The Brass Patch Collection


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This page contains a collection of G2 models meant to mimic brass instruments.  They are all physical models, based on the techniques described in these pages, with special attention paid to final equalization.


All instruments have been equalized to approximate the spectra of sampled instruments contained in the Garritan Personal Orchestra.  In fact, each instrument has been equalized twice, once to a quiet sample and once to a loud one.  The ‘Manliness’ knob morphs between the two timbres.


Each model on this page is a G2 performance, instead of a patch.  This is because each model requires 4 DSPs to generate the sound:  one DSP for the basic model, and three more for equalization.  The G2 expansion board is not required.




Equalization Technique


Brass equalization presents an interesting challenge.  First, the timbre depends on which note is played.  Second, as a brass instrument is played louder, its timbre changes in a significant and distinctive way.


To accomplish this, a 2-dimensional equalization technique is used in these models.  The first dimension is the note number, and the second is the player’s intensity.


A brass bell is basically a bandpass filter.  So the EQ circuit begins with a fixed highpass filter and a voltage-controlled lowpass filter in series, to approximate the passband.  A fixed parametric filter is added for additional trimming.  Finally, the sound goes through a 26-band voltage-controlled equalizer for final shaping.


The circuit has 28 voltage-controlled inputs: the overall volume, the cutoff frequency of the lowpass filter, and the gain controls of the 26-band equalizer.


Each control input is fed by a pair of G2 SeqCtr modules that are themselves controlled by the MIDI note number.  This provides the first dimension of control: the note number.


The outputs of each pair of SeqCtrs are blended together using crossfaders.  Within each pair, one SeqCtr is adjusted to match a quiet note, while the other matches a loud note.  The crossfader’s control input comes from a knob labeled ‘Manliness’.  This provides the second dimension of control: the intensity.


To equalize a particular note, the note is played on the model.  The spectrum is then compared to a sampled spectrum of that note, obtained from the Garritan Personal Orchestra.  The relevant SeqCtr values are adjusted until the spectrum is imitated.


In each case, the Garritan instrument chosen was the solo 1 instrument (Trumpet 1 Solo and Tenor Trombone 1 Solo).


To add the second dimension of control, the same process is repeated using the ‘overlay forte’ samples provided by the Garritan Personal Orchestra.  The second set of SeqCtr modules are adjusted until the model matches the Garritan instrument.




Sample MP3s


The following songs were recorded using these models.  Each model was controlled with Yamaha BC3 breath controller through a Kurzweil ExpressionMate, using variation 8 on slot 1.  The only post-processing added was a convolution reverb.






The Instruments


The models are below.  After each name is the instrument’s natural range.






Variation Programming


In each model, the following variations are programmed: