Cloud Seed User Guide

Architecture

Cloud Seed is made up of three independent blocks:

  • Multitap delay featuring up to 256 taps
  • A series of all-pass delay blocks, up to 12 units.
  • 12 parallel delay lines with diffusers and filters in the feedback path
Block Diagram

Preset Section

Preset Selection

Click the current preset name to select a different preset, or to Save or Delete the current preset.

You can also use the left and right arrow buttons to cycle through presets.

License Dialog

Ghost Note Audio Logo

Click the Ghost Note Audio Logo in the top left corner to open the License dialog:

Here, you can enter your license key and email. After clicking Save, you must restart the plugin for it to take effect.

Mixer

Mixer Section

This controls the mix of sound presented at the plugin’s stereo output.

  • Dry – Controls the amount of dry signal passed through the plugin unaffected.
  • Early – Controls the gain of the signal coming from the diffusion block that is passed directly to the output.
  • Late – Controls the gain of the signal coming from the late reverberation block.

Utility Section

  • Input Mix - Controls the amount of mixing between the two input channels. It lets you send a part of the Left input to the Right channel and vice versa. When set to zero, no mixing occurs. When set to 100%, an even mix of the left and right inputs is fed into both channels (mono input).
  • High Cut, Low Cut – Removes the highest and lowest frequencies from the input signal, before it is fed into the early reverberation section. Toggle these filters on and off using the buttons above the knobs.
  • Cross Seed - This controls how the random values for the left and right channels are mixed. When you select a seed, two series of random numbers are computed from that seed, one for the left channel and one for the right channel.
    • When the Cross-Seed parameter is set to zero, the random patterns used on each channel will be completely different. But when turning the knob up, a mix between the two is used, and at 100% the same random pattern is applied on both channels.
    • Using different delay patterns on each channel makes the output sound "wider", as each channel will process the sound differently, so this knob controls the stereo width of the plugin.
  • Interpolation - A special toggle switch that lets you disable the linear interpolation when using modulation.
    • When on: delay blocks will smoothly interpolate between two samples. This gives a nice sound, but the simple linear interpolation cuts away some of the high frequencies in the signal, so it also acts as a subtle low-pass filter.
    • When off: No interpolation takes place and the playback he "skips" between samples when it is modulated. This gives a very crisp sound, but results in quantization noise, which can be pleasant when using very long decay times, giving the signal a more "airy" feeling. 

Seed Controls

The seeds set the initial condition for the random sequence generators that are used to control various elements in the algorithm. This include the timing and gain of the taps on the multitap delay, the delay and feedback of diffuser blocks, small offsets to the modulation frequencies, and much more.

  • Tap Seed - Controls the random values used to set the timing and gain of the taps in the multi-tap delay section.
  • Diffusion Seed - Control the random values used by the Early Reflections allpass filters. Affects the delays, modulation amount and modulation rate.
  • Delay Seed - Controls the random values used by the delay line. Controls delay time, modulation amount and modulation rate.
  • Late Diffusion Seed - Control the random values used by the Late Reverberation allpass feedback filters. Affects the delays, modulation amount and modulation rate.

Multitap Delay

This section controls the multi-tap delay block. It consists of a 1-second long delay line, with up to 256 “taps” that output the signal at different delay times. The tap timing and the gain is set randomly, controlled by the Tap Seed control.

  • Count – The number of output taps from the delay line
  • Decay - Controls the relative gain between the first and last tap in the sequence. At zero, the sequence does not decay at all, and all taps are roughly equal in amplitude, producing very high echo density but an unnatural decay
  • Pre-delay - Adds a delay to the signal before it enters the reverberation process. Can add a feeling of size to the sound.
  • Length – The maximum length of the tapped delay line, up to 1000ms.

Diffusion

This section contains up to 12 series-connected “Schroeder” allpass reverberators. These are special delay lines, used to "thicken up" the reflections of the reverb. However, they can and will colour the sound, and they also make the response non exponentially decaying, when you put multiple filters in series.

The controls of each allpass unit are scaled with random values, controlled by the Diffusion Seed, so every unit has slightly different parameters. Different seeds will give different results, some will sound very metallic and harsh, while others will sound smooth and pleasant. Experiment to find settings that fit your desired sound.

  • Delay - Controls the delay of the allpass units.
  • Mod Amt - Control the amount of modulation applied to the delay.
  • Feedback - Controls the amount of feedback in each unit. This has a significant effect not just on the decay rate of the diffuser, but also the shape of the decay. Around 70% gives a relatively natural decay. 40-50% creates a “blooming” effect, where the echo density build up before decaying. At 90% or above the effects starts producing a more pronounced metallic resonance.
  • Mod Rate - Controls the rate of modulation applied to the allpass delay. Use low (5-20%) values if you just want to break up resonances. Use higher values to start adding a chorus effect.
  • Diffusion Stages - The number of allpass units. Add more stages to create a more dense early reflection. Adding too many (8+) starts creating a non-linear “blooming” type effect. Combine with feedback around 40-50% for an exaggerated effect.

Late Reflections

The late Reverberation block consists of up to 12 parallel delay lines. The feedback signal of each line is processed through tone shaping filters (See Equalisation section) and a Schroeder allpass diffusion block (identical to the one used in the Early Diffusion section).

Switches:

  • Mode - You can change the order in which the delay and the allpass filter are processed, by using the Mode control. This has an effect of the early onset of the reverb, letting you choose between a faster attack (Pre) and a slower, denser response (Post)
  • Line Count – Determines how many delay lines are active.
  • Diffusion – Actives the diffusion blocks in the feedback path.
  • Diffusion Stage – Determine how many allpass blocks are active in the diffusion stage.

Knobs:

  • Size – The (average) length of delay lines. Actual delay time will vary due to random offsets applied.
  • Decay – Adjusts the feedback of each delay line, so that the decay will reach -60dB in the specified time (often referred to as RT60)
  • Mod Amt - The amount of modulation applied to the delay line.
  • Mod Rate - The rate of the modulation.
  • Delay - Controls the delay of the allpass units.
  • Mod Amt - Control the amount of modulation applied to the delay.
  • Feedback - Controls the amount of feedback in each unit. This has a significant effect not just on the decay rate of the diffuser, but also the shape of the decay. Around 70% gives a relatively natural decay. 40-50% creates a “blooming” effect, where the echo density build up before decaying. At 90% or above the effects starts producing a more pronounced metallic resonance.
  • Mod Rate - Controls the rate of modulation applied to the allpass delay. Use low (5-20%) values if you just want to break up resonances. Use higher values to start adding a chorus effect.

Equalisation

This sections controls the filters in the feedback path of the late reverberation delay lines. Note that the effect of these filters is tightly coupled with the Size parameter, as smaller size delays means the signal passes through these filters more frequently, and thus decays faster if they are enabled.

Switches:

  • Low Shelf - Enables or Disables the Low Shelf filter.
  • High Shelf  - Enables or Disables the High Shelf filter.
  • Lowpass - Enables or Disabled the Low pass filter.

Knobs:

  • Low Freq - The cutoff frequency for the feedback low-shelf filter.
  • Hi Freq - The cutoff frequency for the feedback high-shelf filter.
  • Cutoff - The cutoff frequency for the feedback low-pass filter.
  • Low Gain - The amount of gain reduction in the low shelf filter.
  • Hi Gain - The amount of gain reduction in the high shelf filter.