This is a list of known mistakes and bugs in the book Creating Synthesizer Plug-Ins with C++ and JUCE and/or the accompanying source code.
Chapter 3, page 66 says:
The maximum frequency the signal can contain is known as the Nyquist limit. When using a sampling rate of 44.1 kHz, the Nyquist limit is 22.5 kHz, and the sampled signal can faithfully represent any frequencies lower than 22500 Hz — well above the hearing range of humans. But frequencies higher than 22.5 kHz won't work.
The Nyquist limit at a sampling rate of 44.1 kHz is 22.05 kHz or 22050 Hz, not 22500. Thanks @metajack
Chapter 6, page 125 says:
The while loop adds up sine waves until it reaches the Nyquist limit. The sine values are accumulated in the variable
y.
The variable is not named y but output.
Chapter 11, page 288 says to add a new method updatePeriod and then replace the corresponding lines of code in Synth::render with call to updatePeriod(voice);
However, at the top of p.289 the code still does the following:
for (int v = 0; v < MAX_VOICES; ++v) {
Voice& voice = voices[v];
if (voice.env.isActive()) {
voice.osc1.period = voice.period * pitchBend;
voice.osc2.period = voice.osc1.period * detune;
voice.glideRate = glideRate; // add this line
}
}It should be:
for (int v = 0; v < MAX_VOICES; ++v) {
Voice& voice = voices[v];
if (voice.env.isActive()) {
updatePeriod(voice);
voice.glideRate = glideRate;
}
}The synth works OK with the old lines, but using updatePeriod here is cleaner.
(Also note that updatePeriod does not actually have to be declared inline since it's placed inside the class definition in the .h file. Such methods are considered inline by default.)