MIDIbox Hardware Platform, AOUT Module

The AOUT module provides 8 control voltage (CV) outputs with 12 bit resolution and 2 gate outputs. It is used by various MIDIbox projects to control analog synthesizers and/or FX gear.

Download

PCB data, can be viewed, modified and converted with Eagle Light. The .pdf based schematic has been created with xcircuit. There are no special eagle schematics available, since components have been netlisted in the .brd file directly!
Module	Schematic	Layout Data	Quick-view
MBHP_AOUT_V1	mbhp_aout.pdf	mbhp_aout_v1.brd	mbhp_aout_v1.gif

Additional informations
File	Size	Description
mbhp_aout_orderlist.txt	1k	Reichelt orderlist
bipolar_12v_psu	Wiki	Wiki article about bipolar PSUs (required to get a +/- 12V voltage)
mbhp_aout_balanced_cv.pdf	2k	Balanced output extension, e.g. for a CV range of -5V/+5V

Pinning

Following projects support the MBHP_AOUT module - in general the MAX525 has to be connected to J10 of the core module, some applications require a different pinning if J10 is shared with other modules:

Schematic	AOUT:J1:CS	AOUT:J1:SI	AOUT:J1:SC
AOUT Example	CORE:J10:SO (RC5)	CORE:J10:RC (RC4)	CORE:J10:MD (RD5)
MIDIbox CV	CORE:J10:SO (RC5)	CORE:J10:RC (RC4)	CORE:J10:MD (RD5)
MIDIbox SID	CORE:J6:SI (RC3)	CORE:J6:SC (RC1)	CORE:J6:RC (RC0)
MIDIbox FM	CORE:J6:SI (RC3)	CORE:J6:SC (RC1)	CORE:J6:RC (RC0)
MIDIbox SEQ	CORE:J10:SO (RC5)	CORE:J14 (RD4)	CORE:J10:MD (RD5)
MIDIbox64 (*)	CORE:J10:SO (RC5)	CORE:J10:RC (RC4)	CORE:J8:SO (RD0)
MIDIbox64E	planned

(*) MIDIbox64 supports also the MBHP_SHX8 extension for up to 64 CV outputs.

Soldering Guide

	Start with soldering the 3 bridges which save you from creating a 2-layer board. You can use the cutted legs of caps and resistors, before you throw them away after you finished all the modules! :-)
	Mount the MAX6007B shunt at the backside of the PCB. The side with the single leg goes to the single copper square on your PCB. The two legs on the other side of the 6007 connect to the copper trace and the ground plane. Make sure that you heat up the ground plane with a little bit of solder before you put the 6007 in place. The ground plane will absorb an awful lot of heat, and if your 6007 is already there when you are trying to heat it up it will be fried.
	Mount all the parts except for the ICs and check the power supply voltages (see schematic). Thereafter put the ICs into the socket and measure the voltages again. Connect the PCB to your MIDIbox - the pinning depends on the application, see above. It's a good idea to start with the MIDIbox CV application in order to test the module before using another application, since the calibration is easier.

Setup and Calibration

Each channel provides a separate gain trimmer which allow you to adjust the output voltage range.

MIDIbox CV V1 users: just follow the instructions at the MIDIbox CV V1 page.

MIDIbox CV V2 users: just follow the instructions at the MIDIbox CV V2 page.

MIDIbox SID V1 users: open the "setup_*.asm" file of the application and set the "ENABLE_AOUT" switch to 1. Thereafter rebuild the project and upload the new .hex file to the core. Now you can control channel #1 with the filter knob, and channel #2 with the resonance knob. Channel #3..#5 output the Pulsewidth modulation path, channel #6..8 the pitch modulation path. If you haven't built the control surface, then just send CC#46 (CutOff) and CC#47 (Resonance) to the MIDIbox.
The fun begins once the filter output voltage is modulated by the envelopes and LFOs! :-)

MIDIbox FM users: open the "setup_*.asm" file of the application and set the "ENABLE_AOUT" switch to 1. Thereafter rebuild the project and upload the new .hex file to the core. AOUT channel #1/#2 is assigned to Instrument #1, Channel #3/#4 to Instrument #2, Channel #5/#6 to Instrument #3, Channel #7/#8 to Instrument #4. LFO/Envelope Assignments and the Offset can be configured in the AOUT menu of the Control Surface.

MIDIbox SID V2 users: open the "setup_*.asm" file of the application and set the "ENABLE_AOUT" switch to 1. Thereafter rebuild the project and upload the new .hex file to the core. You can control channel #1 with the filter knob, and channel #2 with the resonance knob with F2A option enabled (-> Ensemble Menu). CutOff and Resonance of the right channel SID are available at Channel #3 and #4. With V2A, volume can be handled a similar way (a second MAX525 required for this case). With F2A and V2A option disabled, up to 8 channels (-> 2 x MAX525) can be controlled from the modulation matrix and within the EXT page. All these possibilities are documented in the MIDIbox SID Users Manual.

Alternative solutions for CV outputs

Last update: 2023-11-04