Rack747 (Full Om release 1.01, BeOS R3)

Rack747 is by any other name: 'Rack303' + 0.5*808 + 40 (a random number plucked from the nether regions to give a result that is loud, fat, and flies). The Rack is a set of monophonic synths, performing a modelling of the classic Roland 303 Bassline. Each synth is associated with its own basic monophonic 16-note sequencer, 4-part 808/909 style drum module, and cheesy effects processor.

All synths in the rack, though running as seperate applications, share a common interface. The sequencers may be locked to each other, sync'd to a midi clock, or simply let freewheel along in whatever order they were started. In song mode, synth, drum and sequence data can be organized into longer patterns.

Strange Psychochemicals, and notes about the demo!!!

The Rack747 half-tab release has functionality equivalent to or better than the previous shareware releases, the last of which was Rack747 5.05. Full current functionality of the Rack is available only in the full-tab release, currently running at Om1.01. This is available directly from me via mail order, and should soon be available on the net through BeDepot (though they've been stuffing me around for 4 months, with no end in sight). What half-tab users get for their money on acquiring a full license are:

1. The kit editting window.
2. Extended bank memory.
3. The ability to load Rack747 add-ons, such as the Oasis sampler, and Twang (a guitar emulator).
4. The ability to export loops to soundfiles.
5. The ability to annoy me with feature requests and expect me to listen (though anybody can try to do this, and I might listen, and certainly will if the ideas are good). In fact I enjoy hearing from anybody that uses this baby.

More notes for everybody who's still on board

The gory details

Common interface shortcuts.

Text fields (the white control boxes) can be modified by:

• The usual click, edit, and return.
• Using the arrow keys to scroll through values.
• Hitting "page up" to bring it to its maximum value, "page down" for its minimum value, and "home" for its median value.
• Some fields correspond to midi values.
• The TAB key shifts to the next field in the window. This is especially useful for the sequence edit displays.
• The CTL and SHIFT keys increase the step size by 2, 5, and 10 (if both are down) respectively.

Generally, the sliders can be moved by:

• Clicking to a position on the bar.
• Grabbing the knob and riding it.
• Modifying the numeric field.
• Sending appropriate midi data.

The pots operate similarly to the sliders, but look completely different, and are mainly used for parameters that won't be "ridden". As they work angularly, control sensitivity is dependent on the distance of the mouse from the center of the pot. Otherwise, they can be adjusted by:

• Clicking to a position on the pot.
• Grabbing the pot and riding it.
• Modifying the numeric field (if there is one).
• Sending appropriate midi data.
• Clicking with the secondary (right) mouse button, which centers the dial.

The menu bar provides access to all the file save and load functions, and toggling of the extra edit windows, the miscellaneous options, and kit editting.

• The sequence/slider settings for the running synths (the data displayed in the edit window) and the memory bank can be saved and loaded interchangeably. A set of patterns can be created interctively, saved to disk, reloaded into the memory (or back into the running synths), twisted to your hearts content. The default save directory is "{rack home}/Patches". Loading the config sets all midi channels and sync parameters, as well as the relationship between sliders and midi controllers.
• The window menu controls the display or not of additional windows.
  • The bank editor provides extra edit screens for banks and offscreen synths, plus save/load access for them.
  • The global mix window provides small sliders for the final mix level of each synth, corresponding crossfader assignments, and the crossfader itself., .
  • The config editor edits the current running midi control configuration.
• The "Metrognome" option controls the flashing light in the edit window, and the sequencer displays in the individual synth controls at the bottom of the main window.
• The kit menu controls facilities for saving loading and editting additional kits.

