painful episode of a post-Brexit purchase from a UK site and let's get to the point.
 

The kit

Ornament and Crime is a polymorphic control voltage generator.  It has four modulation inputs, four trigger inputs, four outputs and a micro-controller to handle them all.  

Bob cheks solder quality

The micro-controller is a standard Teensy 3.2, with an ARM Cortex M4 on board.  It comes pre-loaded with the official firmware.  
Depending on the firmware application, the module can act as an analogue shift register, sequencer, arpeggiator, envelope generator, quantizer and so on.  Hemisphere, one of the alternative firmwares, even offers to choose 2 modes simultaneously from a choice of about 60.

It was the four independent envelope generation function that made me decide that the module was useful for my usage, but I will experiment with the other modes of course.

 

micro USB parts.
Bob for scale

In the article about the Befaco Rampage, I wrote that the kit was not for the faint of heart.  However, this version of Ornament and Crime is two divisions above.  Not only is the density high, but there are some tough parts, such as the OLED screen, the micro-USB connector and the "pogo" pins (aka spring-loaded pins) under the micro-controller board.
 

 

 

 

 

Bob cleans up

The kit is very well thought out.  The two PCBs are well designed and very clear with the part number and value of each component clearly indicated.  The bags are organised according to the progress of the kit. The contents of each bag are listed on the label. The documentation is accessible via a QR code on the box.  It is minimalist and refers extensively to explanatory videos, which are very practical, but sometimes a little fast.

Despite the density and number of components, the assembly went smoothly given the quality of the kit.  As usual, I did many small sessions, methodically, calmly.  It was demanding but in the end I didn't have to correct anything.

 

Back side

The only anecdote worth mentioning is that the documentation asks to pay particular attention to the orientation of the bicolour red/green LEDs and indicates that some kits have been delivered with reversed LEDs (red instead of green and vice versa).  I did a quick check with other LEDs I have and concluded that this be the case.  I decided to solder only one of the 8 diodes legs before a final check.  Once the front panel was assembled, the test clearly showed that my diodes were the right kind and therefore assembled backwards.  Unsoldering everything, turning the LEDs over, re-soldering...
If I had been really smart, I would have tested with *one* diode *before* placing the front panel. 
 

User Interface board.
LEDs are reversed.

Once assembled, the module still needs to be calibrated.  The firmware guides all along the way but it is quite tedious to measure the 50 or so calibration points.  It took me almost an hour, including the time when I had to remember how to use the measurement ranges on my multimeter.  Fortunately, this is a one time thing.

Now I just have to get used to the beast.  We are far from the "one function per button" philosophy of analogue modules. Since this is a geeky project, parameter pages abound in each firmware application. 

Module is alive. 
Testing various options of the envelope generation.
The screen refresh is visible in the picture.

 

New filter

Now that I got rid of my DIY-101 based on Doepfer DIY, I'm back to a one filter configuration.   And that filter, Ripples, does not have a high pass output.  I was in need of a new multimode voltage controlled filter and I chose Erica Synth Multimode VCF kit.

Multimode VCF

This is another straightforward kit.  It is rather dense, despite being comprised of two boards.  The kit comes with three bags of parts : one for each board then there is the traditional potentiometers and jacks.

The kit

Sorting parts

Bob cuts resistors legs

The documentation (online, once again) is heavily illustrated and pretty complete with schematics and placement files.  No step by step instructions though.   Just photos of boards at various steps.

Boards are dense but perfectly labeled.  I noticed a single mistake : boards label called for 51k resistors and I received 56k (or was it the other way around ?).  I reckon a 10% difference is no problem.

This went like a breeze.

Main board, chilling on the bench

Odd capacitor placement

One oddity though is the fact that the boards are so heavily packed, they felt the need to solder the electrolytic capacitors upside down on the control board.  Two of which have to be bended parallel to the PCB because the main board will be above them. I put some insulation tape between the board and the capacitors despite the fact there is no indication to do so.  Better safe than sorry.

These capacitors have to be soldered the last according to the manual.  But I would rather put them after the standard parts and before the jacks and pots : once they are put in place, it is quite full.



Anyway, here it is, mounted in the synth.  That first row is now nearly set.

