Dual-voice pitch shifter & delay
A few cents.
A lot more space.
Two separately tuned voices, from subtle doubling to harmonies and pitch-shifting echoes. Layered and Dual, two algorithms from a classic ’80s rack processor, rebuilt from the ground up.
Explore featuresCHARACTER
On paper, it looks like a precise pitch shifter, tuned in cents and timed in milliseconds. The legendary ’80s rack processor at the root of this sound was no such machine. Every splice was different, the delay moved with the input, and the pitch sat a few cents off.
Pitch shifting works by reading recorded audio back at a different rate. When the read position drifts too far, it jumps back, and the two segments are spliced together. The original hardware analyzes the incoming signal to select a splice point, but it does not always get it right. The slight instability and rough texture at those splice points become part of the sound.
Each jump back changes the delay as well. Because the signal arriving at that moment determines how far the read position jumps, the actual delay varies slightly with the source material, even at the same setting.
Pitch is determined by ratios derived from integer divisions of the hardware clock. As a result, intervals can deviate from their theoretical values by up to a few cents, and the amount varies from interval to interval.
Heard in isolation, these are flaws. Reviews at the time of release also noted glitches and artifacts. But blended into vocals, guitars and synthesizers, these imperfections add thickness and movement to the music. That is why the hardware became a legend.
PurlShift does not correct any of this. Of the twenty-three algorithms in the original hardware, it first recreates two pitch-shifting algorithms, Layered and Dual, at the signal-processing level, down to the logic and timing used to select splice points, the method used to determine pitch, the converters, and the analog input and output circuitry.
Read about the original hardwareCombine pitch, delay and feedback.
Small differences in left and right pitch and delay add stereo width to vocals and instruments.
Subtle detuning
Tune the two voices to different intervals. In Layered mode, blend in the dry signal for three-part harmony.
Harmony
Increasing feedback sends the returning signal through the pitch shifter again. The figure shows Layered: the repeats from both voices sum into a common input and then feed both voices again, so successive repeats create combinations of the two intervals (purple). In Dual, the left and right feedback paths remain separate, so one side keeps rising while the other keeps falling.
Pitch-shifting delay
The difference is in the input and feedback routing.
Create two pitches from a combined input. Both voices feed back into that same input, layering more pitches with each repeat.
Delay per voice Up to 1,000 ms
Process left and right separately. Feedback stays within each channel, so each repeat rises or falls by the selected interval.
Delay per channel Up to 1,000 ms · Feedback stays within each channel
LFO
Drag a cable to the knob you want to modulate. Here, the LFO controls left pitch. Each cycle moves pitch up and down by as much as 400 c, with the knob’s indicator and value following along.
PARAMETER BIND
One Bind knob moves several parameters together over defined ranges. Here, Bind 1 controls right-channel pitch, delay and feedback in Dual mode. At one end is 24 ms doubling; at the other, echoes descending in perfect fifths. Everything between them fits within one turn of the knob—and you only need to automate that one knob in your DAW.
From initial setup to LFO and Bind connections and saving presets. Find the operation you need in the manual.
Read the manualAudio plug-in for macOS
| Parameter | Range | Default |
|---|---|---|
| L / R Pitch | –2400 ~ +1200 c | +9 / –9 c |
| L / R Delay | 0 ~ 1000 ms | 12 / 24 ms |
| L / R Feedback | 0 ~ 100 % | 0 % |
| L / R Mix | 0 ~ 100 % | 100 % |
| Low Freq · High Freq | 0 ~ 47 · 0 ~ 4 | 12 · 2 |
| Source | 0 ~ 100 | 94 |
| Sustain | Off / On | Off |
| Bind 1–4 | 0 ~ 100 % | 0 % |
| LFO | 38 waveforms · Depth · Rate · Phase | Turned Off · 1.00 Hz |
| Levels | IN · OUT L/R ±48 dB · Trim ±24 dB | 0 dB |
| Master | Mix 0 ~ 100 % · Out –24 ~ +12 dB | 100 % · 0 dB |
| Project sample rate | Samples |
|---|---|
| 44.1 kHz | 0 |
| 48 kHz | 112 |
| 88.2 kHz | 205 |
| 96 kHz | 224 |
| 176.4 kHz | 411 |
| 192 kHz | 448 |
Compensation reported to the DAW. Does not include the delay inherent in pitch processing.
CatSiesta · PurlShift
$34 Introductory price · first month after launch
Regular price $49
Prices in USD, excluding tax. Applicable tax is added at checkout.
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