https://wiki.midibox.org/ Wed, 29 Apr 2026 04:33:18 +0000 FeedCreator 1.8 https://wiki.midibox.org/lib/exe/fetch.php?media=wiki:dokuwiki.svg https://wiki.midibox.org/ https://wiki.midibox.org/doku.php?id=pga:buildchanbrd&rev=1220824352&do=diff Building the channel board: This board has many options, and the parts count changes with most of them. You should read it over carefully before starting the build. You'll need to know how many input amps to build, and how you'll want them configured. You'll also need to know which input channels will be routed to which output channels. anonymous@undisclosed.example.com (Anonymous) Sun, 07 Sep 2008 21:52:32 +0000 https://wiki.midibox.org/doku.php?id=pga:buildoutbrd&rev=1220823888&do=diff Building the Output Board: The output board has two purposes. It provides 1 to 4 audio outputs from your mixer, and also provides the interface to the MIDIBox. Here is the bare Output board: The outputs: Depending on your board, you may need only two outputs (line mixer) or all four for a “full” mixer with effects sends. You only need parts for the outputs you will use. There are four amplifier channels on this board, labeled OT1,OT2,OT3 and OT4. For a line mixer, just build 1 and 2. anonymous@undisclosed.example.com (Anonymous) Sun, 07 Sep 2008 21:44:48 +0000 https://wiki.midibox.org/doku.php?id=pga:buildregbrd&rev=1220823504&do=diff Building the regulator board: Parts needed: line cord, fuse and switch. 1 center tapped transformer, 8-12 VAC, 0.5 A or bigger 1 Full wave bridge rectifier, 30Volt or bigger, 1.5 Amp or bigger 2 capacitors, 2700 uf or bigger, 16 volt or bigger 2 7805 voltage regulators anonymous@undisclosed.example.com (Anonymous) Sun, 07 Sep 2008 21:38:24 +0000 https://wiki.midibox.org/doku.php?id=pga:choices&rev=1220801751&do=diff Before you build: Choices and Comments If you have a multimeter or voltmeter, it will come in handy for testing the power supply. You have a LOT of choices with this project. I would not describe this as a beginners level, it is complicated by the use of surface mount components, having to stack the boards correctly, requiring a bipolar power supply, and mostly by the sheer number of options that have to be decided along the way. If you are not familiar with mixing boards, your choices get eve… anonymous@undisclosed.example.com (Anonymous) Sun, 07 Sep 2008 15:35:51 +0000 https://wiki.midibox.org/doku.php?id=pga:compile&rev=1220792782&do=diff Compiling the code Once your pre-compile changes have been made, you are ready to compile the code into an executable form. This project was already well underway before the new development environment was announced. I may port it over at some future time, but for now you will need MPLAB to perform the compile. This should be simple. Install MPLAB on your windows computer, then copy the source directory onto that computer. MPLAB has had problems in the past with long path names, so I usually cr… anonymous@undisclosed.example.com (Anonymous) Sun, 07 Sep 2008 13:06:22 +0000 https://wiki.midibox.org/doku.php?id=pga:configmixer&rev=1220825793&do=diff ConfigMixer, The configuration tool. As I experimented with the mixer, I have had the luxury of being able to create MIDI controls as needed. As I work on an unusual computer, my tools won't be of much use to anybody else. I wanted to create a “universal” tool for configuring the mixer. I wrote “ anonymous@undisclosed.example.com (Anonymous) Sun, 07 Sep 2008 22:16:33 +0000 https://wiki.midibox.org/doku.php?id=pga:inputchoices&rev=1220803304&do=diff Input processing: The choice of input circuits for your mixer channels is a big one, and each of us will have different needs. There are specific requirements for signals going into the PGA4311. Input signals will be unbalanced, and should not exceed +- 2.5 volts at any time. If the voltage swings above 2.5 volts, or below -2.5 volts, the sound quality will be affected (clipping). If the input voltage goes above +5 or below -5 volts, the PGA chip may be damaged. Also, the impedance of the input… anonymous@undisclosed.example.com (Anonymous) Sun, 07 Sep 2008 16:01:44 +0000 https://wiki.midibox.org/doku.php?id=pga:loadapp&rev=1220825449&do=diff Getting the application into your mixer Most people will use MIOS Studio to do this. If your computer is Java-Impaired like mine, but you do have Perl available, you may use HEX2SYX.pl to convert your hex file into a System-Exclusive file. I have used both methods successfully. anonymous@undisclosed.example.com (Anonymous) Sun, 07 Sep 2008 22:10:49 +0000 https://wiki.midibox.org/doku.php?id=pga:midichart&rev=1220798938&do=diff MIDI Implementation Chart This is a living document. I have changed the details of the MIDI