Tiptop Audio SD909 Analog Snare Drum Module

Tiptop Audio SD909 is the iconic TR-909 snare drum and noise generator for use in eurorack format. Tiptop Audio painstakingly tested the module in their lab to sound like a fresh machine coming off of the assembly line back in the 80s. On top of the original circuit, they have added new features that expand the palette of what can be produced with this analog circuit.

The sound of SD909 consists of two main sections: the binary noise generator and two modulated triangle oscillators. The oscillators provide the low end punch while the noise makes up the upper sonic spectrum, resulting in a combination that makes the 909 snare sound so rich. In the SD909 module, the noise generator and oscillators are variable and voltage-controlled, which pushes the circuit beyond its original boundaries, offering new sounds as well as many variations of the original tone. The panel has markings to guide setting the knobs to reproduce the snare sound of the vintage machine.

Just like the other drums in this series, SD909's high-powered output gain stage allows further enhancement of the sound through distortion and clipping. Tiptop Audio has designed a dual pulse-shaper circuit on each gate input so you can trigger SD909 with trigger/gate signals from step sequencers, clock dividers or any other pulse/clock sources. Also, SD909 is equipped with access to the MIXZ MixBus, matching the rest of the Tiptop line of percussive modules.

• Module controls
• TONE knob: sets length of noise section
• LEVEL knob: master output gain level
• TUNE knob: controls pitch of internal VCO
• SNAPPY knob: sets gain of noise section
• VC knob: controls clocking frequency of noise generator
• ACC knob: accent level control, affects loudness and attack levels
• TRIGGER button: triggers sound engine
• Patch points
• NOISE OUT output: pure, unfiltered noise output
• VC-NOISE input: CV control over clocking frequency of noise generator
• ACCENT IN input: gate trigger input to trigger accent
• GATE IN input: gate trigger input to trigger snare sound
• VC-TUNE input: CV control over pitch of internal VCO
• SD OUT output: audio output
• Physical specifications
• Size: 8hp
• Module depth: 46mm
• Power usage: 35mA @ +12V, 30mA @ -12V