Parameter Sections and Groups provide a means of performing the following operations on multiple parameters simultaneously:

• Resetting
• Locking
• Randomizing

Parameter Sections

Parameter sections are determined by the hierarchy of "windows" in the UI (rectangular divisions of user interface display constructs). There are sections for the whole Operator, the full Envelope section (Envelope + Loop + Scaling), the Envelope curve (Envelope), the Envelope loop, and the Key-Scaling controls.

Apply an action to all parameters of a section by performing the operation (mouse + modifiers) on an empty section of the window.

Parameter Groups

Parameter groups are parameters that are logically related.

Apply an action to all parameters of a group by performing the operation (mouse + modifiers) on one parameter within the group and adding the +Alt modifier.

Multi-Op Randomization

Randomization can be applied to the following parameters or parameter groups across all 6 Operators with the addition of the +Ctrl modifier:

• Frequency
• Amp
• Waveform • Sync Phase • Depth
• FB Amt • FB In Op

Aurora FM is now 4-part multitimbral, meaning an instance can now consist of up to 4 different timbres or parts. Parts can be stacked / layered / spread however you like depending on the assigned MIDI channel and Key Range.

What was previously called a Patch is now called a Part, and Patches now consist of 1-4 of these Parts. Parts consist of all the parameters for a timbre, and the Patch only contains:

• The 1-4 Parts
• The Reverb, as a parallel effect, which can be fed by the desired Parts

Click on an unselected Part to make it the Active Part. The controls of the synth edit the parameters of the Active Part.

Note: The Part Level and Pan controls in the Parts list are the same parameters as the Part Level and Pan controls in the main synth window. They've been duplicated to facilitate mixing Parts with respect to each other.

Aurora FM also loads most Yamaha DX/TX .syx SysEx single patch and 32-patch bank files.

As the Aurora FM synthesis engine is fundamentally completely different than the Yamaha FM synthesizers, the patches are translated/mapped to corresponding Aurora FM parameter values using calculations based on publicized DX/TX parameter ranges and implementation details. The patch translation is respectable but not guaranteed to be 100% optimal in all cases. Aurora FM will inherently never be an accurate emulation of a DX7 or other Yamaha FM synthesizer as that was never the intention - it is not an emulator. Aurora FM has a high-resolution 32-bit float engine employing completely proprietary calculations for all components. (However, if you have quantifiable information on how my translation efforts deviate from the ideal, please don't hesitate to get in touch with me. I would like to make the DX/TX parameter translation as close to accurate as possible.)

By importing Yamaha patches, Aurora FM opens you to the world of thousands of DX7/etc. patches that have been created and circulated over the years. You can use them as-is, or tweak and extend them with Aurora FM's superior precision, modulation, and character.

If a .syx single patch or patch bank fails to load, it's most likely because the file isn't valid, but if you know that Aurora FM is failing to load a valid Yamaha DX/TX patch, please let me know and I'll investigate.

Click & Hold on the Patch selector/ one of the Part selectors to pop open the navigator / selector.

Double-click on the selector to begin editing the name. When you're finished, hit Enter, Tab, or click somewhere outside of the edit box.

Names are ASCII-only strings up to 32 characters, as allowed by the VST2 standard. If entering a space causes your transport to start and stop, try using Shift+space (this works in Reaper).

Scrollwheel over the selector to increment/decrement the Patch / Part. Every Patch / Part will be accessed sequentially according to its order in the tree of items. The Patch tree structure will be explained next.

The "Patch Tree" is a tree structure that contains any/all of the following things:

• the Init patch
• the Factory Demo Patches bank (assuming you unzipped it along with the plugin)
• directories:
  • subdirectories of the DLL directory if they contain relevant items
  • the User Patch Dir, if you've specified one
• banks, patches:
  • any Banks or Patches in your DLL directory
  • the Host state patch if any
  • any new/copied unsaved Banks or Patches that you haven't committed to a file
• and lastly, two commands, Load... and Manage..., that appear in the Patch selector, but not in the Part selector

You can override the factory Init Patch with one of your own patches.

If using the factory Init Patch, you can specify how many Init Parts, 1-4, you want it to have.

