Tiptop Audio — SD909

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TIPTOP AUDIO SD909 – Cheat Sheet

The SD909 is a Eurorack recreation of the classic Roland TR-909 snare drum. This module brings all the original snare controls, adds voltage control to key parameters, and provides a separate noise output.

Front Panel Controls

Knobs: - TONE: Sets the length of the noise (Decay). - TUNE: Adjusts the pitch of the internal VCOs (snare body). - SNAPPY: Adjusts the amplitude/gain of the noise. (Note: Can go beyond original 909 settings.) - NOISE: Sets the gain/balance of the noise component in the snare mix. - 909 (NOISE) DOT: Marked region for classic TR-909 sound balance. - ACC (ACCENT): Sets amount of accent (volume emphasis) both manually and under CV control. - 909 (ACCENT) DOT: Marked region for classic TR-909 accent setting. - LEVEL: Controls final output volume.

Buttons: - TRIGGER: Manual trigger to test/play the snare sound.

Inputs & Outputs – Reference

Jack Label	Type	Description	Voltage Range
SD OUT	Output	Main snare drum audio output	Audio signal (modular level)
NOISE OUT	Output	Raw, unfiltered TR-909-style white noise output	Audio signal (modular level)
GATE IN	Input	Main trigger for snare sound (accepts gate/trig)	Typical trigger: 5V–12V
ACCENT IN	Input	CV or gate/trigger for accent amount (overrides internal accent)	0–5V CV or gate/trigger
VC-NOISE	Input	CV to control noise generator clock frequency	0–5V CV (approx.)
VC-TUNE	Input	CV to control snare Tune (VCO pitch)	0–5V CV (approx.)

Usage Tips

Creating a Classic 909 Snare

Connect SD OUT to your mixer/output.
Set all knobs to positions indicated by the “dot” regions labeled "909" for authentic TR-909 sound.
Trigger with either the TRIGGER button or an external gate to GATE IN.
No ACCENT IN: Accent knob acts as gain/level “fine” control (recommended for classic workflow).
Use ACCENT IN: Patch CV or triggers for dynamic snare accents between steps.

Sound Shaping

TONE: Increasing = longer noise burst (decay).
SNAPPY: Higher values = more pronounced/“snappier” white noise.
TUNE: Higher = higher snare pitch.
NOISE: Blends noise with snare “body”; classic amount at “909” dot.
LEVEL: Controls output volume.

Extended Features

NOISE OUT: Use as a white noise source for other patches—excellent for hats, SFX, filtered percussion.
VC Inputs: Modulate VC-TUNE and VC-NOISE for dynamic pitch/metallic FX and noise timbre changes—try sequencers or envelopes for evolving snare textures.

Dynamics & Accent

ACCENT: Provides per-hit loudness variation (classic groove feel).
Unpatched: Accent knob affects every hit, also sets max output gain.
Patched: ACCENT IN allows accent variation per note (CV or gate).

Voltage Ranges (Summary)

Gate/Trigger Inputs: 5V–12V (safe range, standard for Eurorack)
CV Inputs (Tune, Noise, Accent): 0–5V typical (always check with manual or test for range/response)

Generated With Eurorack Processor