phaser

[danial stocks]

But what about manual and resonance? Probably some filter is
>incorporated. Or some strong feedback path? Or are more delay lines
>neccesary?
>
In analog phaser, all pass filters are used. most usually use a fet 
controlled op amp arrangement, some - notably boss super phaser and 
electroharmonix small stone use transconductance op amps.. the OTA designs 
are MUCH easier to set up, and IMO offer better performance, nicer sound 
unless you run the fets ones at a high vtg.. the feedback is often applied 
over 3 stages of the phaser [in the usual 4 stage designs]altho there is 
nothing to really mean you couldn't do it differently, and usually takes the 
form of a fixed+variable res from the appropriate output feeding back into 
the first allpass stage. the manual control is usually a dc offset applied 
to the LFO waveform.. ie it sets the centre point the level of phase shift 
when the modulating waveform is at zero. most phasers have this as a preset 
trimpot inside the box, not accessible to users, but in a well designed 
phaser, it can have a good effect on the sound if you can adjust it,..
Cheers,
Dan
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