This is where you specify the location of the directory that you want to use for storing your Patches, Banks, and sysex.
This directory, along with the directory of the plugin DLL, are the two filesystem directory trees that will get fully scanned for Banks and Patches which will be loaded into the Patch tree.

Save the current Bank, if the current Patch is in a Bank and the Bank needs saving.

If the current Patch is from a single Patch file and has changes, this saves it.
If the current Patch is from a Bank, saves it as a new single Patch file.

This is the new window for drag & drop Bank management.

The Init Patch override and Patch Dir settings live here.

Editable banks appear in the list on the Destination side. This includes your own user Banks and excludes the Factory Patch Bank.

The entire loaded Patch tree appears in the Bank / Patch Browser list on the Source side just like it does in the main Patch selector.

Double-click a patch to load it.

To get started with your own Patch Bank, you'll first need to click New Bank, then Double-click the new Bank's name to edit it and give it an appropriate name.

From there, select source Patches and drag&drop them into the new destination Bank. The default action inserts the Patch into the next slot under the cursor, or you can hold Ctrl to replace the Patch under the cursor instead.

You can also drag Parts from a Source Patch to a Destination Patch, but realistically you're probably going to compose your Patches from the synth and not from here.

Select a Patch or Part and hit the Delete key to remove it.

Click Save Bank to save the selected Bank to file (afmb format). If the Bank already has a file, it will be saved, and if not, you'll be prompted for the new file name and location.

Likewise, click Save Patch to save the selected Patch to a single Aurora FM patch file (afm format).

Click Load to load any other Banks or Patches that are outside of the plugin DLL directory and User Patch Directory and thus not already in the loaded Patch tree.

Operators can be turned on and off by clicking (LMB) the operator number control. On = , Off = .

Sets the operator's output level in terms of dB relative to full-scale for Carriers and Modulation Index (0 - 14) for Modulators.

Next section.

There are several options for the operator's oscillator waveform synchronization using the parameter Sync Ø : 0°, 90°, 180°, 270°, and None.

With a sync phase of 0, the oscillator will always start from phase 0 and thus generate a sine waveform. A phase of 90° is equivalent to a cosine waveform, and 180° and 270° are the two other potential quadrants of a sine wave 90° apart. Finally, with a sync of None, the oscillator will continue running from whichever phase it previously ended on.

The mode for setting the oscillator's frequency can be one of: Ratio, Relative (Reltv), or Fixed.

Ratio and Fixed are standard in FM synthesizers. The unique Relative mode provides an alternate way of specifying a ratio in terms of semitones (s) and cents (c) relative to the key pressed. A relative value of 0s 0c is equivalent to a ratio of 1.0x, a relative value of +12s 0c is equivalent to a ratio of 2.0x, etc.

There are three different polarity modes for the modulation of an operator's pitch or amplitude: Bipolar , Monopolar , and Rectified 

Bipolar

For inherently bipolar mod sources like the LFOs, S&H, or ModEnv, the modulation occurs as you would expect. Modulation cyclically increases above and decreases below the current pitch/amplitude level.

If the modulation amount is positive , positive portions of the waveform are increases and negative portions of the waveform are decreases.

If the modulation amount is negative , this is reversed, so that positive portions of the waveform are decreases and negative portions of the waveform are increases.

For the ModWheel - which is normally considered to be monopolar, starting at 0% and only able to make increases - bipolar modulation means treating the ModWheel as if it's centered at the 50% point, so between 50% and 100% it gives a positive output and between 0% and 50% it gives a negative output. A positive modulation amount will reflect this, while a negative modulation amount will invert this.

Monopolar

For bipolar mod sources, instead of modulating above and below the current pitch/amplitude, the modulation range is shifted so that it's only an increase or a decrease. Positive modulation amounts are increases and negative modulation amounts are decreases.

For the ModWheel, this is the standard operating mode, since the ModWheel is typically considered monopolar.

Rectified

In this mode, the source waveform is rectified - its negative portions are inverted to also be positive, just like how AC is rectified into DC. This mode makes the most sense with a Sine LFO wave (it will also essentially double the modulation rate), while it doesn't make much sense with a Square wave.

