Waldorf microQ Keyboard User Manual

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Waldorf microQ Keyboard User Manual Manual pdf 92 page image

Sound Parameters – Effects93 Waldorf microQ User´s ManualVocoder The Vocoder effect is a special effect type. Only one Vocoder is allowed at a time. When youhave several sounds using a Vocoder, the one in the lowest Instrument slot wins. E.g., if youhave a sound with a Vocoder effect set up for Instrument 1 and another sound with a Vocoderin Instrument 3, only the Vocoder in Instrument 1 works.A Vocoder is a circuit to process the frequency content of one signal with the frequency content ofanother signal. This is done by splitting up the analysis signal (also known as Speech signal) withbandpass filters into several frequency bands. The volume of each frequency band is then evaluatedwith an envelope follower, and the resulting envelope is used to control the volume of a bandpassfilter that processes the synthesis signal (also known as Carrier signal). The synthesis signal is thereforefiltered by as many bandpass filters as the analysis signal, so that each analysis filter finds its synthesisfilter counterpart.This technique was developed as early as World War II, but the plan then was to use it to encryptspeech when transmitted by radio, rather than using it to create musically useful sounds. However,this shouldn’t disturb you and you should feed a Vocoder with speech, drum loops or any othercollection of external audio material you like. The results will always be complex and interesting,sometimes close to the original signal and sometimes much altered. Experiment and have fun.For the Vocoder, you always need two signals, a signal that is analyzed and another signal that isused for processing by the synthesis filters. The analyzed signal always comes from a different source,either the external input or one of the internal routing busses. The synthesis signal is the currentsound, but if you wish to use a different synthesis signal, set up the N/E Select parameter in theMixer/Routing Edit menu to feed the filters with the External In or one of the internal routing busses. Itmight even be interesting if both the analysis and synthesis signal come from the same source,especially when you set the synthesis band offsets to other values than +00. Then a low analysis bandmight deliver the envelope for a high synthesis band and vice versa.To preserve the original signal as much as possible, the synthesis signal should only consist of asimple, unfiltered noise that you generate with the microQ’s noise generator. For a spoken or sungvoice, you should add a sawtooth oscillator such that the pitch determines the frequency of thespeech. To get a natural sounding spoken voice, you should modulate the pitch of this oscillator witha slow sine LFO to simulate the emphasis.Easy Setup for working with the Vocoder☞ Building a Vocoder setup1. Connect the audio input of your microQ with a 1/4-inch mono or stereo plug. In practice, asocalled “insert” or “Y” cable is perfect for a stereo or dual mono signal input for thevocoder. Please be sure to use a line signal. If you want to use a microphone be sure to usea pre amplifier to generate a line signal.2. With the Input Gain parameter in the Global menu you can increase the sensitivity. Pleaserefer to the chapter „Global Parameters“ on page 130 for more details.3. Select a sound program. We recommend the use of sustained pad or string sound.4. Select the Vocoder as effect type for FX slot 1 or 2 and initialize the parameters. This isdone by holding the Shift button while moving the left or right display parameter dial: