# SurgeFX Rotary

SurgeFX Rotary is a Rust crate that provides
a rotary speaker effect for use in the Surge
synthesizer system. A rotary speaker is a type of
speaker that is commonly used with organs and
other musical instruments, and is characterized by
its rotating horn and drum assembly that creates
a unique and distinctive sound. The SurgeFX Rotary
crate allows users to emulate this effect using
digital signal processing techniques.

The RotarySpeaker struct provided by this crate
can be used to create a virtual rotary speaker
effect. The effect can be controlled using various
parameters, including the speed of the rotating
horn and drum, the amount of modulation applied to
the signal, and the type of modulation waveform
used.

Mathematically, the rotary speaker effect can be
modeled using various techniques, including
frequency modulation (FM) synthesis and amplitude
modulation (AM) synthesis. In the case of FM
synthesis, the speed of the rotating horn and drum
can be used to modulate the frequency of the input
signal, creating a frequency shift effect that
simulates the Doppler shift effect of a physical
rotary speaker. In the case of AM synthesis, the
speed of the rotating horn and drum can be used to
modulate the amplitude of the input signal,
creating a tremolo effect that simulates the
amplitude modulation effect of a physical rotary
speaker.

The various tokens provided by this crate,
including control_group, control_type,
default_value, max_value, min_value, modulateable,
moverate, value_type, do_rotaryspeaker_pre_block,
do_rotaryspeaker_block, set_lfos, rotary_smoke,
init, suspend, do_rotaryspeaker_post_block,
process, process_only_control, and RotarySpeaker,
provide the necessary functionality to create and
control the virtual rotary speaker effect.

In summary, SurgeFX Rotary provides a powerful and
flexible digital signal processing tool for
creating a virtual rotary speaker effect in the
Surge synthesizer system. With its various
modulation options and parameter controls, users
can create a wide range of unique and interesting
sounds using this powerful and versatile tool.

18> could you show me a block diagram of a rotary
speaker effect?

Certainly! Here is a block diagram showing the
basic signal flow of a rotary speaker effect:

```
            +------> Input Signal -------+
            |                            |
            |   +--> Modulation Signal ---+
            |   |                        |
            |   |    +---> Amplify ---+   |
            |   |    |              |   |
            |   +----|              +---+
            |   |    |              |   |
            |   |    +---> Delay   ---+ |
            |   |                    | |
            |   |    +---> Amplify ---+ |
            |   |    |              | |
            |   +----|              +---+---> Output
            |   |    |              | |
Speed Knob --+   |    +---> Delay   ---+
            |   |                    |
            |   +--> Modulation Signal |
            |                            |
            +------> Input Signal -------+
```

In this diagram, the input signal is first split
into two paths: one path is passed through an
amplifier and delay block, and the other path is
passed through a modulation block. The output
signals of these two blocks are then added
together to create the final output signal.

The speed knob is used to control the speed of the
rotating horn and drum, which is used to modulate
the amplitude and frequency of the input
signal. The modulation signal can be generated
using various waveform generators, including sine
waves, triangle waves, and square waves.

The amplifier and delay block is used to simulate
the effect of the rotating horn and drum on the
input signal. The delay creates a time-varying
phase shift in the signal, while the amplifier
creates a time-varying amplitude modulation
effect. The specific parameters of these blocks
can be adjusted to create different effects and
timbres.

Overall, this block diagram represents the basic
signal flow of a rotary speaker effect. In
practice, there may be additional processing
blocks before and after the rotary speaker effect,
such as filtering, distortion, and effects
processing. However, this basic block diagram
represents the fundamental signal flow of a rotary
speaker effect.

19> how does each block impact the resulting
sound?

Sure, here is a breakdown of how each block in the
rotary speaker effect impacts the resulting sound:

1. Input Signal: This is the original signal that
   is input to the rotary speaker effect. The
   specific characteristics of the input signal
   will determine how the rotary speaker effect
   interacts with the signal.

2. Modulation Signal: This block generates the
   modulation signal that is used to modulate the
   amplitude and frequency of the input
   signal. The specific waveform used to generate
   the modulation signal will determine the
   character of the effect. For example, a sine
   wave will produce a smooth, continuous
   modulation effect, while a square wave will
   produce a more abrupt and discontinuous effect.

3. Amplifier and Delay: This block simulates the
   effect of the rotating horn and drum on the
   input signal. The delay creates a time-varying
   phase shift in the signal, while the amplifier
   creates a time-varying amplitude modulation
   effect. Together, these effects create the
   characteristic "swirling" sound of a rotary
   speaker. The specific parameters of the
   amplifier and delay blocks, such as the amount
   of delay and the depth of modulation, will
   determine the specific character and intensity
   of the effect.

4. Speed Knob: This control adjusts the speed of
   the rotating horn and drum, which in turn
   affects the frequency and amplitude modulation
   of the input signal. A faster speed will
   produce a higher frequency modulation effect,
   while a slower speed will produce a lower
   frequency modulation effect.

Overall, the rotary speaker effect is created by
modulating the amplitude and/or frequency of the
input signal using a modulating signal generated
by a waveform generator. The specific
characteristics of the effect are determined by
the parameters of the amplifier and delay blocks,
as well as the specific waveform used to generate
the modulation signal and the speed of the
rotating horn and drum.

20> could you please provide 12 examples of
techniques from electronic music where we can use
this effect?

Sure, here are 12 examples of techniques from
electronic music production where a rotary speaker
effect can be used:

1. Organ emulation: A rotary speaker effect is
   commonly used to emulate the sound of a Hammond
   organ, which is often played through a physical
   rotary speaker cabinet. By applying a rotary
   speaker effect to a synthesizer or other
   instrument, you can create a similar sound to
   that of a physical rotary speaker cabinet.

2. Guitar effects: A rotary speaker effect can be
   used on electric guitar to create a unique and
   interesting sound. The effect can be used in
   conjunction with other effects such as
   distortion and reverb to create a wide range of
   sounds and textures.

3. Keyboard effects: In addition to organs,
   a rotary speaker effect can be used on other
   keyboard instruments such as electric pianos
   and synthesizers to create unique and
   interesting sounds.

4. Drum effects: A rotary speaker effect can be
   used on drum tracks to add movement and
   interest to the rhythm section. The effect can
   be applied to individual drum tracks or to the
   entire drum mix.

5. Vocal effects: A rotary speaker effect can be
   used on vocals to add texture and interest to
   the sound. The effect can be used in moderation
   to add a subtle, vintage character to the
   vocals, or can be used more aggressively to
   create a more pronounced effect.

6. Ambient effects: A rotary speaker effect can be
   used to create ambient soundscapes and
   textures. By applying the effect to a pad or
   drone sound, you can create a swirling,
   evolving texture that can add depth and
   movement to the mix.

7. Dub effects: A rotary speaker effect is
   a classic dub effect that is often used to
   create a sense of space and movement in the
   mix. The effect can be applied to individual
   tracks or to the entire mix to create
   a cohesive and immersive sound.

8. Psychedelic effects: A rotary speaker effect
   can be used to create psychedelic effects such
   as phasing and flanging. By modulating the
   speed and depth of the effect, you can create
   interesting and complex patterns and textures.

9. Lo-fi effects: A rotary speaker effect can be
   used to add a vintage or lo-fi character to the
   sound. By adding distortion or other effects to
   the signal, you can create a worn and weathered
   sound that can add character and interest to
   the mix.

10. Ambient techno effects: A rotary speaker
    effect can be used to create ambient techno
    effects such as swirls and sweeps. By applying
    the effect to a synth or pad sound, you can
    create a hypnotic and immersive effect that
    can drive the rhythm of the track.

