Modulated delay question


#1

Hi all,
I was thinking of trying to emulate this thing.
http://ofeuillerat.free.fr/documents/manuals/udstomp.pdf
Valhalla Ubermod is about the closest ( made with JUCE I think ).
In terms of the delay modulation
"Adding Modulation to the Delay Time causes the delay sound’s pitch to change. "
The values aren’t mentioned… As far as I can tell the “speed” refers to the frequency of the modulation. What sort of range should it be ? 1hz to 100hz modulation of say a sine wave ? The other question is how is the pitch being modulated ? PSOLA ? I assume it’s something simpler ? I wonder what PSOLA would sound like in a modulated delay has that been tried? That might sound fantastic …
I have been reading the DAFX book and getting confused. I thought of trying to start with some JUCE delay code that is floating around but it 's a big jump off the deep end. I think I just want to create 8 bands of panned delay with variable delay time 0-700 secs ( integer values bass on sample rate I guess ) , feedback somewhere between 0 and “infinite” ( perhaps floating values between 0 and 10 repeats would be sufficient ) and variable sine wave modulation between 0 hz and 100 hz ( again integer values based on the sample rate would probably be fine ) … Sean


#2

Hello !

You don’t need to overestimate the complexity of the concept :wink:

To get that pitch change with the modulation of delay time, you just need a delay line algorithm which handles fractional delay, allowing you to specify a float delay time in samples for every sample. Then, try different values for the modulation of that delay time (LFO rate + amount), and don’t forget to add smoothing in a way or another.

More information there :


#3

Thanks Ivan!!!
I read those articles. Hopefully one day I will understand it all better! :wink:
I am tempted to break out PYO and try a few delays modulated with PSOLA and an LFO as source of frequency change. It’s probably computationally expensive but I do wonder what it would sound like … Hopefully I will figure out how to modulate and resample a delay line with interpolation before I croak! Sean