Analogue Solutions Telemark /-K - Manual (Page 13)

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analogue Solution – Telemark – 2014 13 | P a g e
Voltage Controlled Amplifier - VCA
The Voltage Controlled Amplifier (VCA) is the circuit that is used to change the output volume. Normally an envelope
signal would be used to do this, so the sound starts loud then gradually fades away. The filter audio output is hard-
wired to the VCA signal input.
The VCA can be controlled in 4 modes
EG2
When EG2 is selected, the envelope signal of EG2 is used to modulate the VCA level. Use it if you
require the VCA level to change over time. (Normal use).
MIDI2/EG When this is selected, EG2 is again used as the modulation source, but the overall envelope
level is in turn controlled by MIDI2 (CV2) This allows velocity / controller dynamics to change
the volume. If MIDI2 source is MIDI volume (controller 7) then MIDI volume changes can be
realised. Typically MIDI Velocity would be the best modulation source.
GATE When GATE is selected, the MIDI note on/off information is used to modulate the VCA. With
this, the VCA level is either off or full on. The audio envelope would be like an organ's, with no
attack or decay time.
ON When ON is selected, the VCA is left permanently on at full level. Use this setting if you wish to
use the Filter as an effects processor, to process external audio fed into Telemark via the EXT1
socket.
Low Frequency Oscillator - LFO
The Low Frequency Oscillator (LFO) is basically identical to a VCO; it is another oscillator, except that it produces
periodic wave forms of low frequency, typically sub-audio. These slow cyclic waveforms are used for modulating
other circuit parameters, for example, for sweeping the filter cut-off up and down, either slowly for a nice sweep, or
faster for a 'wah-wah' type effect. It could be used to modulate the VCO pitch for vibrato.
The LFO block is grouped together with the VCOs as an LFO is an oscillator just like the VCOs are.
SPEED – This sets the frequency (speed) of the LFO which is indicated by the
LED
MODE – This sets the modulation source that is routed to LFO points for
modulation selection. The options are:
SQUARE WAVE MIDI Control (CV2)
TRIANGLE WAVE SAMPLE and HOLD*
*Sample and Hold (S+H) is a flash term that in this instance basically means a
modulation is created that has a new random signal level each time the LFO
completes a cycle (each time the LFO LED lights up a new modulation level is set)
VOLUME - This sets the output level of Telemark, i.e. the output
from the VCA that is sent to the SIGNAL output socket
MODE – Rotary Switch