808 Tom (Pinged)
This is an 808 style tom patch made using a pinged filter as a sound source. Read some notes about the 808 tom here.
1: Switch the VCF to NT2 (Notch). You can also try BP4. You what something with a steep curve that emphasis a narrow range of frequencies.
2: Tune the Filter:
Raise the Q slider all the way up: the filter should start self oscillating.
Plug a tuner into the VCF out jack.
Tune the filter with the frequency slider.
Use the guide below to help select a tuning within the 808’s tom range. The 808 has 3 tom sounds (low, mid, high). Each is the same with different tunings and decay times:
High Tom: Low = E3 +2 cents, Centre = F#3, High = A3
Decay Time: 100 ms
Mid Tom: Low = B2 -49 cents, Centre = C#3 -45 cents, High = D#3 +49 cents
Decay Time: 130 ms
Low Tom: Low = D#2 +49 cents, Centre = F#2 +47 cents, High = G2 +35 cents
Decay Time: 200 ms
3: Patch ENV-B to VCF audio in. Setup ENV-B to output a short click.
4: Lower Q until the filter stops resonating, and patch the VCF out to Main 2.
5: Adjust Q while firing the manual trigger button. Higher values will ring out too much. Lower values will have too much click. It should have a bright resonant body, and a short clunky tail.
6: Switch noise to ‘pink.’
7: Use the LPF to filter the pink noise.
Patch noise out to LPF audio in, and patch the LPF out to main 1. Turn the LPF amount dial fully counter clockwise. Slowly raise the LPF amount back up until you just start to hear it. The noise shouldn’t be too prominent. Once adjusted to you taste, unpatch the LPF from main 1, and rematch it to VCA-A audio in.
8: The Roland engineers intended the noise to be a kind of cheap reverb effect. To create this effect, adjust ENV-A to last a little longer than the main body of the sound.
Optional Variations:
Try sending velocity to filter resonance so louder notes will be brighter and lower velocity notes will be more clicky.
Further Reading
A short blog post on how to recreate the 808 Tom.
Pg. 6 has a brief description of the combined tom/conga circuit (LT/LC (MT/MC, HT/HC)).
Pg. 7 has a block diagram (top right, between the SD and BD).
Pg. 9 the circuit (centre).
Pg. 14 has a chart displaying the frequency, and decay times (LC, MC, HC).
Erics Synths EDU DIY Kick Drum user manual.
For a good explanation of how a bridged-T oscillator works, check out Pg 9 through 12 of the user manual for the Erics Synths EDU DIY Kick Drum.