Main window: sequencer controls

Main window: sequence editor

• The slider controls sequencer tempo.
• The "trans" text field transposes the current sequence by a given amount. It is reset to 0 immediately after acting. It responds to the up and down arrow keys.
• Two sets of 16 text controls display the data in the current sequence, one line for midi note#, and one for velocity (amplitude). Setting a note to 0 will correspond to silence. Ties and sustained notes are indicated by a 0 velocity. Every non-zero velocity starts a new attack.
• The line of text controls below this give access to the built-in 4-part drum module.
  • A single part is displayed at any time, selected by the pull-down menu at the left of this row: click on the number to activate the menu.
  • The check box to the right of this controls muting of this drum part.
  • The inset string field next to this controls a pull-down menu to select an instrument from those available, This is presently limited, but later releases will enable this to be configured.
  • The 16 text controls indicate the drum velocities for this part, or 0 if there's nothing happening on this part of the beat.
  • The pads below these fields are like 808 style press pads, editting the numeric fields above them. They also control drum part tuplet rolls on each beat. With the shift or control key down, left click increments the roll value, and right click decrements it.
  • To the left of this are 3 pots labelled "Tn", "Lv" and "Pn", controlling tune, level, and pan of that drum part.
  • The start and end points are indicated by right and left pointing arrowheads in the gaps between the two rows of sequence data fields. They can be selected by left and right click respectively.
  • The begin point gives the point that the sequence is first started from in its loop. It is indicated by an upwards arrowhead, and is set by a simultaneous L/R mouse click. This is most relevant to the sequence sync function, as this is where the sequencer will be syn'd from.

Main control window: synth controls

• The "Oscillator" region provides control for the main oscillator (i.e. what goes "beep! beep! noodle!").

  The menu box controls the oscillator wave form (saw, square, sine, noise, thin square, triangle). In this case, it's certainly a case of what you hear is what you get. For the full version it will also provide access to any addon oscillators.

  The "Envelope" checkbox turns the amplitude envelope off and on. This envelope tells how loud a single note is over time. If this is off, the attack and decay parameters will have no affect, and the note will be fully on. This is very useful for addons that provide their own enveloping. "Twang" for instance has a natural envelope dependent on it's modelling of a plucked string.

  • "Glide" controls the 303's rude portamento effect.
  • "Attack": controls the attack rate of the amplitude envelope of the synth.
  • "Decay": controls the decay parameter of the amplitude envelope.
  
  
  
• The filter region provides control for the synths filter (i.e. what makes it squelch!).

  The menu box controls the filter choice ("cheesy303", "unity"). For the full version it will also provide access to any addon filters (though none are yet available).

  • "cheesy303" is a low pass filter tuned to be roughly comparable to that of a 303.
  • "unity" is a non-filter. It does nothing, irrespective of parameters. This is actually very useful for some of the addon oscillators. For instance, "Twang" is so heavily filtered it makes little sense to filter it further. For "Oasis", it can be nice to filter, and also, nice not to.

  The "Envelope" checkbox turns the filter envelope off and on. This envelope tells how "squealy" a single note is over time. If this is off, the attack and decay parameters will have no affect, and the note will be dependent only on the cutoff, envmod and resonance parameters.

  Elsewise, the parameters are:

  • Cutoff: filter cutoff point (how "squealy" it is).
  • Res: filter resonance (how "squelchy")
  • EnvMod: the breadth of the filters sweep. Even with the envelope off (and no sweeping), the "true" cutoff point is actually a combination of the "cutoff" and "envmod".
  • Attack: the filter's envelope attack rate
  • Decay: the filter's envelope decay rate
  
  
  
• The FX region controls the running of the Rack's effects loop. There is only one at the moment, "fbdelay", which is a tempo-locked feedback delay unit.
  • feedback: controls the amount of feedback in the line
  • delay: controls the delay time
  
  
  
• The "Mixer" region to the right of the screen controls the mix:
  • Synth level controls the output amplitude of this particular synth.
  • Kit level controls the output amplitude of it's associated drum module.
  • Mix level controls the level of both parts together.
  • Pan controls the L/R panning of both synth and drum parts in the output mix.
  
  
  
• The region below the mixer has four sets of LFO controls. These give a variable rate Low Frequency variation on oscillator frequency ("make the sound warbly"), filter cutoff ("make the sound wobbly"), pan ("yay! spins me out"), and amplitude ("dunno, but try it"), respectively. The first in each set controls rate, the second, depth. The LFOs are reset with each note on, if the reset button is checked, otherwise not.
  
  
• The "Sequencer" field controls a few odd extended modes of the sequencer.
  • "normal" mode is what it is, an interminable loop.
  • "rand note" randomizes notes at the end of a sequencs,
  • "rand beat" randomizes the rhythmic pattern, leaving notes intact,
  • "rand all" does what it says: only for the brave, or lovers of aleoratic music.
  • "shuffle" picks a random memory bank sequence from between the first two sequences in the song list.
  • "song" mode plays the synth from the song field, loading synth &/or sequence parameters automatically from the indicated memory banks.
  • "one-shot" plays the sequence once and then stops. This is handy if you have something that you like scaring small children with, but don't want to be drilled into your head. Highly modulated noise at 300bpm is a case in point.

Main window: synth specific status region

The last region contains controls specific to individual running 303s.

• The left button sets the selected 303 to be "top" (i.e. under control of the screen sliders and buttons). It may have a different label if a different version of the 303 is running under it.
• The start/stop button does what it says...
• The "mute" checkbox turns sound off for this particular 303, without altering sequencer status.
• Next to this is the "sync" field. This gives a particular synth/sequencer to lock onto. When the indicated 303 hits the start of its cycle, this 303 will receive a start message from it, resetting it to its "beginning" note (note: not the sequence start point). This continues until the sync lock is turned off.
• The next field gives the midi receive channel. This takes precedence over the global receive setting.
• The next field gives the midi transmit channel. Control messages are sent from the sliders, and note on/off from the sequenceer. This can be damned useful for pre-hearing sequences if you have a midi keyboard and some headphones handy.
• The rest of the line gives sequencer status ("Play/Stop/Rec"), an indication of which area the 303's sequence was loaded from ("seqi" or "rand", or "stepi"), and a 3 digit indicator for the pan level of it's output (this can be useful for distinguishing between a number of running channels).

Main control window: keyboard shortcuts

• The function keys, f1-f8, are used to select a particular 303 and make it the top one. For this to work, the focus must be on the main window: you may have to hit a TAB or ENTER to do this to do this.
• In a similar manner, CTL-function key toggles the mute of the corresponding 303.
• SHIFT, in conjunction with the function keys starts/stops a sequencer.

Main window: miscellaneous system controls

• First is the number of the "top" 303, the one which is currently being controlled by the sliders and screen knobs. This appears in the upper left corner of the screen.
• Two fields in the upper right corner give the midi TX/RX port. This is currently only "midi1" and "midi2", but will eventually include a few surprises, such as our GeekPort object (in the planning stages), which, in the current state of play, may never see light.
• The two fields below this give channel nos for global midi TX/RX. These channels will send note, and most importantly, control data to whichever 303 is in the top display, irrespective of its own midi channel settings. This can be particularly useful for controlling the 303's from another controller: we have been using local mode on a Yamaha Promix.

The Bank Control Window

• The source and dest menu boxes select the source and destination banks for bank save/load operations.
• The "load sync" button specifies a synth to lock bank operations to. Normally bank operations are immediate. If this feature is activated, load operations will be finalised at the start of the corresponding synths loop.
• The Config button loads the spare configuration (left click) or stores the running one in the bank (right click).
• The bank exchange button swaps the synth and sequencer settings for the current (at present only) memory bank with the corresponding running values.
• The 8 big blue buttons load (left click) the source bank parameters of the correspoding slot into the slot corresponding to the "top" 303 in the destination bank. A right click reverses the direction of this process. Each button has 4 regions, ("drum", "seq", "slid" and "song") for each part of the data in that slot and bank. These regions are selected (highlighted in red) by moving the mouse into that region with the buttons down. On releasing the button, data from the selected bits is transferred. If, instead of releasing, the mouse is moved off the button, a rack icon appears, which can be dragged either to another bank button, or onto the song editor on the main window: if this is done, data is moved to/from the specified slot, rather than to the top one.

The Global Mix Window

The mix window provides an alternate set of controls for the total level of each running Rack747. This on the principle of "you never know what you might need in the bush".

This window allows edit access to the current kit. A kit has 128 slots for samples (numbered 0 to 127), each corresponding to a single drum. When the MIDI spec expands to include the drum module, the index will correspond to the midi note number for that drum.

The name field corresponds to the name that appears in the sequence editor for the particular drum. It is editted by holding down the cursor on that field until the text becomes highlighted, at which point, it may be changed.

The path field gives the full pathname for that sample, which need not be in the Rack "Kits" directory. A drum is added or changed by dragging a sample over the corresponding slot and dropping it. Currently, WAVE, AIFF and raw 16-bit 44100 mono files are properly understood.

This window allows the dumping of one or all of the Rack's loops directly to audio files. It is bought up under the main File menu. It is a standard save panel with 3 additional controls:

• a pull down menu to select the desired format (raw 16 bit stereo, wave or aiff).
• a counter to give the number of loops saved for each Rack747.
• a counter to select either "all" Racks, or any particular one (numbered from 0 on, of course).

When a name is given, the indicated Rack(s) will begin dumping their stuff from the start of their next loop (and will be started if necessary). The file will be called "TKi-name" for Rack i and a file called "name".

This feature is reachable through the "File" menu on the top menu bar. It allows the loading of a new pitch table into all current Racks. These are contained in ascii text files in an inimitably baroque format. Apologies to members of the Bach family.

The first line of the file gives three things:

• A text flag, either "fixed" indicating that the following frequencies will be set to just the indicated note numbers, or "transposed" indicating that the following frequencies represent an "octave" that will be set across the entire range of notes.
• An integer indicating the number of frequencies in the file.
• An integer, indicating the note number that these frequencies will be based from.

The rest of the file should be taken up by floating point numbers, indicating the relevant frequencies.

If the file is to be transposed, the "octave" given is certainly not limited to 12 notes. Whatever it's length, though, it will be started at the appropriate note, and spread. I can hear a sigh of relief from the 13 and 17 note equal temperament crew,

The distribution should contain two examples: "standard_pitch_table" is the standard 12 note equally tempered beast that we all know, and some love. "just_pitch_table" gives a 12 note octave based around a standard just (ptolemaic) scale based on C at 256Hz, with the standard accidentals filled in as best as possibly around this scale (1/1, 9/8, 5/4, 4/3, 3/2, 5/3, 15/8, 2/1). It's an interesting and beautiful scale, with many elegant properties.

Available addons

• Oasis: not a mirage(!). a multi looping sample player that will take the place of the linein and sample&hold oscillators. Actually, my second BeOS app, and about time it sees the light of day in one form or other.
• Twang: fucked up pluck string emulator, and my 3rd BeOS app.

Faq this, faq that

• How do I start a new track?
  Click the icon, use ALT-N or the FILE menu, or launch a Rack747 from a terminal. Bring the new Rack747 to the front display by hitting the corresponding button in the status area, or using the corresponding function key.
• What do all the numbers mean?
  I presume you mean the numbers in the sequence display: most of the others are arbitrary values between 0 and 1. The sequence numbers correspond to midi note no (pitch) and velocity (volume). With a standard pitch table, middle C corresponds to note no 72. With a non-standard pitch table, what you would call "C" is anybody's guess. Personally, I like this notation: it tells no lies, and tells the reasonable truth of "which midi values this note sends/receives". If anybody wants it badly enough, I'll include a pitch class/register notation (like "f#0" or "a#7") as an option. Any better ideas? You tell me ...
• Can the Rack be made more like ReBirth?
  Yes. Get a screen dump, convert it to GIF or JPG and replace the file "background" in the racks home directory. Apart from that, you'll need to cripple several synth and sequencer parameters, but add a record feature for slider values (this feature is great and is scheduled for Rack 1.02 or so).

MIDI specification

With a midi device selected, sequencer running, and transmit turned on, the sequencer will transmit note-ons and note offs for the current playing sequence. Rack glides are transmitted as seperate notes, as midi offers no consistent way of doing this. With or without the sequencer running, but with transmit on, the sliders will transmit midi control data to the appropriate channel.

With midi receive turned on, the rack will respond to noteons, noteoffs and controls. If the sequencer is running, midi note data is overriden, though it will get through briefly. If a noteon is received before the noteoff for the previous note, the rack will glide to that note. Otherwise, it will start a new attack.

The relationship between midi control change messages and sliders is:

• B_PAN controls the pan.
• B_MODULATION controls filter resonance.
• B_BREATH_CTRL controls the filter envmod.
• 0x10 controls the cutoff frequency.
• 0x11 controls the feedback.
• 0x12 controls the tempo.
• 0x13 controls the amplitude slider.
• 0x14 controls the LFO-1 rate.
• 0x15 controls the LFO-1 depth.
• 0x16 controls the LFO-2 rate.
• 0x17 controls the LFO-2 depth.
• 0x18 controls the LFO-3 rate.
• 0x19 controls the LFO-3 depth.
• 0x1a controls the LFO-4 rate.
• 0x1b controls the LFO-4 depth.
• controller 0x0c controls the delay factor.
• controller 0x0d controls the decay parameter.
• controller 0x0e controls the glide parameter.
• controller 0x0f controls the amplitude decay parameter.

Known Bugs and Limitations

• The default sequence gets very annoying.
• 0 is a valid midi note! But it won't get sent! So why am I exclaiming so much!? It should get sent. For the moment, just clap your hands 8.1 times a second, if you really want midi note 0. It'll appear eventually.
• AIFF files sampled at other than 44100 are problematic. This is a problem I have with 80-bit floats: they hurt my head.
• The Rack control protocol can get mangled if several are started within microseconds of each other. This is unlikely to happen without the help of a meta-sequencer such as Qua, or a frantic run of ALT-N startups,
• The alternate mix sliders on the mix window occasionally come up wrong.
• The size of the kit edittable through the kit window is limited. This is due to a problem with a system call (or my use of it) to enlarge shared areas of memory. This will only be apparent if you use the drum module for playing long samples and drum loops. The resizing fails once the area starts to get used. As a hack, I've allocated aa 2M area on startup, which should be enough to handle normal kit sound samples, and short breaks. At the moment, the best way to get heaps of really big samples is to stick them in the standard kit, which gets loaded at startup. Edit the file "Kits/standard" ( a normal text file) with your favourite editor. I find this as annoying as you do, and hopefully either the system call will be fixed in R4, or I'll figure out what stoopid thing I've done, and it'll be fixed real soon ...
• Control change information occasionally gets mangled. This happens somewhere between my keyboard and the BMidi interface, and might not be a problem on other setups.
• Patch files are not transportable between Intel and PPC versions: I haven't yet allowed for the endian thing for this stuff... doh!... This will be fixed in favor of big-endian files. As soon as the problem's fixed I'll provide a conversion utility for little-endian files.

Future directions.

In many ways, I've been surprised by the way the Rack has grown. Honestly, it was only going to be a 20k bassline emulator. But, at least for me, it's turned into quite a useful compositional sketch pad. It's been staunchly reliable live, and carried my but through gigs when every other machine has broken. I think, with the Om series, most of the work on the main engine is done: the proverbial 90% mark has been reached. It's a crude and simple architecture: great for the crude and simple music that we all love, and it's still comprehensible when your brain has been reduced to psycho-mulch. A few things still to go: integrating the drum module with the MIDI system, upgrading to the new Be media server (when it appears), maybe adding peak level meters, and extending the cross-fader's utility. Mainly though, I'll be creating a public API for add-ons (oscillators, filters, and effects), and writing a few myself. Currently in the wings are:

• Freaktal: wierd and noisy fractal waveforms for fun and profit.

The Om series Rack747 can be ordered directly from me, or via the usual Be web sites. Version 1.01 is a low $45US, or equivalent in australian dollars. All registered users will be entitled to regular updates of 1.xx BeOS versions of the rack and add-ons, irrespective of platform.

Details for credit card purchase of the full tab version should be finalised by late July,1998. However, BeDepot are being total slackheads, it's November, and they still can't give me a date (or even a "yes we will" or "no we won't": dickwads!).

Also of interest for Rack users will be the meta-sequencer, Qua, available in beta form by late July 1998. This package offers comprehensive hard disk recording, flexible MIDI sequencing and patching, and algorithmic composition facilities. It enables the Rack to be fully automated, controlled by joystick and Geekport (for us fortunate few) objects, and yet still be fully tweakable.

At this stage, I am also offering free licences to anybody willing to help translate documentation into any other languages that users may require.

The Rack was written by me, Dak, over 1997-1998, in between gigs, and under the influence of psycho-active substances.