Tiptop Audio BD909 Analog Bass Drum Module

Reverse-engineered from the original machine, Tiptop Audio BD909 is an identical recreation of the original all-analog drum circuit from the Roland TR-909. Additional controls and synthesis features have been added that turn this classic circuit into a chest-pounding analog bass drum laboratory, all tightly packed into an 8hp module. The BD909 sound differs from BD808 in that the main sonic energy is centered in the mid to low frequency range, as opposed to the strictly low frequency range of BD808. This frequency range gives the needed headroom that allows your basslines to deeply fill up the low end while the kick drum rides on top, creating a clear and punchy mix.

BD909 includes all the controls found in the original: attack, decay, tune decay, accent and level. Tiptop Audio went beyond that and added controls that further increase the palette of sound this circuit is capable of. First off, they added a tuning control knob for the oscillator and included its own CV input and attenuator that let you tune your 909 kick with your basslines. Next, they added control knobs for the tuning attack and extending tuning decay. Each one affects the other, allowing for very intuitive and interactive sound shaping — this feature opens up numerous 'sweet spots,' and provides the ability to center the energy peak at different parts of the sound. Finally, BD909 offers additional punch and distortion by giving complete control over the internal waveshaper, which allows you to overload the waveform manually or with voltage control.

Beginning with the classic and pure sound of the 909 kick, these additional functions greatly expand BD909's flexibility and let it create powerful analog bass drums that range from soft and smooth to punchy and aggressive — and everything in between.

• Module controls
• OVERLOAD knob: overload control for waveshaper circuit, adds more odd harmonics to waveshape
• LEVEL knob: master output gain level
• 909 ATTACK knob: amp envelope attack stage time
• 909 DECAY knob: amp envelope decay stage time
• TUNE ATTACK knob: tuning envelope attack stage time
• TUNE DECAY knob: tuning envelope decay stage time
• OSC TUNE knob: oscillator pitch
• ACCENT knob: accent level control, affects loudness and attack levels
• VC-TUNE knob: attenuator for tuning CV input
• Patch points
• ACCENT IN input: gate trigger input to trigger accent
• VC-TUNE input: CV control over oscillator tuning
• GATE IN input: gate trigger input to trigger bass drum sound
• VC-OVERLD input: CV control over overload
• BD OUT output: audio output
• Physical specifications
• Size: 8hp
• Module depth: 36mm
• Power usage: 34mA @ +12V, 21mA @ -12V