Seven Years

This blog is now more than 7 years old. The case is complete.  It’s time to look where we stand and have a bit of retrospective.

It’s been three years now since I bought the Tiptop Mantis case to host my modular synthesizer.  A fine decision.  It is a nice case with a good power supply with plenty of room.

Here is the current situation with what’s what.

 

This post is the 54th. The blog has now close to 78000 views. 

 

Along those years, Bob was always there to help me with the Do-It-Yourself aspects. Thanks Bob.

 

 

 

 

 

 

Some highlights of the last years :

- Beads, a granular texture synthesizer, Emilie’s Last stand : April 2021

 

 

 

 

- Tiptop Mantis, a better case for the synth : October 2021
 

 

 

 

- Ornament + Crime, the multi-purpose module : January 2022

 

 

 

 

- Beatstep Pro, the versatile sequencer : April 2024

You’ll find other highlights of this journey in the blog's 3 years retrospective.

The soundcloud playlist was growing as well. Mostly as illustrations of the function of a module for the blog, but not only :
- 14 sound examples of the module at hand;
- 12 sound illustrations of the state of the synthesizer;
- 2 participations to the monthly KVR Music Cafe;
- 1 participation to Audiofanzine Inspired Composition (Compos Inspirées).

 

 

Jay F. · Modular Suitcase

Before/After

I thought it would be a good idea to compare the new case with the old one. So here it is.

Before :

After :

 

More space, better power supply, better ergonomics overall.

Tiptop Mantis

Close up of the new case

My synth suitcase is very cool.  I enjoyed setting up the inside of the case, spending hours building modules and experimenting on my first patches.  

Final shot of the synth suitcase

But, with the last modules I bought (some of them still to be revealed), it became too small. Also, I reckon the power supply is at its limits.  I find that it starts to heat up too much during long sessions.  Finally, the fact that I don't have a removable lid makes it a bit uncomfortable to use.  Although I have used it a few times as a stand for the sequencer or an additional Volca, it's not very convenient to have the lid in the way.

So I decided to buy another modular synthesizer case.
The Mantis from Tiptop Audio is elegant, widely recommended, of a manageable size and not too expensive.

Assembly, following my Modular Grid plan on my phone

Bob pulls the module

Internally, there is a comfortable power supply (more than twice the power of my previous power supply) with shrouded connectors.  
Some of these connectors are mounted horizontally, freeing up space at the bottom of the case (61mm deep at most).

Not enough space

Despite this, there is not enough space for my deepest modules: in the top part modules cannot be deeper than 50 mm. My sample&hold can hardly fit in there because what is sticking out can slip behind the bus board.

 

Also, the feet take up some space, which drastically limits the depth of the modules on the left and right of the bottom row. 

I had to revise my plans by inverting the two rows in relation to the synth-valise. For the better I think.  Anyway, no other choice.

 

 

 

I thought I was indifferent to having threaded rails or sliding nuts. Or even that I liked the fact that I could quickly reposition modules with the sliding nuts. I was wrong.  The threaded rails are much more practical.  The assembly went smoothly.  I just had to plan to run two power cables from the bottom modules to the second row, as there is only room for 12 horizontal connectors and there will be 13 modules in the first row.

Bob plugs the cables

Finally, being able to position the box at 45° is a real space saver and is ergonomically pleasing.  On the other hand, at 90°, I am not confident enough in the two plastic legs.

The cable of the external power adapter is too short. The 230V power cord can be changed easily.  But the connection to the box could be 2x longer.  If you want to have the box vertical, the power supply hangs down and it's a shame.

Oscillators, filters, resonator

No sound example today.   But a quiz: a new module has slipped into the set, can you spot it?
The answer will be the subject of the next article.

Three years

Three years ago, when I started this blog, I wanted to share my experience of making a modular synthesizer. First in English only, the blog contained electrical schematics and technical explanations. A few months later, I decided to create a French version to share this journey in the world of modular synthesizers with more people around me. The French version contains less schematics and more sonic illustrations. The articles are pretty much the same, but the two blogs are not 100% identical.