The modulation range controls (, , and ) are used for providing a usable granularity for selecting the amount of modulation you want - low, medium, and high. For pitch modulation, the range maximums are (+/-) 120 cents, 12 semitones, and 48 semitones. For amplitude modulation, the range maximums are (+/-) 6dB, 20dB, and 40dB. These range options allow for a different minimum increment amount for each range. Small modulations for vibrato are typically less than a few dozen cents and small tremolos might be a few dB, but heavy tremolo and wild effects may need dozens of dB or several octaves. If there was only a 48 semitone range and we wanted 1 cent granularity, there would be 4800 increments just for one polarity of the control, making it very difficult to quickly set a specific amount using the mouse and scrollwheel.

Controls the linear interpolation between a sine wave at 0 depth and the complex waveform selected at 100 depth.
Depth is a moddable parameter and appears in the Mod Matrix as Op# Dp, where # is the operator number.

Each stage with a varying level (this excludes Delay and Sustain) has the option of one of 9 slopes:

The Release stage is special and requires explanation:

1. The Release level does not have to be 0 (-inf). If you set the Release level to a non-0 level, the envelope will hold at that level once it reaches it. You must understand the implications of this! For modulators, this isn't a problem, but for carriers, this will cause the voice to hold indefinitely and never complete.

   

   Also, you'll notice that setting the Release level to a non-0 level causes the Starting level at the Delay time point to be set to the same level. This means that after the Delay time has elapsed (if any), the level will immediately jump to the level set by the Release level and then the Attack stage will begin from that level.

   This functionality exists for compatibility with the Yamaha DX7, as that's how the DX's envelopes operate. You must use it at your own discretion and understand what's happening.

   To force indefinitely sustaining carriers to complete, you can toggle the operator off and on... but you probably shouldn't ever make use of non-completing carriers!

2. The Release time, when set to Time mode (as opposed to Sync mode), isn't actually a fixed time, but rather it's a release Rate, with a value between 100 (fastest) and 0 (very slow). There are several reasons for this:

   

   • The envelope can be at any level when the key is released, not necessarily just the Sustain level. Therefore the amount of level change that needs to happen during the Release is variable. By using a rate instead of a fixed time, release behaviour more closely matches the acoustic behaviour of real sounds. Most natural sounds decay at fixed rates and thus the decay times are proportional to the level - louder sounds take longer to decay, quieter sounds decay more quickly. Therefore the level of the envelope at the time of release will determine how long it actually takes the Release stage to complete.

   • This is how the DX7's envelopes operate. In fact, it's how every stage of the DX's envelope operates; but in this synth, only the Release is treated as a Rate while the other stages are treated as fixed times. This was necessary to preserve compatibility with the DX7. Since we cannot know in advance which level an envelope will be at when a key is released, it would be impossible to accurately predetermine the length of a Release stage, and thus it would not be possible to properly emulate the Release characteristics of a DX envelope. Only by preserving the intended Rate as opposed to pre-calculating a fixed time is it possible to maintain the same characteristics. The other envelope stages do not have this concern because their levels are known in advance and the stage times can't change based on things like when a key was released.

The envelopes are optionally loopable. Set the envelope loop start point and loop end point to any of the stage points. Changing a loop point will automatically turn on envelope looping. To toggle envelope looping on and off, RMB anywhere in the loop indicator.
Looping On.
Looping Off.

When an envelope loop spans the Sustain stage, the Sustain stage will be omitted. This behaviour is necessary to allow looping - without it, the envelope would hold at the Sustain level and never be able to actually loop. The envelope will only loop between the loop start and end points. A looping envelope will: Run through the envelope, starting at the beginning as normal until it reaches the loop end point Jump back to the loop start point and continue again towards the loop end point Repeat this loop for as long as the key is being held Proceed immediately to the Release stage once the key is released, and release as normal

Envelopes' Amplitudes can be scaled by Velocity and Key, and Rates can be scaled by these as well as an additional modulation source.

