Folktek Mescaline arrived and I have been scoping it out.

In this post I’ll describe each of the three parts of Mescaline in detail and describe how they work together.  The Mescaline user manual can be obscure in places, as is sometimes the case when written by someone who already knows the gear.  I will attempt to write descriptions using common modular synthesizer concepts.

Patching

Mescaline has dozens of patch points, most of which are available only on 0.1 inch headers. Patching is by inexpensive prototyping wires with pins.  A few points are on Eurorack standard 3.5 mm jacks.

Frame

The supplied frame is clever and pretty to look at.  It is easy to assemble, following an online video.  It positions the modules for optimal patch lengths, but when patching or pressing buttons the frame flexes a little.  The lower pots on Motion come very close to the jacks on Channel.  I installed it in a sturdy Company of Quail 208 hp Dual Frame to take advantage of power and also the ability to add support modules to the system.  Be careful to check that circuit traces on the back don’t rub against the frame.  Although the traces are covered with solder mask, I lined the edges of the boards with electrical tape to prevent any shorts.

Power

Power can be supplied in several ways.  All that’s needed is +12 volts DC.  Each module has a 2.1 mm barrel input for wall wart power, plus a standard, shrouded Eurorack 10-pin connector.  I measured the current draws.

• Channel – 150 ma
• Motion – 160 ma (maybe more with all the lights on)
• Mental – 15 ma

Each module has patch points for voltages.  The 12 Volts In point can be patched from the 12 Volts Out on another module that is being powered.  Grounds must also be patched when this approach is used.  It’s the default approach, because Folktek supplies only a 12 volt wall wart.  I didn’t do it this way, but tested with a harness breaking out three 2.1 mm plugs from one wall wart for distributing to each module.  I also tested with a Eurorack supply with a 7812 type regulator.  I measured the following voltages on the pin outputs.  The only surprise was the +12V outs, which were unexpectedly lower than the voltage supplied.  I don’t plan on using any of the power patch points.

With 12.5 volt wall wart

Channel: 12V Out – 11.2V; 5V Out – 5.0V

Motion: +12V Out – 11.45V; +9V Out – 8.6V; +5V Out – 4.7V

Mental: +12V Out – 11.41V; +9V Out – 8.6V; +5V Out – 4.7V

With Eurorack 12 volt supply

Channel: 12V Out – 10.5V; 5V Out – 5.0V

Motion: +12V Out – 10.8V; +9V Out – 8.6V; +5V Out – 4.7V

Mental: +12V Out – 10.75V; +9V Out – 8.6V; +5V Out – 4.7V

Channel

Channel consists of three internally connected sub-modules, an oscillator bank, a vactrol VCA, and an FX unit.

Oscillator Bank

Channel has ten oscillators, each with a tuning trim pot on the back to set relative pitch to the others.  As delivered they are set roughly to a chromatic scale.  You can tune them however you like.  A global Pitch knob sets the initial frequency, and there are three Pitch CV inputs.  A quirk that that a 3.5 mm plug must be inserted into the Pitch CV input to enable the Pitch CV patch points to work.  All three CV are summed together and added to the base pitch, set by the Pitch knob.

Each oscillator can be played by one of the ten finger pads.  The response is a gently rising envelope that falls away gradually after the finger is removed.  Each oscillator also has a Key Trigger input, which can be used to sustain a note with a constant voltage, or to play a note by gating it.  Gates from Motion are typically patched to key notes.

Vactrol VCA (VAC)

All oscillators are mixed and hard wired internally to the VAC audio input. The VAC Audio In patch point provides another input to VAC that is summed with the oscillator mix.  If no oscillator is triggered, then this input can be the only signal passing through.  VAC has three CV inputs.  Again, a quirk requires something to be plugged into the VAC V+ In jack to enable CV inputs on the two VAC V+ In patch points.  All three CV mix to set the final level.  A VAC Level trim pot sets the overall gain.  OSC Gain trim pot sets the input gain for the oscillators.  VAC Audio Out is available on a jack and on a patch point.  VAC audio is hard wired to the Left input of the Effects unit.

Effects

One of the nicest features of Mescaline is the FX unit on Channel.  It offers four different effects:  Long Reverb, Tight Delay, Pitch Shift/Delay, and Reverse.  Long Reverb is the default.  Choosing another effect requires pin patching.  The FX knob controls are:  Feedback, Rate, Mix (wet/dry), and Filter.

Right channel input can be patched to the R In jack or to the FX R In patch point.  These inputs will mix if both are used.  R Level In trim pot adjusts the input level.

Outputs are available on jacks L Out and R Out and on patch points FX L Out and FX R Out.  If only the left FX input is utilized, then the dry mix comes out the left only.  The wet mix produces a stereo effect on both outputs.  L OUT LVL and R OUT LVL trim pots adjust the output levels.  Everyone seems to agree these should be set to the minimum to avoid distortion.

I found that Channel can start producing a lot of background noise.  To remedy this, I patched the FX selection and the noise abated.

Here are two Channel sound demos.  The first is simple manual triggering and messing with the Pitch knob.  The second demonstrates the Long Reverb effect.

Motion

Motion includes five sub-modules.

Clock

The clock is really too simple.  It’s just a 555 timer chip with a manual Time control. A patch point labelled 555 Timer Clk provides direct access to this clock, so it could be used even if an external clock is patched in.