This is the 36th article on this blog. I kept on with my goal to publish one article per month on average. Some months were more prolific than others though.
The blog has now more than 19000 views and 10 comments. 21% of the audience comes from the USA.  The most popular article is the one on the Output module with 1200 views.


Since August 2018, Bob, a little Lego figure, accompanies me on every article about building something.  Initially relegated to cleaning tasks, Bob was able to show some skills in drilling or module tuning.  His small size makes him a valuable partner for delicate work.
 

There were so many evolutions between the first family photo in September 2017 where my first modules are finally assembled in a 3U Eurorack synthesizer row beginning and now with almost two finished rows of 84HP.  The synth includes, from top to bottom from left to right, One ADSR envelope generator, one CV quantizer, two oscillators, two filters, four VCA, one phaser effect, one output module, one sample & hold with noise generator, one slew limiter, two attenuators, a mixer, a voltage reference, a double multiple, one chaotic modulation generator, a signal multiplier with CV offset, a double modulation generator, one random generator and a resonator.


First family photograph, September 2017 :

And nearly 3 years after....

Some of the big steps are detailed here below :

- my first module (August 2017 - built on November 2016) : you have to start somewhere

















- the case (February 2018) : modules have a home now









- first kits (May 2018) : I now have nice modulation sources

- repairing my VCO (July 2018) : I finally have a tuned sound source












- Doepfer DIY (September 2018) : comes with my first filter









- Replacing the Doepfer DIY with separated elements (early 2020) : new ADSR, new VCO, new filter.








I learned a lot on this journey into the world of do-it-yourself synthesizers.
First of all, I improved my brazing technique.  I can now make denser builds than before.
I've learned how to design module panels.  I also tested and approved new suppliers, such as Thonk.
But more importantly I learned how to use the synthesizer, how to use it to create generative music, how to create different types of sounds.

I used the synthesizer to make 21 tracks.  Mostly as illustrations of the function of a module for the blog, but not only :
- 11 sound examples of the module at hand;
- 7 sound illustrations of the state of the synthesizer;
- 2 participations to the monthly KVR Music Cafe;
- 1 participation to Audiofanzine Inspired Composition (Compos Inspirées).

Jay F. · Modular Suitcase

And here is the track of the day :

Jay F. · Comet Dust

All sound from the modular synthesizer.  Too many tracks to detail them all. 
Most tracks were performed in a very traditional way for me : first writing and recording a MIDI track, then programming the synth sound and recording the audio using the Korg SQ-1 sequencer as a MIDI to CV converter.  Exceptions : drums were made using the SQ-1 as the sequencer and percussion were generated by the Turing Machine.
DAW : Reaper

Inside the machine

Here is the current state of my suitcase modular synthesizer.

With only 2 rows of 84 HP (plus a couple of modules on the side), it does not look very impressive.  Anyway, with two oscillators, two filters, four VCA and the bottom row full of CV modulators, it can still be put into good use.

Here is my first take on what is called a Krell patch.  You'll find the patch detail below.

It is a single mono track, directly recorded into Reaper with some delay and reverb to give a bit more volume.  It's an assembly of two parts of a longer session.

It is self generated.  There is no sequencer, just a bit of manual parameter change here and there.

The sound is reminiscent of the soundtrack from Forbidden Planet.  The Krell are the extinct race of advanced beings of the planet Altair IV.  Hence the name of that style of auto-generated music.




There a two voices.

First a drone voice : saw wave from Mammouth VCO into Ripples, modulated by Rampage envelope and the output of the sample and hold.
Second : square, triangle and sine from Doepfer VCO mixed into Erica Synth VCF; Band Pass output goes the VCA, then Rings; resonance and cut-off frequency of the filter are modulated by a mix of the two Rampage envelope.
Both oscillators receive pitch CV from 2hp tune fed with the output of the Turing Machine.

The two envelope of Rampage are in cycling (i.e. LFO) mode.  First is relatively fast, the second reasonably slow.  The End of Cycle of the first gives the pulse of the system and the clock to the Turing Machine.
The apparent random behavior is provided by the modulation of the Rampage parameters : fall CV of first envelope is the second envelope and rise CV of the second envelope is the noise output of the Turing Machine.

Here is my first approach to document that specific patch.

