PT2399 FLANGER / FLANGING DEMYSTIFIED

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Forced_Fire
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Post by Forced_Fire »

For your viewing pleasure:


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Post by briggs »

:applause: Sounds like flanging to me 8)
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Post by paparoni »

hi, do you have any schematic on this? thanks

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Post by puppiesonacid »

yeah... I can hear what you mean but its a little more than chorus, not quite enough for flange. gret work though, I have yet to delve and fully understand that end of the effects spectrum. I wish someone would put together a great book on just chorus, delay, flange and phase effects, how to construct them to your exacting tastes etc...



Very very cool bro, keep up the good work.


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Post by JiM »

In a book about playing guitar, i've found a small diagram explaining delay-based effects. It says :
  • From 0 to 7 ms, you can't hear a difference between dry and delayed signal
  • from 7 to 12 ms, phasing occurs
  • progressively from 12 to 20 ms, it becomes flanging
  • from 20 to 35 ms let's call it double-tracking. Add modulation to get chorus.
  • only about 40ms onward can we hear distinct echo
Is it over-simplified ? Of course this depends on the signal frequency.

What i understand from the video, is the two chips are used to get a difference of delay times in the flanger range, even if each one cannot provide such a short delay.
For example, let's set the first chip for 100ms delay, and the second one sweeping around 115ms. When mixed together, you get a 15ms flanging sound, globally delayed by 100ms. As long as you don't mix it with the dry signal, and provided you still can play in rhythm with the sound lagging 100ms behind your fingers, you've got flanging from a pair of PT2399.
Of course you'll want something smaller than 100ms, this was only for the example. :slap:
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Post by xerox »

JiM wrote:In a book about playing guitar, i've found a small diagram explaining delay-based effects. It says :
  • From 0 to 7 ms, you can't hear a difference between dry and delayed signal
  • from 7 to 12 ms, phasing occurs
  • progressively from 12 to 20 ms, it becomes flanging
  • from 20 to 35 ms let's call it double-tracking. Add modulation to get chorus.
  • only about 40ms onward can we hear distinct echo
Is it over-simplified ? Of course this depends on the signal frequency.
Depends on the bandwidth (or rather high frequency content) of the signal. You would definitely hear a difference if you mix two (identical) signals where one is delayed less than 7 ms. Already at 1 ms delay the lowest notch you would get would be at 500hz, which is definitely noticeable.

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Post by JiM »

I was just quoting that book, i did not check if it was the exact/accurate numbers ...

Anyway, you get the picture : with a dual PT2399 design one could get any modulation FX from phaser to chorus, or an echo effect with modulated repeats, or a dual-tap delay. And in true stereo if you want !

The only difficult part is the calibration of the delay times. I'm thinking of a dual pot for overall delay time of both chips, and another pot to add some more delay to one chip. And a trimpot to compensate tolerances. And some way to introduce modulation of the second delay time ... :scratch:

In the end, it might be simpler with some digital pots, and a small microcontroller like Arduino.

EDIT : looks like the modular synth guys have found some ways to get voltage-control over the delay time :
http://electro-music.com/forum/topic-13 ... highlight=
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