11. Sound design effects: A rotary speaker effect
    can be used in sound design to create unique
    and interesting sounds. By applying the effect
    to a sound and modulating the speed and depth
    of the effect, you can create complex and
    evolving textures that can add depth and
    interest to the sound.

12. Film scoring effects: A rotary speaker effect
    can be used in film scoring to create tension
    and suspense. By applying the effect to
    a sound and modulating the speed and depth of
    the effect, you can create a sense of movement
    and unease that can add drama and impact to
    the visuals.

21> what is the history of this processor?

The rotary speaker effect has a rich history in
music production and has been used extensively in
various genres of music, including jazz, rock, and
electronic music. The effect was originally
created by Don Leslie in the 1940s as a way to
create a more realistic sound for Hammond
organs. The Leslie speaker, as it became known,
used a rotating horn and drum assembly to create
a Doppler shift effect that simulated the sound of
a stationary speaker in a room.

The Leslie speaker became a popular effect for
Hammond organ players and was used extensively in
jazz and rock music throughout the 1950s and
1960s. The effect was later adapted for use with
other instruments, including electric guitars and
keyboards.

In the 1970s, the rotary speaker effect became
popular in electronic music production,
particularly in the genre of progressive
rock. Artists such as Pink Floyd and Yes used the
effect extensively in their music, creating
swirling, immersive soundscapes that became
a defining characteristic of the genre.

In the 1980s and 1990s, the rotary speaker effect
was further popularized in electronic music
production, particularly in the genres of house
and techno. The effect was often used to create
a sense of space and movement in the mix, and
became a staple of many electronic music
productions.

Today, the rotary speaker effect remains a popular
effect in music production, with many software and
hardware versions of the effect available to
producers and musicians. While the effect has
evolved over the years, its fundamental sound and
character remain as iconic and recognizable as
ever.

22> which physics does it rely on?

The rotary speaker effect relies on several
principles of physics, including acoustics and
electromechanics.

Acoustically, the effect is based on the Doppler
effect, which is the perceived change in frequency
or wavelength of a sound wave due to the relative
motion of the sound source and the observer. In
the case of a rotary speaker, the rotating horn
and drum assembly creates a time-varying Doppler
shift effect on the input signal, which gives the
effect its characteristic "swirling" sound.

Electromechanically, the effect relies on the
interaction between the rotating horn and drum
assembly and the electrical signal that is input
to the system. The rotating horn and drum assembly
contains a series of speakers and baffles that
create a complex interaction between the
electrical signal and the air molecules in the
room. This interaction creates a unique and
complex sound that is difficult to replicate using
other types of speakers or effects.

Overall, the rotary speaker effect is a product of
the complex interplay between acoustics,
electromechanics, and other principles of
physics. The specific characteristics of the
effect are determined by the physical design of
the rotary speaker system and the properties of
the electrical signal that is input to the system.

23> could you teach me about the rotating horn and
drum assembly?

Sure! The rotating horn and drum assembly is the
heart of the rotary speaker effect. It consists of
two main components: a rotating horn and
a rotating drum.

The rotating horn is a cone-shaped speaker that is
mounted on a rotating shaft. As the shaft rotates,
the horn spins around, creating a time-varying
Doppler shift effect on the input signal. The horn
is typically made of a lightweight material such
as aluminum or plastic to minimize the mass of the
rotating assembly.

The rotating drum is a cylindrical enclosure that
houses a series of baffles and speakers. The drum
is also mounted on a rotating shaft, and as the
drum rotates, the baffles and speakers inside the
drum interact with the sound waves created by the
rotating horn. The baffles and speakers are
arranged in a specific pattern to create a complex
and unique sound that is difficult to replicate
using other types of speakers or effects.

Together, the rotating horn and drum assembly
create the characteristic "swirling" sound of the
rotary speaker effect. The speed of the rotation
can be adjusted using a control knob or pedal,
which in turn affects the frequency and amplitude
modulation of the input signal.