Doepfer on Acid

Close-up

So now that I decided to relegate my DIY-101 module based on Doepfer DIY in a box, it is time to say farewell.  I previously wrote that I will certainly regret the filter.  This is why.

The following track is entirely based on the Doepfer DIY filter.  There is no other filter involved.  All sounds are produced by the modular, except the drum part (909 samples) and an overdub on the pads (Korg Polysix emulation).
The base of the track is made of a single PWM output from the Doepfer A-110-1 VCO, into the Doepfer DIY filter.  Each of the filter output (LP, BP, HP) is treated in a different path and recorder separately.
Low pass takes the role of the bass, band pass gives some overtone and high pass gives the high pitch percussions.

The modular synth suitcase as featured in this track

The Korg SQ-1 sequences the lot.  There is a single sequence in two modes : zip of 16 steps on intro, and bridge, 2 lines of 8 steps (one for low pass, one for high pass) for the verses and outro.  High pitched percussions are driven by the Turing Machine, hence their random aspect.  Filter frequency is driven by two envelopes and manipulated by hand as well.

Wind effects are pink noise from the Random module to Doepfer DIY filter, mixing HP and LP before going to the VCA.

Lead synth is a mix of saw and square wave from Doepfer A110-1 VCO through Doepfer DIY filter.  Portamento courtesy of Befaco Rampage.

Pads are a mix of the modular and the addition of pads from Polysix emulation from Korg Legacy Collection, with heavy use of chorus.

Drums : 909 samples in NI Kontakt 5

DAW: Reaper

Effects : TAL Dub II, TAL Chorus-60, TAL Tube, TAL Reverb II, NI SuperCharger, Thomas Mundt LoudMax

Synth in action

Turing Machine

The latest kit I built is the Music Thing Modular Turing Machine mkII. 

Turing Machine chilling on desk

Even if the boards are quite crowded, this is an easy build, thanks to the excellent documentation that comes with it.  The online build manual from Thonk is very well organized (smallest parts to tallest) and massively illustrated.  The fact that both value and component references are printed on the board is a real bonus.

Resistors first

Nothing special to tell, apart from the fact I soldered a 51k resistor instead of a 5.1k.  I simply misread and didn't double check.  Nothing serious : desoldering the wrong one, soldering the good one.

I used the documented trick to put some masking tape to align the diodes to the facade.  My diodes were well aligned but this left some greasy mark on the beautiful  facade.

Make sure your masking tape is not too old and will not leave marks by testing on the back side !

Finished boards

What is a Turing Machine ?

Bob calibrates the module

It is a pseudo random looping sequencer made from logic chips.  It is based around a shift register circuit.

You cannot program it or save sequences.  It produces clocked randomly changing control voltages.

The big knob controls how much randomness you put into it.  At noon, you're supposed to have a fully random sequence.  The more you go left or right, the more the loop is locked and stable, according to the length control.

Being fully made from logic chips with no software, the module can be clocked at audio rates to creates random wavetables as well.

Ready to assemble !

A word about the name by the designer, Tom Whitwell : "The Turing Machine is not a real Turing Machine the way Alan Turing explained it. The name is vaguely relevant because the module uses a loop of data being changed, but computer scientists find it very annoying. "

In the rack

Finally, here is a sonic example of a piece composed of 4 random tracks where the pulse output of the Turing Machine triggers an envelope and the output is passed through a quantizer to produce exact notes.  I added some pads and drums from software synths and voilà :

Tune by 2hp

Tune, unboxed

I needed a 2 HP module to fill the case.
And I wanted a pitch quantizer to experiment with randomly generated melodies.
So I ended up with Tune from 2hp.

2hp is a company that makes module 1 cm wide (or 2 HP).  They have quite an impressive range.
I reckon that a synth exclusively made of 2 HP modules would be a nightmare to operate as the controls are small and would be too close to one another. But I guess it's OK to have one or two in your rack.

What does it do ?
According to 2hp : "Tune is a multi-scale pitch quantizer. It features 11 scales ranging from chromatic to octatonic with everything in between. In addition, the bias control allows the user to transpose the melody to a different octave or starting note."