implementation many times, and I invite you to change it as well. This should provide a rough guide to your starting point. Linked documents are courtesy of Jeff Glatt. For any controls that show coarse and fine, MBMixer will support coarse only. Unless specified, each control is applied to the channel received on only. anonymous@undisclosed.example.com (Anonymous) Sun, 07 Sep 2008 14:48:58 +0000 https://wiki.midibox.org/doku.php?id=pga:patches&rev=1220826100&do=diff Saving and Loading patches. There is space in the MBMixer to store 64 complete, 16 channel board images. These may be saved and loaded by individual channels, or as complete boards. One “special” board is board zero. This board will be loaded automatically every time the MBMixer is powered up, or anytime an “All Sound Off” message (CC#120) is received on any channel. Each channel save will include flags (effects pre/post settings, effects mutes, WithFX setting), Volume, Pan/Balance, Expression,… anonymous@undisclosed.example.com (Anonymous) Sun, 07 Sep 2008 22:21:40 +0000 https://wiki.midibox.org/doku.php?id=pga:postconfigsoftware&rev=1220825650&do=diff Software configuration Some software options must be made before compiling, others should be made after the application is loaded and running. These are the after-compile options: Note: there is an application included to allow configuration by creating MIDI files from a command line. See “ anonymous@undisclosed.example.com (Anonymous) Sun, 07 Sep 2008 22:14:10 +0000 https://wiki.midibox.org/doku.php?id=pga:preconfigsoftware&rev=1220792713&do=diff Software configuration Some software options must be made before compiling, others should be made after the application is loaded and running. These are the pre-compile options: The MIDIBox mixer supports named channels. You will find that reading “Yamaha MU90-R” is a lot more descriptive than “Channel Four”. These names are set in file “USER_LCD.inc”, beginning near line 101. You should find a group of sixteen lines that look something like this: anonymous@undisclosed.example.com (Anonymous) Sun, 07 Sep 2008 13:05:13 +0000 https://wiki.midibox.org/doku.php?id=pga:purpose&rev=1220718530&do=diff Project Overview: The MidiBox Mixer The MBMixer project was designed as a replacement for an old stereo line mixer that I built a few decades ago. It has served well, but the pots get old and scratchy, and it just seems so “old fashioned” to have to reach around the front of the rack to adjust the volume. So I decided to design a replacement that could never get scratchy pots, and maybe even add remote control by MIDI. After a bit of research, the PGA4311 chips were looking very promising. Sinc… anonymous@undisclosed.example.com (Anonymous) Sat, 06 Sep 2008 16:28:50 +0000 https://wiki.midibox.org/doku.php?id=pga:smtsoldering&rev=1220816388&do=diff Hand-Soldering Surface Mount parts: If you have never soldered surface mount before, I'll offer a few tips. Use a smaller soldering iron. The big trigger guns are out of the question. If you can afford it, a temperature controlled iron is your best bet. That doesn't just mean it has a knob (mine doesn't) but that it has a thermostat in the tip, and it will maintain the same temperature regardless of load (or a cool breeze coming by). I use an old Weller WTCPT series. There are other good brands… anonymous@undisclosed.example.com (Anonymous) Sun, 07 Sep 2008 19:39:48 +0000 https://wiki.midibox.org/doku.php?id=pga:softwareoverview&rev=1220792580&do=diff Language and development environment: MIOS and it's applications run on the PIC series of processors. Applications may be written in C or assembly. The MBMixer is written in assembly, as that is the language I am most comfortable with. During development of the MBMixer, a new development environment was announced for MIOS, that uses GCC and SDCC instead of the MPLAB package supplied by Microchip. I may move the code over to the new environment at some time, but for this release, I am still work… anonymous@undisclosed.example.com (Anonymous) Sun, 07 Sep 2008 13:03:00 +0000 https://wiki.midibox.org/doku.php?id=pga:stackboards&rev=1220823059&do=diff Stack Pins, holding the project together. The boards are stacked together. This is a both blessing and a curse. On the bright side, it keeps the boards small, it keeps critical signal paths short, and it makes expansion easy. On the downside, the more connections a project has, the more likely that something will come loose. There are so many points here that I may have created a monster. Depending on the type of pins you use, you may be able to gently solder the pins together after all th… anonymous@undisclosed.example.com (Anonymous) Sun, 07 Sep 2008 21:30:59 +0000