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User Manual --- CV Options


MIDIbox SID V2 is the worldwide first (and only) SID synth which allows you to control external analog components from the synth engine. Meanwhile the control options are so powerful, that it even allows you to control analog synths from the mighty sound engines, which gives you much more possibilities than common MIDI-CV interfaces! Note that it isn't required to connect MBHP_SID modules to use these features.

AOUT modules

Three different AOUT (Digital-Analog converter) modules are part of the MIDIbox Hardware Platform, and supported by the firmware:

In order to select the right AOUT driver, the setup_*.asm file of the release package has to be edited (search for ENABLE_AOUT); thereafter a new .hex file has to be build as described here.


Analog outputs can either be controlled directly from the EXT menu, and the modulation matrix of the Lead Engine, or you can enable one or more x2A function within the Ensemble to forward waveforms, generated by the synth engine, to the analog outputs.

The AOUT channel assignments for x2A functions are static, and need to be selected in the setup_*.asm file.

Digital Switches (Gates)

In addition to the analog outputs, the firmware allows to control 8 digital outputs (e.g. switches, gates, triggers) as well. The state of the outputs is stored within the patch structure, so that the setup can be recalled. In addition, the outputs are accessible via control surface (-> EXT menu), NRPNs, Knobs, Wavetable sequencer, etc...
The outputs are either available at J5 of the core module (set DEFAULT_J5_FUNCTION to 3), and/or on a DOUT shiftregister (set ENABLE_AOUT to != 0, and set DEFAULT_EXT_SWITCH_DOUT to a value between 1 and 16).

Optionally, internal gate/slide and accent signals can be forwarded to the digital outputs as well, which gives you the possibility to trigger external synths the same way like the 2*3 SID oscillators (per core).

Using external Filters

You are able to add external filters or other analog effects to the SID channel. The output levels are stored with the patch, and it is even possible to control them via MIDI, and to modulate the outputs from the modulation matrix. This opens a lot of new possibilities for sound experiments with the good old SID chip.

In following demo sample, cutoff and resonance of two CEM3378 filters are controlled from MIDIbox SID V2 (see also this posting for additional infos):

During this session, two SSM2044 via AOUT_NG module were used to filter the outputs of two SIDs. mbsidv2_bassline_demo4.mp3
Forum Article

An envelope modulated multi patch played with two CEM3378 filters:

Controlling Analog Synths

More informations in this and this posting.

Sound samples, which have been created during a sunday-afternoon session with rsf Kobol Expanders:
mbsidv2_kobol_modulation.mp3 Experiments with Stereo Modulation
Only for synth freaks with some endurance! LP Filter and Pitch of two Kobols are modulated through the mod matrix with multiple LFOs, combined with different operators. LFO settings are tweaked during the sound is playing. Only a single note is played! The random-like "tunes" are result of the modulation (in fact, the gate was not connected this time) I especially like the brass-like sound at 4:22
mbsidv2_kobol_bass_stereo.mp3 Stereo Bass
Just to check the detune function and simple stereo effects
mbsidv2_kobol_arp.mp3 Arpeggiator
Nice arpeggiator sequence (just push the button and play a single note)
mbsidv2_kobol_bassline_fun.mp3 Bassline Fun
Bassline sequences. Note the killer bass of the lower bassline!

Last update: 2023-11-04

Copyright 1998-2023, Thorsten Klose. All rights reserved.