One thing I found a bit odd with this module is the placement of the potentiometer.  I would have put the c-off cv and reso cv close to the corresponding jacks, same with the audio level.  So I would have preferred an inversion of the two rows of potentiometer.  I would have found it more logical.

VCF in place

I do not have any 2 HP blank.  A clear oversight from my side.  I now have that small 1cm gap between the Mammouth VCO and the Erica Synth VCF.  It is supposed to be filled later with a 2 HP multiple.

So, here is a small piece of sound from the synth as it is.





Two tracks recorded live from the modular. Each track is sequenced by one channel of the Korg SQ-1.

DAW : Reaper

Usual effects : TAL Dub II, NI Supercharger, Voxengo OldSkoolVerb, Thomas Mundt LoudMax.

Bass voice : saw and square from Doepfer VCO to Erica Synth VCF Low Pass directly to VCA. Modulated by envelope from Befaco Rampage. Very standard.

Drum voice : mix of two parts.

1. Ripples pinged by Rampage, modulated by second envelope of Rampage and sequencer.

2. Rings, same trigger, same sequence.

Mammouth VCO

Here is my second module from Mammouth Machine : a VCO (Voltage Controlled Oscillator) to take the place of the oscillator of the DIY Doepfer based module that I plan to relegate in a box.  Having two oscillators will allow either to enlarge the sound palette (via mixing or FM), or to have two separate synthesis voices.

Finished Module

Not much more to add than for the ADSR assembly from the same producer.  Same workmanship, same (splendid) wooden, laser-cut face.  I applied the same 2 coats of transparent matte varnish.
Small detail: this kit included the flat cable to connect the module to the bus board.  Curiously, this was not the case for the ADSR.

On the bench

I did have two little problems, though.

Ongoing calibration.

First was with the kit: I received two electrolytic capacitors of 4.7uF instead of 47uF.   With another type of module, I would have smiled and soldered the 4.7uF capacitors, but a VCO needs all the power supply stability it can get.  Maybe 4.7uF is enough.  Nevertheless, I decided to replace these capacitors with the closest value I had in stock.  No 47uF in the drawer, the 100uF are too big.  Remain two 22uF capacitors which fit like a glove.

Then, a small omission in the manual: I couldn't find out how to use the tuning trimpot to calibrate the module, when it's obviously the V/oct scale adjustment, which is critical and not that easy to adjust.
Luckily I had a little help from Bob to do the calibration.

First rows.

And now, as promised, a little bit of sound :



There are two synth voices in this track.
For the first one, the two, slightly detuned, square waves from the VCO are mixed, then sent to Ripples, whose frequency is modulated by the ADSR output.
For the second voice, the sine of the Doepfer oscillator is directed to Rings, then the phaser.
The whole is mixed in the output module.

Rampage generates the two main envelopes. One triggers the other and vice-versa.  The random outputs of the Sample&Hold and the Turing Machine are used to control the rise and fall times as well as the Rings parameters.
Notes are randomly drawn by the Turing Machine and calibrated by the 2hp Tune module.

DAW: Reaper
Usual Suspects : TAL Reverb II, TAL Chorus-60

Mammouth ADSR

ADSR module

I finally decided to replace the Doepfer DIY-based module with separate elements. First, because the quality of the electronics is not up to my (modest) expectations: the oscillator is quite poor and keeps detuning, the VCA does not close completely and is influenced by the LFO, the envelope generator is not very reactive. I'll regret the filter though. Separate elements in kit will also save me some space: my realizations are not very dense.

Since I'm lucky enough to have a local producer, I went to Mammouth Boutique, in our good old town of Liège.

This ADSR module is the first module from Mammouth Machine I built.

Kit is of quality : bulk components in bags, super clear PCB indications, online manual but very well done.  Only caveat for english speaking people : manuals are in french.

The kit

Bob helps to fix the switch

The components are loose in the bags and are not identified other than by their marking, whereas other suppliers offer specific labeling.
But there is nothing wrong with that.  The information on the PCB and in the manual is very clear. A small cheat sheet comes in the kit with resistor values color coding and capacitor indications. With a little care, everything goes well. Nevertheless, I tested every resistance with an ohmmeter, but that's what my perfectionist side is all about.




