21 Oct
2002
21 Oct
'02
8:43 p.m.
On Mon, Oct 21, 2002 at 07:11:41 +0200, Tim Goetze wrote:
Yes, you can always pep things up with a nonlinear effect of somekind
before the cabinet+speaker sim. In FFT convolvers you take several
impulses at different amplitudes and shift between them.
I wouldn't worry too much aboout being very close the the impulse, the're
only for a particular input amplitude and I can't remember when they came
from so may not be fantastic.
I'm wondering if this technique can be used for reverbs too - generate a
purely "white" synthetic reverb tail, and apply an IIR the aproximate
shape of the rooms impulse to it to make it sound more real...
- Steve
Steve Harris wrote:
Lets just put it down to chache issues and ignore it ;)
On Mon, Oct 21, 2002 at 02:39:05 +0200, Tim Goetze
wrote:
a quick test (%s/double/float/g) shows the cpu usage doubling,
but i'm unsure what may cause this huge performance drop. pleased to announce the release of
'unmatched'.
'unmatched' is a simple effort to recreate some aspects of
the tone shaping of a real instrument amplifier. unlike
Excellent. Can I ask how you did the FIR -> IIR mapping? Is it neccesary
or significantly better to use doubles for the coefficents? doubles should, on average, mean we seldom hit the
denormal number
bounds, or at least less frequently than with floats. i also expect
doubles to be beneficial to the filter stability by minimizing
round-off error, though i may be wrong here. lastly, x87 uses 80 bits
Yes, though can manually truncate the floats, and floats will give half
the cache footprint, so play better with other software. I dont really
have a feel for when doubles are neccesary for filters yet.
Have you
experimented with adding a delay line and LP filter to simulate
reflections off the back wall of the cabinet?
actually the next thing i'd have done do to come closer to the
original impulse would be an added IIR operating behind a delay
line, yes. the current plugin response does not capture the later
parts of the original response so well (now that you mention it,
i think it must be those reflections). however personally i'll
probably do more research on nonlinear effects before refining
this method.