Bizarre Flanger idea. Anyone think of this? Could it work?

[redeffect]

Anybody thought of putting a short delay/comb filter(1-10ms) in the Feedback loop of a flanger? Could it work? What would be the sonic ramifacations of doing this? I was going to try this; but first wanted some f'back on the concept first. Always looking to try something new/different, if you know what I mean... Thanx in advance...
red

[Mark Hammer]

In the same way that the location of the notches created by combining real-time and slightly delayed versions of a signal will depend on the amount of time lag between them, the accentuation of notches will change by virtue of the lag between what goes into the BBD and what comes out of it.  There is an outside chance it will make the higher regen settings less metallic sounding.

Of course, there is also a high chance that by having a separate delay with its own clock, you'll get heterodyning.

Perhaps the best place to start is by simply placing one or two fixed phase-shift stages (no fets required, just a fixed resistor) in the regen path.  You won't be time-shifting the entire spectrum but you'll be able to tell what happens when desynchrony between BBD-out and regen is increased.

Actually, now that I think of it, couldn't a person alter the "metallicness" of high regen settings at different points in the sweep by using allpass filters that have the cap to ground vs the cap between stages?  (one of these introduces more phase shfit as frequency goes lower, the other introduces more phase-shift as frequency goes higher).  That's an interesting prospect.

[redeffect]

Thanx Mark! How 'bout a clue as to implimenting the fixed resistor thing. (RC in series?) The APF idea sounds interesting. How about sweeping the APFs w/an LFO. I know; now i'm getting real weird. A phase shifter in the f'back of a flanger. They dont call me redeffect for nothing 
thanx, red

[gez]

Perhaps the best place to start is by simply placing one or two fixed phase-shift stages (no fets required, just a fixed resistor) in the regen path.  You won't be time-shifting the entire spectrum but you'll be able to tell what happens when desynchrony between BBD-out and regen is increased.

I suppose another way of looking at this is the regen is taken from the last stage of a phaser (minus the modulation) but the output taken from a previous stage.   Looking at it like this would make it 'easy' to mod a lot of phasers.

[Mark Hammer]

I'm reading, Gez, but I'm not clicking.  Explain a little more.

Redeffect,

For the moment, let's start small.  You could take a dual op-amp and plunk it on a daughter board with in/out/V+/gnd/Vref leads.  It "goes" between the regen amount pot and the spot where the regen signal and dry input to the BBD are normally mixed.

One op-amp serves as buffer to separate the allpass stage and the regen pot.  The other op-amp has 10k in the feedback loop, 10k going to the inverting input, and 39k plus a .01uf cap at the noninverting input.  If the cap goes to ground, then phase-shift is negligible above around 400hz and inceases below 400hz.  If the 39k resistor goes to grund, then phase-shift increases above 400hz.

As phase-shift is increased, it is sort of like adding time-delay, except that time delay imposed varies with frequency.  The naive prediction here is that if the cap went to ground, increasing the asynchrony of regen, that peaks and notches should be accentuated less as sweep goes low (i.e., towards the longest delay time in the sweep cycle).

An alternative is to have two allpass stages, one with cap to ground, and the other with resistor to ground, such that phase shift is more or less evenly distributed across the spectrum.  Taking the tankiness away at all points inthe sweep cycle.

I am hoping that Ton or Sebastian or Scott can confirm or deny that this might occur.

[gez]

I'm reading, Gez, but I'm not clicking. 

I'm barely clicking myself Mark, but if I've read you correctly you could adapt a 'standard' (is there such a thing?) phaser to do what you've suggested...sort of!

Think of a multi-stage phaser that you already possess, one with regen from its output.  Instead of taking the output to the mixer from the last stage, take it from an earlier one, 'disable' the modulation in all the stages after this and you pretty much have what you were suggesting...I think (brain pretty fried today)! 

[redeffect]

Cool. Think I'll start small. I'm going to cobble this thing up and give it a go. I will report whatever(?) happens as soon as I get a free moment to do it (job, wife, kid ,yardwork,ugh!) This might take some time; but I am determined to make it (something...) happen. Thanks for the input; and as always, more is welcome!
all the best.
red

[A.S.P.]

from a lost thread in one of the last forum-transitions on sept. 23rd `05:
(a thread, the search-function-friend won`t find: http://diystompboxes.com/sboxforum/viewtopic.php?t=37275)

...You can dial in tremendous amounts of feedback from either the Wet out or from a point within the Swept Phaser signal path, or none. The sonic mayhem that this pedal unleashes must be heard to be believed!

I'm not the kind of guy who buys pedals. Not at all. But I'd certainly buy this one again in a hurry. If you're really keen on modulation FX, the F****** H**x is one you don't want to miss. Whoever designed this thing is a menace to society - in a good way.

BTW, the PCB is labelled "Foxy Mistress!" Fun stuff.

Matt Farrow
_________________
Pharaoh Amplifiers

whenever you think you just invented something,
you`ll find out it has already been done...  

[redeffect]

Good "heads up" A.S.P. I really didnt think I'd "invented" anything. It was just an idea I wanted to "throw out there". I still think its worth a shot; and will report my findings. BTW, the orignal idea was to use a short delay/comb filter. The APF ideas came later. I will try both...
thanx!

[A.S.P.]

yes, sure I read the first post ~4 hrs ago...

too late for me to go to search for all those other questions...