small stone Phaser

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Posts: 35
Joined: Mon Oct 13, 2014 6:57 am

small stone Phaser

Postby hlrf » Sat Sep 12, 2015 10:35 am

Gonna return the borrowed pedal so I try to recreate it with Bidule.

The Biquad Filter set to Allpass is equivalent to 2-stage phase shifter so two of them makes 4-stage.
Frequency range and Q as shawn.

There's a color switch on the pedal that introduces an additional feedback path, I didn't find a "right" method to do and just ignored it.

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Posts: 3436
Joined: Tue Apr 19, 2005 4:18 pm
Location: Oakland, California

Re: small stone Phaser

Postby jersmi » Sun Sep 13, 2015 3:13 pm

The biquad allpass works pretty well, interesting sound. Q adds a nice touch. Allpass 2 filter also does a nice job (more dramatic), both have their distinct character. (Btw, the original Allpass filter sounds bad imho because its delay time does not behave so well with LFO.)

Because of the phase shifting "notch" frequency concept, don't you need a separate filter for each "notch" stage? Here are two mods, I'll call them "4-stage" phase shifters, one with Allpass Filter 2, one with Biquads. No attempt at replicating existing pedals, just a bit of trial and error with the basic idea. Note how inversing the right side (and adding small delay) can really change the stereo field....
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Posts: 35
Joined: Mon Oct 13, 2014 6:57 am

Re: small stone Phaser

Postby hlrf » Tue Sep 22, 2015 10:58 am

I think notch is formed by the phase-shift of filter naturally, the official allpass and comb act like weird delays to me hehe, but comb2 is a delay workhorse; I'm new to filter stuffs but made an allpass function combo that works like I expected (an 1-stage phase-shift, 180 degree at higher freq.), the biquid is more efficient and variable though. (modulating Q is wonderful sounding)
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