The Basic Organ
Here is where we’ll begin
making a basic pipe organ. Pipe organs
are basically “blown pipes”, and we’ve already done that, so we’re most of the
Some differences are:
- Organs are polyphonic. Our earlier pipes were monophonic, and
we eventually added extra logic to simulate the smooth note-to-note
transitions. That won’t be
- Organ pipes don’t have much expressive ability,
when compared to a flute or recorder.
It’s basically a pipe, a supply of compressed air, and a switch.
- When you press a key on an organ, multiple pipes
will usually sound. It’s similar to
the multiple drawbars a Hammond organ (the Hammond drawbars
were modeled after pipe organs).
- Most pipe organs have different kinds of pipes,
such as flutes, diapasons, and reeds.
Here, we’ll concentrate here
on flute pipes. We’ll begin with a
standard 8’ flute pipe (tuned like the 8’ drawbar on a Hammond organ). We’ll then begin adding more pipes for a richer
Our first 8’ pipe
Below is a patch for an 8’
organ pipe. It’s in two pictures. The second picture is the FX area, which
contains a reverb module. What’s a pipe
organ without reverb?
This patch is basically a
version of our earlier “blown pipe” model, with a few changes.
- It’s polyphonic.
It pretty much has to be.
- Most of the expressive ability has been
removed. After all, a pipe organ
rank isn’t terribly expressive. But
there’s another reason: care has
been taken to minimize the DSP usage of this patch. We’ll soon be adding more pipes, and we
want to preserve as much polyphony as we can.
- An additional SeqCtr module has been added for
fine-tuning the frequency of the loop’s lowpass filter. This lets us shape the tone of the pipe
across the keyboard. Note: as with all lowpass filters in the loop,
changing the cutoff frequency will throw the note out of tune, and require
some pitch correction using the pitch SeqCtrs.
What are the controls?
Looking at the Parameter
Overview, the controls are pretty simple:
and fine transposition controls: This lets us transpose and
tune the patch.
level: This is a crossfader that varies the input
air level from 40 to 46 Clavia units.
level and color: Shapes the amount and color of the air
hissing in the pipe. We could
certainly appreciate something more interesting here, like a vocal filter,
but we’re trying to minimize DSP usage.
envelope: Controls the attack and release times of
the incoming air.
- Reverb: Gotta
include this in any pipe organ patch!