Keywords: Blue, Csound

BlueX7
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### BlueX7

### Note

This instrument is currently undergoing re-implementation.

A 6 Operator Phase Modulation instrument using Russell Pinkston's DX7 Emulation Patches.

The BlueX7 editor contains two tabs, the 'patch' tab, where the sound creation parameters are tweaked and a second tab called 'csound' which can contain further post-processing algorithms or special routing of the instrument's output.

The patch tab contains three panels: Common, LFO and operators. The common panel deals with global aspects of the instrument like transposition, FM algorithm used, feedback, operator enable/disable and LFO characteristics. The transposition made by Key Transpose is handled in half-tones, with C3 being the normal (central) pitch.

There are 32 algorithms to choose from which represent the original DX7 possibilities. You can see a visual representation of the algorithm on the left of this panel.

Feedback represents the amount of feedback into a modulator. The position and result of this feedback depends entirely on the algorithm used. The range of feedback is 0 to 7(this range is the same as on the original DX7). The operator on/off checks turn on and off operators (current, this is here but the emulation patches do not use them).

The LFO panel sets the global LFO parameters. The parameters are: Speed, Delay, PMD (Pitch Modulation Depth) and AMD (Amplitude Modulation Depth). They all have ranges from 0 to 99(the range is the same as on the original DX7). Additionally you can select the shape of the LFO from: triangle, saw up, saw down, square, sine and sample-and-hold. You can also sync the operators: if sync is on, changing Modulation Sensitivity for pitch (marked with an asterisk *) on any of the operators will affect the rest.

Finally you have the 6 operators plus an envelope generator (PEG) each on its own tab. All six operators have the same parameters divided in the following sections:

- Oscillator

- Keyboard Level Scaling

- Operator

- Modulation sensitivity

- Envelope Generator

An important feature of the BlueX7 is that it can import DX7 banks. A large collection can be found in the bigdx7.zip file within the dx72csound.zip file from: http://www.parnasse.com/dx72csnd.shtml. (to steven: reading this page it seems part of the model is unfinished, which may answer some of my questions above)

On the 'csound' tab you find by default:

    blueMixerOut aout, aout

This routes the output of the instrument directly to the stereo output of csound. You can include further code to process the 'aout' signal produced by the BlueX7, or to route it as needed. For example, if you are outputing in mono, you could code such as:

    out aout

To call the BlueX7 instrument in the orchestra, create a GenericScore object in the timeline, and call the the BlueX7 instrument. BlueX7 requires 2 additional p-fields. P-field 4 is the pitch class of the note in format octave.semitone (e.g. C4 is 4.00, C#1 is 1.01 and F6 is 6.05). P-field 5 contains the midi velocity for the note with values from 0 to 127. For example:

    i1 0 1 8.00 100
    i1 + 1 8.02 100
    i1 + 1 8.04 100
    i1 + 1 8.05 100
    i1 + 1 8.07 100

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