[sdiy] 808 drums...how they work?
stewpye at optusnet.com.au
Tue Jul 14 23:22:21 CEST 2009
The pdf service manual should be easy to find in a google search. It is
The bass drum circuit will show you how to get longer decays and pitch
sweep. The toms will show you how to add a tuning control.
From what I recall, if you want to trigger the drum sounds using an
external trigger you can eliminate the trigger and accent transistors at
the front of each circuit and feed a positive going pulse in. Something
like the Midi to SDS would be good for this.
Florian Anwander wrote:
> Hi Dan
> I recommend the full service manual for the 808; it contains a
> theoretical circuit description.
>> 1. Do these drums use resonator circuits
> yes (as far as they don't use noise)
>> 2, If they do, what excitation source do they use and how is IT
>> created. ( what is an optimal excitation source,etc)
> Finally it is a trigger pulse coming from the coming from CPU, which
> in detail consists from a not timing relevant signal for enabling the
> individual instrument, an hi/lo voltage presenting the accent and
> finally a master trigger which determines the length. For some
> instruments it is filtered by simple passive RC-filters.
>> 3. if they are resonators, do they use feedback to allow for longer
>> decays? most resonators i have built have a very short decay so I am
>> interested in finding ways of making nice, long, tones.
> Search for those tons of 808/606 modifications on the web.
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