Euterpe Synthesizer Laboratories Vertice, User Manual

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24

]

the Filters section

Emphasis mean 

Resonance

. We chose this antiquated formulation to remember the 

synthesizers of the 60s, when the word Resonance was not a standard yet.

Emphasis is a 

level-controllable audio signal feedback across the filter’s path

. It can 

produce some very interesting timbre variations that you can explore.

Use the 

Emphasis

 controls to increase the presence of the C

f

 in the sound, or to create 

whistles, wind, drops, goa-kick and a very unstable auto-oscillation.

In this filterbank the basic range of the three controls are heavily subjected to 

Emphasis Attitude settings giving two deeply-diferent behaviors. 

To give to our filterbank personality and 

uniqueness we work a lot around this 

Emphasis-related function that we label as 

Emphasis Attitude.

This switch allows you to choose between 

Classic Steiner's way, named Diode             

and our personal design, the Transistor           

(actually this is the BJT Npn transistor 

symbol...)

NOTE: in the following "pot-pictures" 

arrows indicate where the circuit generally 

start the auto-oscillation behavior.

Classic way (

): this passive re-injection of signal into the audio path is the key to 

obtain the classic synthesizers sound of sweeping filter but not only: it's useful for 

increase the high frequency band levels to emphasize too dark tracks, making vibrating 

and prominent Charleston lines or to shape the impact of weak snares.

The most important thing you can know about 

this

 Emphasis control (other kind of filter 

have other kind of response) is that it increases the level of the output signal of many 

dB, especially in the mid-frequency range, since it is limited only by passive resistors, 

nothing else. In the next chapter you can find some graphs concerning this behavior 

(page 27).

In addition to that it's very useful to know how Emphasis effects the resultant filter 

slopes, making it more or less aggressive on the harmonic contents. Generally speaking, in Vertice MORE EMPHASIS 

= MORE AGGRESSIVE SLOPES

Alternative Emphasis way (

): in order to tame the too much dynamics that the Classic 

Emphasis way has, something funny but not so frequently musically usable, in this long year 

of Vertice re-design work we projected our own personal resonance way. The selected simbol 

to label it is the transistor because two active silicon transistors are used to compress and 

distort audio signal traveling into them. 

This is maybe the first time a dynamic and tonal distortion is dedicated specifically to the 

resonance path, that is only a part of the signal in the filterboard, and that is SUMMED into it, 

giving unmistakable nuances. 

Furthermore this more controlled resonance path give a very useful static auto-oscillation, 

something that allows you to use Vertice also like a triple oscillator, if you dare.

You have to know that this Transistor way, like so much things in Vertice, is very sensitive to the incoming signal level. 

Moderate the input if you want the Transistor Emphasis "VCO effect" very prominent and "in face" or drown it into a sea 

of very loud wave (maybe using also the overload funcion) to get out more nasty nuances.

 Filters output phases

In this particular case the phase shift between the input and the output signal is equal to the vector of

−

π

2

+

π

4

= −

90

°

+

45

°

= −

π

4

= −

45

°

In other configurations phase differences introduced by the capacitor's constructive characteristics, which 

are not small at all, show themselves in various way but we ignored here the subject for evident lack of need. 

These phase changes are the reason why over-aggressive cut slopes (e.g. 36 or more dB/oct) are less musical 

than a smooth one and they can be sources of unwanted cancellations and other audio artifacts. This is true 

for all the processes that involve filters, especially analog or digital equalizers, from which we generally want 

strictly functional, not creative, performances, so smooth, clean and transparent.