Re: [Jack-Devel] Variable delay line problem

On Fri, April 13, 2012 8:20 am, Stéphane VAXELAIRE wrote:
> I understood that a flanger is just an extremely short delay line (max
> 15ms) with a variable delay length.
> The variable length can follow an LFO wave, I tried with a simple cosine
> here.


The LFO should be very low frequency.   You are effectively phase
modulating the input signal with the LFO, which is going to produce
sidebands (in the frequency domain) around the input signal at the offset
of the LFO frequency.

>     // Compute an index between 0 and max based on a LFO, in this case
> simple cos(2*PI*n)

Wouldn't that make the cosine wave at the same frequency as the sampling
rate?  e.g. 48kHz?

> distorted version of the original sound

Phase modulation at 48kHz would not sound nice.  Maybe that is the
problem, although I may made a simple mental error due to not having
enough coffee circulating through my brain yet.

Check just the LFO signal you are using to modulate the delay.  I think
you want something around 1Hz or 0.5Hz as a starting point.

-- 
Chris Caudle

1334329176.27787_0.ltw:2,a <7a40f252b9bb23c7c4d7ab6657129db9.squirrel at email dot powweb dot com>