Audio Waveshaper for Sawtooth Multiplying
A wave multiplier that works with sawtooth waves. Modulate it with a envelope to get a “synced saw” sound; modulate it with an LFO to get a “supersaw” sound; set it right on the edge of a harmonic to add a thin pulse to a saw that adds sizzle and ziss.
Set it to emphasize the 7th or 9th hamonic, to simulate the multiple-slip motion of softly bowed strings (near bridge): sul ponticello!
Plus low-level alternative output.
“I fed the Rasp with my wave folded complex output from my Pittsburgh Primary Oscillator, modulated the feed signal with breath, sending out through a lowpass and then VCA, and then through a Flanger… pretty decent cello-ish sounds.“
Basic Patch
Video
Driven by a sine input, with a little LFO modulation for thickness.
Visually, a symmetrical effect, like 1960s Dr Who!
Example Spectra
Sounds are usually brighter and less uniform than the input, but rarely will any harmonic be completely suppressed. The Rasp output is suitable for any patch where a saw-ish spectrum is suitable, but will be less cliched than saws.
 Saw Input |  Input: All harmonics, decreasing Yellow line shows slope of -6db/8ve for comparison. -6db represent a halving in volume, so -18db is 1/8th the volume. |
 |  Output: Less bright. Every 3n +1 harmonics lower, 9 – 16 softer |
 |  Output: Harmonics 4,5,9 boosted, 11- 21 louder |
 |  Output: Bright. 1st harmonic 1/8 level, harmonics drop out every 5 or 2 (4 zero-crossing points per cycle) |
Audio Examples
- Elergy: Violin-ish patch, using Shell, Rasp, Splice and a digital Hi-Q EQ bank.
(Note: Some of these examples may require you to log into the website to play.)
Physical: 6HP wide, 70 mm deep, 16 pin power socket (10 pin can be used).
Power (Current): +12V: 60mA (50mA no input), -12V: 45mA, +5V NA.
Status: In stock. ROHS and non-ROHS PCB available.
More Info:
- Rasp Waveshaper: the Backstory
- Theory of Operation
- Release Notes: Version 1 PCB
- Interactive Component Placement
- Bill of Materials (BOM)
- Pricing and Purchasing
- fricko General Building Guide
Caveat: Rasp works best with VCO signals that are close to the Eurorack standard of 10V PP (i.e +/-5V). Some VCOs do not comply with the Eurorack “typical” values and produce much less. If you have such a VCO, you should boost the signal through some amplifier before feeding it into Rasp.
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