DSP Robotics Support

Hello!

I got interested in infinite rising/falling Flanger effects recently, so I decided to make one; the Quilcom BFP. The illusion is similar to the famous Shepard Tone, whereby a scale seems to ascend forever.

https://en.wikipedia.org/wiki/Shepard_tone

Since the BFP uses smooth rather than stepped changes, it’s actually more aligned to the “Shepard-Risset glissando”.

This is a flanging rather than a phasing effect, and it makes use of 4 flanger modules and a 4-phase LFO which controls the delays and cross-fading.

I’ve included a paper I found, which describes 3 methods, using either all-pass filters, frequency shifting or delay-based comb filters (which is what I used in the BFP).
Experimentally I found that using 4 flangers, rather than 2, gave more appealing results, to my ears anyway.

Here’s my YouTube video;

https://youtu.be/Sp2SjH80lVE

Download the BFP here:

https://www.dropbox.com/s/slxix8nngiuyv ... 3.zip?dl=0

It’s certainly another one-trick pony, but I hope you find a use for it sometime.

Comments always appreciated.

Cheers

Spogg

Ha Cool,

I was meaning to have a go at something like this this myself but you beat me to it. While checking it, it didnt make any sound with the latest beta and its because you are still using martins envelope code which has an error on line 53:

movaps xmm4,F0P001; mulps xmm4,xmm0; andps xmm4,fastRelease; addps xmm1,xmm41;

the last part should be "addps xmm1,xmm4;" there is no such thing as "xmm41". You should make sure you replace this in your toolbox for the future

Ooh, thanks Adam.

I was puzzled at first because there is no envelope generator in the BFP, but the one affected is in the test synth I included. I wasn’t aware of this error (only a similar one in Martin’s LFOs) so I’ve now updated my toolbox.
It’s great the way FS4 picks up these errors!

Cheers

Spogg

Yeah, when FS4 comes out I will be busted.

Even God makes mistakes Martin. Just think about wasps for example. What was He thinking?

I think the his biggest mistake was mosquitoes. I wish he could have just Ctrl+Z on those.

It may be a one-trick pony, but it's a very neat sounding trick! It may just be me, but it seems to have an interesting psychological effect - when it's rising, a big sense of something building, and even an impression of the tempo increasing; and the reverse when descending. I can imagine the upwards direction sounding great during the anticipatory break before a big bass-drop in a techno track, for example. And the animated barber-pole is the icing on the cake, of course!

Thanks for the paper, too. As it happens, I'm working on a project based around a quad frequency shifter, and I'm planning on adding the phase-locked "SyLFO" LFOs I posted a while ago - so in principle, a barber-pole mode would be eminently possible now that I've read the paper and seen your practical example.

Thank you so much trog!

It’s not just you who gets that odd feeling with the rise and fall. It was that weird auditory sensation that made me want to have a go.

When I was researching this I came upon a mention of something similar with an illusion of ever-rising/falling tempo. I didn’t pursue it because it was off-topic for my needs. But I was fascinated...

I have to confess that the most time-consuming part was that animation, so I’m glad you commented!

Cheers

Spogg

I'm surprised no one's mentioned Angelo Badalamenti's soundtrack from Twin Peaks, which used some Barberpole-ish sounds.