Bob screws it in place

Pitch Control Voltage (CV) is, in Eurorack standard, one octave per volt.  Add one volt in control voltage and double the frequency of the note.    There is no reference to a specific note (like 0V = C).  The CV gives you an interval : about 83 mV per semi-tone.
Reference or starting note is given when adjusting the tune knob of the VCO when no CV is entered.

So you enter a voltage in Tune and Tune gives you back the closest multiple of 83 mV aligned with the scale of your choosing.  Ain't that cool ?

In action

A touch of sound to finish.



Rampage is giving the tempo of the piece.  The end of cycle signal of each section is used as trigger for the other one : when one envelope ends, the other is triggered to start.  The rise time of the second envelope is controlled by the random generator, hence the variations in time and in the sound.
This patch uses the three available envelopes : two from the rampage and one from the DIY-101.  The two synth sounds are modulated by these envelopes thanks to Veils.
Rings generates the percussive sound in sync with the start of the first rampage envelope.  Variations of the structure parameter are given by the random generator.
All sound generators uses pitch CV coming from Tune.  The input of Tune also comes from the random generator.
Finally, I added a bit of chorus as well as tons of delay and reverb in the final mix.

You can never have enough VCAs !

According to the popular motto : "You can never have enough VCAs !" 
So I bought four of them in a single module from Mutable Instruments.

Veils, unboxed

VCAs are Voltage Controlled Amplifiers and are essentials to shape the amplitude of sounds and other signals.

Not much to add here other than this excerpt from the MI website :
"Veils provides four VCAs with an adjustable response curve.
Veils’ outputs are daisy-chained, allowing adjacent groups of 2, 3, or all 4 channels to be mixed together."


As its becoming crowded inside the synth case, Bob went down and gave me a hand to plug the module on the bus board.

More to come....

Veils, installed

DIY-101 synth voice - part 2

This is the second part of the making of my Doepfer DIY synth based module.  You can find the first part here.

Finished module in action.

Now is the time for some cabling.

There are 7 connectors on the circuit, numbered JP1 to JP7.  Moreover, I have to connect the 5V and common ground.
With the synth, I  ordered the set of dedicated flat cables to ease the interconnection.

I started with Ground, 5V and all connections that were not linked to a specific connector.

Before cabling connectors.

Pin 1 above

Then I did cable connector after connector, cutting the wires, splitting the flat cable, stripping with my nails and finally soldering … One wire at a time, in order not to lose track. 
I started with JP2 and JP3, as I reckoned they connected mostly to pots and jacks below the circuit and that would prove difficult if I finish with them.
All ground pins on those connectors were ignored as I chose to have a common ground from the 5V power connector.

Pin 1 below

Thanks to the schematics from M-19, I noticed the dot indicating the first signal (red line) on the connector was sometimes above or below in the Doepfer documentation tables.   I fell in the trap on my first schema.

Ongoing cabling

I also verified twice each wire connection before soldering.  And I did well. I noticed a couple of mistakes on my schematics this way.  I annotated my drawings along the way.

 

 

Annotated schematics

Bob checks a solder joint

 Bob managed to get some useful Quality Control time. 

My first tests showed I made some minor mistakes :
- switches pins are reversed with regards to the switch handle position;
- a couple of signals were wrongfully soldered on the switch pin of the jack, instead of the tip;
- I detected one or two bad solder joints that escaped Bob's control.





Here is the finished product.

Finished

Bob fixes knobs.

Finally, I let Bob place the knobs.









Tuning the VCO proved problematic.  Even after I let the board heat up for 20 minutes, I really had a hard time approaching the 1V/oct slope.
I'm not 100% sure yet, but the VCO is not very stable and slowly drifts, even with the tempco option installed.  Is the circuit defective ?  Is the design problematic ?  Was it damaged during my early tests with a home made power supply ?  I don't know.  The rest works like a charm.

Tuning the beast

Finally, all the Eurorack power flat cables I got for my DIY modules were 16-pin to 16-pin.  And JP1 is aligned in a way it is not possible to use a 16-pin connector properly.

I had to divert the 10-pin to 16-pin cable from Rings to put the module in place.

Time to buy some 16-pin to 10-pin cables next time I guess.




Finally in place.   Ready to wiggle.