Euterpe Synthesizer Laboratories Vertice, User Manual

The Moog CV standard, which later becomes the almost-only one on the market (actually Don Buchla designed 

his systems to use 1.2 V/Oct rather than 1 V/Oct and for a very good reason: a semi-tone is 0.1V rather than 0.083 

recurring), is about 1V/oct for the controls moving on the frequencies range (VCO frequency and note-related 

cutoff movements) and +/-5V for the other control types (but in the Organ there are 10 octaves! Exactly dude...)

In the VERTICE filterbank the 1V/oct correspondence is highly satisfactory in the range of normal required 

applications, e.g.. keyboard tracking, but do not expect perfect musical intervals correspondence.

On the other hand the VERTICE filterbank, because of its very early analog architecture, doesn't use the standard 

+/-5V CV system; it manages the CV in a different 

but compatible

 way which allows to feed only positive voltage, 

in the range of 0/+10V, into the various CV inputs available. 

It's means some things:

• 

in the case of 

+5V source (e.g. Oakley MU ADSR/VCA) it's common to achieve 

almost-full

 modulations. In 

the normal circumstances there is no problem to obtain a convenient musical modulation, especially when 

driving the 

MasterCƒ

 control (because 

MasterCƒ

 have an extended range if compared with the one of the 

singular filterboards)

• 

In the case of 

+/-5V source, like the Doepfer A-143-4 or some Moog module, you can obtain a 

very large

range of control. This kind of source requires a little bit of adjustments with the 

MasterCƒ 

and the singular 

Cƒ

 but it's the best solution to fully modulate your VERTICE

• 

In the case of less powerful sources, like the Moog Voyager main LFO (

+/-2,5V), the behavior is quite similar 

to a +5V source, but limited. It is not the full excursion but in the most case it's sufficiently usable, maybe 

with some limits. The fact here is that often you don't need the full 20-20kHz excursion to be musically 

productive, so a +/-2,5V CV can be fruitfylly used as a modulation source

• 

There is one ultimate case: in combination with a more powerful source, which is rare, maybe you can't use 

an half of your CV waveform. In a simple oscillating modulation it means a perceived halving of the frequency 

rate, nothing more. However using the related control (Cƒ) as an offset pot you can obtain a good response 

even from a 

+/-10V source, and remember that the pot discussed here is an attenuator, so use it to attenuate 

when needed.  :)

The CV pots

This pot is a simple 

passive attenuator

: it means that it "discharge" part of the injected energy to the 

main ground plane of Vertice. This is a non-professional, non-clean approach and I'm here to underline 

it. Why?  Well, First because there is nothing bad about trashing a bit the audio signal moving the zero 

volt plane 

according to the external modulation

: you can see this sort of dirt like the microphone recesses 

in a good old-school all-together 2inch tape recording, when the other-members-of-the-band sounds 

contribute to create the sound nuance around the main signal in the observed microphone. 

The second reason is that you will note it, soon or later, simply giving zero audio signal and a consistent 

load of CV so why don't explain that this is normal and wanted? You will notice that you can hear the cutoffs 

moving and stomping, something like drops or similar sounds (the audio result depend from a bunch of 

different factors). So, don't worry about a bit of CV modulation into your audio signal: generally there is a 

difference of so many dB between them that it is not a problem, is a simple nuance.

Polarized CV

To virtually expand a 

linear

 +5V source you can use a simple mechanism which simulates a 0/+10V 

signal: use a polarized summing module. Some example can be the Doepfer A-138e, the Synovatron CVTools 

or our E.S.L. Matrice 01. A polarized level pot is a very easy circuit where the CV sent into can be attenuate 

in two ways: linear, via standard attenuation circuitry, and, of course, polarized: in this second mode you 

can obtain a full attenuation in the flat position of the pot, a positive response from one side and a negative 

response from the other. 

In the case of a normal level control a +/-5V modulation is been attenuated by an amount of V due to the 

limiting of the resistance of the pot and circuitry involved. So you can use e.g.. +/-5, +/-4, +/-3 and so on, and 

of course all the values in the middle of these steps. 

When you use a polarized way instead, with a 

linear

 +5V source you can obtain a 

false

 0/+10V output range, 

tricking the three filters to work at full interval. It is useful for example if you want to control the VERTICE 

filterbank from a too-far system. 

Polarized, a +5V can become a +/-5V depending to the position of the pot, so it can be “mistaken” for a 

0/+10V signal by the VERTICE filters. Obviously the filters must be set on purpose for this trick: it can be done 

simply giving it a “more open” basic position on the panel.

If you use a 

modulated signal

 instead of a linear one then you will obtain a simple inverted output, not so 

useful in this case, but still remains funny (for one or two minutes maybe).

[

34

]

the Filters section