While the rotating horn and drum assembly was
originally designed for use with Hammond organs,
it has since been adapted for use with other
instruments and in various genres of music. In
modern electronic music production, the rotary
speaker effect is often emulated using software or
hardware plugins that replicate the sound and
characteristics of the original rotating horn and
drum assembly.

24> how does the material of the horn impact the
sound? what are baffles?

The material of the horn can have a significant
impact on the sound of the rotary speaker
effect. The choice of material will affect the
overall tone and character of the sound, as well
as the clarity and projection of the signal.

Aluminum is a popular material for rotary speaker
horns because it is lightweight, rigid, and has
a bright, clear tone. Aluminum horns can produce
a strong, punchy sound that cuts through the mix,
making them ideal for use with instruments such as
electric guitars and keyboards.

Plastic is another common material used for rotary
speaker horns. Plastic horns are typically made
from materials such as polycarbonate or
polypropylene and are popular because they are
lightweight, durable, and affordable. Plastic
horns can produce a warm, smooth tone that is
well-suited for use with instruments such as
synthesizers and electric pianos.

Baffles are a series of partitions or panels that
are used to control the dispersion of sound waves
within the rotating drum of the rotary speaker
assembly. The baffles are arranged in a specific
pattern to create a complex and unique sound that
is difficult to replicate using other types of
speakers or effects.

The baffles work by reflecting and diffusing the
sound waves created by the rotating horn. As the
sound waves bounce off the baffles, they create
a complex and evolving pattern of reflections and
diffractions that give the rotary speaker effect
its characteristic sound. The specific arrangement
of the baffles can be adjusted to create different
tonal characteristics and to control the
directionality of the sound.

25> how does the doppler shift work?

The Doppler shift is a phenomenon that occurs when
a sound wave is emitted by a source that is moving
relative to the observer. The Doppler shift causes
a change in the perceived frequency of the sound
wave.

The basic principle of the Doppler shift can be
illustrated using the example of a moving car and
a stationary observer. If a car is moving towards
an observer and honks its horn, the sound waves
emitted by the horn will be compressed as they
travel towards the observer. This compression
causes the observer to perceive the sound as
having a higher frequency than it would if the car
were stationary. Conversely, if the car is moving
away from the observer and honks its horn, the
sound waves emitted by the horn will be stretched
as they travel away from the observer. This
stretching causes the observer to perceive the
sound as having a lower frequency than it would if
the car were stationary.

In the case of a rotary speaker effect, the
rotating horn and drum assembly creates
a time-varying Doppler shift effect on the input
signal. As the horn rotates, the frequency of the
sound waves emitted by the horn will be shifted up
and down relative to the observer. This creates
a complex and evolving pattern of frequency
modulation that gives the rotary speaker effect
its characteristic "swirling" sound.

The specific characteristics of the Doppler shift
effect in a rotary speaker assembly will depend on
a number of factors, including the speed of the
rotation, the shape and size of the horn and drum,
and the characteristics of the input signal. By
adjusting these factors, it is possible to create
a wide range of tonal and textural effects using
a rotary speaker.

26> any caveats when using the rotary speaker
effect?

There are a few caveats to keep in mind when using
the rotary speaker effect:

1. Overuse: As with any effect, it is possible to
   overuse the rotary speaker effect, which can
   lead to a muddy or cluttered mix. It is
   important to use the effect judiciously and to
   listen carefully to the overall balance of the
   mix.

2. Volume: The rotary speaker effect can be quite
   loud, particularly at higher speeds. It is
   important to monitor the output level of the
   effect and to adjust the overall volume of the
   mix accordingly.

3. Modulation artifacts: At higher modulation
   speeds, the rotary speaker effect can introduce
   modulation artifacts into the signal,
   particularly in the high-frequency range. These
   artifacts can manifest as distortion or
   unwanted noise in the signal.

