Tiptop Audio BD909
Authentic 909 bass drum engine for modular systems
8 HP Eurorack module
The BD909 is a Eurorack recreation of the Roland TR-909 analog bass drum sound generator, faithfully reproducing the original circuit while adding extended tuning controls, voltage-controllable overload, and independent accent. Its energy is centered in the mid-range of the sonic spectrum, sitting naturally in a mix alongside deep bass lines without frequency conflict.
Features
- Authentic analog recreation of Roland TR-909 bass drum circuit
- Triangle VCO with sine wave shaper for core sound generation
- Three tuning knobs: OSC TUNE, Tune Attack, Tune Decay for wide tonal range
- VC-TUNE input with attenuator knob for voltage-controlled pitch
- Overload control adds odd harmonics from subtle punch to full distortion
- VC-OVERLD CV input for voltage-controlled waveshaper distortion
- Independent ACCENT level control (original 909 had only one global accent)
- ACCENT IN normalized to GATE IN when no plug inserted
- ACCENT IN accepts gate, trigger, or CV signal
- ACCENT knob acts as fine output gain control when accent input is not patched
- Dynamic accent physically hits the internal envelope harder for louder and punchier response
- LEVEL and ACCENT provide two-tier gain staging for precise mix placement
Controls & Jacks (15)
- Overload — Controls the amount of harmonic distortion added to the waveshaper. Low doses add punch; higher settings create increasingly distorted and d
- VC Overload CV In — Control voltage input for overload modulation
- Accent In — Accent/dynamic control input accepting gate or CV signals
- Level — Sets the output volume level for mixing with other drum sounds.
- Decay — Controls the decay time of the envelope segment.
- Osc Tune — Offsets the starting and ending frequency of the bass drum sound; main tool for shaping overall pitch range.
- BD Out — Bass drum audio output
- VC Tune — Attenuator knob for scaling control voltage to the tuning circuit.
- Attack — Controls the attack time of the envelope segment.
- Accent — Sets the accent level. Acts as a fine gain control when no external accent signal is connected; controls the difference in gain between acce
- Tune Attack — New control that adds variation to the sound and affects the Tune Decay knob, creating additional sweet spots beyond the original TR-909.
- Gate In — Trigger input for the bass drum sound
- Tune Decay — Original tune knob from the 909 machine with extended range; controls the frequency decay behavior of the bass drum pitch.
- VC Overload — Attenuator knob for scaling control voltage to the overload circuit.
- VC-OVERLD — Control voltage input for overload modulation
How-To Guides
- Classic 909 Kick
- Punchy Overloaded Kick
- Total Destruction Kick
- CV-Controlled Overload Swell
- Wide Pitch Sweep Kick
- Dynamic Accent Groove
- Accent as Fine Gain Control
- CV Pitched Kick
- Kick and Sub Bass Layering
- Short Snappy Click Kick
Explore the interactive BD909 panel on BleepDex — tap any control to learn what it does.
