Hip bass drum is project brought to you by Craig Anderton. Compared to other drum circiuits it’s very simple (but unique) design. The schematics scanned form Polyphony, October ’83 can be found all over internet. It is hard to find any clear demo of the drum, so I made one.
The core of the circuit is somehow similar to Rolands 808 BD and it is build around excited bridged T-network (you can find some more details on 808 bass drum in Roland TR808 Service Manual, page 5). The most exciting things are THUD control and LED limiting circuit – together they work miracles.
I think it is the most clever and smallest tweakable DIY drum circuit. It uses 2 opamps as only active components. There are some RC / transistor bass drums, but the only thing you can really control pitch and volume :/
I made a small mistake and didn’t threw out the RES (resonance) control, as original instruction says. It is almost unuseful and sometimes works as very unefficient decay control. Also LIMIT control has the biggest impact on sound on first, second and last position – it could be replaced by 3 position switch for more efficient front panel.
And don’t forget to add 1M resistor to GND on trigger input! (It will be marked on some schematics you will find).
The drum sound very “sine-ish”, the CLICK LEVEL control increases the volume drastically, so watch out for your speakers.
If you don’t like the boomy sound of the 808, you should build one! Or you can just include one into your dream modular system on Modulargrid!