10.6

32Logic Pro Instruments
The filter is assigned to track keyboard pitch. By default, the centered knob at 523Hz
provides a medium pitched sound that works well. If you want to change the octave,
multiply or divide by two, and round to the nearest whole number that sounds best. For
example, set the Frequency knob at 262Hz for one octave lower.
6. Adjust the modulation Depth on the filter to increase the impact the source signal has
on the sine wave generated by the FM filter, and listen to the results. For more grit, try
adjusting the Feedback control, which allows the filter output to apply modulation to
itself.
7. FM in Alchemy requires experimentation to develop more complex sounds. Here are a
few things to try:
• Use other types of VA oscillators or samples as your modulation source.
• Run multiple FM filters in series or parallel to see what best meets your needs. When
doing so, resist high initial modulation and feedback depths so you can get a feel for
the degree of control you have in shaping the overall sound.
• Use independent envelopes for the frequency and volume of your source (or on FM
filters earlier in the signal path) to hear the results this provides.
Important: Due to technical requirements, FM is often best done at the source filter
level. As you progress through the signal path, gain increases (and therefore FM)
become increasingly heavily modulated and distorted. You will find that it is easier to
work with FM at the source level than as a master filter or effect.
Use a comb filter as a sound source
When making comb filters your primary sound source, you may find that longer master
envelope release settings are required for a natural feel when playing. This results in more
overlapping notes, higher polyphony, and therefore more CPU overhead. Because of this,
you may need to carefully adjust envelope release times and reduce the maximum number
of voices in the Master section.
1. In Logic Pro, from the Name bar, click the File button and choose Initialize Preset from
the pop-up menu to reset all Alchemy parameters to default settings.
2. Switch to advanced view, then click the A button to show source A parameters.
3. Click the source A filter On button to enable the filter, then choose Comb PM from the
Filter type pop-up menu.
4. Control-click the Frequency knob, and choose Envelope Follower >Source A.
The filter is assigned to track keyboard pitch. By default, the centered knob at 523Hz
will provide a medium pitched sound that works well. If you want to change the octave,
multiply or divide by two, and round to the nearest whole number that sounds best. For
example, set the Frequency knob at 262Hz for one octave lower.
5. Control-click the Volume knob for source A (choose the lowest feasible level), and
assign a New AHDSR from the menu.
6. Set up an envelope for your impulse signal to excite the comb filter. You can choose any
impulse type, from VA noise to resynthesized samples. The aggressive nature of FM
also makes this a good choice of impulse for comb filters.