The Quantix-8 memory contain 2048 waveform/scales of 256 unsigned bytes each. So it require a 18 bits number to adress the entire memory locations. The 8 lowest bits are to scan the current waveform , the 10 others are to select waveforms and they are organised in 32 banks ( 5bits msb) of 64 waves (6 bits)..
The fast ADC sample the incoming signal and convert this voltage into a 8 bits value . This value is the lsb of the RAM adress bus ( A0-A7) by the latch U4. When an adress is set on the adress buss, the ram reply by setting the corresponding 8 bits value, stored at this adress, on the data buss. The output DAC convert all values present on the data buss into an analog voltage ...
Now, if a calibrated up-saw signal is applied on the converter input, the fast ADC count adresses from 0 to 255 and the ram provide the corresponding values stored into the RAM memory. So with a up-saw waveform ((vco or lfo ) plugged on the fast ADC input, the digital waveform selected in memory is completly 'scanned' each at cycle and so available as a voltage at the Quantix-8 output.
Waveform selection : Bank/wave numbers to select the waveform to play, are defined by adresses A8 to A18. Each modification of thoses adresses select another waveform to play. Banks and waves numbers are set by panel pots and their restective CV inputs, but also by MIDI or they can be assigned to external ZERO and GATE logic I/Os on the front panel. As all those features can be used at the same time. This offer a very large choice of combinations to drive the Quantix-8. All setting are send in real time by sysex messages.
Wavetable Oscillator :
This suppose to feed the fast ADC with a up-saw signal at audio frequency, at least for linear wavetable synthesis ... But it is possible to use other waveforms : a down saw with play the waveform reverse, a triangle will play one time direct one time reverse, etc ....
A fast, stable and calibrated VCO is generaly used to scan/loop the 256 bytes of the selected waveform and to get 1V/Oct control of the vco frequency...
The Quantix-8 editor software allow a realtime edition of the currently played waveform shape, using fast sysex messages... "What you draw, is what you ear " !
Alternate definition of a memory based CV-quantizer :
it is a wavetable oscillator unable to run at audio rate
It work exactly the same than the wavetable oscillator, but instead of an audio frequency signal, a LOW frequency or a constant voltage is send to the fast ADC input. Any kind of CV source can be used to drive the Quantix-8 fast ADC input : analog sequencer,keyboard or midi CV /Gate interface, lfos, envelopes, followers, all kind of sensors, etc...
For 1V/Oct and tempered cv-quantise the memory should contain cv-scales instead of 'waveform'. Scales are generaly up-stair ramps...Use the scale generator into the editor software to set scales...The 'manual' grid editor can be helpful too.
MIDI Dump & edition
- The editor software detect automaticaly any Quantix-8 online and set up a parameters page with a 'speed button' for each module to access it instantly. A total of 4 Quantix-8 Modules is managed this way by the software.