posted 26 May 2003 16:38            

RotoryFlanger2.kym

Attached is a rotary flanger. Its based on the same principal as the rotary phaser posted some time ago. This is by using David's 90 deg phase shifter and the original signal (delayed to compensate). From this any phase shift can be extrapolated.

The flanger was always more powerful than the phaser and one of the reasons was the feedback which gave a richer notch filter. This gave me a problem when trying to make a rotary flanger. The problem was that the feedback needed to have the same rotating phase shift to create a moving notch filter, but the 90 deg phase shifter had it own quit long delay which meant it couldn't be used in the feedback path without making the feedback delay far too long for flanging.

This is how I got round it.

By using two delay lines one for the normal signal and one for the 90 deg signal, I could then produce any phase shift on there outputs (with no additional delay) by selectivly mixing these two signals. I could then feed this mixed signal back to the first delay line. I could then mix a second signal 90deg out of phase with the first mix and feed it back into the second delay line.

I think it works but I haven't yet been able to hear it correctly on this cappy 66. I can only hear a reduced bandwidth version which gives a strange bass down ward sound while the rest of the flanging rises. If anyone has a chance to test it I'd like to know if this full bandwidth version is same on a 320, or else I'll have to wait till I get to back to my 320 later in the week.

enjoy