[PD] Pre Loading a Delay Line

[Frank Barknecht]

Hallo,

(the early bird...)

padawan12 at obiwannabe.co.uk hat gesagt: // padawan12 at obiwannabe.co.uk wrote:

> Yes, but that wouldn't be appropriate for a xylophone. I think it
> depends on the excitation mode and what instrument you're modelling
> whether to pass the excitation impulse directly through (or through
> a body formant), or only take it from the "cold" side of the delay
> where it's one period late. I think this is how you decide.. If it's
> a displacement that you're modelling, like plucking a bass string at
> the middle (antinode) then yes you want to have the delay, that's
> the time until you really hear anything from the moment the pick is
> released, the time to propagate along the string. But for struck
> instruments, the hammer excites the whole thing locally, and the
> waves spread out and travel back and forth until they fall into
> phase with the waveguide (delay), (Karplus-Strong), and then you
> want to hear the delay contents as quickly as you can, so you want
> the buffer to be preloaded with an image of the impulse. 

Hm, I still don't quite get it: In the patch Michael already plays out
the excitation pulse because his "pickup" is next to the [delwrite~]
so everything that goes into the delay is played out, especially the
first excitation. The second repetition of the (filtered) excitation
will arrive after the first delay period, but doesn't it have to wait
that long? Because if it would come any earlier you would have a tone
with a different and *higher* frequency because basically you just set
the delay period to be shorter for a short time. Or am I totally
off-track?

> Are you doing that here? How do you do it, I cant see it? Is that
> why you set the blocksize so low? 

The blocksize is low because it specifies the lowest possible delay
time, if you have a feedback delay and through that the highes
possible frequency of the delay waveguide. See Miller's book, the
chapters on recirculating and non-recirculating delay lines. 

For a bass player the block size could be larger, though. ;)

Ciao
-- 
 Frank Barknecht                 _ ______footils.org_ __goto10.org__