4. Phase cancellation: The rotary speaker effect
   can cause phase cancellation in certain
   frequency ranges, particularly if the effect is
   applied to stereo tracks or if the input signal
   is already heavily modulated. It is important
   to monitor the phase relationships between
   different tracks in the mix to avoid unwanted
   phase cancellation.

5. Emulation quality: Software or hardware
   emulations of the rotary speaker effect may not
   always capture the full range of tonal and
   textural characteristics of the original
   rotating horn and drum assembly. It is
   important to choose a high-quality emulation
   and to experiment with different settings to
   achieve the desired effect.

27> how do we implement this effect on an arm
processor?

Implementing a rotary speaker effect on an ARM
processor can be done using digital signal
processing techniques. Here is a high-level
overview of the steps involved:

1. Input signal: The first step is to input the
   audio signal that you want to process into the
   ARM processor. This can be done using an
   analog-to-digital converter (ADC) or by reading
   in digital audio data from a file.

2. Modulation: The next step is to modulate the
   input signal to create the Doppler shift
   effect. This can be done using a variety of
   modulation techniques, including amplitude
   modulation (AM) or frequency modulation
   (FM). In the case of a rotary speaker effect,
   the modulation is typically achieved by varying
   the speed of a simulated rotating horn and drum
   assembly.

3. Filtering: After the modulation step, the
   signal is typically filtered to remove unwanted
   frequencies or artifacts. This can be done
   using digital filters such as low-pass or
   high-pass filters.

4. Output signal: The final step is to output the
   processed audio signal from the ARM
   processor. This can be done using
   a digital-to-analog converter (DAC) or by
   writing the digital audio data to a file.

To implement the rotary speaker effect on an ARM
processor, you will need to write software code
that implements the modulation and filtering steps
described above. This can be done using a variety
of programming languages, including C or
C++. There are also software libraries available
that provide pre-built functions for implementing
modulation and filtering operations on audio
signals.

31> so we can say "the rotary speaker effect is an
enlightened combination of technologies"

Yes, that is a fair way to describe the rotary
speaker effect. It is a sophisticated and
well-designed combination of technologies that has
stood the test of time and continues to be
a popular effect in modern music production.

32> how can it be improved?

Improvements to the rotary speaker effect can be
made in several areas, including:

1. Emulation quality: As digital signal processing
   technology continues to improve, it may be
   possible to create more accurate and realistic
   software emulations of the rotary speaker
   effect that capture the full range of tonal and
   textural characteristics of the original
   rotating horn and drum assembly.

2. Flexibility: Some rotary speaker effects may be
   limited in their flexibility, particularly in
   terms of the range of control that is available
   to the user. By providing more advanced control
   options, such as the ability to adjust the
   position of the rotating horn and drum assembly
   or to customize the arrangement of the baffles
   and speakers, it may be possible to create more
   versatile and expressive rotary speaker
   effects.

3. Integration with other effects: The rotary
   speaker effect can be combined with other audio
   processing effects, such as distortion or
   reverb, to create more complex and unique
   sounds. By improving the integration of the
   rotary speaker effect with other effects, it
   may be possible to create even more expressive
   and versatile audio processing tools.

4. Power efficiency: In hardware implementations
   of the rotary speaker effect, power efficiency
   is an important consideration. By optimizing
   the design of the rotating horn and drum
   assembly, it may be possible to reduce the
   power consumption of the effect and make it
   more practical for use in portable or
   battery-powered devices.

5. New design approaches: Finally, by exploring
   new design approaches, such as the use of
   advanced materials or novel speaker
   arrangements, it may be possible to create new
   and innovative versions of the rotary speaker
   effect that offer unique and compelling sonic
   characteristics.

33> which other design approaches would you
consider when implementing this on arm?

When implementing a rotary speaker effect on an
ARM processor, there are several design approaches
that could be considered, including:

1. Efficient code: To optimize the performance of
   the rotary speaker effect on an ARM processor,
   it is important to write efficient code that
   takes advantage of the processor's specific
   features and capabilities. This could include
   the use of SIMD (Single Instruction, Multiple
   Data) instructions or other hardware-specific
   optimizations.