The face is made of wood, laser cut. The wood is untreated, I decided to delicately apply two thin coats of transparent matte varnish to ensure a certain durability over time.

Ongoing

No particular remark on this kit, everything went perfectly.

[edit Feb 29, 2020] After my first tests, I noticed a residual voltage (about 60mV) after the end of the envelope.  This leaves a VCA a bit open and I could hear a faint noise.  It does not look to be problematic in real conditions though.

Rampage

The second kit from Befaco I built is the Rampage.

And it is not for the faint of heart.

Befaco Rampage

The kit is good quality (as was the A*B+C).  However, with 227 parts (about 560 pins to solder), 3 connectors and around 40 jacks, pots and various switches, I wouldn't quality it as easy.

Rampage kit

I chose this module as an alternative to Make Noise's Math, one of the most recommended module in forums.  With some exceptions, Rampage fills the same roles.  Moreover, it is available as a kit which fulfills my desire to build my synth as much as I can.

Main board close-up

According to Befaco website :
"The module is built around two voltage controlled integrators. Integrators (also known as Lag Processors or Slew limiters) allow you to process your voltages, converting sharp square waves in ramp-like waveforms.
These lovely devices can, for instance, convert a gate signal into a simple envelope, or achieve a “portamento” or “glide” effect when applied to pitch CV."

A properly patched Rampage can assume more than 20 different functions : envelope generator, oscillator, comparator, polyrythmic gate generator, trigger delay, etc…

Before mechanical assembly

Assembly instructions are similar to the previous kit : same advantages, same drawbacks.

With a kit of that size and density, you have to be systematic in order to make sure to be "good first time".  Debugging such a circuit afterwards was not in my intentions.

Calibration of the triangle shape

 
I estimated that the two Schottky diodes of the kit were too large for the PCB footprint and I replaced them by some in my stock.

I also found an oddity in the presence of a solder joint below one of the potentiometer.  I reckon there should be enough room between the back of the pot and the joint when the pot is tightly attached to the panel, but I decided to mask it anyway with some insulation tape.

Better safe than sorry.

Still, I implemented the mod presented in this Muff Wiggler thread to ensure reliable gates by soldering 1M pull-downs resistors at the outputs.

Additional pull-down resistors

Finally, a photograph of the Befaco boys in action and a bit of sound.

Befaco boys in action

Here above, Rampage channel A is programmed as an LFO which frequency is determined by the output of the S&H and cadences the patch.  Channel B is the envelope triggered by channel A and whose attack is also determined by the ouput of the S&H.
A*B+C plays the role of the VCA.   The sound source is the pink noise from the S&H module.
The sound is coming out via Rings (whose parameters are, ... guess what ? ... controlled by the output of the S&H) and the phaser.
Additional effects : NI Supercharger, TAL Reverb II & LoudMax

A * B + C

To complete my synth, I recently bought 2 DIY kits from Befaco.

The first one is called A*B+C.

Finished module

The kit is  good quality and rather simple.

Before soldering

The A*B+C is a dual, four-quadrant multiplier with VC Offset.

It can perform different operations on its inputs :
- amplifier and inverter of A input.
- VCA on A, with envelope CV on B.
- VC offset generation with C input.
- attenuation/inversion of C input
- ring modulation of audio signals in A and B.

Moreover, the output of the the first channel is normaled to the mixer of the second channel.  So the module can serve as CV/audio mixer.

Before assembly

Assembly instructions are good but could have been clearer, especially for the final assembly.
A couple of photos wouldn't have been too much.  But I didn't encounter any major issue.

My only gripe was about some parts that had a larger size than their footprint on the PCB.  I had to replace the two Schottky diodes with those I had in stock and solder 2 couples of resistors vertically. One resistor even had to be soldered on the other side of the board.

Once again, nothing major in my view.

Profile view.  You can see the vertically mounted resistors

Finally, the module suffers from a high level of background noise as indicated in this Muff Wiggler forum thread.   Anyway, it does not seem prohibitive.   There is a suggested mod but it looks like it modifies the potentiometers behaviour, so I didn't want to perform it (and I didn't have the necessary 1/8 W resistors).   Time will tell.