[sdiy] TR-808 Kick Drum modelling explanation

[Adam Inglis]

On 17/06/2015, at 9:49 PM, Richie Burnett wrote:

> It has a big effect on the sounds for which the raw trigger pulse is  
> used to drive the ringing T filter directly. The 808BD and 808SD are  
> good examples of this, as is the 606BD.  It has much less effect in  
> cases where an analogue drum sound generator just triggers off one  
> of the edges (rising or falling) of the trigger pulse.  So for  
> instance trigger pulse width doesn't effect hand-clap sounds much in  
> the 808 and 909.


It's interesting that the 606 and 808 share this method of triggering,  
where there is a "common trigger" pulse sent to all voices,  
representing the Accent amount, which is "AND ed" to the individual  
voice trigger pulse. Yet, the CR-8000 built around the same time and  
using the same Bridged T type voice generators, has triggers that vary  
from 4 ms to over 70 ms without any noticeable tonal change (they are  
tempo-dependent) and the Accent is implemented completely differently  
(basically the output volume is briefly increased at the mix buss,  
post-voice generator).