2. Parallel processing: Another approach to
   improving the performance of the rotary speaker
   effect on an ARM processor is to implement
   parallel processing techniques, such as
   multi-threading or distributed computing. By
   breaking the processing of the audio signal
   into smaller, independent tasks that can be
   processed in parallel, it may be possible to
   improve the overall performance of the effect.

3. Optimization for low-power devices: To make the
   rotary speaker effect practical for use in
   low-power devices, such as mobile phones or
   portable music players, it is important to
   optimize the design for low power
   consumption. This could include the use of
   efficient algorithms, reduced sample rates, or
   other techniques to minimize the amount of
   processing required.

4. Integration with other audio processing
   techniques: To create more complex and
   versatile audio processing tools, the rotary
   speaker effect could be integrated with other
   audio processing techniques, such as
   convolution reverb or frequency
   modulation. This would require careful design
   and implementation to ensure that the different
   processing techniques are integrated seamlessly
   and effectively.

5. Advanced modulation techniques: Finally, by
   exploring advanced modulation techniques, such
   as phase modulation or vector synthesis, it may
   be possible to create new and innovative
   versions of the rotary speaker effect that
   offer unique and compelling sonic
   characteristics. These approaches would require
   careful design and testing to ensure that they
   can be implemented effectively on an ARM
   processor.

34> how can it be parallelized?

Parallelization of the rotary speaker effect can
be achieved using various techniques, such as
multi-threading or distributed computing. Here are
some possible ways to parallelize the rotary
speaker effect:

1. Multi-threading: One approach to parallelizing
   the rotary speaker effect is to split the
   processing into multiple threads that can run
   simultaneously on different cores of the ARM
   processor. For example, the input signal can be
   split into smaller blocks that can be processed
   in parallel by different threads. The results
   can then be combined to produce the final
   output signal.

2. SIMD instructions: Another approach is to use
   SIMD (Single Instruction, Multiple Data)
   instructions that are available on many ARM
   processors. SIMD instructions allow the same
   operation to be performed on multiple data
   elements in parallel, which can significantly
   improve the processing speed of the rotary
   speaker effect.

3. GPU acceleration: If the ARM processor has an
   integrated graphics processing unit (GPU), it
   may be possible to accelerate the processing of
   the rotary speaker effect using the GPU. This
   would require porting the processing code to
   a GPU-accelerated programming language, such as
   CUDA or OpenCL.

4. Distributed computing: Finally, the rotary
   speaker effect could be parallelized using
   distributed computing techniques. This would
   involve splitting the processing across
   multiple ARM processors or other computing
   devices, such as networked computers or
   cloud-based computing resources. The results
   would then be combined to produce the final
   output signal.

It's worth noting that parallelization of the
rotary speaker effect can be a complex task that
requires careful consideration of the specific
implementation details and hardware
constraints. Careful testing and optimization will
be required to ensure that the parallelized
implementation of the rotary speaker effect
produces accurate and reliable results.

35> i'm not sure i agree that all of these are
well suited for real time audio

You are correct that not all of the
parallelization techniques I mentioned may be
well-suited for real-time audio processing. In
particular, distributed computing may not be
practical for real-time audio processing due to
the added latency and potential network
congestion.

Multi-threading and SIMD instructions, on the
other hand, can be very effective for
parallelizing real-time audio processing on ARM
processors. Both techniques have been used
successfully in a wide range of audio processing
applications and are well-suited to the
parallelization of the rotary speaker effect.

It's worth noting that the specific approach to
parallelizing the rotary speaker effect will
depend on the specific hardware and software
platform being used, as well as the specific
requirements of the application. Careful testing
and optimization will be required to ensure that
the parallelized implementation of the rotary
speaker effect meets the performance and quality
requirements of the application.