Circuit and block diagram of the 808 conga. Including a chart listing pitch and decay times.

The 808 features three conga/tom pairs (low, mid, and high), each sharing the same basic circuit design with differences in frequency, amplitude, and decay time. It has a bright, resonant attack that quickly transitions into a dull, non-resonant decay. This is achieved via a bridged-T oscillator whose frequency is forced down as the sound fades, creating a subtle downward pitch bend effect. This distinguishes them from the claves or cowbell which have a more ringing or pinging sound.

Key Component:

Each tom/conga pair has a bridged-T network based oscillator (low=IC15, mid=IC17, high=IC18) tuned to different frequencies for each part.

If you look at the circuit diagram you can see that each bridged-T is split in 2. When switched to tom, both halves are combined. When switched to conga one half is bypassed.

808 Conga Tuning Guide:

High Conga (HC)

Frequency Range: Low = 370 Hz, Centre = 400 Hz, High = 455 Hz

Note Equivalents: Low = F#4, Centre = G4 +35 cents, High = A#4 -42 cents

Decay Time: 80 ms

Mid Conga (MC)

Frequency Range: Low = 250 Hz, Centre = 280 Hz, High = 310 Hz

Note Equivalents: Low = B3 +21 cents, Centre = C#4 +18 cents, High = D#4 -6 cents

Decay Time: 100 ms

Low Conga (LC)

Frequency Range: Low = 165 Hz, Centre = 185 Hz, High = 220 Hz

Note Equivalents: Low = E3 +2 cents, Centre = F#3, High = A3

Decay Time: 180 ms

Breakdown of the 808’s Conga Circuit:

1: The Body of the Sound:

Each conga/tom pair uses a bridged T-network based oscillator as a sound source. A bridged-T oscillator is an elegant circuit that combines a VCO, VCA, and ENV together using minimal components. Unlike standard oscillators that sustain indefinitely, the bridged-T design creates a self-dampening sine wave that rings briefly when triggered and naturally fades away, making it perfect for drum sounds.

2: A Subtle Pitch Bend:

The bridged-T oscillator’s pulse is created by a feedback loop. As the feedback inside the bridged T-network dies down, two diodes (D80/D81 on the low, D82/D83 on the mid, and D84/D85 on the high) starve the circuit of electricity. These diodes' resistance increases as the sound fades, shortening the decay time and dampening the resonance, resulting in a subtle downward pitch sweep. This mimics how acoustic drums naturally change tone over time.

If you want to keep the sound authentic to the 808, don’t exaggerate the pitch bend. It should sound less like a boing, and more like a tonk.

Note: The low congas have a longer decay than the high.

Block diagram of how to recreate the 808 conga on any synthesizer.

Synthesizing an 808 Conga:

1: The Body of the Sound:

Use a sine oscillator: refer to the tuning guide above.

2: Filter:

Rout the oscillator through a filter. Use a band-pass, or notch filter.

Tune the filter to the same frequency as the oscillator.

Boost and accentuate the tuned frequency by using adding a mild to low amount of resonance.

Subtly modulate the filter frequency with a decay only envelope. The pitch drop shouldn’t be too immediately noticeable.

3: VCA & Envelope:

Pass the signal from the filter through a VCA or LPG.

Shape the VCA with a tight decay only envelope: 80 to 180 ms.

The initial attack should have a click.

4: Optional Drive:

You can try adding a small amount of overdrive. Set the amount so the initial attack gets boosted and then has less effect on the tail. You don’t want the whole sound to get overdriven. The goal is to make only the attack brighter.

5: Variations:

Try sending velocity to filter resonance so louder notes will be brighter and lower velocity notes will be more clicky.

Control pitch with velocity.

Exaggerate the pitch drop. Increase the filter frequency’s envelope modulation.

Cascadia Patch:

See a Cascadia patch for the 808 Conga here.

808 Conga Synthesis

Further Reading

808 Conga Synthesis

Further Reading

808 Tom Synthesis

808 Rimshot Synthesis