Frap Tools 321
Three-channel attenuverter, offset, and precision mixer
6 HP Eurorack module
The 321 is a three-channel attenuverter, offset, and mixer module. Each channel independently scales, inverts, and offsets an incoming signal before summing all three to a mix output, making it a versatile utility for shaping CVs and audio signals in any modular patch.
Features
- Three independent attenuverter channels (Red, Yellow, Green)
- Per-channel offset control for adding or subtracting a fixed voltage
- Per-channel phase inversion switch
- Per-channel -6dB attenuation switch
- Individual outputs per channel
- Summing mixer with dedicated output level control
- Unpatched sum output normalled from sum output
Controls & Jacks (28)
- Unpatched Sum— Indicates signal level at the Unpatched Sum output.
- All Sum— Indicates signal level at the All Sum output.
- Unpatched Sum Output— Summed output of sections whose individual output is not patched. Features a -6dB switch for headroom.
- All Sum Output— Summed output of all three sections regardless of patching. Features a -6dB switch for headroom.
- Red Scale— Red section attenuverter. Scales the input signal from silence to full level, with phase inversion via the polarity switch.
- Red Offset— Red section offset. Adds a positive or negative DC offset to the signal. Outputs steady voltage when nothing is patched.
- Red Clip— Lights when the red section signal is clipping.
- Red Polarity— Shows the current signal polarity of the red section.
- Red Scale LED— Indicates the scale level for the red section.
- Red Offset LED— Indicates the offset level for the red section.
- Yellow Scale— Yellow section attenuverter. Scales the input signal from silence to full level, with phase inversion via the polarity switch.
- Yellow Offset— Yellow section offset. Adds a positive or negative DC offset to the signal. Outputs steady voltage when nothing is patched.
- Yellow Clip— Lights when the yellow section signal is clipping.
- Yellow Polarity— Shows the current signal polarity of the yellow section.
- Yellow Scale LED— Indicates the scale level for the yellow section.
- Yellow Offset LED— Indicates the offset level for the yellow section.
- Green Scale— Green section attenuverter. Scales the input signal from silence to full level, with phase inversion via the polarity switch.
- Green Offset— Green section offset. Adds a positive or negative DC offset to the signal. Outputs steady voltage when nothing is patched.
- Green Clip— Lights when the green section signal is clipping.
- Green Polarity— Shows the current signal polarity of the green section.
- Green Scale LED— Indicates the scale level for the green section.
- Green Offset LED— Indicates the offset level for the green section.
- Red Input— Red section signal input. Accepts audio or CV.
- Red Output— Red section signal output. Patching here removes this section from the Unpatched Sum.
- Yellow Input— Yellow section signal input. Accepts audio or CV.
- Yellow Output— Yellow section signal output. Patching here removes this section from the Unpatched Sum.
- Green Input— Green section signal input. Accepts audio or CV.
- Green Output— Green section signal output. Patching here removes this section from the Unpatched Sum.
How-To Guides
- Precision CV Scaling with DC Offset
- Inverted CV Mirror
- Three-Source CV Mixer
- Three-Channel Audio Mixer
- Static CV Offset Generator
- Halved LFO Range
- Bipolar to Unipolar CV Conversion
- Pre-Processing for Ring Modulation
- Inverted Envelope for Ducking
Explore the interactive 321 panel on BleepDex — tap any control to learn what it does.