Clock Divider

While the manual says there are two clock dividers, since they both share the same clock and both have identical divisions, even though duplicate patch points are provided for convenience, there is virtually one clock divider.  By default the divider is driven by the manual Clock, but an external clock can be patched in, for example to get a voltage-controlled clock.  The divisions are 1, 2, 4, 6, 8, 12, and 16.  Divided outputs are typically patched to the Trigger Sequencer and CV Sequencer Clock Inputs.  But they can be used directly to gate keys in Channel, etc..

Trigger Sequencer

Trig Seq Clk In is echoed on the Trig Seq Clk Out jack for external triggering duties.  Two buttons, Add and Sub, manually add or subtract active step outputs.  Patch points also allow to add and subtract, and there is a Trig Seq Reset input too. Two sets of eight outputs offer different functionality.

Trigger Seq Gate outputs are +5V gates, active with the corresponding step.  These are typically patched to activate keys on Channel.

Trigger Seq Out are unusual and call for more explanation.  Referring to the block diagram, when a step is active an optically coupled switch is enabled, connecting two patch points.  Out 1-4 are connected to the common terminal Main 1-4, but they are also connected to each other if more than one is active.  Likewise Out 5-8 are connected to the common Main 1-8 when their step is active.  These are bi-directional switches, so the labels of Out and Main are a little confusing.  The intended use of these switches is to connect Trigger points in Mental.  But I see no reason that they couldn’t be used to route other audio or CV in the system.

CV Sequencer

Like Trigger Sequencer CV Sequencer has clock inputs and outputs.  And there is an additional CV Seq Clk Out patch point.  Likewise, Add and Sub buttons and patch points allow to add and remove steps from the sequence.  And there is a CV Seq Reset patch point.  Eight knobs establish the voltage added when the step is active.  If multiple steps are simultaneously active, the voltages sum.  The voltage output is taken from the CV Seq V+ Out jack and/or from the CV Out patch point.  A typical use would be to control the master Pitch on Channel.

Note that Motion offers two different ways to sequence Channel.  It can trigger keys and it can sequence the master pitch at the same time, using different clock divisions.

Mod

Finally there is the strange Mod.  Mod is a voltage-controllable triangle wave oscillator that will go up to an audio rate with a very distorted waveform.   A knob labelled Mod sets the initial frequency and there is a CV In patch point.  Even Mod can be sequenced!

Output is available on the Mod Out jack, CV Out and Mod LED patch points.  These outputs are of approximately a 2-4 volt triangle wave, i.e. a 2 volt peak to peak signal, offset by +2 volts.  The Mod LED output has the same amplitude but a slightly higher bias point, about +2.5 volts.

The really cool feature of Mod is two points Mod 1 and Mod 2, of which the resistance across them is proportional to the level of the Mod Out.  Again, the intent is to patch Mod 1 and Mod 2 to two Trigger points in Mental.  But they could also be patched as an audio or CV signal attenuator anywhere in the system.  Just don’t expect anything to come out of them if only one is patched!  It is a bi-directional variable resistor.

In the following demo, Motion is sequencing Channel with one key activated.  I play around a bit with the speed of the sequence and change the clock division.  Notice that when the clock is stopped, the active steps remain on.  Then they resume.  Then a second key is activated.  Notice also there is no enveloping.  That’s because the VAC on Channel is just fully on.  By patching a clock signal to VAC V+ In, envelopes can be generated for a more conventional sequence.

Mental

Mental is my favorite of the three modules, because it is both unusual and obscure.  Its user interface consists of a set of 18 patch points.  Pin 17 is +5 volts and pin 18 is a ground.  They aren’t labelled, so be careful not to patch these together!  A group of trim pots on the back allows adjustments to be made, but there’s no clear procedure.  Generally, you want to adjust them so that no sound emits from Mental unless some patch points are connected.  Patches can be done in many ways.  The simplest is just to connect different points and listen to the result.  Each point has four pins and they like being cross connected to multiple other trigger points.  Just experiment.  Next, try patching from Trig Sequencer Outs and Mains to automate connecting points.

Patchable Pots

Four pots, labelled Patch 1-4 are available.  I’ve drawn their schematics.  Main is the bottom of the pot (counter-clockwise connects it to B).  A is the top of the pot and B is the wiper, but having a 150 ohm resistor in series.  You can connect any three Trigger points to a pot and see what happens.  You could also patch Main to ground, a signal to A, and have a potentiometer output at B.  Patch 1 and 2 use 10K pots, while Patch 3 and 4 use 43K pots.

Convert

Converts are a simple way to hook 3.5 mm patch cords together with pin patch cords.  Notice the 100 ohm resistor isolating the jack sleeve from the module ground.  In fact this isolation resistor is found on all the jacks on Mental and on Motion.  But not on Channel.  All the jack sleeves on Channel are directly grounded.

Breadboard

It’s not shown in my top view photo, because I had not assembled it yet.  Mescaline ships with a small collection of resistors, capacitors, and an LED.  The manual says you can build circuits on the breadboard, but no circuits are given.  I would really like to see the schematic for Mental.

Outputs

Four outputs, two jacks and two patch points, all carry the same signal, as far as I can tell.  The level of all of these is controlled by the Volume knob.  However, the Trigger patch points sometimes have audio on them that you could pass over to channel if you wanted to.  Typically you would patch a Mental output over to Channel to VAC Audio In or FX R In.

This little demo recording starts out by manually moving connections between Trigger points.  Then the Trigger Sequencer Outs from Motion are used to automate connections.  Mental can produce very interesting complex sounds.