Extra Rate Mod Source

An additional modulation source can be used to scale/modulate the envelope rate, and different scaling amounts can be applied to stages that increase (Atk) and to stages that decrease (Dcy) in level.

Sine, Triangle, Square, Saw Up, Saw Down

0°, 90°, 180°, 270°

LFO1, LFO2, ModEnv, Random

LFO1+LFO2, LFO1+Env, LFO1+Rand, LFO2+Env, LFO2+Rand, Env+Rand

The primary mod sources operate in one of two modes: monophonic (shared by all voices) or polyphonic (each voice has its own). Additionally, these mod sources can be perpetually free-running or they can be reset each time a new key is played.

Thus, there are three Voice Modes: , , and .

The Delay parameter for the LFOs and S&H determines how much of a delay there is before the mod source outputs its full amplitude to the voices. Note that in the case of resetting, the reset always happens when the key is pressed and the delay time does not affect when the reset occurs. Furthermore, when the delay parameter is used, the mod source doesn't immediately kick in after the delay expires; instead, the mod source's amplitude will ramp up for up to one second before the delay time ends. So for example, if the delay time is 0.5s, the modulation output will immediately begin ramping up and after 0.5s it will be at full amplitude; if the delay time is 2.1s, there will be no mod source output for 1.1s, and then its output will ramp up from 1.1s to 2.1s and be at full level after that.

When the input source of the S&H is either of the LFOs, the LFO's Delay time is ignored and the S&H output is governed by its own Delay parameter.

MW>Amp controls the ModWheel>Amplitude scaling. At 0, the ModWheel has no influence on the mod source output (amplitude). At 100, the mod source amplitude is fully governed by the level of the ModWheel, so if the ModWheel's at 0% then there will be no mod source output, and as the ModWheel is moved up to 100% the amplitude of the mod source will likewise increase to its full amplitude. For amounts between 1 and 99, there will always be some mod source output regardless of the position of the ModWheel and the ModWheel will only control a portion of the mod source's output level. With negative values, this effect is inverted, so at -100 the mod source output will be maximal with the ModWheel at 0% and it will decrease to nothing as the ModWheel is moved up to 100%.

Src>Amp operates the same way on the Variable Mod Source of your choosing.

Output from the LFO's is band-limited / smoothed to avoid nasty artifacts when modulating a parameter directly tied to the audible signal (example: the sharp transition of a non-band-limited square wave introduces an audible tick when modulating an operator's amplitude). However, the Sample and Hold takes the UNsmoothed output from the LFO's as its input. The Smoothing control allows you to choose how much or how little smoothing you want applied to its signal sampling.

8 - 24 bit output. 24 is actually a misnomer: it's the full, unrestricted dynamic range of the synth engine. At 23 and below, the output is truncated to the specified bit depth.

Off/On. No effect when Bit Depth is 24. Otherwise, filtered random noise dither is applied to the truncated output.

This effect works best in Mono mode. In Poly mode, since portamento glides from the voice's previous note's pitch to the new note's pitch, the effects are rather unpredictable.

There are a variety of alternate temperaments and non-traditional scales available:

• 12-EDO - aka. 12-TET, 12-tone equal division of the octave, 12-tone equal temperament, etc. The one you know.
• Just Intonation 5-limit symmetric 1/2/asymmetric
• Just Intonation 7-limit
• Harmonic
• 15-/17-/19-/22-/24-/31-EDO
• Bohlen-Pierce
• MTS-ESP - microtuning via ODDSound's MTS-ESP client

You can research these tunings to understand the theory behing them and what they accomplish.

The Key selector, representing a key from MIDI note 60-71 (C->B), is used to specify at which key the scale is anchored to the corresponding pitch in 12-EDO. All keys above and below that will derive their tunings from the selected scale. (Does nothing in 12-EDO scale.)

The intensity and polarity/direction of the modulation - the range over which the target parameter's value will change depending on the modulation source's output.

Positive modulation amounts - cause positive mod source output values to increase the target parameter's value, while negative output values decrease the target parameter's value.

Negative modulation amounts - the inverse effect - positive mod source output values will decrease the target parameter's value, while negative output values will increase the target parameter's value.